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Sample records for advanced cataractous lenses

  1. Loss of Thiol Repair Systems in Human Cataractous Lenses

    PubMed Central

    Wei, Min; Xing, Kui-Yi; Fan, Yin-Chuan; Libondi, Teodosio; Lou, Marjorie F.

    2015-01-01

    Purpose. The purpose of this study was to investigate the thiol repair systems of thioltransferase (TTase) and thioredoxin (Trx) and oxidation-damaged proteins in human cataractous lenses. Methods. Cataractous lenses in humans (57–85 years of age) were classified into cortical, nuclear, mixed, mature, and hypermature cataract types by using a lens opacity classification system, and were obtained by extracapsular cataract extraction (ECCE) procedure. Cortical and nuclear cataracts were grouped by decreasing order of visual acuity into optical chart reading (R), counting fingers (CF), hand motion (HM), and light perception (LP). ECCE lens homogenate was analyzed for glutathione (GSH) level and enzyme activities of TTase, glutathione reductase (GR), Trx, and thioredoxin reductase (TR). Cortical and nuclear cataractous lenses (8 of each) with visual acuity better than HM were each dissected into cortical and nuclear portions for measurement of glyceraldehyde 3-phosphate dehydrogenase (G3PD) activity. Clear lenses (in humans 49–71 years of age) were used as control. Results. Compared with control, all cataractous lenses lost more than 80% GSH and 70% GR; TR and Trx activity; and 40% to 70% TTase activity, corroborated with the loss in visual acuity. Among cataracts with R and CF visual acuity, cortical cataract lost more cortical G3PD activity (18% of control) than that of nuclear cataract (50% of control), whereas GSH depletion and TTase inactivation were similar in both cataracts. Conclusions. Thiol repair systems were damaged in all types of cataracts. Cortical and nuclear cataracts showed differential G3PD inactivation in the cortex, implying those 2 type of cataracts might be formed through different mechanisms. PMID:25537203

  2. 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine) is a newly identified advanced glycation end product in cataractous and aged human lenses.

    PubMed

    Argirov, Ognyan K; Lin, Bin; Ortwerth, Beryl J

    2004-02-20

    Post-translational modifications of proteins take place during the aging of human lens. The present study describes a newly isolated glycation product of lysine, which was found in the human lens. Cataractous and aged human lenses were hydrolyzed and fractionated using reverse-phase and ion-exchange high performance liquid chromatography (HPLC). One of the nonproteinogenic amino acid components of the hydrolysates was identified as a 3-hydroxypyridinium derivative of lysine, 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine). The compound was synthesized independently from 3-hydroxypyridine and methyl 2-[(tert-butoxycarbonyl)amino]-6-iodohexanoate. The spectral and chromatographic properties of the synthetic OP-lysine and the substance isolated from hydrolyzed lenses were identical. HPLC analysis showed that the amounts of OP-lysine were higher in water-insoluble compared with water-soluble proteins and was higher in a pool of cataractous lenses compared with normal aged lenses, reaching 500 pmol/mg protein. The model incubations showed that an anaerobic reaction mixture of Nalpha-tert-butoxycarbonyllysine, glycolaldehyde, and glyceraldehyde could produce the Nalpha-t-butoxycarbonyl derivative of OP-lysine. The irradiation of OP-lysine with UVA under anaerobic conditions in the presence of ascorbate led to a photochemical bleaching of this compound. Our results argue that OP-lysine is a newly identified glycation product of lysine in the lens. It is a marker of aging and pathology of the lens, and its formation could be considered as a potential cataract risk-factor based on its concentration and its photochemical properties.

  3. [The Use of Polymers for Intraocular Lenses in Cataract Surgery].

    PubMed

    Fizia-Orlicz, Anna; Misiuk-Hojło, Marta

    2015-01-01

    According to the World Health Organization, cataract remains the leading cause of the curable visual impairment worldwide. Cataract can only be cured by surgery during which the cloudy lens is replaced with an artificial intraocular lens. It is one of the most common surgeries being performed worldwide. There are age-related, congenital, traumatic and metabolic types of cataract which have been distinguished. Age-related cataract is the most common one and it affects people over 60 with the greatest frequency. In reference to patients whose cornea does not fulfill the requirements for a standard refractive surgery, the number of refractive intraocular lens replacement is increasing. Manufacturers aim to enhance materials in order to minimize surgical complication while increasing the patient’s eyesight. The increase in average lifespan along with patients’ expectations stimulate competition among manufacturers who bring new products and solutions into to the market. There is an augmented demand for premium lenses such as toric, multifocal or accommodating. These lenses bring patients the promise of life without the need for wearing glasses. As far as the main materials used in the production of intraocular lens are concerned, there are hydrophobic, hydrophilic, acrylic and silicone lenses in use. In this paper the author discusses characteristics as well as advantages and disadvantages of the above-mentioned materials. The associated surgical complications and the new areas of development regarding the materials used in lenses manufacturing are also examined.

  4. Elemental distribution in frozen-hydrated rat lenses with galactose cataract

    SciTech Connect

    Koyama-Ito, H. )

    1990-01-01

    The elemental distributions in frozen-hydrated rat lenses with galactose cataract were compared before and after the onset of the nuclear cataract to investigate the possible role of ion levels in the lens opacification due to the phase separation of the lens cytoplasm. The maps of the weight concentrations of the minor elements, S, Cl, K and Ca, on the basis of wet weight in the central plane of lens were obtained by X-ray analysis with the high energy ion microprobe at a resolution of 50 microns. Before the onset of the nuclear cataract, the distributions of Cl and K, were almost normal, except in the lens posterior periphery with high Cl and low K. In the lens with the nuclear opacity, sudden changes were observed. The Cl increased throughout the lens, and K decreased throughout the lens except at lens anterior thin layer. However, the totalized monovalent ion level changed only slightly. The Ca level increased throughout the lens after the onset of the nuclear cataract, suggesting a possible role of Ca in the nuclear opacification of galactose cataract of rats. The distributions of S were similar to the protein density distributions previously known both in the normal and in the cataractous lenses.

  5. Cataract

    MedlinePlus

    ... version of this page please turn Javascript on. Cataract What Is a Cataract? Click for more information A Clouding of the ... cannot spread from one eye to the other. Cataracts and Aging Most cataracts are related to aging. ...

  6. Promoter demethylation of Keap1 gene in human diabetic cataractous lenses

    SciTech Connect

    Palsamy, Periyasamy; Ayaki, Masahiko; Elanchezhian, Rajan; Shinohara, Toshimichi

    2012-07-06

    Highlights: Black-Right-Pointing-Pointer We found significant Keap1 promoter demethylation in diabetic cataractous lenses. Black-Right-Pointing-Pointer Demethylation of Keap1 gene upregulated the expression of Keap1 mRNA and protein. Black-Right-Pointing-Pointer Elevated levels of Keap1 are known to decrease the levels of Nrf2. Black-Right-Pointing-Pointer Thereby, the levels of antioxidant enzymes are suppressed by decreased Nrf2 level. -- Abstract: Age-related cataracts (ARCs) are the major cause of visual impairments worldwide, and diabetic adults tend to have an earlier onset of ARCs. Although age is the strongest risk factor for cataracts, little is known how age plays a role in the development of ARCs. It is known that oxidative stress in the lens increases with age and more so in the lenses of diabetics. One of the central adaptive responses against the oxidative stresses is the activation of the nuclear transcriptional factor, NF-E2-related factor 2 (Nrf2), which then activates more than 20 different antioxidative enzymes. Kelch-like ECH associated protein 1 (Keap1) targets and binds to Nrf2 for proteosomal degradation. We hypothesized that hyperglycemia will lead to a dysfunction of the Nrf2-dependent antioxidative protection in the lens of diabetics. We studied the methylation status of the CpG islands in 15 clear and 21 diabetic cataractous lenses. Our results showed significant levels of demethylated DNA in the Keap1 promoter in the cataractous lenses from diabetic patients. In contrast, highly methylated DNA was found in the clear lens and tumorized human lens epithelial cell (HLEC) lines (SRA01/04). HLECs treated with a demethylation agent, 5-aza-2 Prime deoxycytidine (5-Aza), had a 10-fold higher levels of Keap1 mRNA, 3-fold increased levels of Keap1 protein, produced higher levels of ROS, and increased cell death. Our results indicated that demethylation of the CpG islands in the Keap1 promoter will activate the expression of Keap1 protein, which

  7. Melatonin Reduces Cataract Formation and Aldose Reductase Activity in Lenses of Streptozotocin-induced Diabetic Rat

    PubMed Central

    Khorsand, Marjan; Akmali, Masoumeh; Sharzad, Sahab; Beheshtitabar, Mojtaba

    2016-01-01

    Background: The relationship between the high activity of aldose reductase (AR) and diabetic cataract formation has been previously investigated. The purpose of the present study was to determine the preventing effect of melatonin on streptozotocin (STZ)-induced diabetic cataract in rats. Methods: 34 adult healthy male Sprague-Dawely rats were divided into four groups. Diabetic control and diabetic+melatonin received a single dose of STZ (50 mg/kg, intraperitoneally), whereas the normal control and normal+melatonin received vehicle. The melatonin groups were gavaged with melatonin (5 mg/kg) daily for a period of 8 weeks, whereas the rats in the normal control and diabetic control groups received only the vehicle. The rats’ eyes were examined every week and cataract formation scores (0-4) were determined by slit-lamp microscope. At the end of the eighth week, the rats were sacrificed and markers of the polyol pathway and antioxidative (Glutathione, GSH) in their lens were determined. The levels of blood glucose, HbA1c and plasma malondialdhyde (MDA), as a marker of lipid peroxidation, were also measured. Results: Melatonin prevented STZ-induced hyperglycemia by decreased blood glucose and HbA1c levels. Slit lamp examination indicated that melatonin delayed cataract progression in diabetic rats. The results revealed that melatonin feeding increased the GSH levels, decreased the activities of AR and sorbitol dehydrogenase (SDH) and sorbitol formation in catractous lenses as well as plasma MDA content. Conclusion: In summary, for the first time we demonstrated that melatonin delayed the formation and progression of cataract in diabetic rat lenses. PMID:27365552

  8. Unilateral Scleral Fixation of Posterior Chamber Intraocular Lenses in Pediatric Complicated Traumatic Cataracts

    PubMed Central

    Hyun, Dong Won; Cho, Sung Won

    2009-01-01

    Purpose The purpose of this study was to evaluate the visual outcomes and complications of unilateral scleral fixation of posterior chamber intraocular lenses (SF-PCIOLs) in pediatric complicated traumatic cataracts without capsular support. Methods This study involved five eyes of five children who underwent unilateral SF-PCIOL. All patients had a unilateral complicated traumatic cataract associated with anterior or posterior segment injury. Visual acuity (VA), IOL position, and postoperative complications were assessed during follow-up. Results The mean age of patients at the time of SF-PCIOL was 90 months (range, 66-115). The mean duration of follow-up time after surgery was 22 months (range, 5-55). In all patients, the best-corrected VA was either improved or was stable at last follow-up following SF-PCIOL implantation. There were no serious complications. Conclusions Unilateral scleral fixation of PCIOL can be a safe and effective procedure for pediatric, unilateral, complicated traumatic cataracts without capsular support in selected cases. PMID:19794939

  9. Emerging Technology in Refractive Cataract Surgery

    PubMed Central

    Saraiva, João; Neatrour, Kristin; Waring IV, George O.

    2016-01-01

    Technology in cataract surgery is constantly evolving to meet the goals of both surgeons and patients. Recent major advances in refractive cataract surgery include innovations in preoperative and intraoperative diagnostics, femtosecond laser-assisted cataract surgery (FLACS), and a new generation of intraocular lenses (IOLs). This paper presents the latest technologies in each of these major categories and discusses how these contributions serve to improve cataract surgery outcomes in a safe, effective, and predictable manner. PMID:27433353

  10. Clinical and experimental advances in congenital and paediatric cataracts

    PubMed Central

    Churchill, Amanda; Graw, Jochen

    2011-01-01

    Cataracts (opacities of the lens) are frequent in the elderly, but rare in paediatric practice. Congenital cataracts (in industrialized countries) are mainly caused by mutations affecting lens development. Much of our knowledge about the underlying mechanisms of cataractogenesis has come from the genetic analysis of affected families: there are contributions from genes coding for transcription factors (such as FoxE3, Maf, Pitx3) and structural proteins such as crystallins or connexins. In addition, there are contributions from enzymes affecting sugar pathways (particularly the galactose pathway) and from a quite unexpected area: axon guidance molecules like ephrins and their receptors. Cataractous mouse lenses can be identified easily by visual inspection, and a remarkable number of mutant lines have now been characterized. Generally, most of the mouse mutants show a similar phenotype to their human counterparts; however, there are some remarkable differences. It should be noted that many mutations affect genes that are expressed not only in the lens, but also in tissues and organs outside the eye. There is increasing evidence for pleiotropic effects of these genes, and increasing consideration that cataracts may act as early and readily detectable biomarkers for a number of systemic syndromes. PMID:21402583

  11. Cataract

    MedlinePlus

    ... Colors that seem faded Glare - headlights, lamps or sunlight may seem too bright. You may also see ... a hat with a brim to block ultraviolet sunlight may help to delay cataracts. NIH: National Eye ...

  12. Couching for cataract: advanced medical achievements of China in 1976?

    PubMed

    Fan, Ka-wai

    2011-01-01

    Cataracts have been a common disease in China for centuries. As early as the Tang dynasty, physicians of Chinese medicine had developed 'jin pi shu', a method of couching, to cure the disease. In 1976, a new method, invented by Tang Youzhi, was acknowledged as one of the most advanced medical achievements in communist China. This paper explores the significance of Tang's method for Mao Zedong's China. Tang's method achieved two goals set by Chairman Mao for medical and health policies: to serve rural China and to integrate Chinese and Western medicine.

  13. The Cataract-linked Mutant Connexin50D47A Causes Endoplasmic Reticulum Stress in Mouse Lenses.

    PubMed

    Berthoud, Viviana M; Minogue, Peter J; Lambert, Paul A; Snabb, Joseph I; Beyer, Eric C

    2016-08-19

    Mice expressing connexin50D47A (Cx50D47A) exhibit nuclear cataracts and impaired differentiation. Cx50D47A does not traffic properly, and homozygous mutant lenses show increased levels of the stress-responsive αB-crystallins. Therefore, we assessed whether expression of Cx50D47A led to endoplasmic reticulum (ER) stress in the lens in vivo Although pharmacologic induction of ER stress can be transduced by three different pathways, we found no evidence for activation of the IRE1α or ATF6 pathways in Cx50D47A-expressing lenses. In contrast, heterozygous and homozygous Cx50D47A lenses showed an increase in phosphorylated PERK immunoreactivity and in the ratio of phosphorylated to total EIF2α (2.4- and 3.3-fold, respectively) compared with wild type. Levels of ATF4 were similar in wild type and heterozygous lenses but elevated in homozygotes (391%). In both heterozygotes and homozygotes, levels of calreticulin protein were increased (184 and 262%, respectively), as was Chop mRNA (1.9- and 12.4-fold, respectively). CHOP protein was increased in homozygotes (384%). TUNEL staining was increased in Cx50D47A lenses, especially in homozygous mice. Levels of two factors that may be pro-survival, Irs2 and Trib3, were greatly increased in homozygous lenses. These results suggest that expression of Cx50D47A induces ER stress, triggering activation of the PERK-ATF4 pathway, which potentially contributes to the lens pathology and leads to increased expression of anti-apoptotic factors, allowing cell survival.

  14. Quantitative proteomics analysis with iTRAQ in human lenses with nuclear cataracts of different axial lengths

    PubMed Central

    Zhou, Haiyan; Yan, Weijia; Wang, Xinchuan; Ma, Yong; Wang, Jianping

    2016-01-01

    Purpose The goal of this study was to identify and quantify the differentially expressed proteins in human nuclear cataract with different axial lengths. Methods Thirty-six samples of human lens nuclei with hardness grade III or IV were obtained during cataract surgery with extracapsular cataract extraction (ECCE). Six healthy transparent human lens nuclei were obtained from fresh healthy cadaver eyes during corneal transplantation surgery. The lens nuclei were divided into seven groups (six lenses in each group) according to the optic axis: Group A (mean axial length 28.7±1.5 mm; average age 59.8±1.9 years), Group B (mean axial length 23.0±0.4 mm; average age 60.3±2.5 years), Group C (mean axial length 19.9±0.5 mm; average age 55.1±2.5 years), Group D (mean axial length 28.7±1.4 mm; average age 58.0±4.0 years), Group E (mean axial length 23.0±0.3 mm; average age 56.9±4.2 years), and Group F (mean axial length 20.7±0.6 mm; average age 57.6±5.3 years). The six healthy transparent human lenses were included in a younger group with standard optic axes, Group G (mean axial length 23.0±0.5 mm; average age 34.7±4.2 years).Water-soluble, water-insoluble, and water-insoluble–urea-soluble protein fractions were extracted from the samples. The three-part protein fractions from the individual lenses were combined to form the total proteins of each sample. The proteomic profiles of each group were analyzed using 8-plex isobaric tagging for relative and absolute protein quantification (iTRAQ) labeling combined with two-dimensional liquid chromatography tandem mass spectrometry (2D-LC-MS/MS). The data were analyzed with ProteinPilot software for peptide matching, protein identification, and quantification. Differentially expressed proteins were validated with western blotting. Results We employed biological and technical replicates and selected the intersection of the two sets of results, which included 40 proteins. From the 40 proteins identified, six were

  15. [Indications for cataract surgery].

    PubMed

    Gloor, B

    1982-09-01

    Progress in surgical methods and advances in the correction of aphakia with contact lenses or intraocular lenses on the one hand, and the greater demands made by patients on the other are the reasons why the cataract surgery is indicated much earlier today than 20 years ago. Occupational considerations and the visual acuity required to keep a driver's licence may be determining factors in the timing of surgery and the choice of one or the other methods o correcting aphakia. To advise the patient correctly, an accurate preoperative assessment of the visual function which can be expected postoperatively has be made. Of the preoperative examinations, results with the test wih the Moiré pattern following Lotmar are mentioned. If the patient's occupation places high demands on visual acuity, as e.g. for bus drivers - 1.0 on the better and 0.8 on the second eye - it seems less risky to go for a contact lens than for an intraocular lens (cystoid macular edema!). Advantages and disadvantages and the special indications and contraindications of correction with cataract glasses, with contact lenses or with different types of intraocular lenses are tabulated. The mathematical conditions which sampling statistics and the success rates of different types of intraocular lenses and surgical procedures have to fulfill, such as extracapsular versus intracapsular cataract extraction, are explained in order to provide a basis of knowledge rather than merely belief. Finally, the indications for different types of surgery in special situations and with different forms of cataract are described, e.g. phakolytic glaucoma, subluxation and luxation of the lens and congenital cataracts.

  16. Age-related changes in the kinetics of human lenses: prevention of the cataract

    PubMed Central

    Pescosolido, Nicola; Barbato, Andrea; Giannotti, Rossella; Komaiha, Chiara; Lenarduzzi, Fiammetta

    2016-01-01

    The crystalline lens is a transparent, biconvex structure in the eye that, along with the cornea, helps to refract light to be focused on the retina and, by changing shape, it adjusts focal distance (accommodation). The three classes of structural proteins found in the lens are α, β, and γ crystallins. These proteins make up more than 90% of the total dry mass of the eye lens. Other components which can be found are sugars, lipids, water, several antioxidants and low weight molecules. When ageing changes occur in the lens, it causes a gradual reduction in transparency, presbyopia and an increase in the scattering and aberration of light waves as well as a degradation of the optical quality of the eye. The main changes that occur with aging are: 1) reduced diffusion of water from the outside to the inside of the lens and from its cortical to its nuclear zone; 2) crystalline change due to the accumulation of high molecular weight aggregates and insoluble proteins; 3) production of advanced glycation end products (AGEs), lipid accumulation, reduction of reduced glutathione content and destruction of ascorbic acid. Even if effective strategies in preventing cataract onset are not already known, good results have been reached in some cases with oral administration of antioxidant substances such as caffeine, pyruvic acid, epigallocatechin gallate (EGCG), α-lipoic acid and ascorbic acid. Furthermore, methionine sulfoxide reductase A (MSRA) over expression could protect lens cells both in presence and in absence of oxidative stress-induced damage. Nevertheless, promising results have been obtained by reducing ultraviolet-induced oxidative damage. PMID:27803872

  17. Use of intraocular lenses in children with traumatic cataract in south India

    PubMed Central

    Eckstein, M.; Vijayalakshmi, P; Killedar, M.; Gilbert, C.; Foster, A.

    1998-01-01

    AIMS—To assess the long term results of intraocular lens (IOL) implantation for traumatic cataract in young children in a developing country.
METHODS—Prospective hospital based study of 52 children (age 2-10 years) undergoing unilateral cataract extraction and IOL insertion for traumatic cataract performed by a single surgeon in south India. Children were reviewed regularly and followed up initially for 3 years.
RESULTS—There were no serious operative complications. Clinically significant posterior capsule opacification was almost universal (92%) and YAG capsulotomy or membranectomy was performed on 48 eyes. Some degree of pupil capture affected 35% of eyes and was complete in 6%. Visual acuity was 6/12 or better in 67% of eyes at the last follow up examination.
CONCLUSION—The visual acuity results 3 years after implantation of posterior chamber IOLs in older children with traumatic cataracts in south India were encouraging. In developing countries where follow up is unreliable it is essential to plan to clear the axial part of the posterior capsule either at the time of surgery or soon afterwards.

 Keywords: intraocular lens; children; cataract; India PMID:9828776

  18. Properties of membranes derived from the total lipids extracted from clear and cataractous lenses of 61–70-year-old human donors

    PubMed Central

    Mainali, Laxman; Raguz, Marija; O'Brien, William J.; Subczynski, Witold K.

    2015-01-01

    Human lens-lipid membranes prepared from the total lipids extracted from clear and cataractous lens cortexes and nuclei of 61–70-year-old donors by use of a rapid solvent-exchange method were investigated. The measured cholesterol-to-phospholipid (Chol/PL) molar ratio in these membranes was 1.8 and 4.4 for cortex and nucleus of clear lenses, respectively, and 1.14 and 1.45 for cataractous lenses. Properties and organization of the lipid bilayer were investigated by use of electron paramagnetic resonance spin-labeling methods. Formation of Chol crystals was confirmed by use of differential scanning calorimetry. Pure cholesterol bilayer domains (CBDs) were formed in all the membranes investigated. It was shown that in clear lens membranes of the nucleus, Chol exists in three different environments: (1) dispersed in phospholipid bilayers (PCDs), (2) in CBDs, and (3) in Chol crystals. In clear lens membranes of the cortex, and in cortical and nuclear cataractous lens membranes, Chol crystals were not detected, because of the lower Chol content. Profiles of membrane properties (alkyl-chain order, fluidity, oxygen transport, and hydrophobicity) across the PCD were very similar for clear and cataractous membranes. Profiles of the oxygen transport parameter across the CBD were, however, different for cortical clear and cataractous membranes—the amount and size of CBDs was less in cataractous membranes. These results suggest that high Chol content, formation of CBDs, and formation of Chol crystals should not be regarded as major predispositions for the development of age-related cataracts. PMID:25502634

  19. Advances in the management of congenital and infantile cataract.

    PubMed

    Lloyd, I C; Ashworth, J; Biswas, S; Abadi, R V

    2007-10-01

    Congenital and infantile cataracts produce deprivation amblyopia and can thus cause lifelong visual impairment. Successful management is dependent on early diagnosis and referral for surgery when indicated. Accurate optical rehabilitation and postoperative supervision are essential.The timing of surgery and its relationship to the duration of deprivation is important. Unilateral congenital cataract surgery within 6 weeks of birth produces the best outcomes. The equivalent 'latent' period for bilateral visual deprivation may be longer at around 10 weeks. Visual deprivation has a significant impact on the development of fixation stability. Major form deprivation, even after early surgery, leads to nystagmus. This is mostly manifest latent nystagmus (MLN). The latent period for fixation stability may be as short as 3 weeks. Preoperative congenital nystagmus (CN) can convert to more benign MLN after surgery. Infantile IOL implantation is becoming increasingly accepted. A satisfactory long-term refractive result requires that allowance be made for childhood axial growth and myopic shift. In a series of 25 infants (33 eyes) implanted before 12 months of age, the mean myopic shift at 12 months was 4.83 D. This increased to 5.3 D in infants implanted before 10 weeks. The initial desired refractive outcome following IOL implantation is thus hypermetropia, with the degree dependent on the age of the child. Glaucoma or ocular hypertension is a common complication following paediatric cataract surgery. Microphthalmia and surgery in early infancy are risk factors. Tonometry results may be influenced by the increased corneal thickness seen in aphakic and pseudophakic children. The long-term prognosis of eyes with aphakic glaucoma is not necessarily poor but intraocular pressure control may require three or more medications. Surgical intervention appears to be necessary in over a quarter of eyes. Posterior capsule opacification (PCO) is common in infants undergoing primary lens

  20. Serious Adverse Events After Cataract Surgery

    PubMed Central

    Stein, Joshua D.

    2013-01-01

    Purpose Over the past several decades there have been many advances in the equipment, instrumentation and techniques of performing cataract surgery. This review will address the impact of these advances on the safety profile of cataract surgery. Recent Findings Recent studies have demonstrated a decline in the risk of serious postoperative adverse events (endophthalmitis, suprachoroidal hemorrhage, retinal detachment) following cataract surgery. Factors that increase the risk of serious complications from cataract surgery include patient-related factors (male sex, concomitant diabetic retinopathy, same day cataract surgery combined with another intraocular surgery, tamsulosin use) and surgeon-related factors (low surgical volume, limited experience, operating on patients who are most prone to adverse events). Summary Cataract surgery continues to be a very safe surgical procedure with few patients experiencing serious sight-threatening adverse events. Studies in the literature have helped surgeons identify patients who are at high risk for surgical complications and to develop strategies to limit surgical complications when operating on these patients. As multifocal intraocular lenses, femtosecond laser technology, and other surgical innovations continue to gain popularity, it will be interesting in the coming years to determine whether there will be a continued reduction in complications of cataract surgery. PMID:22450221

  1. Advanced manual lensometry: a self-learning guide for evaluating multifocal and specialty lenses, progressive lenses, prisms, and rigid contact lenses.

    PubMed

    Garber, N

    2000-01-01

    Advanced manual lensometry techniques are required when automated lensometry may not be appropriate for reading special lenses or rigid contact lenses. These advanced techniques are challenging but provide accurate diagnostic and lens verification data. One should never assume that the glasses the patient is wearing match what the doctor prescribed. The prescription should be checked at least once, even when there are no patient complaints. If possible, learn and practice these special procedures under the supervision of an optician or ophthalmic clinical trainer. This will help to verify that you are performing these special techniques correctly.

  2. Using ultrasound backscattering signals and Nakagami statistical distribution to assess regional cataract hardness.

    PubMed

    Caixinha, Miguel; Jesus, Danilo A; Velte, Elena; Santos, Mário J; Santos, Jaime B

    2014-12-01

    This study aims to analyze the protein aggregates spatial distribution for different cataract degrees, and correlate this information with the lens acoustical parameters and by this way, assess the cataract regional hardness. Different cataract degrees were induced ex vivo in porcine lenses. A 25 MHz ultrasonic transducer was used to obtain the acoustical parameters (velocity, attenuation, and backscattering signals). B-scan and Nakagami images were constructed. Also, lenses with different cataract degrees were sliced in two regions (nucleus and cortex), for fibers and collagen detection. A significant increase with cataract formation was found for the velocity, attenuation, and brightness intensity of the B-scan images and Nakagami m parameter ( ). The acoustical parameters showed a good to moderate correlation with the m parameter for the different stages of cataract formation. A strong correlation was found between the protein aggregates in the cortex and the m parameter. Lenses without cataract are characterized using a classification and regression tree, by a mean brightness intensity ≤0.351, a variance of the B-scan brightness intensity ≤0.070, a velocity ≤1625 m/s, and an attenuation ≤0.415 dB/mm·MHz (sensitivity: 100% and specificity: 72.6%). To characterize different cataract degrees, the m parameter should be considered. Initial stages of cataract are characterized by a mean brightness intensity >0.351 and a variance of the m parameter >0.110. Advanced stages of cataract are characterized by a mean brightness intensity >0.351, a variance of the m parameter ≤0.110, and a mean m parameter >0.374. For initial and advanced stages of cataract, a sensitivity of 78.4% and a specificity of 86.5% are obtained.

  3. [Contribution of contact lenses to the reduction of aniseikonia in myopic patients after unilateral cataract operations (author's transl)].

    PubMed

    Kreis-Gosselin, F; Prevost, G; Bonnac, P

    1981-01-01

    The most rapid method for determining the best mode of optical compensation in myopic patients following cataract operations was studied, by employing a graphic method for calculating theoretical aniseikonia and measuring subjective aniseikonia with a new stereo-projector. Several examples of the method chosen are given, this involving optical equipment--glasses, lens, myopisation--aniseikonia being reduced to a maximum.

  4. Increased levels of advanced glycation endproducts in the lenses and blood vessels of cigarette smokers.

    PubMed Central

    Nicholl, I. D.; Stitt, A. W.; Moore, J. E.; Ritchie, A. J.; Archer, D. B.; Bucala, R.

    1998-01-01

    BACKGROUND: Advanced glycation endproducts (AGEs) arise from the spontaneous reaction of reducing sugars with the amino groups of macromolecules. AGEs accumulate in tissue as a consequence of diabetes and aging and have been causally implicated in the pathogenesis of several of the end-organ complications of diabetes and aging, including cataract, atherosclerosis, and renal insufficiency. It has been recently proposed that components in mainstream cigarette smoke can react with plasma and extracellular matrix proteins to form covalent adducts with many of the properties of AGEs. We wished to ascertain whether AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers. MATERIALS AND METHODS: Lens and coronary artery specimens from nondiabetic smokers and nondiabetic nonsmokers were examined by immunohistochemistry, immunoelectron microscopy, and ELISA employing several distinct anti-AGE antibodies. In addition, lenticular extracts were tested for AGE-associated fluorescence by fluorescence spectroscopy. RESULTS: Immunoreactive AGEs were present at significantly higher levels in the lenses and lenticular extracts of nondiabetic smokers (p < 0.003). Anti-AGE immunogold staining was diffusely distributed throughout lens fiber cells. AGE-associated fluorescence was significantly increased in the lenticular extracts of nondiabetic smokers (p = 0.005). AGE-immunoreactivity was significantly elevated in coronary arteries from nondiabetic smokers compared with nondiabetic nonsmokers (p = 0.015). CONCLUSIONS: AGEs or immunochemically related molecules are present at higher levels in the tissues of smokers than in nonsmokers, irrespective of diabetes. In view of previous reports implicating AGEs in a causal association with numerous pathologies, these findings have significant ramifications for understanding the etiopathology of diseases associated with smoking, the single greatest preventable cause of morbidity and mortality in the

  5. Cost-Utility Analyses of Cataract Surgery in Advanced Age-Related Macular Degeneration

    PubMed Central

    Ma, Yingyan; Huang, Jiannan; Zhu, Bijun; Sun, Qian; Miao, Yuyu; Zou, Haidong

    2016-01-01

    ABSTRACT Purpose To explore the cost-utility of cataract surgery in patients with advanced age-related macular degeneration (AMD). Methods Patients who were diagnosed as having and treated for age-related cataract and with a history of advanced AMD at the Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University, were included in the study. All of the participants underwent successful phacoemulsification with foldable posterior chamber intraocular lens implantation under retrobulbar anesthesia. Best-corrected visual acuity (BCVA) and utility value elicited by time trade-off method from patients at 3-month postoperative time were compared with those before surgery. Quality-adjusted life years (QALYs) gained in a lifetime were calculated at a 3% annual discounted rate. Costs per QALY gained were calculated using the bootstrap method, and probabilities of being cost-effective were presented using a cost-effectiveness acceptability curve. Sensitivity analyses were performed to test the robustness of the results. Results Mean logarithm of the minimum angle of resolution BCVA in the operated eye increased from 1.37 ± 0.5 (Snellen, 20/469) to 0.98 ± 0.25 (Snellen, 20/191) (p < 0.001); BCVA in the weighted average from both eyes (=75% better eye + 25% worse eye) was changed from 1.13 ± 0.22 (Snellen, 20/270) to 0.96 ± 0.17 (Snellen, 20/182) (p < 0.001). Utility values from both patients and doctors increased significantly after surgery (p < 0.001 and p = 0.007). Patients gained 1.17 QALYs by cataract surgery in their lifetime. The cost per QALY was 8835 Chinese yuan (CNY) (1400 U.S. dollars [USD]). It is cost-effective at the threshold of 115,062 CNY (18,235 USD) per QALY in China recommended by the World Health Organization. The cost per QALY varied from 7045 CNY (1116 USD) to 94,178 CNY (14,925 USD) in sensitivity analyses. Conclusions Visual acuity and quality of life assessed by utility value improved significantly after surgery

  6. Cataract (image)

    MedlinePlus

    A cataract is a cloudy or opaque area in the lens of the eye. Cataracts usually develop as a person gets older and ... substances can also accelerate the development of a cataract. Cataracts can cause visual problems such as difficulty ...

  7. Feasibility study of using high-frequency ultrasonic Nakagami imaging for characterizing the cataract lens in vitro.

    PubMed

    Tsui, Po-Hsiang; Huang, Chih-Chung; Chang, Chien-Cheng; Wang, Shyh-Hau; Shung, K Kirk

    2007-11-07

    A cataract is a clouding of the crystalline lens that reduces the amount of incoming light and impairs visual perception. Phacoemulsification is the most common surgical method for treating advanced cataracts, and determining the optimal phacoemulsification energy is dependent on measuring the hardness of the lens. This study explored the feasibility of using an ultrasonic parametric image based on the Nakagami distribution to quantify the lens hardness. Young's modulus was measured in porcine lenses in which cataracts had been artificially induced. High-frequency ultrasound at 35 MHz was used to obtain the B-mode and Nakagami images of the cataract lenses. The averaged integrated backscatter and Nakagami parameters were also estimated in the region of interest. The experimental results show that the conventional B-scan and integrated backscatter are inadequate for quantifying the lens hardness, whereas Nakagami imaging allows different degrees of lens hardening to be distinguished both globally and locally based on the concentration of fiber coemption therein.

  8. Feasibility study of using high-frequency ultrasonic Nakagami imaging for characterizing the cataract lens in vitro

    NASA Astrophysics Data System (ADS)

    Tsui, Po-Hsiang; Huang, Chih-Chung; Chang, Chien-Cheng; Wang, Shyh-Hau; Shung, K. Kirk

    2007-11-01

    A cataract is a clouding of the crystalline lens that reduces the amount of incoming light and impairs visual perception. Phacoemulsification is the most common surgical method for treating advanced cataracts, and determining the optimal phacoemulsification energy is dependent on measuring the hardness of the lens. This study explored the feasibility of using an ultrasonic parametric image based on the Nakagami distribution to quantify the lens hardness. Young's modulus was measured in porcine lenses in which cataracts had been artificially induced. High-frequency ultrasound at 35 MHz was used to obtain the B-mode and Nakagami images of the cataract lenses. The averaged integrated backscatter and Nakagami parameters were also estimated in the region of interest. The experimental results show that the conventional B-scan and integrated backscatter are inadequate for quantifying the lens hardness, whereas Nakagami imaging allows different degrees of lens hardening to be distinguished both globally and locally based on the concentration of fiber coemption therein.

  9. Management of cataracts in infancy and childhood.

    PubMed

    Davies, P D; Tarbuck, D T

    1977-04-01

    In recent years there has been a considerable improvement in our understanding of the mechanism of stimulus deprivation amblyopia and a continuous development of better surgical techniques for the removal of cataracts in very young patients. In spite of these advances and the fact that modern constant wear soft contact lenses are now a reliable proposition, there has not been a parallel improvement in the visual results achieved after cataract extraction and aphakia continues to present considerable problems of management in children. This study analyses over 100 cases treated at Moorfields Eye Hospital in recent years. As a result of our findings a Paediatric Aphakia Service has been established in order to integrate the surgical, contact lens, and orthoptic care of these patients.

  10. Cataracts and macular degeneration.

    PubMed

    Shoch, D

    1979-09-01

    The intraocular lens restores general vision and some degree of independence and mobility to patients with dense cataracts and macular degeneration. The patient, however, must be repeatedly warned that fine central vision, particularly reading, will not be possible after the surgery. An aphakic spectacle leaves such patients a narrow band of vision when superimposed over the macular lesion, and contact lenses are too small for the patient to manage insertion without help.

  11. Congenital cataract

    MedlinePlus

    ... Congenital and inherited cataracts. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology . 16th ed. Philadelphia, PA: Lippincott ... Cataracts and systemic disease. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology . 16th ed. Philadelphia, PA: Lippincott ...

  12. A rapid, comprehensive liquid chromatography-mass spectrometry (LC-MS)-based survey of the Asp isomers in crystallins from human cataract lenses.

    PubMed

    Fujii, Norihiko; Sakaue, Hiroaki; Sasaki, Hiroshi; Fujii, Noriko

    2012-11-16

    Cataracts are caused by clouding of the eye lens and may lead to partial or total loss of vision. The mechanism of cataract development, however, is not well understood. It is thought that abnormal aggregates of lens proteins form with age, causing loss of lens clarity and development of the cataract. Lens proteins are composed of soluble α-, β-, and γ-crystallins, and as long lived proteins, they undergo post-translational modifications including isomerization, deamidation, and oxidation, which induce insolubilization, aggregation, and loss of function that may lead to cataracts. Therefore, analysis of post-translational modifications of individual amino acid residues in proteins is important. However, detection of the optical isomers of amino acids formed in these proteins is difficult because optical resolution is only achieved using complex methodology. In this study, we describe a new method for the analysis of isomerization of individual Asp residues in proteins using LC-MS and the corresponding synthetic peptides containing the Asp isomers. This makes it possible to analyze isomers of Asp residues in proteins precisely and quickly. We demonstrate that Asp-58, -76, -84, and -151 of αA-crystallin and Asp-62 and -96 of αB-crystallin are highly converted to lβ-, dβ-, and dα-isomers. The amount of isomerization of Asp is greater in the insoluble fraction at all Asp sites in lens proteins, therefore indicating that isomerization of these Asp residues affects the higher order structure of the proteins and contributes to the increase in aggregation, insolubilization, and disruption of function of proteins in the lens, leading to the cataract.

  13. [History of cataract operations in Hungary].

    PubMed

    Marsovszky, László

    2013-11-10

    The history of the cataract operations dates back to thousands of years ago. Initially, surgery was carried out using rudimentary operating techniques resulting in the loss of many eyes. Cataract surgery has evolved immersely and now it is a highly refined surgical practice. Evolution of the cataract surgery was closely linked to broadening of anatomical-pathological knowledge and to the development of the instruments applied. Although Daviel performed the first intentional cataract removal in 1747, almost one hundred years passed before the extracapsular cataract extraction method finally replaced the old couching technique. By the middle of the 20th century, with the progression of the operation techniques and instruments, different forms of intracapsular cataract extraction methods became prevalent. Introduction and widespread use of the artificial intraocular lenses from the second half of the 20th century led to the rediscovery and further perfection of the extracapsular cataract extraction technique. Today, phacoemulsification through small incision, along with the foldable intraocular lenses is the gold standard of cataract surgery. The aim of this study is to present the different cataract surgery methods applied throughout the centuries, as well as the difficulties encountered. It discusses pioneering steps of each era, in order to give a closer look at the most frequently performed surgical intervention in ophthalmology.

  14. Propolis, a Constituent of Honey, Inhibits the Development of Sugar Cataracts and High-Glucose-Induced Reactive Oxygen Species in Rat Lenses

    PubMed Central

    Shibata, Teppei; Shibata, Shinsuke; Shibata, Naoko; Kiyokawa, Etsuko; Singh, Dhirendra P.

    2016-01-01

    Purpose. This study investigated the effects of oral propolis on the progression of galactose-induced sugar cataracts in rats and the in vitro effects of propolis on high-glucose-induced reactive oxygen species (ROS) and cell death in cultured rat lens cells (RLECs). Methods. Galactose-fed rats and RLECs cultured in high glucose (55 mM) medium were treated with propolis or vehicle control. Relative lens opacity was assessed by densitometry and changes in lens morphology by histochemical analysis. Intracellular ROS levels and cell viability were measured. Results. Oral administration of propolis significantly inhibited the onset and progression of cataract in 15% and 25% of galactose-fed rats, respectively. RLECs cultured with high glucose showed a significant increase in ROS expression with reduced cell viability. Treatment of these RLECs with 5 and 50 μg/mL propolis cultured significantly reduced ROS levels and increased cell viability, indicating that the antioxidant activity of propolis protected cells against ROS-induced damage. Conclusion. Propolis significantly inhibited the onset and progression of sugar cataract in rats and mitigated high-glucose-induced ROS production and cell death. These effects may be associated with the ability of propolis to inhibit hyperglycemia-evoked oxidative or osmotic stress-induced cellular insults. PMID:27242920

  15. Absence of beta-amyloid in cortical cataracts of donors with and without Alzheimer's disease.

    PubMed

    Michael, Ralph; Rosandić, Jurja; Montenegro, Gustavo A; Lobato, Elvira; Tresserra, Francisco; Barraquer, Rafael I; Vrensen, Gijs F J M

    2013-01-01

    Eye lenses from human donors with and without Alzheimer's disease (AD) were studied to evaluate the presence of amyloid in cortical cataract. We obtained 39 lenses from 21 postmortem donors with AD and 15 lenses from age-matched controls provided by the Banco de Ojos para Tratamientos de la Ceguera (Barcelona, Spain). For 17 donors, AD was clinically diagnosed by general physicians and for 4 donors the AD diagnosis was neuropathologically confirmed. Of the 21 donors with AD, 6 had pronounced bilateral cortical lens opacities and 15 only minor or no cortical opacities. As controls, 7 donors with pronounced cortical opacities and 8 donors with almost transparent lenses were selected. All lenses were photographed in a dark field stereomicroscope. Histological sections were analyzed using a standard and a more sensitive Congo red protocol, thioflavin staining and beta-amyloid immunohistochemistry. Brain tissue from two donors, one with cerebral amyloid angiopathy and another with advanced AD-related changes and one cornea with lattice dystrophy were used as positive controls for the staining techniques. Thioflavin, standard and modified Congo red staining were positive in the control brain tissues and in the dystrophic cornea. Beta-amyloid immunohistochemistry was positive in the brain tissues but not in the cornea sample. Lenses from control and AD donors were, without exception, negative after Congo red, thioflavin, and beta-amyloid immunohistochemical staining. The results of the positive control tissues correspond well with known observations in AD, amyloid angiopathy and corneas with lattice dystrophy. The absence of staining in AD and control lenses with the techniques employed lead us to conclude that there is no beta-amyloid in lenses from donors with AD or in control cortical cataracts. The inconsistency with previous studies of Goldstein et al. (2003) and Moncaster et al. (2010), both of which demonstrated positive Congo red, thioflavin, and beta

  16. Patient considerations in cataract surgery - the role of combined therapy using phenylephrine and ketorolac.

    PubMed

    Gonzalez-Salinas, Roberto; Guarnieri, Adriano; Guirao Navarro, María Concepción; Saenz-de-Viteri, Manuel

    2016-01-01

    Cataract, a degradation of the optical quality of the crystalline lens, progressive and age-related, is the leading cause of treatable blindness worldwide. Cataract surgery is the most common surgical procedure performed by ophthalmologists and is the only effective treatment for cataracts. Advances in the surgical techniques and better postoperative visual outcomes have progressively changed the primary concern of cataract surgery to become a procedure refined to yield the best possible refractive results. Sufficient mydriasis during cataract removal is critical to a successful surgical outcome. Poor pupil dilation can lead to serious sight-threatening complications that significantly increase the cost of surgery and decrease patients comfort. Mydriasis is obtained using anticholinergic and sympathomimetic drugs. Phenylephrine, an α1-adrenergic receptor agonist, can efficiently dilate the pupil when administered by intracameral injection. Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs) like ketorolac, which inhibit the synthesis of prostaglandins, are used to decrease intraoperative miosis, control pain and inflammation associated with cataract surgery, and to prevent the development of cystoid macular edema following surgery. Recently, a new combination of phenylephrine and ketorolac (Omidria(®)) has been approved by United States Food and Drug Administration for use during cataract surgery to maintain intraoperative mydriasis, prevent miosis, and reduce postoperative pain and inflammation. Clinical trials have shown that this new combination is effective, combining the positive effects of both drugs with a good safety profile and patient tolerability. Moreover, recent reports suggest that this combination is also effective in patients with high risk of poor pupil dilation. In conclusion, cataract is a global problem that significantly affects patients' quality of life. However, they can be managed with a safe and minimally invasive surgery

  17. Patient considerations in cataract surgery – the role of combined therapy using phenylephrine and ketorolac

    PubMed Central

    Gonzalez-Salinas, Roberto; Guarnieri, Adriano; Guirao Navarro, María Concepción; Saenz-de-Viteri, Manuel

    2016-01-01

    Cataract, a degradation of the optical quality of the crystalline lens, progressive and age-related, is the leading cause of treatable blindness worldwide. Cataract surgery is the most common surgical procedure performed by ophthalmologists and is the only effective treatment for cataracts. Advances in the surgical techniques and better postoperative visual outcomes have progressively changed the primary concern of cataract surgery to become a procedure refined to yield the best possible refractive results. Sufficient mydriasis during cataract removal is critical to a successful surgical outcome. Poor pupil dilation can lead to serious sight-threatening complications that significantly increase the cost of surgery and decrease patients comfort. Mydriasis is obtained using anticholinergic and sympathomimetic drugs. Phenylephrine, an α1-adrenergic receptor agonist, can efficiently dilate the pupil when administered by intracameral injection. Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs) like ketorolac, which inhibit the synthesis of prostaglandins, are used to decrease intraoperative miosis, control pain and inflammation associated with cataract surgery, and to prevent the development of cystoid macular edema following surgery. Recently, a new combination of phenylephrine and ketorolac (Omidria®) has been approved by United States Food and Drug Administration for use during cataract surgery to maintain intraoperative mydriasis, prevent miosis, and reduce postoperative pain and inflammation. Clinical trials have shown that this new combination is effective, combining the positive effects of both drugs with a good safety profile and patient tolerability. Moreover, recent reports suggest that this combination is also effective in patients with high risk of poor pupil dilation. In conclusion, cataract is a global problem that significantly affects patients’ quality of life. However, they can be managed with a safe and minimally invasive surgery

  18. Intraocular lens employed for cataract surgery

    NASA Astrophysics Data System (ADS)

    Roszkowska, A. M.; Torrisi, L.

    2014-04-01

    The aim of this paper is to illustrate the techniques of cataract surgery with implantation of intraocular lenses and some physical properties of the used materials. The new technology, coupled with extensive experience and the studied cases, permits to increase the standardization and accuracy of the engravings, by reducing the use and handling of surgical instruments inside the eye. At present it is possible to replace the cataract with crystalline lenses based on biopolymers such as PMMA, silicone, acrylic hydrophilic and hydrophobic acrylic. These materials are increasingly able to replace the natural lens and to ensure the fully functional of the eye. The role of femtosecond lasers in cataract surgery, to assist or replace several aspects of the manual cataract surgery, are discussed.

  19. Patient-reported benefit of ReSTOR® multi-focal intraocular lenses after cataract surgery: Results of Principal Component Analysis on clinical trial data

    PubMed Central

    Berdeaux, Gilles; Viala, Muriel; Roborel de Climens, Aude; Arnould, Benoit

    2008-01-01

    Background Restoration of functional distance and near vision independently of additional correction remains a goal for cataract surgery. ReSTOR®, a new multi-focal intraocular lens (IOL) addresses this issue with an improvement in both distance and near vision, often without need for glasses. This analysis attempted to discuss the patient-reported benefit of ReSTOR® using a full but organised representation of data. Methods Two non-randomised, open-label clinical trials conducted in Europe and the United-States were conducted to compare the efficacy of ReSTOR® to AcrySof® mono-focal IOLs. A total of 710 patients in need of bilateral cataract extraction were included in the pooled study. The TyPE, a patient questionnaire, was fully completed by 672 of them before and after each eye surgery. The TyPE, composed of 67 items measuring overall visual functioning in both conditions (with and without wearing glasses), evaluates limitations, troubles and satisfaction in distance and near vision. A principal component analysis (PCA) of the TyPE questionnaire was performed on pooled data from baseline and post-surgery observations in order to fully represent the change in the TyPE data over time. ReSTOR® and mono-focal groups were used as illustrative variables. The coordinates of the first 2 factors were compared between visits and between IOLs (ReSTOR® vs. mono-focal), using paired t-tests and t-tests, respectively. Results The first factor of the PCA explained 55% of the variance and represented 'visual functioning and patient satisfaction'. The second factor explained 6% of the variance and was interpreted as 'independence from glasses'. An overall difference in factorial coordinates in both factors was seen between baseline and the first eye surgery, and between the first and the second eye surgery. No difference between ReSTOR® and mono-focal IOL groups was observed at baseline. After surgery, ReSTOR® treated-patients had higher coordinates on both "visual

  20. Development and testing of new biologically-based polymers as advanced biocompatible contact lenses

    SciTech Connect

    Bertozzi, Carolyn R.

    2000-06-01

    Nature has evolved complex and elegant materials well suited to fulfill a myriad of functions. Lubricants, structural scaffolds and protective sheaths can all be found in nature, and these provide a rich source of inspiration for the rational design of materials for biomedical applications. Many biological materials are based in some fashion on hydrogels, the crosslinked polymers that absorb and hold water. Biological hydrogels contribute to processes as diverse as mineral nucleation during bone growth and protection and hydration of the cell surface. The carbohydrate layer that coats all living cells, often referred to as the glycocalyx, has hydrogel-like properties that keep cell surfaces well hydrated, segregated from neighboring cells, and resistant to non-specific protein deposition. With the molecular details of cell surface carbohydrates now in hand, adaptation of these structural motifs to synthetic materials is an appealing strategy for improving biocompatibility. The goal of this collaborative project between Prof. Bertozzi's research group, the Center for Advanced Materials at Lawrence Berkeley National Laboratory and Sunsoft Corporation was the design, synthesis and characterization of novel hydrogel polymers for improved soft contact lens materials. Our efforts were motivated by the urgent need for improved materials that allow extended wear, and essential feature for those whose occupation requires the use of contact lenses rather than traditional spectacles. Our strategy was to transplant the chemical features of cell surface molecules into contact lens materials so that they more closely resemble the tissue in which they reside. Specifically, we integrated carbohydrate molecules similar to those found on cell surfaces, and sulfoxide materials inspired by the properties of the carbohydrates, into hydrogels composed of biocompatible and manufacturable substrates. The new materials were characterized with respect to surface and bulk hydrophilicity, and

  1. Cataract - adult

    MedlinePlus

    Lens opacity; Age-related cataract ... of the eye. Until a person is around age 45, the shape of the lens is able ... is close or far away. As a person ages, proteins in the lens begin to break down. ...

  2. Cataract Surgery

    MedlinePlus

    ... Foods Rich in Vitamin C Help Curb Cataracts Mar 28, 2016 Los Alimentos Ricos en Vitamina C Ayudan a Controlar el Desarrollo de Cataratas Mar 28, 2016 Follow The Academy Professionals: Education Guidelines ...

  3. Cataract removal

    MedlinePlus

    ... incision. Extracapsular extraction: The doctor uses a small tool to remove the cataract in mostly one piece. This procedure uses a larger incision. Laser surgery: The doctor guides a machine that uses laser energy to make the incisions ...

  4. Use of non-subjective analysis of lens transparency in experimental radiation cataract research

    NASA Technical Reports Server (NTRS)

    Worgul, B. V.; Medvedovsky, C.; Wu, B.

    1995-01-01

    Historically the major impediment to radiation cataract follow-up has been the necessarily subjective nature of assessing the degree of lens transparency. This has spurred the development of instruments which produce video images amenable to digital analysis. One such system, the Zeiss Scheimpflug slit lamp measuring system (SLC), was incorporated into our ongoing studies of radiation cataractogenesis. It was found that the Zeiss SLC measuring system has high resolution and permits the acquisition of reproducible images of the anterior segment of the eye. Our results, based on about 650 images of lenses followed over a period of 91 weeks of radiation cataract development, showed that the changes in the light scatter of the lens correlated well with conventional assessment of radiation cataracts with the added advantages of objectivity, permanent and transportable records and linearity as cataracts become more severe. This continuous data acquisition, commencing with cataract onset, can proceed through more advanced stages. The SLC exhibits much greater sensitivity reflected in a continuously progressive severity thereby avoiding the artifactual plateaus in staging which occur using conventional scoring methods.

  5. Relationships between human cataracts and environmental radiant energy. Cataract formation, light scattering and fluorescence.

    PubMed

    Zigman, S; Sutliff, G; Rounds, M

    1991-01-01

    This preliminary report has two parts. The first is based upon data obtained from a group of cataract patients in southern Florida (USA) with the object of relating the types of cataracts removed to their personal background and their protein biochemistry. Intra-capsular cataract surgery patients at the Venice Eye Clinic (Florida) were interviewed, and their extracted lenses were classified. The parameters were: age, place of residency, occupation, medical and family history and indoor/outdoor activity. Subcapsular cataracts were found mainly in the youngest patients and in those who were in Florida the least. Mixed cataracts predominated in the oldest patients, while non-nuclear cataracts were associated most with outdoor activity. Water-insoluble protein was elevated in nuclei of lenses with nuclear opacities. Soluble proteins in the nuclei of nuclear cataracts had increased levels of voided (heavy) protein, beta-crystallins, and less than 20 Kd peptides. The above changes were enhanced in brunescent cataracts. In lenses with cortical opacities, only increased size heterogeneity in the beta-crystallin region was observed. The second part of this report is based upon direct measurements of the optical properties of freshly extracted intra-capsular cataracts obtained in Rochester, New York (USA). The purpose was to attempt to learn the relative contributions that absorption, scattering, and fluorescence make toward obscuring vision. A general conclusion is that the shorter wavelengths of radiant energy in environmental lighting influence the above-stated optical properties the most, and thus appear to be the major contributors to obscured vision.

  6. Lanosterol synthase mutations cause cholesterol deficiency–associated cataracts in the Shumiya cataract rat

    PubMed Central

    Mori, Masayuki; Li, Guixin; Abe, Ikuro; Nakayama, Jun; Guo, Zhanjun; Sawashita, Jinko; Ugawa, Tohru; Nishizono, Shoko; Serikawa, Tadao; Higuchi, Keiichi; Shumiya, Seigo

    2006-01-01

    The Shumiya cataract rat (SCR) is a hereditary cataractous strain. It is thought that the continuous occurrence of poorly differentiated epithelial cells at the bow area of the lens forms the pathophysiological basis for cataract formation in SCRs. In this study, we attempted to identify the genes associated with cataract formation in SCRs by positional cloning. Genetic linkage analysis revealed the presence of a major cataract locus on chromosome 20 as well as a locus on chromosome 15 that partially suppressed cataract onset. Hypomorphic mutations were identified in genes for lanosterol synthase (Lss) on chromosome 20 and farnesyl diphosphate farnesyl transferase 1 (Fdft1) on chromosome 15, both of which function in the cholesterol biosynthesis pathway. A null mutation for Lss was also identified. Cataract onset was associated with the specific combination of Lss and Fdft1 mutant alleles that decreased cholesterol levels in cataractous lenses to about 57% of normal. Thus, cholesterol insufficiency may underlie the deficient proliferation of lens epithelial cells in SCRs, which results in the loss of homeostatic epithelial cell control of the underlying fiber cells and eventually leads to cataractogenesis. These findings may have some relevance to other types of cataracts, inborn defects of cholesterol synthesis, and the effects of cholesterol-lowering medication. PMID:16440058

  7. Sunlight and Cataracts: Are Athletes at Risk?

    ERIC Educational Resources Information Center

    Cinque, Chris

    1989-01-01

    Reports on a recent study of Chesapeake Bay watermen, which indicates a possible association between long-term exposure of the eyes to ultraviolet B rays and risk of cataract development. Authorities recommend protective lenses for outdoor athletes, especially those involved in winter sports. (SM)

  8. [The development of cataract surgery after 1745].

    PubMed

    Pouw, C A M Karin; Zegers, Richard H C

    2013-01-01

    Nowadays, cataract surgery is the most commonly performed surgical procedure in the Netherlands. This is due to the increasing incidence of cataracts, the changing indication for surgery in our society where good vision is becoming increasingly important, and the quality of the operation. How was this modern procedure developed? Cataracts were treated by couching until the middle of the 18th century. Since then, many discoveries by a number of doctors changed the procedure gradually from couching to lens extraction and through extracapsular to intracapsular extraction with the simultaneous implantation of an intraocular lens. This article outlines the development and also discusses some of the many inventions in the field of instrumentation and materials that have brought this intervention to its current high level; these include the cryo-probe, implantation of artificial lenses, the use of hyaluronic acid, phaco-emulsification, smaller incisions without sutures and the development of foldable intraocular lenses.

  9. Entropic Imaging of Cataract Lens: An In Vitro Study

    PubMed Central

    Shung, K. Kirk; Tsui, Po-Hsiang; Fang, Jui; Ma, Hsiang-Yang; Wu, Shuicai; Lin, Chung-Chih

    2014-01-01

    Phacoemulsification is a common surgical method for treating advanced cataracts. Determining the optimal phacoemulsification energy depends on the hardness of the lens involved. Previous studies have shown that it is possible to evaluate lens hardness via ultrasound parametric imaging based on statistical models that require data to follow a specific distribution. To make the method more system-adaptive, nonmodel-based imaging approach may be necessary in the visualization of lens hardness. This study investigated the feasibility of applying an information theory derived parameter – Shannon entropy from ultrasound backscatter to quantify lens hardness. To determine the physical significance of entropy, we performed computer simulations to investigate the relationship between the signal-to-noise ratio (SNR) based on the Rayleigh distribution and Shannon entropy. Young's modulus was measured in porcine lenses, in which cataracts had been artificially induced by the immersion in formalin solution in vitro. A 35-MHz ultrasound transducer was used to scan the cataract lenses for entropy imaging. The results showed that the entropy is 4.8 when the backscatter data form a Rayleigh distribution corresponding to an SNR of 1.91. The Young's modulus of the lens increased from approximately 8 to 100 kPa when we increased the immersion time from 40 to 160 min (correlation coefficient r = 0.99). Furthermore, the results indicated that entropy imaging seemed to facilitate visualizing different degrees of lens hardening. The mean entropy value increased from 2.7 to 4.0 as the Young's modulus increased from 8 to 100 kPa (r = 0.85), suggesting that entropy imaging may have greater potential than that of conventional statistical parametric imaging in determining the optimal energy to apply during phacoemulsification. PMID:24760103

  10. Hesperetin prevents selenite-induced cataract in rats

    PubMed Central

    Nakazawa, Yosuke; Oka, Mikako; Bando, Masayasu

    2015-01-01

    Purpose This study investigated the ability of hesperetin, a natural flavonoid, to prevent selenite-induced cataracts in a rat model. Methods Animals were divided into four treatment groups: G1 (control group), G2 (hesperetin-treated group), G3 (selenite-induced cataract group), and G4 (hesperetin-treated selenite cataract group). Animals in the G1 and G3 groups were injected with vehicle alone, while those in the G2 and G4 groups received a subcutaneous injection of hesperetin (0.4 μg/g bodyweight on days 0, 1, and 2, corresponding to P13, P14, and P15). Sodium selenite (20 μmol/g bodyweight given 4 h after the hesperetin injection on day 0) was administered to rats in the G3 and G4 groups to induce cataract formation. Lenses were observed with slit-lamp microscopy, and filensin degradation and the decreased glutathione (GSH) and ascorbic acid levels in the lens were measured on day 6. Results Lenses in the G3 group showed mature central opacity, while some lenses in the G4 group lacked central opacity and had lower-grade cataracts. All lenses in the G1 and G2 groups were transparent. Expression of the 94 kDa and 50 kDa forms of filensin was significantly decreased in the lenses in the G3 group compared with those in the G1 and G2 groups. Interestingly, these forms of filensin rescued the rat lenses in the G4 group. In the G3 group lenses, the GSH and ascorbic acid levels were lower than in the control group but were normalized in the G4 group lenses. Conclusions The results suggest that hesperetin can prevent selenite-induced cataract formation. PMID:26283862

  11. Aging and Health: Cataracts

    MedlinePlus

    ... Problems Glaucoma Macular Degeneration Join our e-newsletter! Aging & Health A to Z Cataracts Basic Facts & Information ... Are Cataracts? Cataracts are a common result of aging and occur frequently in older people. About one ...

  12. Effects of histone acetylation on superoxide dismutase 1 gene expression in the pathogenesis of senile cataract

    PubMed Central

    Rong, Xianfang; Qiu, Xiaodi; Jiang, Yongxiang; Li, Dan; Xu, Jie; Zhang, Yinglei; Lu, Yi

    2016-01-01

    Histone acetylation plays key roles in gene expression, but its effects on superoxide dismutase 1 (SOD1) expression in senile cataract remains unknown. To address this problem, the study was to investigate the influence of histone acetylation on SOD1 expression and its effects in the pathogenesis of senile cataract. Senile cataract was classified into three types—nuclear cataract (NC), cortical cataract (CC), and posterior subcapsular cataract (SC)—using the Lens Opacities Classification System III. In senile cataracts, SOD1 expression decreased significantly. Both H3 and H4 were deacetylated at −600 bp of the SOD1 promoter of cataract lenses, and hypoacetylated at −1500, −1200, and −900 bp. In hypoacetylated histones, the hypoacetylation pattern differed among the cataracts. In vitro, anacardic acid (AA) significantly reduced H3 and H4 acetylation at the SOD1 promoter, decreased protein expression, and induced cataract formation in rabbits. AA also inhibited HLEC viability and increased cell apoptosis. In contrast, trichostatin A (TSA) was able to efficaciously stop AA’s effects on both rabbit lenses and HLECs. Decreased histone acetylation at the SOD1 promoter is associated with declined SOD1 expression in senile cataracts. Histone acetylation plays an essential role in the regulation of SOD1 expression and in the pathogenesis of senile cataracts. PMID:27703255

  13. Delay of cataract development in the Shumiya cataract rat by the administration of drinking water containing high concentration of magnesium ion.

    PubMed

    Nagai, Noriaki; Ito, Yoshimasa; Inomata, Mitsushi; Shumiya, Seigo; Tai, Hideyuki; Hataguchi, Yoshihiro; Nakagawa, Koji

    2006-06-01

    We discovered that the cataract development in the Shumiya cataract rat (SCR) can be prevented by the administration of deep-sea drinking water (DDW). A standard diet based on the American Institute of Nutrition guidelines (AIN-76) and DDW containing a high mineral concentration such as low, medium and high Mg2+ content (50, 200 and 1000 mg of Mg2+/l, respectively) were used in this study. SCRs were freely fed with combinations of the standard diet and purified water or DDW during 5-15 weeks of age. The opacities of SCR lenses were documented by anterior eye segment analysis system EAS-1000. The onset of opacification of cataractous SCR lenses administered a combination of standard diet and purified water started at 11 weeks of age, and mature cataracts had formed at 13 weeks of age. However, the supplementation of Mg2+ by administration with medium DDW showed the greatest effect of delay of cataract onset in SCR. In addition, even cataractous SCR lenses at 14 weeks of age showed differences in opacity level. The opacification and Ca2+ of the lenses in cataractous SCR administered medium DDW were lower than those administered purified water. In conclusion, the present study demonstrates that administration of DDW potently delays cataract development in SCR, and this may be caused by inhibiting the increase in Ca2+ levels in the lens.

  14. Femtosecond And Picosecond Laser Ablation Of Intraocular Lenses: An Advanced Technique For Their Surface Modification

    NASA Astrophysics Data System (ADS)

    Serafetinides, A. A.; Makropoulou, M.; Spyratou, E.; Bacharis, C.; Barberoglou, M.; Englezis, A.; Kalpouzos, C.; Loukakos, P.; Pouli, P.

    2011-09-01

    Ophthalmology is entering a very interesting period with new diffractive multifocals, improved refractive multifocals, and accommodative lenses, all coming out at the same time. A new diffractive-refractive design for providing intermediated vision is apodization. In an apodized pattern, physical diffractive step heights are reduced in height, in an almost continuously varying manner. This study is aimed to investigate the use of ultrashort laser pulses to ablate the surface of intraocular lenses, and thus provide an alternative to conventional techniques. Ablation experiments were performed on hydrophilic and hydrophobic intraocular lenses (IOLs). The samples were irradiated with a Ti:Sapphire laser at λ = 0.785 μm, pulse duration 150 fs, repetition rate 1 kHz and with a Nd:YAG 4ω laser at λ = 0.266 μm, pulse duration 155 ps, repetition rate 10 Hz. We investigated the ablation efficiency and the surface modification with a Scanning Electron Microscope (SEM). The experimental results and the theoretical assumptions on the relevant ablation mechanism are discussed.

  15. Measuring aniseikonia using scattering filters to simulate cataract

    NASA Astrophysics Data System (ADS)

    Wilson, Jason

    2011-12-01

    The relationship between anisometropia and aniseikonia (ANK) is not well understood. Ametropic cataract patients provide a unique opportunity to study this relationship after undergoing emmetropizing lens extraction. Because light scatter may affect ANK measurement in cataract patients, its effect should also be evaluated. The Basic Aniseikonia Test (BAT) was evaluated using afocal size lenses to produce specific changes in retinal height. Several light scattering devices were then evaluated to determine which produced effects most similar to cataract. Contrast sensitivity and visual acuity (VA) losses were measured with each device and compared to those reported in cataract. After determining the most appropriate light scattering device, twenty healthy patients with normal visual function were recruited to perform the BAT using the filters to simulate cataract. Cataract patients were recruited from Vision America and the University of Alabama at Birmingham School of Optometry. Patients between 20 and 75 years of age with at least 20/80 VA in each eye, ≥ 2D ametropia, and normal binocular function were recruited. Stereopsis and ANK were tested and each patient completed a symptom questionnaire. ANK measurements using afocal size lenses indicated that the BAT underestimates ANK, although the effect was minimal for vertical targets and darkened surroundings, as previously reported. Based on VA and contrast sensitivity loss, Vistech scattering filters produced changes most similar to cataract. Results of the BAT using Vistech filters demonstrated that a moderate cataract but not a mild cataract may affect the ANK measurement. ANK measurements on cataract patients indicated that those with ≥ 2 D ametropia in each eye may suffer from induced ANK after the first cataract extraction. With upcoming healthcare reform, unilateral cataract extraction may be covered, but not necessarily bilateral, depending on patient VA in each eye. However, a questionnaire about symptoms

  16. Evaluation of the degree of turbidity of cataract lens and its correlation with retinal visual acuity

    NASA Astrophysics Data System (ADS)

    Akchurin, Garif G.; Bakutkin, Valery V.; Zimnyakov, Dmitry A.; Radchenko, Elena Y.; Tuchin, Valery V.; Akchurin, Alexander G.

    1999-06-01

    Experimental in vitro studies of speckle-modulated laser field arising after transmission through different type of human cataractous lenses are presented. Computer analysis of digital imaging has allowed to determinate the degree of destruction of spatial coherence scattered laser beam and the angle of resolution of the retina using Retinal Analyzer of Vision (AROL-1) in diagnosis of cataract. Measurement of retinal visual acuity (RVA) in 135 patient with different types of cataract (senile, complicated, posterior capsular) before and after cataract extraction and also in vitro measurement of RVA with extracted cataractal lenses has shown that laser retinometer can be used for evaluating visual acuity within 0.3 - 1, practically for all types of cataracts.

  17. Ophthalmic halo reduced lenses design

    NASA Astrophysics Data System (ADS)

    Limon, Ofer; Zalevsky, Zeev

    2015-05-01

    The halo effect is a very problematic visual artifact occurring in extended depth of focus or multi-focal ophthalmic lenses such as e.g. intra-ocular (after cataract surgery) or contact lenses when used in dark illumination conditions. This artifact is generated due to surface structures added on top of those lenses in order to increase their depth of focus or to realize multiple focal lengths. In this paper we present novel solution that can resolve this major problem of ophthalmic lenses. The proposed solution involves modification to the surface structure that realizes the extended depth of focus. Our solution is fabricated and numerically and experimentally validated also in preliminary in-vivo trials.

  18. [Ten most progression of cataract research in China].

    PubMed

    2015-04-01

    Ten researches that may represent the most advanced cataract related studies in China were reviewed, which were recommended and voted by specialists from Chinese Cataract and Intraocular Lens Society. These researches focused on the following fields: the clinical study of the refractive cataract surgery, the clinical study on the premium intraocular lens, location and function study of the disease-associated genes of congenital cataract, the mechanism and prevention of age-related cataract, the mechanism and prevention of oxidative damage of crystalline lens and so on. These studies represented the level of crystalline lens related disease field in China.

  19. Rapidly progressing bilateral cataracts in a patient with beta thalassemia and pellagra.

    PubMed

    Athanasiadis, Ioannis; Konstantinidis, Aristeidis; Kyprianou, Ioannis; Robinson, Rosemary; Moschou, Vaia; Kouzi-Koliakos, Kokkona

    2007-09-01

    Soon after the diagnosis of pellagra in a 20-year-old patient with beta thalassemia, bilateral intumescent cataracts rapidly developed. We believe the patient's crystalline lenses were at an increased oxidative state due to iron overload from the thalassemia. Depletion of the lens epithelial cells of an important antioxidative agent (glutathione) as a result of niacin (vitamin B3) deficiency due to pellagra reduced the antioxidative capacity of the lenses. The oxidative damage led to rapid development of cataracts.

  20. [Cataract surgery - essentials for the general practitioner].

    PubMed

    Amstutz, Ch; Thiel, M A; Kaufmann, Claude

    2010-08-11

    Age-related cataracts are mainly caused by life-long accumulation of oxidative stress on the lens fibres. Symptoms include reduced visual acuity, requiring more light for reading, and glare. The only treatment that provides a cure for cataracts is surgery. Phacoemulsification represents the preferred method of lens removal. It involves fragmentation of the lens using ultrasound and insertion of an artificial intraocular lens. The preoperative assessment the general practitioner provides to surgeon and anesthesia team has an important share in the low complication rate of the procedure in the event of co-existing systemic disease. Growing patient expectation for spectacle independence following cataract surgery is met to some extent using techniques for astigmatism control and presbyo-pia-correcting intraocular lenses.

  1. The Evolution of Cataract Surgery: Controversies Through the Ages.

    PubMed

    Martin, Aifric Isabel; Sutton, Gerard; Hodge, Christopher

    2013-01-01

    Cataracts have been in public consciousness since ancient times. Throughout the ages, the comfort of established practices, at times, has obstructed the implementation of improved policies. The opposition to lensectomy, hygiene practices, intraocular lenses, and phacoemulsification (phaco) are explored. As femtosecond laser cataract surgery attempts to secure a foothold in cataract treatment, we consider whether it is destined to be a forgotten footnote or if, like other contributions to the history books, the difficulties of establishing a new technique are abstracting the benefits represented.

  2. Automatic Cataract Hardness Classification Ex Vivo by Ultrasound Techniques.

    PubMed

    Caixinha, Miguel; Santos, Mário; Santos, Jaime

    2016-04-01

    To demonstrate the feasibility of a new methodology for cataract hardness characterization and automatic classification using ultrasound techniques, different cataract degrees were induced in 210 porcine lenses. A 25-MHz ultrasound transducer was used to obtain acoustical parameters (velocity and attenuation) and backscattering signals. B-Scan and parametric Nakagami images were constructed. Ninety-seven parameters were extracted and subjected to a Principal Component Analysis. Bayes, K-Nearest-Neighbours, Fisher Linear Discriminant and Support Vector Machine (SVM) classifiers were used to automatically classify the different cataract severities. Statistically significant increases with cataract formation were found for velocity, attenuation, mean brightness intensity of the B-Scan images and mean Nakagami m parameter (p < 0.01). The four classifiers showed a good performance for healthy versus cataractous lenses (F-measure ≥ 92.68%), while for initial versus severe cataracts the SVM classifier showed the higher performance (90.62%). The results showed that ultrasound techniques can be used for non-invasive cataract hardness characterization and automatic classification.

  3. Pediatric cataract: challenges and future directions

    PubMed Central

    Medsinge, Anagha; Nischal, Ken K

    2015-01-01

    Cataract is a significant cause of visual disability in the pediatric population worldwide and can significantly impact the neurobiological development of a child. Early diagnosis and prompt surgical intervention is critical to prevent irreversible amblyopia. Thorough ocular evaluation, including the onset, duration, and morphology of a cataract, is essential to determine the timing for surgical intervention. Detailed assessment of the general health of the child, preferably in conjunction with a pediatrician, is helpful to rule out any associated systemic condition. Although pediatric cataracts have a diverse etiology, with the majority being idiopathic, genetic counseling and molecular testing should be undertaken with the help of a genetic counselor and/or geneticist in cases of hereditary cataracts. Advancement in surgical techniques and methods of optical rehabilitation has substantially improved the functional and anatomic outcomes of pediatric cataract surgeries in recent years. However, the phenomenon of refractive growth and the process of emmetropization have continued to puzzle pediatric ophthalmologists and highlight the need for future prospective studies. Posterior capsule opacification and secondary glaucoma are still the major postoperative complications necessitating long-term surveillance in children undergoing cataract surgery early in life. Successful management of pediatric cataracts depends on individualized care and experienced teamwork. We reviewed the etiology, preoperative evaluation including biometry, choice of intraocular lens, surgical techniques, and recent developments in the field of childhood cataract. PMID:25609909

  4. Aspherics in spectacle lenses

    NASA Astrophysics Data System (ADS)

    Dürsteler, Juan Carlos

    2016-12-01

    A review of the use of aspherics in the last decades, understood in a broad sense as encompassing single-vision lenses with conicoid surfaces and free-form and progressive addition lenses (PALs) as well, is provided. The appearance of conicoid surfaces to correct aphakia and later to provide thinner and more aesthetically appealing plus lenses and the introduction of PALs and free-form surfaces have shaped the advances in spectacle lenses in the last three decades. This document basically considers the main target optical aberrations, the idiosyncrasy of single lenses for correction of refractive errors and the restrictions and particularities of PAL design and their links to science vision and perception.

  5. Cataract surgery - slideshow

    MedlinePlus

    ... this page: //medlineplus.gov/ency/presentations/100079.htm Cataract surgery - series—Normal anatomy To use the sharing ... lens of an eye is normally clear. A cataract is when the lens becomes cloudy as you ...

  6. Cataracts in Diabetic Patients: A Review Article

    PubMed Central

    Javadi, Mohammad-Ali; Zarei-Ghanavati, Siamak

    2008-01-01

    The number of people with diabetes mellitus is increasing and cataracts are one of the most common causes of visual impairment in these subjects. Advances in cataract surgical techniques and instrumentation have generally improved the outcomes; however,surgery may not be safe and effective in certain individuals with pre-existing retinal pathology or limited visual potential. This review article aims to address different aspects surrounding cataracts in diabetic patients. In a computerized MEDLINE search,relevant studies were selected by two authors using the keywords “diabetes mellitus”, “cataract”, “diabetic retinopathy” and “diabetic maculopathy”. PMID:23479523

  7. Inhibition of diabetic-cataract by vitamin K1 involves modulation of hyperglycemia-induced alterations to lens calcium homeostasis.

    PubMed

    Sai Varsha, M K N; Raman, Thiagarajan; Manikandan, Ramar

    2014-11-01

    This study investigated the potential of vitamin K1 against streptozotocin-induced diabetic cataract in Wistar rats. A single, intraperitoneal injection of streptozotocin (STZ) (35 mg/kg) resulted in hyperglycemia, accumulation of sorbitol and formation of advanced glycation end product (AGE) in eye lens. Hyperglycemia in lens also resulted in superoxide anion and hydroxyl radical generation and less reduced glutathione suggesting oxidative stress in lens. Hyperglycemia also resulted in increase in lens Ca2+ and significant inhibition of lens Ca2+ ATPase activity. These changes were associated with cataract formation in diabetic animals. By contrast treatment of diabetic rats with vitamin K1 (5 mg/kg, sc, twice a week) resulted in animals with partially elevated blood glucose and with transparent lenses having normal levels of sorbitol, AGE, Ca2+ ATPase, Ca2+, and oxidative stress. Vitamin K 1 may function to protect against cataract formation in the STZ induced diabetic rat by affecting the homeostasis of blood glucose and minimizing subsequent oxidative and osmotic stress. Thus, these results show that Vitamin K1 inhibits diabetic-cataract by modulating lens Ca2+ homeostasis and its hypoglycemic effect through its direct action on the pancreas.

  8. Cataracts in Congenital Toxoplasmosis

    PubMed Central

    Arun, Veena; Noble, A. Gwendolyn; Latkany, Paul; Troia, Robert N.; Jalbrzikowski, Jessica; Kasza, Kristen; Karrison, Ted; Cezar, Simone; Sautter, Mari; Greenwald, Mark J.; Mieler, William; Mets, Marilyn B.; Alam, Ambereen; Boyer, Kenneth; Swisher, Charles N.; Roizen, Nancy; Rabiah, Peter; Del Monte, Monte A.; McLeod, Rima

    2008-01-01

    Purpose To determine the incidence and natural history of cataracts in children with congenital toxoplasmosis. Methods Children referred to the National Collaborative Chicago-based Congenital Toxoplasmosis Study (NCCCTS) between 1981 and 2005 were examined by ophthalmologists at predetermined times according to a specific protocol. The clinical course and treatment of patients who developed cataracts was reviewed. Results In the first year of life, 134 of 173 children examined were treated with pyrimethamine, sulfadiazine, and Leucovorin, while the remaining 39 were not treated. Cataracts occurred in 27 eyes of 20 patients (11.6%, 95% confidence interval [7.2%, 17.3%]). Fourteen cataracts were present at birth, and 13 developed postnatally. Locations of the cataracts included anterior polar (3 eyes), anterior subcapsular (6), nuclear (5), posterior subcapsular (7), and unknown (6). Thirteen cataracts were partial, 9 total, and 5 with unknown complexity. Twelve cataracts remained stable, 12 progressed, and progression was not known for 3. Five of 27 eyes had cataract surgery, with 2 of these developing glaucoma. Sixteen eyes of 11 patients had retinal detachment and cataract. All eyes with cataracts had additional ocular lesions. Conclusions In the NCCCTS cohort, 11.6% of patients were diagnosed with cataracts. There was considerable variability in the presentation, morphology, and progression of the cataracts. Associated intraocular pathology was an important cause of morbidity. PMID:18086432

  9. Nutritional modulation of cataract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cataract, or lens opacification, remains a major cause of blindness worldwide. Cataracts reduce vision in over eighty million people, causing blindness in eighteen million people. The number afflicted by cataract will increase dramatically as the proportion of the elderly global population increase...

  10. Comparison of optical coherence tomography imaging of cataracts with histopathology

    NASA Astrophysics Data System (ADS)

    DiCarlo, Cheryl D.; Roach, William P.; Gagliano, Donald A.; Boppart, Stephen A.; Hammer, Daniel X.; Cox, Ann B.; Fujimoto, James G.

    1999-10-01

    This paper presents a comparison of in vivo optical coherence tomography (OCT) captured cataract images to subsequent histopathological examination of the lenticular opacities. OCT imaging was performed on anesthetized Rhesus monkeys, known as the delayed effects colony (DEC), with documented cataracts. These monkeys were exposed to several types of radiation during the mid and late 1960s. The radiation and age related cataracts in these animals were closely monitored using a unique grading system developed specifically for the DEC. In addition to this system, a modified version of a common cataract grading scheme for use in humans was applied. Of the original 18 monkeys imaged, lenses were collected at necropsy from seven of these animals, processed, and compared to OCT images. Results showed a direct correlation between the vertical OCT images and the cataractous lesions seen on corresponding histopathological sections of the lenses. Based on the images obtained and their corresponding documented comparison to histopathology, OCT showed tremendous potential to aid identification and characterization of cataracts. There can be artifactual problems with the images related to movement and shadows produced by opacities. However, with the advent of increased speed in imaging and multiplanar imaging, these disadvantages may easily be overcome.

  11. Accelerated heavy ions and the lens. IV. Biomicroscopic and cytopathological analyses of the lenses of mice irradiated with 600 MeV/amu sup 56 Fe ions

    SciTech Connect

    Worgul, B.V.; Medvedovsky, C.; Powers-Risius, P.; Alpen, E. )

    1989-11-01

    The lenses of mice exposed to 600 MeV/amu iron ions were evaluated by slit-lamp biomicroscopy and cytopathological analyses. The doses ranged from 0.05 to 1.6 Gy, and the lenses were assessed at several intervals postirradiation. Cataract, the development of which is dependent on both time and dose, is significantly more advanced in all of the exposed mice when compared to the unirradiated controls. The great difference between the severity of the cataracts caused by 0.05 Gy (the lowest dose used) and those that developed spontaneously in the control animals is an indication that 0.05 Gy may far exceed the threshold dose for the production of cataracts by accelerated iron ions. Cytopathologically, a similar dose dependence was observed for a number of end points including micronucleation, interphase death, and meridional row disorganization. In addition the exposure to the 56Fe ions produced a long-term effect on the mitotic population and a pronounced focal loss of epithelial cytoarchitecture. The microscopic changes support the view that the mechanism of heavy-ion-induced cataractogenesis is the same as that for cataracts caused by low-LET radiation.

  12. Assessing the changes in the biomechanical properties of the crystalline lens induced by cold cataract with air-pulse OCE

    NASA Astrophysics Data System (ADS)

    Wu, C.; Singh, M.; Liu, C.-H.; Han, Z.; Li, J.; Raghunathan, R.; Larin, K. V.

    2015-11-01

    A cataract is the increase in opacity of the crystalline lens that can pathologically degrade visual acuity. In this study, we utilized a phase-sensitive optical coherence elastography (OCE) system to study the effects of a cold cataract on the biomechanical properties of the porcine crystalline lens in vitro. The cold cataract was induced by placing the whole lens in a low temperature environment until the lens was obviously clouded. Air-pulse OCE measurements were conducted on 6 lenses before and after cold cataract induction. A low amplitude displacement (≤ 10 µm) was induced by a focused air-pulse and the temporal deformation profiles from the surface and within the lenses were analyzed. The results demonstrated that the stiffness of the porcine lens increased after induction of the cold cataract, and it demonstrated the feasibility of OCE to assess the biomechanical changes in the lens due to cataract.

  13. Effect of radioprotective agents on X-ray cataracts

    SciTech Connect

    Reddy, V.N.; Ikebe, H.; Giblin, F.J.; Clark, J.I.; Livesey, J.C. )

    1989-01-01

    The effect of some protective agents on cataract development is briefly reviewed and new evidence is presented on the efficacy of a phosphorothioate compound (Amifostine) in inhibiting the development of X-ray-induced cataract. Morphological studies showed that at the end of 4 months, lenses from X-irradiated rats which had not received any drugs showed liquefaction in the equatorial region and at the posterior pole, as well as a marked swelling of the fibers in the anterior cortex. Animals which received 1.16g/kg of WR77913 showed considerable protection against the development of radiation induced cataracts with morphological changes in the lens being less severe than in animals receiving no drugs. When animals were treated with 0.5g/kg of Amifostine (WR2721) the lenses showed much greater protection against cataract development than with WR77913. Amifostine appears to be more effective than WR77913 in inhibiting X-ray-induced cataract development. 20 refs.

  14. Ocular growth in infant aphakia. Bilateral versus unilateral congenital cataracts.

    PubMed

    Lorenz, B; Wörle, J; Friedl, N; Hasenfratz, G

    1993-12-01

    In a prospective study the changes in the ocular axial lengths and in the overall refractions were examined in cases of unilateral and bilateral congenital cataract requiring surgery during the first year of life. Measurements were taken on 18 children with unilateral and on 20 children with bilateral congenital cataract at the time of surgery and up to eight years postoperatively. Surgery was performed via a pars plana/plicata approach, and all infants were fitted with contact lenses. In cases of unilateral cataract, the ocular axial length tended to be superior to the age-matched values already prior to surgery. After four to eight years, one third of the eyes were clearly above normal. In cases of bilateral cataract, the axial lengths were reduced at the age of surgery in the majority of cases, and particularly in eyes that required surgery during the first six months of life. The curvatures of the contact lenses tended to remain unchanged in bilateral cataract, and decreased by about 0.7 mm in unilateral cases. This also reflects the high degree of microphthalmia in bilateral cases. After four to eight years, the degree of microphthalmia had usually increased. The overall refraction decreased significantly in unilateral and bilateral cataract during the first four years of life. The mean values were higher in bilateral than in unilateral cataract at all ages. The mean decrease was 15 diopters in unilateral cataract (SD +/- 5.5 dpt), and 10 diopters in bilateral cataract (SD +/- 6 dpt). When correlating the age-matched differences in the ocular axial lengths at the time of surgery with the overall refractions after four to eight years, a good correlation was found in the unilateral cases (eight eyes), and a poor correlation in the bilateral cases (24 eyes). The data indicate that intraocular implants should not be used in bilateral cataract requiring surgery during the first year of life as long as there is no possibility to change their refraction while in

  15. Types of Contact Lenses

    MedlinePlus

    ... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...

  16. Non-destructive analysis of the conformational changes in human lens lipid and protein structures of the immature cataracts associated with glaucoma

    NASA Astrophysics Data System (ADS)

    Lin, Shan-Yang; Li, Mei-Jane; Liang, Run-Chu; Lee, Shui-Mei

    1998-09-01

    Previous study has supposed a possible mechanism of exacerbating cataract formation in cataractous human lens capsules induced by hypertension or glaucoma. To clarify the glaucoma-induced cataract formation of the eyes lens, changes in the human lens lipid and protein structures of immature cataractous patients with or without glaucoma were investigated. Two normal lenses, ten immature cataractous lenses without any complication and four immature cataractous lenses with glaucoma were used after surgical operation. Each de-capsulated human lens sample was sliced with a number 15 surgical blade. The intact nuclear lens regions were used for non-destructive analysis. The lens lipid and protein structures, as well as compositions of these lens samples, were determined using a Fourier transform infrared (FTIR) microspectroscopy with second-derivative, de-convolution and curve-fitting methods. The results indicate that the IR spectrum of glaucomatous lenses appeared as a shoulder only at 2853 cm -1, thus the composition of the symmetric CH 2 stretching band at 2853 (2852) cm -1 decreased more significantly in glaucomatous lens to only one half of that in normal and immature cataractous lenses. The composition of the asymmetric CH 3 stretching band at 2965 cm -1 for normal lens decreases markedly from 32 to 20% for immature cataractous lenses with or without glaucoma. The compositional ratio of component at 2965 cm -1 to component at 2928 (2930) cm -1 for normal lenses was about 0.702, and that ratio for cataractous lenses without glaucoma was 0.382 but for glaucomatous lenses was 0.377. The maximum peak position of amide I band for IR spectra of the normal lens, immature cataractous lenses without complications or glaucomatous lenses appeared respectively at 1632, 1630 or 1622 cm -1, assigned to β sheet structure. A marked difference in peak intensity of amide I band for the normal lenses and immature cataractous human lenses with or without glaucoma was observed. The

  17. Nutritional modulation of cataract

    PubMed Central

    Weikel, Karen A; Garber, Caren; Baburins, Alyssa; Taylor, Allen

    2014-01-01

    Lens opacification or cataract reduces vision in over 80 million people worldwide and blinds 18 million. These numbers will increase dramatically as both the size of the elderly demographic and the number of those with carbohydrate metabolism-related problems increase. Preventative measures for cataract are critical because the availability of cataract surgery in much of the world is insuficient. Epidemiologic literature suggests that the risk of cataract can be diminished by diets that are optimized for vitamin C, lutein/zeaxanthin, B vitamins, omega-3 fatty acids, multivitamins, and carbohydrates: recommended levels of micronutrients are salutary. The limited data from intervention trials provide some support for observational studies with regard to nuclear – but not other types of – cataracts. Presented here are the beneficial levels of nutrients in diets or blood and the total number of participants surveyed in epidemiologic studies since a previous review in 2007. PMID:24279748

  18. Surgical removal of cataracts due to Diplostomum species in Gulf sturgeon (Acipenser oxyrinchus desotoi).

    PubMed

    Bakal, Robert S; Hickson, Brian H; Gilger, Brian C; Levy, Michael G; Flowers, James R; Khoo, Lester

    2005-09-01

    Twenty 6-yr-old (1995-yr-class) Gulf of Mexico sturgeon (Acipenser oxyrinchus desotoi) were diagnosed as having bilateral cataracts. Histopathologic assessment of the lenses of two of the fish revealed the presence of a diplostomid trematode. Pharmacological treatment of the trematodes may be effective for killing the parasites, but the damage to the lenses and resulting cataracts are nonreversible. Because these animals were to be used in a subsequent study as sentinels in the natural environment, it was necessary to return the animals' vision to as close to normal as possible. Electroretinograms were performed on each fish's eyes to ensure that retinal function was present. Cataracts then were surgically removed by phacoemulsification and aspiration. The animals tolerated the surgical procedures well. This report is the first known report of surgical correction of cataracts in sturgeon species. It also is the first known attempt to correct vision problems in fish being returned to the wild.

  19. Genetics of Congenital Cataract.

    PubMed

    Pichi, Francesco; Lembo, Andrea; Serafino, Massimiliano; Nucci, Paolo

    2016-01-01

    Congenital cataract is a type of cataract that presents at birth or during early childhood, and it is one of the most easily treatable causes of visual impairment and blindness during infancy, with an estimated prevalence of 1-6 cases per 10,000 live births. Approximately 50% of all congenital cataract cases may have a genetic cause, and such cases are quite heterogeneous. Although congenital nuclear cataract can be caused by multiple factors, genetic mutation remains the most common cause. All three types of Mendelian inheritance have been reported for cataract; however, autosomal dominant transmission seems to be the most frequent. The transparency and high refractive index of the lens are achieved by the precise architecture of fiber cells and homeostasis of the lens proteins in terms of their concentrations, stabilities, and supramolecular organization. Research on hereditary congenital cataract has led to the identification of several classes of candidate genes that encode proteins such crystallins, lens-specific connexins, aquaporin, cytoskeletal structural proteins, and developmental regulators. In this review, we highlight the identified genetic mutations that account for congenital nuclear cataract.

  20. Changes in the distribution of lens calcium during development of x-ray cataract

    SciTech Connect

    Hightower, K.R.; Giblin, F.J.; Reddy, V.N.

    1983-09-01

    The present study was designed to examine the possible role of calcium in the opacification of x-ray-induced cataract in rabbit. The results demonstrate that the concentration of calcium in x-rayed lenses, just prior to lens hydration (7.5 weeks postirradiation), was twice that present in contralateral control lenses. At this stage of immature cataract, the lens nucleus remained transparent and maintained a normal level of calcium, but the lens cortex, containing regions of subcapsular opacification, accumulated a level of calcium that was twice that of the control. In the completely opaque mature cataract, (8-9 weeks post x-ray), both the cortex and nucleus had gained significant amounts of calcium. As the concentration of total calcium increased in the immature x-ray cataract, the amount of the cation bound to membranes and insoluble proteins of the cytosol also increased comparably. However, the relative proportion of calcium in the various fractions remained unaltered in the immature cataract; in both control lenses and immature cataracts, 20% of the total calcium remained in the membrane pellet and 70% was located in the soluble protein fraction. Only in the mature stage of cataract was a shift in the distribution of calcium apparent, as the proportion of calcium in the soluble protein fraction increased to 90%. Although only 7% of the total calcium in a mature cataract was bound to membrane, the amount represented a fivefold increase over the control. The results of this study demonstrate that an elevation in lens calcium accompanies the opacification process in x-ray cataract. The work also suggests that changes in calcium levels are not likely to result from inactivation of Ca-ATPase.

  1. [Correction of ametropia following early surgery of congenital cataract].

    PubMed

    Avetisov, S E

    2003-01-01

    Variants of an approach towards choosing the means for aphakia correction after an early surgery for congenital cataract, made during the first life year of infant, are presented in the case study. The main requirements, which must be applicable to a correction method under the mentioned conditions, are substantiated. The key advantages of contact lenses are shown, from such stand point, versus other correction methods, including spectacles, intraocular lenses and refractive epikeratoplasty. Unstable anatomic-and-optic ocular parameters in the first-year life infants are the principle obstacle for the primary IOL implantation. The issue on a secondary IOL implantation must be individually decided at the age of 10 to 12.

  2. Surgical options for correction of refractive error following cataract surgery.

    PubMed

    Abdelghany, Ahmed A; Alio, Jorge L

    2014-01-01

    Refractive errors are frequently found following cataract surgery and refractive lens exchange. Accurate biometric analysis, selection and calculation of the adequate intraocular lens (IOL) and modern techniques for cataract surgery all contribute to achieving the goal of cataract surgery as a refractive procedure with no refractive error. However, in spite of all these advances, residual refractive error still occasionally occurs after cataract surgery and laser in situ keratomileusis (LASIK) can be considered the most accurate method for its correction. Lens-based procedures, such as IOL exchange or piggyback lens implantation are also possible alternatives especially in cases with extreme ametropia, corneal abnormalities, or in situations where excimer laser is unavailable. In our review, we have found that piggyback IOL is safer and more accurate than IOL exchange. Our aim is to provide a review of the recent literature regarding target refraction and residual refractive error in cataract surgery.

  3. Methylphenidate (Ritalin)-associated cataract and glaucoma.

    PubMed

    Lu, Chao-Kung; Kuang, Tung-Mei; Chou, Joe Ching-Kuang

    2006-12-01

    Methylphenidate hydrochloride (Ritalin) is the drug of choice for attention deficit hyperactivity disorder (ADHD). However, an association of Ritalin with glaucoma has been reported. We report a case of Ritalin-associated cataract and glaucoma. A 10-year-old boy was diagnosed with ADHD and had received methylphenidate hydrochloride, 60 mg/day for 2 years. He presented with blurred vision. Best-corrected visual acuity was 6/60 in both eyes. Ocular examinations revealed intraocular pressure (IOP) of 30 mmHg under medication, dense posterior subcapsular opacity of lens, pale disc with advanced cupping, and marked constriction of visual field. Despite maximal anti-glaucomatous medication, IOP still could not be controlled. The patient then received combined cataract and glaucoma surgery. Visual acuity improved and IOP was within normal limits in both eyes postoperatively. Large dose of methylphenidate may cause cataract and glaucoma. The mechanism remains unclear. Doctors should be aware of the possible ocular side effects of methylphenidate.

  4. Feasibility and Complications between Phacoemulsification and Manual Small Incision Surgery in Subluxated Cataract

    PubMed Central

    Goel, Ruchi; Kamal, Saurabh; Kumar, Sushil; Kishore, Jugal; Malik, K. P. S.; Angmo Bodh, Sonam; Bansal, Smriti; Singh, Madhu

    2012-01-01

    Purpose. To compare the feasibility of cataract surgery with implantation of endocapsular supporting devices and intraocular lens (IOL) in subluxated cataract in phacoemulsification and manual small incision cataract surgery (MSICS). Design. Prospective randomized intervention case series consisting of 60 eyes with visually significant subluxated cataract. Method. The patients were randomly distributed between the two groups equally. The main outcome measure was implantation of in-the-bag IOL, requirement of additional procedure and complications, if any. Results. Capsular bag retention in subluxated lenses is possible in 90% cases in phacoemulsification versus 76.67% cases in MSICS (P = 0.16). Both groups, achieved similar best corrected visual acuity (P = 0.73), although additional procedures, intraoperative, and postoperative complications were more common in MSICS. Conclusions. Achieving intact capsulorhexis and nuclear rotation in MSICS may be difficult in cases with large nucleus size and severe subluxation, but subluxated cataracts can be effectively managed by both phacoemuslification and MSICS. PMID:22523646

  5. 1004 cases of traumatic cataract surgery with implantation of an intraocular lens.

    PubMed

    Fyodorov, S N; Egorova, E V; Zubareva, L N

    1981-04-01

    Traumatic cataracts occurring after ocular trauma were removed by phacoemulsification, cryoextraction or extracapsular cataract extraction, depending on the degree of lens absorption. All eyes received sputnik-style iridocapsular lenses. Most cases were complicated by the presence of synechiae and/or the need for iridoplasty. The surgical technique varied with the specific nature of the ocular pathology. Eyes with penetrating injuries has a higher complication rate. Anterior chamber shallowing or collapse was the most frequent intraoperative complication, and was directly related to the incidence of postoperative complications. Most postoperative complications were typical of those associated with cataract surgery in complicated situations.

  6. Facts about Cataract

    MedlinePlus

    ... alcohol use. The environment (prolonged exposure to ultraviolet sunlight). What are the symptoms of a cataract? The ... vision. Colors seem faded. Glare. Headlights, lamps, or sunlight may appear too bright. A halo may appear ...

  7. Cataract Surgery Tool

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The NASA-McGannon cataract surgery tool is a tiny cutter-pump which liquefies and pumps the cataract lens material from the eye. Inserted through a small incision in the cornea, the tool can be used on the hardest cataract lens. The cutter is driven by a turbine which operates at about 200,000 revolutions per minute. Incorporated in the mechanism are two passages for saline solutions, one to maintain constant pressure within the eye, the other for removal of the fragmented lens material and fluids. Three years of effort have produced a design, now being clinically evaluated, with excellent potential for improved cataract surgery. The use of this tool is expected to reduce the patient's hospital stay and recovery period significantly.

  8. Cataracts - what to ask your doctor

    MedlinePlus

    What to ask your doctor about cataracts; Lens implants - what to ask your doctor ... What is a cataract? How will cataract surgery help my vision? If I have cataracts in both eyes, can I have surgery on ...

  9. LC-MS display of the total modified amino acids in cataract lens proteins and in lens proteins glycated by ascorbic acid in vitro.

    PubMed

    Cheng, Rongzhu; Feng, Qi; Ortwerth, Beryl J

    2006-05-01

    We previously reported chromatographic evidence supporting the similarity of yellow chromophores isolated from aged human lens proteins, early brunescent cataract lens proteins and calf lens proteins ascorbylated in vitro [Cheng, R. et al. Biochimica et Biophysica Acta 1537, 14-26, 2001]. In this paper, new evidence supporting the chemical identity of the modified amino acids in these protein populations were collected by using a newly developed two-dimensional LC-MS mapping technique supported by tandem mass analysis of the major species. The pooled water-insoluble proteins from aged normal human lenses, early stage brunescent cataract lenses and calf lens proteins reacted with or without 20 mM ascorbic acid in air for 4 weeks were digested with a battery of proteolytic enzymes under argon to release the modified amino acids. Aliquots equivalent to 2.0 g of digested protein were subjected to size-exclusion chromatography on a Bio-Gel P-2 column and four major A330nm-absorbing peaks were collected. Peaks 1, 2 and 3, which contained most of the modified amino acids were concentrated and subjected to RP-HPLC/ESI-MS, and the mass elution maps were determined. The samples were again analyzed and those peaks with a 10(4) - 10(6) response factor were subjected to MS/MS analysis to identify the daughter ions of each modification. Mass spectrometric maps of peaks 1, 2 and 3 from cataract lenses showed 58, 40 and 55 mass values, respectively, ranging from 150 to 600 Da. Similar analyses of the peaks from digests of the ascorbylated calf lens proteins gave 81, 70 and 67 mass values, respectively, of which 100 were identical to the peaks in the cataract lens proteins. A total of 40 of the major species from each digest were analyzed by LC-MS/MS and 36 were shown to be identical. Calf lens proteins incubated without ascorbic acid showed several similar mass values, but the response factors were 100 to 1000-fold less for every modification. Based upon these data, we conclude

  10. Cataract and Cataract Surgery: Nationwide Prevalence and Clinical Determinants

    PubMed Central

    2016-01-01

    This study aimed to investigate the prevalence and clinical determinants of cataract and cataract surgery in Korean population. The 2008–2012 Korean National Health and Nutrition Examination Survey was analyzed, which included 20,419 participants aged ≥ 40 years. The survey is a multistage, probability-cluster survey, which can produce nationally representative estimates. Prevalence of cataract and cataract surgery was estimated. Clinical determinants for those were investigated using logistic regression analyses (LRAs). The prevalence of cataract was 42.28% (95% confidence interval [CI], 40.67–43.89); 40.82% (95% CI, 38.97–42.66) for men and 43.62% (95% CI, 41.91–45.33) for women (P = 0.606). The prevalence of cataract surgery was 7.75% (95% CI, 7.30–8.20); 6.38% (95% CI, 5.80–6.96) for men and 9.01% (95% CI, 8.41–9.61) for women (P < 0.001). Cataract was associated with older age (P < 0.001), men (P = 0.032), lower household income (P = 0.031), lower education (P < 0.001), hypertension (P < 0.001), and diabetes mellitus (DM) (P < 0.001). Cataract surgery was consistently associated with older age, occupation, DM, asthma, and anemia in two LRAs, which compared participants with cataract surgery to those without cataract surgery and those having a cataract but without any cataract surgery, respectively. Hypertension, arthritis, and dyslipidemia were associated with cataract surgery at least in one of these LRAs. These results suggest that there are 9.4 million individuals with cataract and 1.7 million individuals with cataract surgery in Korea. Further studies are warranted to reveal the causality and its possible mechanism of developing/exacerbating cataract in novel determinants (i.e., anemia, asthma, and arthritic conditions) as well as well-known determinants. PMID:27247507

  11. Cataract and Cataract Surgery: Nationwide Prevalence and Clinical Determinants.

    PubMed

    Park, Sang Jun; Lee, Ju Hyun; Kang, Se Woong; Hyon, Joon Young; Park, Kyu Hyung

    2016-06-01

    This study aimed to investigate the prevalence and clinical determinants of cataract and cataract surgery in Korean population. The 2008-2012 Korean National Health and Nutrition Examination Survey was analyzed, which included 20,419 participants aged ≥ 40 years. The survey is a multistage, probability-cluster survey, which can produce nationally representative estimates. Prevalence of cataract and cataract surgery was estimated. Clinical determinants for those were investigated using logistic regression analyses (LRAs). The prevalence of cataract was 42.28% (95% confidence interval [CI], 40.67-43.89); 40.82% (95% CI, 38.97-42.66) for men and 43.62% (95% CI, 41.91-45.33) for women (P = 0.606). The prevalence of cataract surgery was 7.75% (95% CI, 7.30-8.20); 6.38% (95% CI, 5.80-6.96) for men and 9.01% (95% CI, 8.41-9.61) for women (P < 0.001). Cataract was associated with older age (P < 0.001), men (P = 0.032), lower household income (P = 0.031), lower education (P < 0.001), hypertension (P < 0.001), and diabetes mellitus (DM) (P < 0.001). Cataract surgery was consistently associated with older age, occupation, DM, asthma, and anemia in two LRAs, which compared participants with cataract surgery to those without cataract surgery and those having a cataract but without any cataract surgery, respectively. Hypertension, arthritis, and dyslipidemia were associated with cataract surgery at least in one of these LRAs. These results suggest that there are 9.4 million individuals with cataract and 1.7 million individuals with cataract surgery in Korea. Further studies are warranted to reveal the causality and its possible mechanism of developing/exacerbating cataract in novel determinants (i.e., anemia, asthma, and arthritic conditions) as well as well-known determinants.

  12. Lensing duct

    DOEpatents

    Beach, Raymond J. , Benett

    1994-01-01

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic.

  13. Lensing duct

    DOEpatents

    Beach, R.J.; Benett, W.J.

    1994-04-26

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding is described. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic. 3 figures.

  14. Virtual Mentor Cataract Surgery Trainer

    DTIC Science & Technology

    2009-09-01

    AD_________________ AWARD NUMBER: W81XWH-08-1-0531 TITLE: Virtual Mentor Cataract Surgery Trainer...REPORT TYPE Annual 3. DATES COVERED 20 Aug 2008 – 19 Aug 2009 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Virtual Mentor Cataract Surgery ...Distribution Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Virtual Mentor Cataract Surgery Trainer is a computer based, cognitive

  15. Liquefaction for cataract extraction

    PubMed Central

    Labiris, Georgios; Toli, Aspasia; Polychroni, Damaskini; Gkika, Maria; Angelonias, Dimitrios; Kozobolis, Vassilios P.

    2016-01-01

    A systematic review of the recent literature regarding the implementation of the liquefaction in cataract surgery and its short-term and long-term outcomes in various parameters that affect the quality of patients' life, including visual rehabilitation and possible complications was performed based on the PubMed, Medline, Nature and the American Academy of Ophthalmology databases in November 2013 and data from 14 comparative studies were included in this narrative review. Liquefaction is an innovative technology for cataract extraction that uses micropulses of balanced salt solution to liquefy the lens nucleus. Most studies reported that liquefaction is a reliable technology for mild to moderate cataracts, while fragmentation difficulties may be encountered with harder nuclei. PMID:26949656

  16. Liquefaction for cataract extraction.

    PubMed

    Labiris, Georgios; Toli, Aspasia; Polychroni, Damaskini; Gkika, Maria; Angelonias, Dimitrios; Kozobolis, Vassilios P

    2016-01-01

    A systematic review of the recent literature regarding the implementation of the liquefaction in cataract surgery and its short-term and long-term outcomes in various parameters that affect the quality of patients' life, including visual rehabilitation and possible complications was performed based on the PubMed, Medline, Nature and the American Academy of Ophthalmology databases in November 2013 and data from 14 comparative studies were included in this narrative review. Liquefaction is an innovative technology for cataract extraction that uses micropulses of balanced salt solution to liquefy the lens nucleus. Most studies reported that liquefaction is a reliable technology for mild to moderate cataracts, while fragmentation difficulties may be encountered with harder nuclei.

  17. Cadmium and lead exposure and risk of cataract surgery in U.S. adults.

    PubMed

    Wang, Weiye; Schaumberg, Debra A; Park, Sung Kyun

    2016-11-01

    Cataract is a major cause of visual dysfunction and the leading cause of blindness. Elevated levels of cadmium and lead have been found in the lenses of cataract patients, suggesting these metals may play a role in cataract risk. This study aimed to examine the associations of blood lead, blood cadmium and urinary cadmium with cataract risk. We identified 9763 individuals aged 50 years and older with blood lead and cadmium levels, and a randomly selected subgroup of 3175 individuals with available urinary cadmium levels, from the National Health and Nutrition Examination Surveys (NHANES) from 1999 to 2008 (mean age=63years). Participants were considered to have cataract if they self-reported prior cataract surgery in NHANES's vision examination. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed using survey logistic regression models. We identified 1737 cataract surgery cases (the weighted prevalence=14.1%). With adjustment for age, race/ethnicity, gender, education, diabetes mellitus, body mass index, cigarette smoking (serum cotinine and pack-years) and urine hydration, every 2-fold increase in urinary cadmium was associated with a 23% higher risk of cataract surgery (OR=1.23, 95% CI: 1.04, 1.46, p=0.021). We found no associations of cataract surgery with blood cadmium (OR=0.97, 95% CI: 0.89, 1.07) and blood lead (OR=0.97, 95% CI: 0.88, 1.06). Mediation analysis showed that for the smoking-cadmium-cataract pathway, the ratio of smoking's indirect effect to the total effect through cadmium was more than 50%. These results suggest that cumulative cadmium exposure may be an important under-recognized risk factor for cataract. However, these findings should be interpreted with a caution because of inconsistent results between urinary cadmium and blood cadmium.

  18. Senile cataracts and myopia

    SciTech Connect

    Belkin, M.; Jacobs, D.R.; Jackson, S.M.; Zwick, H.

    1982-01-01

    A retrospective survey of 32 persons with myopia and 38 persons with emmetropia who had been operated on at two US Army hospitals on the California coast showed that the persons with myopia who had worn eyeglasses for at least 20 years underwent cataract extraction at a significantly (P less than .00005) older age than the persons with emmetropia (median age at the time of the operation was 70 years, compared with 64 years). These results support the theory that some protection against solar ultraviolet radiation is offered the eyes by eye wear worn continuously and that solar ultraviolet radiation may be a contributing factor in the formation of human senile cataracts.

  19. Inhibitory Effect of Crocin(s) on Lens α-Crystallin Glycation and Aggregation, Results in the Decrease of the Risk of Diabetic Cataract.

    PubMed

    Bahmani, Fereshteh; Bathaie, Seyedeh Zahra; Aldavood, Seyed Javid; Ghahghaei, Arezou

    2016-01-26

    The current study investigates the inhibitory effect of crocin(s), also known as saffron apocarotenoids, on protein glycation and aggregation in diabetic rats, and α-crystallin glycation. Thus, crocin(s) were administered by intraperitoneal injection to normal and streptozotocin-induced diabetic rats. The cataract progression was recorded regularly every two weeks and was classified into four stages. After eight weeks, the animals were sacrificed and the parameters involved in the cataract formation were measured in the animal lenses. Some parameters were also determined in the serum and blood of the rats. In addition, the effect of crocin(s) on the structure and chaperone activity of α-crystallin in the presence of glucose was studied by different methods. Crocin(s) lowered serum glucose levels of diabetic rats and effectively maintained plasma total antioxidants, glutathione levels and catalase activity in the lens of the animals. In the in vitro study, crocin(s) inhibited α-crystallin glycation and aggregation. Advanced glycation end products fluorescence, hydrophobicity and protein cross-links were also decreased in the presence of crocin(s). In addition, the decreased chaperone activity of α-crystallin in the presence of glucose changed and became close to the native value by the addition of crocin(s) in the medium. Crocin(s) thus showed a powerful inhibitory effect on α-crystallin glycation and preserved the structure-function of this protein. Crocin(s) also showed the beneficial effects on prevention of diabetic cataract.

  20. A computer system for the collection and analysis of information for cataract

    NASA Astrophysics Data System (ADS)

    Kirillovykh, K. D.; Nikitaev, V. G.; Ulin, S. E.; Polyakov, E. V.; Trubilin, V. N.; Orlova, O. M.

    2017-01-01

    Automation system for ophthalmologist proposed. The system allows to collect anamnesis(pre-history) using a questionnaire. Its use contributes to the early detection of cataracts. This system will allow the doctor to choose the possible types of intraocular lenses for phacoemulsification. Results of system work are shown.

  1. Effect of hesperetin on chaperone activity in selenite-induced cataract

    PubMed Central

    Oka, Mikako; Tamura, Hiroomi; Takehana, Makoto

    2016-01-01

    Abstract Background. Chaperone activity of α-crystallin in the lens works to prevent protein aggregation and is important to maintain the lens transparency. This study evaluated the effect of hesperetin on lens chaperone activity in selenite-induced cataracts. Methodology. Thirteen-day-old rats were divided into four groups. Animals were given hesperetin (groups G2 and G4) or vehicle (G1 and G3) on Days 0, 1, and 2. Rats in G3 and G4 were administered selenite subcutaneously 4 hours after the first hesperetin injection. On Days 2, 4, and 6, cataract grades were evaluated using slit-lamp biomicroscopy. The amount of a-crystallin and chaperone activity in water-soluble fraction were measured after animals sacrificed. Results. G3 on day 4 had developed significant cataract, as an average cataract grading of 4.6 ± 0.2. In contrast, G4 had less severe central opacities and lower stage cataracts than G3, as an average cataract grading of 2.4 ± 0.4. The a-crystallin levels in G3 lenses were lower than in G1, but the same as G4. Additionally, chaperone activity was weaker in G3 lenses than G1, but the same as in G4. Conclusions. Our results suggest that hesperetin can prevent the decreasing lens chaperone activity and a-crystallin water solubility by administered of selenite. PMID:28352791

  2. New technology update: femtosecond laser in cataract surgery

    PubMed Central

    Nagy, Zoltan Z

    2014-01-01

    Femtosecond lasers represent a new frontier in cataract surgery. Since their introduction and first human treatment in 2008, a lot of new developments have been achieved. In this review article, the physical principle of femtolasers is discussed, together with the indications and side effects of the method in cataract surgery. The most important clinical results are also presented regarding capsulotomy, fragmentation of the crystalline lens, corneal wound creation, and refractive results. Safety issues such as endothelial and macular changes are also discussed. The most important advantage of femtolaser cataract technology at present is that all the important surgical steps of cataract surgery can be planned and customized, delivering unparalleled accuracy, repeatability, and consistency in surgical results. The advantages of premium lenses can be maximally used in visual and presbyopia restoration as well. The advantages of premium lenses can be maximally used, not only in visual, but in presbyopia restoration as well. Quality of vision can be improved with less posterior chamber lens (PCL) tilt, more centralized position of the PCL, possibly less endothelial damage, less macular edema, and less posterior capsule opacification (PCO) formation. This technological achievement should be followed by other technical developments in the lens industry. Hopefully this review article will help us to understand the technology and the results to demonstrate the differences between the use of femtolasers and phacoemulsification-based cataract surgery. The most important data of the literature are summarized to show ophthalmologists the benefits of the technology in order to provide the best refractive results to the patient. PMID:24970994

  3. Automatic Cataract Classification based on Ultrasound Technique Using Machine Learning: A comparative Study

    NASA Astrophysics Data System (ADS)

    Caxinha, Miguel; Velte, Elena; Santos, Mário; Perdigão, Fernando; Amaro, João; Gomes, Marco; Santos, Jaime

    This paper addresses the use of computer-aided diagnosis (CAD) system for the cataract classification based on ultrasound technique. Ultrasound A-scan signals were acquired in 220 porcine lenses. B-mode and Nakagami images were constructed. Ninety-seven parameters were extracted from acoustical, spectral and image textural analyses and were subjected to feature selection by Principal Component Analysis (PCA). Bayes, K Nearest-Neighbors (KNN), Fisher Linear Discriminant (FLD) and Support Vector Machine (SVM) classifiers were tested. The classification of healthy and cataractous lenses shows a good performance for the four classifiers (F-measure ≥92.68%) with SVM showing the highest performance (90.62%) for initial versus severe cataract classification.

  4. An outbreak of cataract with lens rupture and nuclear extrusion in wolf-fish (Anarhicas spp.).

    PubMed

    Bjerkås, E.; Bjerkås, I.; Moksness, E.

    1998-01-01

    Eight spotted (Anarhicas minor Olafsen) and five common wolf-fish (Anarhicas Lupus L), developed cataracts shortly after an episode of increased water temperature and decreased salinity 5 years prior to examination. On clinical examination, the cataracts were mostly bilateral and complete, and a majority of the lenses were lobulated. Inflammatory reaction was, apart from one eye with severe inflammation, limited to iris atrophy. Of the 14 eyes collected for pathomorphological examination, eight had lens rupture with extrusion of the nucleus to the posterior chamber, two showed partly dislocated nuclei with posterior protrusion and two lenses were morgagnian. A multilayered squamous epithelium with abundant desmosomes had developed on the surface of seven of the extruded nuclei. The main cause of the cataracts was considered to be the rapid decrease in water salinity, causing osmotic changes within the eyes with secondary swelling of lens fibers and rupture of the lens capsules.

  5. Planned posterior assisted levitation in severe subluxated cataract: surgical technique and clinical results.

    PubMed

    Lifshitz, Tova; Levy, Jaime; Kratz, Assaf; Belfair, Nadav; Tsumi, Erez

    2012-01-01

    We report the surgical technique and outcome of planned posterior assisted levitation (P-PAL) in four cases of subluxated cataract. P-PAL was planned as the preferred approach in all cases. A spatula was inserted via the pars plana, the whole lens was lifted to the anterior chamber and then removed through a scleral tunnel incision. Anterior chamber intraocular lenses were implanted in all cases. All four eyes had severe subluxation of the crystalline lenses with marked phacodonesis. Two eyes had history of blunt trauma, and the other two eyes had severe pseudoexfoliation with spontaneous lens subluxation. Follow-up ranged from 1 to 2 years in three cases. The postoperative visual acuity was 20/80 or better. No intraoperative complications were observed. In conclusion, the P-PAL technique was successfully performed during cataract surgery in four eyes with severe subluxated cataracts. There were no complications over the long-term follow-up.

  6. Gravitational Lensing

    SciTech Connect

    Lincoln, Don

    2015-06-24

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  7. Gravitational Lensing

    ScienceCinema

    Lincoln, Don

    2016-07-12

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  8. Endophthalmitis following cataract extraction.

    PubMed

    McClellan, K; Coster, D J; Badenoch, P R; Sanders, R; Chandraratnam, E; Kupa, A

    1987-02-01

    We describe a case of bacterial endophthalmitis complicating routine cataract extraction and intraocular lens implantation in a 91-year-old woman. The ocular and systemic factors that may have predisposed to intraocular infection in this case, and the possibility of predicting these pre-operatively, are discussed.

  9. Comparing the content of lipids derived from the eye lenses of various species.

    PubMed

    Panz, Tomasz; Lepiarczyk, Magdalena; Zuber, Agnieszka

    2011-01-01

    The lipid content in the eye lens was analyzed and compared among various species in this study. The eye lens lipids of the following species were investigated: cow, horse, duck, and freshwater trout. Additionally, the lipids derived from cataractous bovine lens and from cataractous human eye lens lipoprotein complexes were analyzed. The following lipid classes were detected in clear lenses: cholesterol, sphingomyelin, phosphatidylcholine, phosphatidyletanolamine, and phosphatidylserine. In cataractous bovine lens and in lipoprotein complexes from human nuclear cataract, phosphatidyloinositol and phosphatidyloglycerol were detected. Cholesterol and sphingomyelin, essential for hypothetical formation of cholesterol-rich domains, were the most abundant lipids in the lenses of all investigated species. These two components of eye lens lipid fraction were analyzed quantitatively using thin layer chromatography and spectrophotometric assay; the other lipids were identified qualitatively using thin layer chromatography.

  10. (An)aerobic bacteria found in secondary-cataract material. A SEM/TEM study.

    PubMed

    Kalicharan, D; Jongebloed, W L; Los, L I; Worst, J G

    1992-01-01

    Twenty four patients, who had marked reduction of vision due to secondary-cataract developed after an ECCE, were treated by surgical cleaning of the posterior lens capsule. During this procedure globular secondary-cataract material was removed and collected for morphological examination by SEM and TEM. Fragments of various sizes and shapes, including some with a 'golf ball' structure, were seen; these closely resembled particles frequently found in cataractous lenses. In addition, in 18 patients micro-organisms were found: rod-shaped bacteria, cocci, and in 2 cases yeasts. These findings were the more remarkable because these were clinically quiet eyes with no signs of intra-ocular inflammation and cultures have been persistently negative. We imagine that these bacteria must have entered the eye during the cataract extraction and have settled there without causing an infection.

  11. Pharmacological Chaperone for Alpha-Crystallin Partially Restores Transparency in Cataract Models

    PubMed Central

    Makley, Leah N.; McMenimen, Kathryn A.; DeVree, Brian T.; Goldman, Joshua W.; McGlasson, Brittney N.; Rajagopal, Ponni; Dunyak, Bryan M.; McQuade, Thomas J.; Thompson, Andrea D.; Sunahara, Roger; Klevit, Rachel E.; Andley, Usha P.; Gestwicki, Jason E.

    2016-01-01

    Cataracts reduce vision in 50% of individuals over 70 years of age and are a common form of blindness worldwide. Cataracts are caused when damage to the major lens crystallin proteins causes their misfolding and aggregation into insoluble amyloids. Using a thermal stability assay, we identified a class of molecules that bind α-crystallins (cryAA and cryAB) and reversed their aggregation in vitro. The most promising compound improved lens transparency in the R49C cryAA and R120G cryAB mouse models of hereditary cataract. It also partially restored solubility in aged mouse and human lenses. These findings suggest an approach to treating cataracts by stabilizing α-crystallins. PMID:26542570

  12. Phakic Intraocular Lenses

    MedlinePlus

    ... Implants and Prosthetics Phakic Intraocular Lenses Phakic Intraocular Lenses Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Phakic intraocular lenses are new devices used to correct nearsightedness. These ...

  13. Cataract Surgery: Fraud, Waste, and Abuse. A Report by the Chairman of the Subcommittee on Health and Long-Term Care of the Select Committee on Aging. House of Representatives, Ninety-Ninth Congress, First Session.

    ERIC Educational Resources Information Center

    Congress of the U.S., Washington, DC. House Select Committee on Aging.

    This report is a summary of the findings from the Subcommittee on Health and Long-Term Care of the United States House of Representatives Select Committee on Aging investigation of cataract surgery and the use of intraocular lenses (IOL's) in the United States. The document provides background on the definition and treatment of cataracts and…

  14. Strategic issues in preventing cataract blindness in developing countries.

    PubMed Central

    Ellwein, L. B.; Kupfer, C.

    1995-01-01

    Cataract blindness is a public health problem of major proportions in developing countries. Intracapsular cataract extraction with aphakic spectacles has been the standard surgical technique for restoring sight. Because of image magnification in the operated eye, however, the result in unilaterally blind patients is less than satisfactory. Fortunately, with the availability of low-cost intraocular lenses (IOL) and ophthalmologists trained in extracapsular surgery, it is now practical to intervene successfully in the unilateral case. The need for increased attention on the quality of the visual high prevalence of cataract blindness in developing countries and an increasing cataract incidence due to an aging population require substantial increases in surgical volume. The third issue relates to cost. If significant increases in surgical volume and quality of outcomes are to be realized without an increased need for external funding, service delivery must be made more efficient. The expansion of IOL surgery for unilateral blindness is a favourable trend in ensuring financial sustainability of delivery systems; patients can be operated on while still economically productive and able to pay rather than waiting for bilateral blindness and a less favourable economic and social impact. If the quality, volume, and cost issues are to be successfully addressed, operational and structural changes to eye care delivery systems are necessary. These changes can be effected through training, technology introduction, management of facilities, social marketing, organizational partnerships, and evaluation. With improved understanding of the critical factors in successful models their widespread replication will be facilitated. PMID:8846495

  15. Virtual Mentor Cataract Surgery Trainer

    DTIC Science & Technology

    2010-09-01

    TITLE: Virtual Mentor Cataract Surgery Trainer PRINCIPAL INVESTIGATOR: Principal Investigator: John I. Loewenstein MD Co-Investigator: Bonnie A...AND SUBTITLE Virtual Mentor Cataract Surgery Trainer 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-08-1-0531 5c. PROGRAM ELEMENT NUMBER...AVAILABILITY STATEMENT Approved for public release; distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The Virtual Mentor Cataract Surgery

  16. Contact Lenses for Vision Correction

    MedlinePlus

    ... Ophthalmologist Patient Stories Español Eye Health / Glasses & Contacts Contact Lenses Sections Contact Lenses for Vision Correction Proper ... to Know About Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd ...

  17. AKT activation promotes PTEN hamartoma tumor syndrome–associated cataract development

    PubMed Central

    Sellitto, Caterina; Li, Leping; Gao, Junyuan; Robinson, Michael L.; Lin, Richard Z.; Mathias, Richard T.; White, Thomas W.

    2013-01-01

    Mutations in the human phosphatase and tensin homolog (PTEN) gene cause PTEN hamartoma tumor syndrome (PHTS), which includes cataract development among its diverse clinical pathologies. Currently, it is not known whether cataract formation in PHTS patients is secondary to other systemic problems, or the result of the loss of a critical function of PTEN within the lens. We generated a mouse line with a lens-specific deletion of Pten (PTEN KO) and identified a regulatory function for PTEN in lens ion transport. Specific loss of PTEN in the lens resulted in cataract. PTEN KO lenses exhibited a progressive age-related increase in intracellular hydrostatic pressure, along with, increased intracellular sodium concentrations, and reduced Na+/K+-ATPase activity. Collectively, these defects lead to lens swelling, opacities and ultimately organ rupture. Activation of AKT was highly elevated in PTEN KO lenses compared to WT mice. Additionally, pharmacological inhibition of AKT restored normal Na+/K+-ATPase activity in primary cultured lens cells and reduced lens pressure in intact lenses from PTEN KO animals. These findings identify a direct role for PTEN in the regulation of lens ion transport through an AKT-dependent modulation of Na+/K+-ATPase activity, and provide a new animal model to investigate cataract development in PHTS patients. PMID:24270425

  18. Glasses and Contact Lenses

    MedlinePlus

    ... dientes Video: Getting an X-ray Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A What's in this ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  19. Gravitational lenses

    SciTech Connect

    Turner, E.L.

    1988-07-01

    For several years astronomers have devoted considerable effort to finding and studying a class of celestial phenomena whose very existence depends on rare cosmic accidents. These are gravitational-lens events, which occur when two or more objects at different distances from the earth happen to lie along the same line of sight and so coincide in the sky. The radiation from the more distant object, typically a quasar, is bent by the gravitational field of the foreground object. The bending creates a cosmic mirage: distorted or multiple images of the background object. Such phenomena may reveal many otherwise undetectable features of the image source, of the foreground object and of the space lying between them. Such observations could help to resolve several fundamental questions in cosmology. In the past decade theoretical and observational research on gravitational lenses has grown rapidly and steadily. At this writing at least 17 candidate lens systems have been discussed in the literature. Of the 17 lens candidates reported so far in professional literature, only five are considered to have been reliably established by subsequent observations. Another three are generally regarded as weak or speculative cases with less than 50 percent chance of actually being lens systems. In the remaining nine cases the evidence is mixed or is sparse enough so that the final judgment could swing either way. As might be concluded, little of the scientific promise of gravitational lenses has yet been realized. The work has not yielded a clear value for the proportionality constant or any of the other fundamental cosmological parameter. 7 figs.

  20. X-Ray induced cataract is preceded by LEC loss, and coincident with accumulation of cortical DNA, and ROS; similarities with age-related cataracts

    PubMed Central

    Zitnik, Galynn; Tsai, Ryan; Wolf, Norman

    2010-01-01

    Purpose To compare age-related cataractous (ARC) changes in unirradiated mice lenses to those induced by head-only X-irradiation of 3 month-old mice. Methods lens epithelial cells (LECs) as well as partially degraded cortical DNA were visualized in fixed sections using 4',6-diamidino-2-phenylindole (DAPI) staining, and in fresh lenses using the vital stain Hoechst 33342. reactive oxygen species (ROS) activity was also visualized directly in fresh lenses using the vital dye Dihydrorhodamine (DHR). In fixed lenses an antibody specific for 8-OH Guanosine (8-OH-G) lesions was used to visualize DNA oxidative adducts from ROS damage. Alpha smooth muscle actin was visualized using specific antibodies to determine if myofibroblasts were present. Fluorescence was quantified using Laser Scanning Confocal Microscopy (LSCM). The degree of lens opacity and cataract formation was determined by slit lamp, or from digitalized images of light reflections taken with a low magnification light microscope. Results Using DNA- and ROS-specific vital fluorescent dyes, and laser scanning confocal microscopy we have previously described 4 changes in the aging rodent lenses: 1) a significantly decreased density of surface LECs in lenses from old compared to younger mice and rats; 2) a very large increase in retained cortical nuclei and DNA fragments in the secondary lens fibers of old rodent lenses; 3) increased cortical ROS in old rodent lenses; 4) increased cataract concomitantly with the cortical DNA and ROS increases. In the current study we report that these same 4 changes also occur in an accelerated fashion in mice given head-only X-irradiation at 3 months of age. In addition to vital staining of fresh lenses, we also examined sections from fixed eyes stained with DAPI or hematoxylin and eosin (H&E) and found the same loss of surface LECs and accumulation of undigested nuclei and debris in secondary lens fibers occur with age or following X-irradiation. In addition sections from fixed

  1. IOL Implants: Lens Replacement and Cataract Surgery (Intraocular Lenses)

    MedlinePlus

    ... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology Information for: International Ophthalmologists Media Medical Students Patients and Public Technicians and Nurses ...

  2. Microorganisms found in secondary cataract material of ECCE patients, a study with SEM and TEM.

    PubMed

    Kalicharan, D; Jongebloed, W L; Los, L I; Worst, J G

    1993-01-01

    Globular secondary cataract material, removed from 24 patients with ECCE after ophthalmic cleaning of the anterior capsule, were investigated with SEM and TEM. Besides spherical, somewhat oval shaped bodies of various shape and size comparable with those found in cataractous lenses, (an)aerobic bacteria and yeast cells were found in approximately 70% of the cases, all of them in eyes without intra-ocular inflammation. Probably these bacteria have been transferred from the conjunctiva during IOL.-implantation and were encapsulated without starting an inflammation.

  3. Age and Smoking Related Changes in Metal Ion Levels in Human Lens: Implications for Cataract Formation.

    PubMed

    Langford-Smith, Alex; Tilakaratna, Viranga; Lythgoe, Paul R; Clark, Simon J; Bishop, Paul N; Day, Anthony J

    2016-01-01

    Age-related cataract formation is the primary cause of blindness worldwide and although treatable by surgical removal of the lens the majority of sufferers have neither the finances nor access to the medical facilities required. Therefore, a better understanding of the pathogenesis of cataract may identify new therapeutic targets to prevent or slow its progression. Cataract incidence is strongly correlated with age and cigarette smoking, factors that are often associated with accumulation of metal ions in other tissues. Therefore this study evaluated the age-related changes in 14 metal ions in 32 post mortem human lenses without known cataract from donors of 11 to 82 years of age by inductively coupled plasma mass spectrometry; smoking-related changes in 10 smokers verses 14 non-smokers were also analysed. A significant age-related increase in selenium and decrease in copper ions was observed for the first time in the lens tissue, where cadmium ion levels were also increased as has been seen previously. Aluminium and vanadium ions were found to be increased in smokers compared to non-smokers (an analysis that has only been carried out before in lenses with cataract). These changes in metal ions, i.e. that occur as a consequence of normal ageing and of smoking, could contribute to cataract formation via induction of oxidative stress pathways, modulation of extracellular matrix structure/function and cellular toxicity. Thus, this study has identified novel changes in metal ions in human lens that could potentially drive the pathology of cataract formation.

  4. Age and Smoking Related Changes in Metal Ion Levels in Human Lens: Implications for Cataract Formation

    PubMed Central

    Langford-Smith, Alex; Tilakaratna, Viranga; Lythgoe, Paul R.; Clark, Simon J.; Bishop, Paul N.; Day, Anthony J.

    2016-01-01

    Age-related cataract formation is the primary cause of blindness worldwide and although treatable by surgical removal of the lens the majority of sufferers have neither the finances nor access to the medical facilities required. Therefore, a better understanding of the pathogenesis of cataract may identify new therapeutic targets to prevent or slow its progression. Cataract incidence is strongly correlated with age and cigarette smoking, factors that are often associated with accumulation of metal ions in other tissues. Therefore this study evaluated the age-related changes in 14 metal ions in 32 post mortem human lenses without known cataract from donors of 11 to 82 years of age by inductively coupled plasma mass spectrometry; smoking-related changes in 10 smokers verses 14 non-smokers were also analysed. A significant age-related increase in selenium and decrease in copper ions was observed for the first time in the lens tissue, where cadmium ion levels were also increased as has been seen previously. Aluminium and vanadium ions were found to be increased in smokers compared to non-smokers (an analysis that has only been carried out before in lenses with cataract). These changes in metal ions, i.e. that occur as a consequence of normal ageing and of smoking, could contribute to cataract formation via induction of oxidative stress pathways, modulation of extracellular matrix structure/function and cellular toxicity. Thus, this study has identified novel changes in metal ions in human lens that could potentially drive the pathology of cataract formation. PMID:26794210

  5. Diplopia as the Complication of Cataract Surgery

    PubMed Central

    Gawęcki, Maciej; Grzybowski, Andrzej

    2016-01-01

    The authors present systematic review of aetiology and treatment of diplopia related to cataract surgery. The problem is set in the modern perspective of changing cataract surgery. Actual incidence is discussed as well as various modalities of therapeutic options. The authors provide the guidance for the contemporary cataract surgeon, when to expect potential problem in ocular motility after cataract surgery. PMID:26998351

  6. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

  7. Etiopathogenesis of cataract: An appraisal

    PubMed Central

    Gupta, Varun B; Rajagopala, Manjusha; Ravishankar, Basavaiah

    2014-01-01

    Natural eye lens is a crystalline substance to produce a clear passage for light. Cataract is opacity within the clear lens of the eye and is the dominant cause of socio-medical problem i.e., blindness worldwide. The only available treatment of cataract is surgery. However, insufficient surgical facilities in poor and developing countries and post-operative complications inspire researchers to find out other modes of treatment for cataract. In this review, an attempt has been made to appraise various etiological factors of cataract to make their perception clear to build up counterpart treatment. Present study is an assortment of various available literatures and electronic information in view of cataract etiopathogenesis. Various risk factors have been identified in development of cataracts. They can be classified in to genetic factors, ageing (systemic diseases, nutritional and trace metals deficiencies, smoking, oxidative stress etc.), traumatic, complicated (inflammatory and degenerative diseases of eye), metabolic (diabetes, galactosemia etc.), toxic substances including drugs abuses, alcohol etc., radiation (ultraviolet, electromagnetic waves etc.) are implicated as significant risk factors in the development of cataract. PMID:24618482

  8. Symbolic algebra approach to the calculation of intraocular lens power following cataract surgery

    NASA Astrophysics Data System (ADS)

    Hjelmstad, David P.; Sayegh, Samir I.

    2013-03-01

    We present a symbolic approach based on matrix methods that allows for the analysis and computation of intraocular lens power following cataract surgery. We extend the basic matrix approach corresponding to paraxial optics to include astigmatism and other aberrations. The symbolic approach allows for a refined analysis of the potential sources of errors ("refractive surprises"). We demonstrate the computation of lens powers including toric lenses that correct for both defocus (myopia, hyperopia) and astigmatism. A specific implementation in Mathematica allows an elegant and powerful method for the design and analysis of these intraocular lenses.

  9. Iris-supported lens implantation v. simple cataract extraction. An analysis of data.

    PubMed

    Galin, M A; Obstbaum, S A; Boniuk, V; Galin, A; Silverstone, D

    1977-04-01

    In a study of a selected age (greater than 60) and ocularly matched population requiring cataract extraction, a perfectly executed intracapsular cataract extraction followed by the introduction of a Fyodorov Type II ("Sputnik") lens did not lead to irreversible anterior or posterior segment changes different from those seen in a group followed for from 5 to 9 years. It did lead to an incidence of implant support dislocation and to membrane formation in about 10% of cases, reducible to about 2% with correctly made lenses and the appropriate use of postoperative drugs. The incidence of corneal degeneration (0), retinal detachment (2%), and intraretinal cystic maculopathy (3%) was equal in each group. Visual acuity levels were also equal. In appropriate cases, if the surgery is carried out with sufficient skill, the reward to risk ratio of implantation not only justifies but indicates the use of such lenses.

  10. [Studies of the changes in crystalline lens transparency in subjects at risk of developing cataract].

    PubMed

    Gerkowicz, K; Prost, M; Gerkowicz, M; Katski, W; Jedrzejewski, D

    1991-12-01

    The aim of the survey was a comparison of transparency of the lenses examined by means of in vivo spectrophotometry of the eye in metalurgists threatened by development of cataract--with the results obtained in persons not engaged in metalurgy and selected by chance from the population. The investigations showed that the transparency of the lenses was lower in the group of the metalurgists than in the control group in spite of the fact that the ophthalmological examination did not detect any lens changes. The results of this study show that the in vivo spectrophotometry may find some employment for detection of changes in the lens which may occur in persons threatened by development of cataract.

  11. [Cataract operation following goniotrepanation].

    PubMed

    Polychronakos, D; Deligiannidis, P; Polychronakos, A

    1984-03-01

    Cataract surgery after goniotrepanation has been performed on 75 eyes at the St. Demetrius Hospital Eye Clinic in Thessaloniki , Greece, in recent years. The patients' ages ranged from 46 to 84 years. Intraocular pressure was between 8 and 19 mm Hg in all but 4 eyes which had IOPs of between 22 and 30 mm Hg. In order to leave the fistula untouched, the incision with the Graefe knife was made in the area of the cornea close to the limbus; it was closed with 7 sutures (7-0 silk). Prolapse of the vitreous occurred in 7 cases. It was possible to follow up 52 of the eyes: IOP remained regulated postoperatively with one exception (26 mm Hg); the upper pressure limit was 18 mm Hg.

  12. Flavin nucleotides in human lens: regional distribution in brunescent cataracts.

    PubMed

    Bhat, K S; Nayak, S

    1998-12-01

    The biochemical mechanism(s) underlying brunescent cataracts remain unclear. Oxidative stress due to reactive oxygen species may have a role in the pigmentation process in eye lens. We have analysed human cataractous lenses for flavins by high-performance liquid chromatography (HPLC), since flavins are light sensitive and act as endogenous sensitizers generating reactive oxygen species in the eye. The most significant observation in this study is that higher levels of flavin nucleotides occur in brown lens compared to yellow lens. The concentration of flavin nucleotides (flavin monouncleotide, FMN + flavin adenine dinucleotide, FAD) was highest in the nuclear region of the lens followed by the cortical and capsule-epithelial regions. However, the ratio of FAD/FMN was lowest in the nuclear region of the lens followed by other regions. On the other hand, riboflavin was not detected in any of the lens (cataractous) regions. These results suggest that the observed increase in flavin nucleotides in the ocular tissue could contribute towards deepening of lens pigmentation.

  13. A Comparison of Different Operating Systems for Femtosecond Lasers in Cataract Surgery.

    PubMed

    Wu, B M; Williams, G P; Tan, A; Mehta, J S

    2015-01-01

    The introduction of femtosecond lasers is potentially a major shift in the way we approach cataract surgery. The development of increasingly sophisticated intraocular lenses (IOLs), coupled with heightened patient expectation of high quality postsurgical visual outcomes, has generated the need for a more precise, highly reproducible and standardized method to carry out cataract operations. As femtosecond laser-assisted cataract surgery (FLACS) becomes more commonplace in surgical centers, further evaluation of the potential risks and benefits needs to be established, particularly in the medium/long term effects. Healthcare administrators will also have to weigh and balance out the financial costs of these lasers relative to the advantages they put forth. In this review, we provide an operational overview of three of five femtosecond laser platforms that are currently commercially available: the Catalys (USA), the Victus (USA), and the LDV Z8 (Switzerland).

  14. A Comparison of Different Operating Systems for Femtosecond Lasers in Cataract Surgery

    PubMed Central

    Wu, B. M.; Williams, G. P.; Tan, A.; Mehta, J. S.

    2015-01-01

    The introduction of femtosecond lasers is potentially a major shift in the way we approach cataract surgery. The development of increasingly sophisticated intraocular lenses (IOLs), coupled with heightened patient expectation of high quality postsurgical visual outcomes, has generated the need for a more precise, highly reproducible and standardized method to carry out cataract operations. As femtosecond laser-assisted cataract surgery (FLACS) becomes more commonplace in surgical centers, further evaluation of the potential risks and benefits needs to be established, particularly in the medium/long term effects. Healthcare administrators will also have to weigh and balance out the financial costs of these lasers relative to the advantages they put forth. In this review, we provide an operational overview of three of five femtosecond laser platforms that are currently commercially available: the Catalys (USA), the Victus (USA), and the LDV Z8 (Switzerland). PMID:26483973

  15. Cataract-specific posttranslational modifications and changes in the composition of urea-soluble protein fraction from the rat lens

    PubMed Central

    Yanshole, Lyudmila V.; Cherepanov, Ivan V.; Snytnikova, Olga A.; Yanshole, Vadim V.; Sagdeev, Renad Z.

    2013-01-01

    Purpose To determine age-related changes in the composition of the urea-soluble (US) protein fraction from lenses of senescence-accelerated OXYS (cataract model) and Wistar (control) rats and to establish posttranslational modifications (PTMs) occurring under enhanced oxidative stress in OXYS lenses. Methods The identity and the relative abundance of crystallins in the US fractions were determined using two-dimensional gel electrophoresis (2-DE) and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MS). The identities and the positions of PTMs were established using MS/MS measurements. Results Two-dimensional gel electrophoresis maps of US protein fractions were obtained for lenses of 3-, 12-, and 62-week-old Wistar and OXYS rats, and the relative abundance of different isoforms of α-, β-, and γ-crystallins was determined. β-Crystallins were the major contributor of the US fraction in 3-week-old lenses (above 50%), γ-crystallins in 12-week-old lenses (50–60%), and in 62-week-old lenses, the contributions from all three crystallin families leveled out. The major interstrain difference was the elevated level of α-crystallins in the US fraction from 12-week-old OXYS lenses. Spots with increased relative abundance in OXYS maps were attributed to the cataract-specific spots of interest. The crystallins from these spots were subjected to MS/MS analysis, and the positions of acetylation, oxidation, deamidation, and phosphorylation were established. Conclusions The increased relative abundance of α-crystallins in the US fraction from 12-week-old OXYS lenses points to the fast insolubilization of α-crystallins under oxidative stress. Most of the PTMs attributed to the cataract-specific modifications also correspond to α-crystallins. These PTMs include oxidation of methionine residues, deamidation of asparagine and glutamine residues, and phosphorylation of serine and threonine residues. PMID:24227915

  16. Cataract surgery in ancient Egypt.

    PubMed

    Blomstedt, Patric

    2014-03-01

    Ophthalmology was one of the most important specialties in Egyptian medicine, and more specialists are known in this field than in any other. This specialization seems, however, to have been of a purely noninvasive nature. Even though it has been claimed that cataract surgery was performed in pharaonic Egypt, careful analysis of the sources does not support the claim. No example of cataract surgery or of any other invasive ophthalmologic procedure can be found in the original sources.

  17. TOPICAL REVIEW Gravitational lensing

    NASA Astrophysics Data System (ADS)

    Bartelmann, Matthias

    2010-12-01

    Gravitational lensing has developed into one of the most powerful tools for the analysis of the dark universe. This review summarizes the theory of gravitational lensing, its main current applications and representative results achieved so far. It has two parts. In the first, starting from the equation of geodesic deviation, the equations of thin and extended gravitational lensing are derived. In the second, gravitational lensing by stars and planets, galaxies, galaxy clusters and large-scale structures is discussed and summarized.

  18. Cataract surgery in pseudoexfoliation syndrome.

    PubMed

    Sangal, Neha; Chen, Teresa C

    2014-01-01

    Pseudoexfoliation (PXF) syndrome is characterized by the deposition of distinctive fibrillar material in the anterior segment of the eye. It is an age-related process that is associated with open and narrow angle glaucomas and the formation of cataracts. Not only is PXF associated with the formation of dense nuclear cataracts, it is also well known that those presenting with PXF are at a higher risk of developing complications during, and even after, cataract surgery. Complications associated with cataract surgery in PXF can occur from poor pupillary dilation, zonular weakness leading to intraoperative or postoperative lens dislocation and vitreous loss, postoperative intraocular pressure (IOP) spikes potentiating glaucomatous damage, capsular phimosis, prolonged inflammation, and postoperative corneal decompensation. The surgeon should be prepared to encounter the various potential intraoperative and postoperative complications in eyes with pseudoexfoliation syndrome during cataract surgery. In this way, the surgeon can plan his/her surgical technique to help avoid surprises during cataract surgery and be prepared to manage the potential postoperative complications that can occur in pseudoexfoliation eyes.

  19. Contact Lenses on Submarines

    DTIC Science & Technology

    2014-09-26

    NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY SUBMARINE BASE, GROTON, CONN. REPORT NUMBER 1048 CONTACT LENSES ON SUBMARINES... CONTACT LENSES ON SUBMARINES by James F. Socks, CDR, MSC, USN NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY REPORT NUMBER 1048 NAVAL MEDICAL RESEARCH...DRSCHLAB Approved for public release; distribution unlimited SUMMARY PAGE PROBLEM To determine the feasibility of wearing contact lenses aboard

  20. Cataract, cost: curious questions.

    PubMed

    Moran, D J

    1999-02-01

    An investigation of the pricing of implantable prosthetic devices in Australia reveals some alarming practices. A governmental mechanism exists to prop up the pricing of 7500 listed devices to levels that are unacceptably high by world standards. Private hospitals and doctors are able, legally, to profit by marking up the cost of these devices from the market price to this artificially inflated price. Even the open market prices of implantable prosthetic items, such as intra-ocular lenses, are high by international standards. In a time of budgetary constraint for health spending and rapidly increasing use of these devices, these issues urgently need to be addressed in Australia.

  1. Lenses for JWST

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald; Richard, Johan; Kneib, Jean-Paul; Repp, Andrew; Atek, Hakim; Egami, Eiichi; Windhorst, Rogier; Edge, Alastair

    2016-08-01

    JWST will dramatically advance our knowledge and understanding of the first generations of galaxies at z>10, their role in the re-ionization of the Universe, and the evolutionary processes that gave rise to the complexity and diversity of galaxies at the current epoch. As demonstrated by HST legacy projects like CLASH and the Hubble Frontier Fields, gravitational amplification by massive galaxy clusters can significantly extend the depth of the required observations. However, for JWST, reducing any diffuse background light will be just as crucial. We here propose Spitzer/IRAC observations of six massive cluster lenses, specifically selected as candidates for observation with JWST. By (a) quantifying the amount of intra-cluster light and (b) enabling us to improve our current lens models, the data resulting from the requested observations will be instrumental for the final selection of cluster targets that maximize the scientific returns of deep JWST observations.

  2. Aldose reductase expression as a risk factor for cataract.

    PubMed

    Snow, Anson; Shieh, Biehuoy; Chang, Kun-Che; Pal, Arttatrana; Lenhart, Patricia; Ammar, David; Ruzycki, Philip; Palla, Suryanarayana; Reddy, G Bhanuprakesh; Petrash, J Mark

    2015-06-05

    Aldose reductase (AR) is thought to play a role in the pathogenesis of diabetic eye diseases, including cataract and retinopathy. However, not all diabetics develop ocular complications. Paradoxically, some diabetics with poor metabolic control appear to be protected against retinopathy, while others with a history of excellent metabolic control develop severe complications. These observations indicate that one or more risk factors may influence the likelihood that an individual with diabetes will develop cataracts and/or retinopathy. We hypothesize that an elevated level of AR gene expression could confer higher risk for development of diabetic eye disease. To investigate this hypothesis, we examined the onset and severity of diabetes-induced cataract in transgenic mice, designated AR-TG, that were either heterozygous or homozygous for the human AR (AKR1B1) transgene construct. AR-TG mice homozygous for the transgene demonstrated a conditional cataract phenotype, whereby they developed lens vacuoles and cataract-associated structural changes only after induction of experimental diabetes; no such changes were observed in AR-TG heterozygotes or nontransgenic mice with or without experimental diabetes induction. We observed that nondiabetic AR-TG mice did not show lens structural changes even though they had lenticular sorbitol levels almost as high as the diabetic AR-TG lenses that showed early signs of cataract. Over-expression of AR led to increases in the ratio of activated to total levels of extracellular signal-regulated kinase (ERK1/2) and c-Jun N-terminal (JNK1/2), which are known to be involved in cell growth and apoptosis, respectively. After diabetes induction, AR-TG but not WT controls had decreased levels of phosphorylated as well as total ERK1/2 and JNK1/2 compared to their nondiabetic counterparts. These results indicate that high AR expression in the context of hyperglycemia and insulin deficiency may constitute a risk factor that could predispose the

  3. Early detection of cataract and response to pantethine therapy with non-invasive static and dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Ansari, Rafat R.; King, James F.; Seeberger, Teri; Clark, John I.

    2003-07-01

    Cataractogenesis is a risk factor for space travelers. Here on earth, half of all blindness is due to cataracts. At this time, the only known treatment is surgical removal of the lens. In this paper, we present static and dynamic light scattering (DLS) measurements of early onset of cataract before it has any effect on vision and to test the effectiveness of pantethine as an anticataract agent in reversing cataracts. In this preliminary study, experiments were conducted on 12 rodents. Static measurements were performed by scanning the animal eye (cornea to retina) at a laser power of 80 microwatts to collect photons or scattered intensity in steps of 10 microns. The rodents studied were control, selenite injected, and selenite plus pantethine injected. Selenite was used to induce cataracts. Static and dynamic changes (increase in light scatter and crystalline size) in the lenses are quantitatively measured as early as 1 day post selenite injections. Scattering intensity and DLS measurements from lenses of animals administered pantethine resembled controls. These subtle molecular changes are not noticeable when the animals are examined with conventional ophthalmic instruments because their lenses remain transparent. Acknowledgements: Technical support from C.Ganders, University of Washington, Seattle, NEI research grant EY04542 (JIC) and support under a NASA-NEI/NIH interagency agreement (RRA) are greatly appreciated. JFK works for QSS Inc. at NASA GRC.

  4. Genetics Home Reference: hyperferritinemia-cataract syndrome

    MedlinePlus

    ... Facebook Share on Twitter Your Guide to Understanding Genetic Conditions Search MENU Toggle navigation Home Page Search ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions hyperferritinemia-cataract syndrome hyperferritinemia-cataract ...

  5. Cataract Surgery in the Glaucoma Patient

    PubMed Central

    Kung, Jennifer S.; Choi, Daniel Y.; Cheema, Anjum S.; Singh, Kuldev

    2015-01-01

    To summarize the role of cataract surgery in the glaucoma patient, in terms of the effect on intraocular pressure (IOP) as well as diagnostic and therapeutic considerations for those with both conditions. Recent evidence suggests that cataract extraction may produce a significant and sustained IOP reduction in individuals with open-angle glaucoma, ocular hypertension, and angle-closure glaucoma. Cataract removal may improve the practitioner's ability to interpret perimetric testing, and re-establishing perimetric and optic nerve imaging baselines is recommended after cataract surgery. The sequence of cataract surgery relative to glaucoma surgery impacts the likelihood of complications and surgical success. There are multiple benefits to perform cataract surgery prior to glaucoma surgery while cataract surgery after trabeculectomy increases the risk of subsequent filtration failure. As “minimally invasive glaucoma surgeries” continue to improve in terms of efficacy, there is an evolving role for combined cataract and glaucoma surgery in patients with early to moderate stages of glaucoma. PMID:25624668

  6. Update and clinical utility of the LenSx femtosecond laser in cataract surgery

    PubMed Central

    Roberts, Timothy V; Lawless, Michael; Sutton, Gerard; Hodge, Chris

    2016-01-01

    The introduction of femtosecond lasers to cataract surgery has been the major disruptive technology introduced into ophthalmic surgery in the last decade. Femtosecond laser cataract surgery (FLACS) integrates high-resolution anterior segment imaging with a femtosecond laser allowing key steps of cataract surgery to be performed with computer-guided laser accuracy, precision, and reproducibility. Since the introduction of FLACS, there have been significant advances in laser software and hardware as well as surgeon experience, with over 250 articles published in the peer-reviewed literature. This review examines the published evidence relating to the LenSx platform and discusses surgical techniques, indications, safety, and clinical results. PMID:27799728

  7. EDITORIAL: Focus on Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Jain, Bhuvnesh

    2007-11-01

    Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

  8. Isorhamnetin-3-glucoside alleviates oxidative stress and opacification in selenite cataract in vitro.

    PubMed

    Devi, V Gayathri; Rooban, B N; Sasikala, V; Sahasranamam, V; Abraham, Annie

    2010-09-01

    Oxidative stress has long been recognized as an important mediator in the pathogenesis of cataract and the goal of this study was to determine the efficacy of isorhamnetin-3-glucoside (IR3G) in alleviating the toxicity induced by sodium selenite in in vitro culture condition. IR3G is the bioactive flavonoid isolated and characterized from the leaves of Cochlospermum religiosum. Enucleated rat lenses were maintained in organ culture containing M-199 medium alone (G-I), supplemented with 0.1 mM selenite (G-II) and selenite + 25 microg/ml IR3G (G-III). Treatment to G-III was from the second to fifth day while selenite administration to G-II & III was done on the third day. The antioxidant potential of the compound was assessed by Cu(2+) induced lipoprotein diene formation and superoxide scavenging assays. Morphological examination of the lenses also gave a supporting data. Antioxidant enzymes-superoxide dismutase (SOD), catalase and concentration of reduced glutathione (GSH) were significantly lower, while TBARS showed an increase in G-II than that in G-III and G-I lenses. Activity of Ca(2+)-ATPase was decreased and level of calcium was increased in G-II than G-III and G-I lenses. These data suggest that IR3G is able to significantly retard selenite cataract in vitro by virtue of its antioxidant property.

  9. Influence of Corticosteroids and Vitamin E Deficiency on Onset and Cytopathology of Radiation-Induced Cataract

    NASA Astrophysics Data System (ADS)

    Junk, A. K.; Worgul, B. V.

    Cataracts characteristic of those arising from radiation exposure have been reported among the astronaut and cosmonaut corps. This being the case it is critical to appreciate how radiogenic cataracts relate to those arising from other exogenous causes such as therapeutics, which may, one day, have to be administered on an extended mission. Because they produce precisely the same clinical picture, corticosteroids are examples of a class of drugs that potentially can exacerbate damage to the lens from radiation. On the other hand, Vitamin E, a free radical scavenger, has been shown to ameliorate oxidative damage as caused by ionizing radiation and evidence is accumulating that it may constitute protection from radiogenic damage. An experimental study was conducted to understand if corticosteroids with and in the absence of Vitamin E deficiency modulate the onset of cataract induced by ionizing radiation. The right eyes of 72 28-day-old Brown-Norway rats were irradiated with 6 Gy of 240 kV X-rays, the shielded left eyes served as controls. Half of the animals were maintained on a Vitamin E free diet after irradiation, the others were kept on regular chow. In each nutritional group 18 rats additionally received dexamethasone. The initial daily dose of 10 mg/kg body weight injected subcutaneously was reduced to 0.5 mg/kg over the course of 6 months. Cataract onset and development were followed by weekly slit-lamp exam. After 6 month the lenses were harvested for microscopic analyses. Irradiated eyes in all treatment subgroups showed early cataract onset [5 wks versus 11 wks in controls (p<0.0001)]. Corticosteroids accounted for accelerated cataract development in both irradiated (p<0.0005) and non-irradiated eyes (p<0.0001) relative to respective control eyes. Vitamin E deficiency did not affect cataract incidence in combination with radiation or steroids alone. Unexpectedly, when compared to irradiated controls, cataract development was inhibited in the group that

  10. Influence of corticosteroids and vitamin E deficiency on onset of radiation-induced cataract

    NASA Astrophysics Data System (ADS)

    Junk, A. K.; Worgul, B. W.

    Cataracts characteristic of those arising from radiation exposure have been reported among the astronaut and cosmonaut corps. This being the case it is critical to appreciate how radiogenic cataracts relate to those arising from other exogenous causes such as therapeutics, which may, one day, have to be administered on an extended mission. Because they produce precisely the same clinical picture, corticosteroids are examples of a class of drugs that potentially can exacerbate damage to the lens from radiation. On the other hand, Vitamin E, a free radical scavenger, has been shown to ameliorate oxidative damage as caused by ionizing radiation and evidence is accumulating that it may constitute protection from radiogenic damage. An experimental study was conducted to understand if corticosteroids with, and in the absence of Vitamin E deficiency modulate the onset of cataract induced by ionizing radiation. The right eyes of seventy-two 28-day-old Brown-Norway rats were irradiated with 6 Gy of 240 kV X-rays, the shielded left eyes served as controls. Half of the animals were maintained on a Vitamin E free diet after irradiation, the others were kept on standard chow. Fifty per cent of the animals in each nutritional group received dexamethasone. The initial daily dose of 10 mg/kg body weight injected subcutaneously was reduced to 0.5 mg/kg over the course of six months. Cataract onset and development were followed by weekly slit-lamp exam. After six month the lenses were harvested for microscopic analyses. Irradiated eyes in all treatment subgroups showed early cataract onset [5 wks vs. 11 wks in controls ( p < 0.0001)]. Corticosteroids accounted for accelerated cataract development in both irradiated ( p < 0.0005) and non-irradiated eyes ( p < 0.0001) relative to respective control eyes. Vitamin E deficiency did not affect cataract incidence in combination with radiation or steroids alone. Unexpectedly, when compared to irradiated controls, cataract development was

  11. Accumulation of argpyrimidine, a methylglyoxal-derived advanced glycation end product, increases apoptosis of lens epithelial cells both in vitro and in vivo.

    PubMed

    Kim, Junghyun; Kim, Ohn Soon; Kim, Chan-Sik; Sohn, Eunjin; Jo, Kyuhyung; Kim, Jin Sook

    2012-02-29

    The formation of advanced glycation end products (AGEs) has been considered to be a potential causative factor of injury to lens epithelial cells (LECs). Damage of LECs is believed to contribute to cataract formation. The purpose of this study was to investigate the cytotoxic effect of AGEs on LECs both in vitro and in vivo. We examined the accumulation of argpyrimidine, a methylglyoxal-derived AGE, and the expression of apoptosis-related molecules including nuclear factor- kappaB (NF-κB), Bax, and Bcl-2 in the human LEC line HLE-B3 and in cataractous lenses of Zucker diabetic fatty (ZDF) rats, an animal model of type 2 diabetes. In cataractous lenses from twenty-oneweek- old ZDF rats, LEC apoptosis was markedly increased, and the accumulation of argpyrimidine as well as subsequent activation of NF-κB in LECs were significantly enhanced. The ratio of Bax to Bcl-2 protein levels was also increased. In addition, the accumulation of argpyrimidine triggered apoptosis in methylglyoxal- treated HLE-B3 cells. However, the presence of pyridoxamine (an AGEs inhibitor) and pyrrolidine dithiocarbamate (a NF-κB inhibitor) prevented apoptosis in HLE-B3 cells through the inhibition of argpyrimidine formation and the blockage of NF-κB nuclear translocalization, respectively. These results suggest that the cellular accumulation of argpyrimidine in LECs is NF-κB-dependent and pro-apoptotic.

  12. Thermal cataract formation in rabbits

    SciTech Connect

    Kramar, P.; Harris, C.; Guy, A.W.

    1987-01-01

    Intraocularly circulating hot water was used to produce cataracts in nine eyes of seven rabbits by maintaining their retrolental temperatures between 43 degrees C and 45 degrees C. A rapid rate of heating (1.3 degrees C/min) plus a sharp temperature gradient across the eye may have been contributing factors in the consistent production of cataracts at these temperatures. Biomicroscopy and light microscopy showed lens changes similar to those associated with acute exposure to microwave radiation. These findings support the assumption that microwave cataractogenesis is due to the local production of elevated temperatures.

  13. Terahertz Brewster lenses.

    PubMed

    Wichmann, Matthias; Scherger, Benedikt; Schumann, Steffen; Lippert, Sina; Scheller, Maik; Busch, Stefan F; Jansen, Christian; Koch, Martin

    2011-12-05

    Typical lenses suffer from Fresnel reflections at their surfaces, reducing the transmitted power and leading to interference phenomena. While antireflection coatings can efficiently suppress these reflections for a small frequency window, broadband antireflection coatings remain challenging. In this paper, we report on the simulation and experimental investigation of Brewster lenses in the THz-range. These lenses can be operated under the Brewster angle, ensuring reflection-free transmission of p-polarized light in an extremely broad spectral range. Experimental proof of the excellent focusing capabilities of the Brewster lenses is given by frequency and spatially resolved focus plane measurements using a fiber-coupled THz-TDS system.

  14. Mechanical properties of intra-ocular lenses

    NASA Astrophysics Data System (ADS)

    Ehrmann, Klaus; Kim, Eon; Parel, Jean-Marie

    2008-02-01

    Cataract surgery usually involves the replacement of the natural crystalline lens with a rigid or foldable intraocular lens to restore clear vision for the patient. While great efforts have been placed on optimising the shape and optical characteristics of IOLs, little is know about the mechanical properties of these devices and how they interact with the capsular bag once implanted. Mechanical properties measurements were performed on 8 of the most commonly implanted IOLs using a custom build micro tensometer. Measurement data will be presented for the stiffness of the haptic elements, the buckling resistance of foldable IOLs, the dynamic behaviour of the different lens materials and the axial compressibility. The biggest difference between the lens types was found between one-piece and 3-piece lenses with respect to the flexibility of the haptic elements

  15. Studies on the eye lens in poikilothermal animals. I. Comparative studies on cation maintenance systems in rainbow trout and rat lenses.

    PubMed

    Iwata, S; Hikida, M

    1985-08-01

    The response of the poikilothermal lens to various incubation temperatures in vitro was compared with that of the homothermal lens. The rainbow trout lens was used as the poikilothermal lens and the rat lens as the homothermal lens. In contrast to rat lenses, cataract developed at 37 degrees C in rainbow trout lenses, which was called 'warm cataract'. Warm cataract developed not only when lenses were incubated in vitro but also when rainbow trout were kept in water at 37 degrees C. Water, Na+, Ca2+ and insoluble protein increased and K+ and Mg2+ decreased in warm cataract lenses, but GSH and soluble protein sulfhydryl levels did not change. This cataract was irreversible after only 5 min incubation at 37 degrees C. On the other hand, rainbow trout lenses remained transparent without the change of cation balance at 0-25 degrees C while cold cataract developed in rat lenses. Na,K-ATPase activity was detected at 0 degrees C in rainbow trout lens homogenates, but not in rat lens homogenates. Na+-K+ ratio (Na+/K+) increased when the rainbow trout lens was treated with ouabain at 0 degrees C. In the rainbow trout lens, lactic acid was produced continuously for 30 days at 0 degrees C while it was not in the rat lens between 1 hr and 10 days after. These results strongly suggest that Na,K-ATPase acts as a cation pump at 0 degrees C and that ATP is supplied by glycolysis in the rainbow trout lens in order to maintain the transparency. The above results also suggest that enzymes and membrane structures in rainbow trout lens are adapted to a cold-temperature habitat and that Na,K-ATPase and anaerobic glycolysis are important for the maintenance of lens transparency at low temperatures.

  16. Ultrashort laser ablation of PMMA and intraocular lenses

    NASA Astrophysics Data System (ADS)

    Serafetinides, A. A.; Makropoulou, M.; Fabrikesi, E.; Spyratou, E.; Bacharis, C.; Thomson, R. R.; Kar, A. K.

    2008-10-01

    The use of intraocular lenses (IOLs) is the most promising method to restore vision after cataract surgery. Several new materials, techniques, and patterns have been studied for forming and etching IOLs to improve their optical properties and reduce diffractive aberrations. This study is aimed at investigating the use of ultrashort laser pulses to ablate the surface of PMMA and intraocular lenses, and thus provide an alternative to conventional techniques. Ablation experiments were conducted using various polymer substrates (PMMA samples, hydrophobic acrylic IOL, yellow azo dye doped IOL, and hydrophilic acrylic IOL consist of 25% H2O). The irradiation was performed using 100 fs pulses of 800 nm radiation from a regeneratively amplified Ti:sapphire laser system. We investigated the ablation efficiency and the phenomenology of the ablated patterns by probing the ablation depth using a profilometer. The surface modification was examined using a high resolution optical microscope (IOLs) or atomic force microscope—AFM (PMMA samples). It was found that different polymers exhibited different ablation characteristics, a result that we attribute to the differing optical properties of the materials. In particular, it was observed that the topography of the ablation tracks created on the hydrophilic intraocular lenses was smoother in comparison to those created on the PMMA and hydrophobic lens. The yellow doped hydrophobic intraocular lenses show higher ablation efficiency than undoped hydrophobic acrylic lenses.

  17. Development of feline microsatellites and SNPs for evaluating primary cataract candidate genes as cause for cataract in Angolan lions (Panthera leo bleyenberghi).

    PubMed

    Philipp, Ute; Steinmetz, Andrea; Distl, Ottmar

    2010-01-01

    Primary cataracts (CAT) are characterized as any form of opacities of the eye lenses and are not accompanied by other diseases. CAT may impair vision depending on their size, location, and their state of progression. In order to investigate the cause of congenital or juvenile CAT in inbred Angolan lions kept in German zoos, we analyzed the genomic sequences of 4 crystalline genes CRYAA, CRYAB, CRYBB2, and CRYBB1. In addition, 10 CAT candidate genes (GJA3, LIM2, CRYGA, CRYGB, CRYGC, CRYGD CRYGS, BFSP2, CRYBA4, and CRYBB1) were analyzed using adjacent microsatellites. We identified 10 single nucleotide polymorphisms in the Angolan lion crystalline genes and 9 segregating microsatellites. Nonparametric and parametric linkage analyses did not reveal any linkage between one of the analyzed markers and CAT. So, we concluded that these genes can be excluded as causative for the familial primary cataract phenotype in these Angolan lions.

  18. Cosmological test using strong gravitational lensing systems

    NASA Astrophysics Data System (ADS)

    Yuan, C. C.; Wang, F. Y.

    2015-09-01

    As one of the probes of universe, strong gravitational lensing systems allow us to compare different cosmological models and constrain vital cosmological parameters. This purpose can be reached from the dynamic and geometry properties of strong gravitational lensing systems, for instance, time-delay Δτ of images, the velocity dispersion σ of the lensing galaxies and the combination of these two effects, Δτ/σ2. In this paper, in order to carry out one-on-one comparisons between ΛCDM universe and Rh = ct universe, we use a sample containing 36 strong lensing systems with the measurement of velocity dispersion from the Sloan Lens Advanced Camera for Surveys (SLACS) and Lens Structure and Dynamic survey (LSD) survey. Concerning the time-delay effect, 12 two-image lensing systems with Δτ are also used. In addition, Monte Carlo simulations are used to compare the efficiency of the three methods as mentioned above. From simulations, we estimate the number of lenses required to rule out one model at the 99.7 per cent confidence level. Comparing with constraints from Δτ and the velocity dispersion σ, we find that using Δτ/σ2 can improve the discrimination between cosmological models. Despite the independence tests of these methods reveal a correlation between Δτ/σ2 and σ, Δτ/σ2 could be considered as an improved method of σ if more data samples are available.

  19. Dose-response relationship for α-tocopherol prevention of ultraviolet radiation induced cataract in rat.

    PubMed

    Wang, Jing; Löfgren, Stefan; Dong, Xiuqin; Galichanin, Konstantin; Söderberg, Per G

    2011-07-01

    The purpose of this study is to establish the dose response relationship for α-tocopherol protection of ultraviolet radiation (UVR) induced cataract in the rat. Four groups of 20 six-week-old albino Sprague Dawley rats received 5, 25, 50, and 100 IU/day α-tocopherol, whilst another group of 20 rats without any α-tocopherol feeding was the control group. After 4 weeks of feeding, each rat was unilaterally exposed to 8 kJ/m(2) UVR-300 nm for 15 min. At 1 week after exposure, the rats were sacrificed and lens light scattering was measured quantitatively. Lens total reduced (GSH) and oxidized (GSSG) glutathione; glutathione reductase (GR) and peroxidase (GPx) were determined spectrophotometrically. The UVR-exposed lenses in the α-tocopherol fed groups developed superficial cataract, whereas lenses in the control group developed cortical and equatorial opacities. Light scattering in lenses from the α-tocopherol-supplemented rats was lower than in lenses from the control group. The difference of light scattering between the exposed and contralateral non-exposed lens decreased with increasing doses of α-tocopherol to an asymptote level. UVR-exposure caused a significant depletion of lens GSH in rats without or at low α-tocopherol supplementation. The depletion of GSH became less with higher α-tocopherol supplementation. There was no detectable difference in lens GSSG, GR or GPx at any level of α-tocopherol supplementation. Orally administered α-tocopherol dose dependently protects against UVR-induced cataract. The protection is associated with an α-tocopherol dose-dependent GSH depletion secondary to UVR exposure. UVR-induced light scattering only occurs if the GSH depletion exceeds a threshold.

  20. Learning through Different Lenses

    ERIC Educational Resources Information Center

    Jeweler, Sue; Barnes-Robinson, Linda

    2015-01-01

    When parents and teachers help gifted kids use the metaphor "learning through different lenses," amazing things happen: Horizons open up. Ideas are focused. Thoughts are magnified and clarified. They see the big picture. Metaphoric thinking offers new and exciting ways to see the world. Viewing the world through different lenses provides…

  1. One Episode, Two Lenses

    ERIC Educational Resources Information Center

    Drijvers, Paul; Godino, Juan D.; Font, Vicenc; Trouche, Luc

    2013-01-01

    A deep understanding of students' learning processes is one of the core challenges of research in mathematics education. To achieve this, different theoretical lenses are available. The question is how these different lenses compare and contrast, and how they can be coordinated and combined to provide a more comprehensive view on the topic of…

  2. Cataract Surgery in a Patient with Amyotrophic Lateral Sclerosis: A Case Report

    PubMed Central

    Cenk Kohen, Maryo; Beril Kucumen, Raciha

    2011-01-01

    Abstract We report a cataract operation with complications in a patient with amyotrophic lateral sclerosis (ALS). The patient had a grade 4 mature brown cataract. Phacoemulsification with intraocular lens (IOL) implantation was planned; however, due to unexpected complications occurring during surgery, the operating technique was revised to an intracapsular cataract extraction. A very high vitreous pressure was found and therefore scleral fixating IOL was not implanted after anterior vitrectomy because of the possibility of choroidal effusion. The postoperative visual acuity improved sufficiently for the patient to communicate. Visual communication is of vital importance for an ALS patient and his caregivers. Therefore, surgery may be advisable in patients at a terminal stage with an advanced cataract, even if their general health condition may not seem appropriate for such an operation. Nevertheless, the intra- and postoperative course of the surgery may show unexpected complications and the surgeon should be prepared for such conditions. PMID:21886620

  3. Results of cataract surgery in the very elderly population

    PubMed Central

    Michalska-Małecka, Katarzyna; Nowak, Mariusz; Gościniewicz, Piotr; Karpe, Jacek; Słowińska-Łożyńska, Ludmiła; Łypaczewska, Agnieszka; Romaniuk, Dorota

    2013-01-01

    Aim The aim of our study was to retrospectively evaluate the effectiveness and safety of cataract surgery and intraocular lens implantation (IOL) for patients aged 90 years or older, whom we define as “very elderly.” Methods The study involved a total number of 122 patients (122 eyes) with senile cataracts. The mean age of patients was 91.2 ± 2.3 years (range 90–100 years old). Phacoemulsification (phaco) was done on 113 of 122 eyes, and 9 of 122 eyes had extracapsular cataract extraction (ECCE). Postoperative visual acuity and intraocular pressure (IOP) were analyzed on the first postoperative day, 3 months after surgery, and 6 months after surgery. Results Best corrected visual acuity (BCVA) improved in 100 of 122 eyes (82.0%). BCVA remained the same in 20 of 122 eyes (16.4%) and decreased in 2 of 122 eyes (1.6%), mainly because of coexisting age-related macular degeneration (AMD). The BCVA 3 months after surgery was ≥0.8 in 23 of 122 eyes (18.9%), between 0.5 and 0.7 in 28 of 122 eyes (22.3%), and between 0.2 and 0.4 in 33 of 122 eyes (27.1%). We found significant implications of cataract surgery on decreasing IOP in the studied group of patients suffering from glaucoma compared to the patients without glaucoma. Conclusion Advanced age is not a contraindication for cataract surgery. The results of the study showed that when systemic conditions are stable, both phaco and ECCE with IOL for very elderly patients are effective and safe. PMID:23966774

  4. Lens and cataract: clastogenic responses in epithelial cells of the organ-cultured rat lens

    SciTech Connect

    Geard, C.R.; Worgul, B.V.

    1987-01-01

    The epithelial cells of the vertebrate lens have an unique character and a probable involvement in cataract formation, which could be initiated by exogenous stimuli. Individual rat lenses were organ-cultured, and the effects of mitomycin C and gamma rays on sister chromatid exchanges (SCE), chromosomal aberrations, and cellular kinetics assessed in cells from the epithelial monolayer. SCE showed about a 5.5-fold increase over the mitomycin C dose range (0, 17, 83, 170 nM), while chromosomal aberrations increased 38-fold. In cells from untreated lenses, SCE were 1600 times more frequent than aberrations and at a level consistent with in vivo assessments in other cell types. Gamma rays (up to 4 Gy) had a greater inhibiting effect on cellular progression, while 17 nM mitomycin C and 1 Gy induced similar clastogenic responses. This first demonstration of such changes in lens epithelial cells expands on the cell types available for monitoring potential mutagen-carcinogens. Additionally chromosomal changes resulting from lens cellular challenge could be the basis of later cytopathological changes in the lens, of which cataract is the primary concern to humans. Potential cataractogens warrant monitoring, and the study outlined may aid in this endeavor, as well as contributing to an understanding of cataract etiology.

  5. Characterization of Cat-2t, a radiation-induced dominant cataract mutation in mice

    SciTech Connect

    Graw, J.; Bors, W.; Gopinath, P.M.; Merkle, S.; Michel, C.; Reitmeir, P.; Schaeffer, E.S.; Summer, K.H.; Wulff, A. )

    1990-07-01

    A dominant cataract mutation was detected recently among the offspring of x-ray-irradiated male mice. The mutation, which causes total lens opacity, has provisionally been designated by the gene symbol Cat-2t. In the lenses of heterozygous and homozygous Cat-2t mutants, the epithelial and fiber cells were swollen and the lens capsule was ruptured. The histologic analysis demonstrated a complete destruction of the cellular organization of the lens, which might be caused by its altered developmental processes. The data derived from biochemical investigations indicate that biochemistry of the cataractous Cat-2t lenses is affected: the osmotic state as indicated by the increased water content and increased Na(+)-K(+)-adenosinetriphosphatase (ATPase) activity; the energy state as indicated by the decreased adenosine triphosphate (ATP) concentration; and the redox state as indicated by the enhanced content of oxidized glutathione. Additionally, the lenticular protein composition is altered because of the presence of vimentin in the water-soluble fraction. This cannot be explained by the enhanced crosslinking activity of transglutaminase. The changes of the osmotic, energy, and redox states are considered to be secondary in relation to the altered lenticular development. In contrast, the variations concerning vimentin and transglutaminase might be a biochemical indication of the changed development. Possible similarities to other dominantly expressed murine cataract mutants are discussed.

  6. A Fiber Optic Probe for the Detection of Cataracts

    NASA Technical Reports Server (NTRS)

    Ansari, Rafat R.; Dhadwal, Harbans S.

    1993-01-01

    A compact fiber optic probe developed for on-orbit science experiments was used to detect the onset of cataracts, a capability that could eliminate physicians' guesswork and result in new drugs to 'dissolve' or slow down the cataract formation before surgery is necessary. The probe is based upon dynamic light scattering (DLS) principles. It has no moving parts, no apertures, and requires no optical alignment. It is flexible and easy to use. Results are presented for excised but intact human eye lenses. In a clinical setting, the device can be easily incorporated into a slit-lamp apparatus (ophthalmoscope) for complete eye diagnostics. In this set-up, the integrated fiber optic probe, the size of a pencil, delivers a low power cone of laser light into the eye of a patient and guides the light which is backscattered by the protein molecules of the lens through a receiving optical fiber to a photo detector. The non-invasive DLS measurements provide rapid determination of protein crystalline size and its size distribution in the eye lens.

  7. Artisan Aphakic Lens for Cataract Surgery in Anterior Megalophthalmos

    PubMed Central

    Galvis, Virgilio; Tello, Alejandro; Miotto, Giuseppe; Rangel, Carlos M.

    2012-01-01

    A 44-year-old man with anterior megalophthalmos arrived at the clinic presenting a cataract in the right eye. The corneal diameter was 13 mm. Iridodonesis and phacodonesis were evident during slit lamp examination. Anterior chamber depth was 5.89 mm, and the diameter of the capsular bag was approximately 14.45 mm. Due to the large capsular bag, a standard posterior chamber intraocular lens was considered inadequate because of potential instability. Phacoemulsification and an implantation of an iris-claw lens (Artisan for aphakia®, Ophtec) in the posterior chamber were performed with good results. In the fourth postoperative month, uncorrected distance visual acuity was 20/30, and 20/20 was achieved with +0.75 −1.25 × 10°. We consider retropupillary aphakic iris-claw intraocular lenses to be a worthwhile option in these cases of megalophthalmos and cataract, since instability is avoided and the procedure is less challenging than suturing the lens. PMID:23341820

  8. Crystal cataracts: Human genetic cataract caused by protein crystallization

    NASA Astrophysics Data System (ADS)

    Pande, Ajay; Pande, Jayanti; Asherie, Neer; Lomakin, Aleksey; Ogun, Olutayo; King, Jonathan; Benedek, George B.

    2001-05-01

    Several human genetic cataracts have been linked recently to point mutations in the D crystallin gene. Here we provide a molecular basis for lens opacity in two genetic cataracts and suggest that the opacity occurs because of the spontaneous crystallization of the mutant proteins. Such crystallization of endogenous proteins leading to pathology is an unusual event. Measurements of the solubility curves of crystals of the Arg-58 to His and Arg-36 to Ser mutants of D crystallin show that the mutations dramatically lower the solubility of the protein. Furthermore, the crystal nucleation rate of the mutants is enhanced considerably relative to that of the wild-type protein. It should be noted that, although there is a marked difference in phase behavior, there is no significant difference in protein conformation among the three proteins.

  9. Factors Associated with Complications and Postoperative Visual Outcomes of Cataract Surgery; a Study of 1,632 Cases

    PubMed Central

    Thanigasalam, Thevi; Reddy, Sagili Chandrashekara; Zaki, Rafdzah Ahmad

    2015-01-01

    Purpose: Cataract surgery is the most common intraocular surgery performed all over the world and has advanced technically in recent years. As in all surgeries, complications are unavoidable. Herein we report factors associated with complications and visual outcomes of cataract surgery. Methods: This retrospective cohort study included data of 1,632 cataract surgeries performed from 2007 to 2010 which was obtained from the cataract registry of the Malaysian National Eye Database. Demographic features, ocular and systemic comorbidites, grade of surgeon expertise and duration of surgery, type of anesthesia, intraoperative and postoperative complications, and the type of intraocular lens were recorded. Best corrected visual acuities were compared before and after the operation. Results: Mean patient age was 66.9 years with equal gender distribution. The majority of subjects had age related cataracts. Phacoemulsification was done faster than other surgeries, especially by specialist surgeons. History of prior ocular surgery and operations performed under general anesthesia were associated with greater complications. Phacoemulsification was associated with less complications and better visual outcomes. The age and etiology of cataract did not affect complications. Malays, absence of ocular comorbidities, left eyes and eyes operated under local anesthesia were more likely to experience more visual improvement. Gender, age, cause of cataract, systemic comorbidities and surgeon expertise as well as intra-and postoperative complications did not affect the visual outcomes. Conclusion: Phacoemulsification had good visual outcomes in cataract surgery. Duration of surgery, expertise of the surgeon and complications did not affect the visual outcomes. PMID:27051481

  10. Lens epithelial cell apoptosis appears to be a common cellular basis for non-congenital cataract development in humans and animals

    PubMed Central

    1995-01-01

    Cataract is a major ocular disease that causes blindness in many developing countries of the world. It is well established that various factors such as oxidative stress, UV, and other toxic agents can induce both in vivo and in vitro cataract formation. However, a common cellular basis for this induction has not been previously recognized. The present study of lens epithelial cell viability suggests such a general mechanism. When lens epithelial cells from a group of 20 cataract patients 12 to 94 years old were analyzed by terminal deoxynucleotidyl transferase (TdT) labeling and DNA fragmentation assays, it was found that all of these patients had apoptotic epithelial cells ranging from 4.4 to 41.8%. By contrast, in eight normal human lenses of comparable age, very few apoptotic epithelial cells were observed. We suggest that cataract patients may have deficient defense systems against factors such as oxidative stress and UV at the onset of the disease. Such stress can trigger lens epithelial cell apoptosis that then may initiate cataract development. To test this hypothesis, it is also demonstrated here that hydrogen peroxide at concentrations previously found in some cataract patients induces both lens epithelial cell apoptosis and cortical opacity. Moreover, the temporal and spatial distribution of induced apoptotic lens epithelial cells precedes development of lens opacification. These results suggest that lens epithelial cell apoptosis may be a common cellular basis for initiation of noncongenital cataract formation. PMID:7790371

  11. Pre-cataract surgery test using speckle pattern

    NASA Astrophysics Data System (ADS)

    Jutamulia, Suganda; Wihardjo, Erning; Widjaja, Joewono

    2016-11-01

    A laser diode device for pre cataract surgery test is proposed. The operation is based on the speckle generated on the retina by the cataract lens, when the cataract lens is illuminated with a coherent laser light.

  12. DETAIL OF NORTHEAST CUT STONE ABUTMENT FROM SOUTHWEST. Cataract ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DETAIL OF NORTHEAST CUT STONE ABUTMENT FROM SOUTHWEST. - Cataract Falls Bridge, Spanning Mill Creek, bypassed section of CR 279 (Cataract Falls Unit of Leiber State Recreation Area), Cataract, Owen County, IN

  13. The Chemopreventive Peptide Lunasin Inhibits d-Galactose- Induced Experimental Cataract in Rats.

    PubMed

    Dai, Guangzhi; Zhang, Ping; Ye, Pei; Zhang, Miaoqing; Han, Ning; Shuai, Haoyue; Tan, Shuhua

    2016-01-01

    Oxidative damage to the constituents of the eye lens is a major mechanism in the initiation and development of cataract. Lunasin, a 43-amino acids chemoprevention peptide, has been proved to possess potent anti-oxidative activity other than its established anticancer activities. Herein, we explored whether lunasin has preventative effects on d-galactose-induced experimental cataract in rat. After modeling, SD rats were administrated by instillation, 80 µM of lunasin eye drops to each eye thrice daily and consecutively for 30 days. As a result, lunasin treatment effectively inhibited the progression of d-galactose-induced experimental cataract, and protected the lenses of rats from oxidative damage and attenuated the lipid peroxidation through up-regulation of antioxidant enzymes, and inhibited the activation of polyol pathway by decreasing AR activity. Additionally, in vitro studies proved that lunasin treatment could protect human lens epithelial cells (hLECs) against d-galactose induced cell damage and apoptosis, and up-regulate antioxidant enzymes. This is the first demonstration that lunasin could inhibit d-galactose-induced experimental cataract in rats by protecting against oxidative damage and inhibiting the activation of polyol pathway.

  14. Effects of ELL-associated factor 2 on ultraviolet radiation-induced cataract formation in mice.

    PubMed

    Jiang, Yanhua; Fu, Rongrong; Zhao, Jiangyue; Wu, Di; Qiao, Guang; Li, Ruoxi; Zhang, Jinsong

    2015-11-01

    ELL-associated factor 2 (Eaf2) has an important role in crystalline lens development and maturation; however, its role in ultraviolet radiation (UV)-induced cataract formation has remained elusive. The present study compared UV-induced cell apoptosis, activation of caspase-3 and caspase-9 and changes in protein expression levels of B-cell lymphoma 2 (bcl-2), bcl-2-associated X protein (bax) and phosphorylated extracellular signal-regulated kinase in wild-type and Eaf2-knockout mice. The results showed that Eaf2 knockout can reduce UV-induced apoptosis in crystalline lenses and mitigate the formation of cataracts. Further functional studies indicated that Eaf2 can induce the activation of caspase-3 and caspase-9, increase the protein expression of the pro-apoptotic protein bax and inhibit the expression of the anti-apoptotic protein bcl-2; thereby, Eaf2 promotes cell apoptosis and is implicated in the formation and development of cataracts. The present study laid a theoretical foundation for the development of drugs for cataract treatment.

  15. Effects of ELL-associated factor 2 on ultraviolet radiation-induced cataract formation in mice

    PubMed Central

    JIANG, YANHUA; FU, RONGRONG; ZHAO, JIANGYUE; WU, DI; QIAO, GUANG; LI, RUOXI; ZHANG, JINSONG

    2015-01-01

    ELL-associated factor 2 (Eaf2) has an important role in crystalline lens development and maturation; however, its role in ultraviolet radiation (UV)-induced cataract formation has remained elusive. The present study compared UV-induced cell apoptosis, activation of caspase-3 and caspase-9 and changes in protein expression levels of B-cell lymphoma 2 (bcl-2), bcl-2-associated X protein (bax) and phosphorylated extracellular signal-regulated kinase in wild-type and Eaf2-knockout mice. The results showed that Eaf2 knockout can reduce UV-induced apoptosis in crystalline lenses and mitigate the formation of cataracts. Further functional studies indicated that Eaf2 can induce the activation of caspase-3 and caspase-9, increase the protein expression of the pro-apoptotic protein bax and inhibit the expression of the anti-apoptotic protein bcl-2; thereby, Eaf2 promotes cell apoptosis and is implicated in the formation and development of cataracts. The present study laid a theoretical foundation for the development of drugs for cataract treatment. PMID:26328919

  16. Vitrectomy as a Risk Factor for Complicated Cataract Surgery.

    PubMed

    Fenberg, Moss J; Hainsworth, Kenneth J; Rieger, Frank G; Hainsworth, Dean P

    2016-01-01

    A retrospective review of 98 cases of complicated cataract surgery and/or delayed intraocular lens (IOL) dislocation examined the relationship between vitrectomy and cataract surgery complications. Nine (9.2%) of the 98 patients had a history of vitrectomy, before or after cataract surgery, and each had complicated cataract surgery. Six patients who underwent vitrectomy before cataract surgery experienced intraoperative complications. Three patients in whom vitrectomy was performed after uneventful cataract surgery subsequently had delayed IOL dislocation.

  17. Stress-Detection Lenses

    NASA Technical Reports Server (NTRS)

    1996-01-01

    An Ames Research Center scientist invented an infrared lens used in sunglasses to filter out ultraviolet rays. This product finds its origins in research for military enemy detection. Through a Space Act Agreement, Optical Sales Corporation introduced the Hawkeye Lenses not only as sunglasses but as plant stress detection lenses. The lenses enhance the stressed part of the leaf, which has less chlorophyll than healthy leaves, through dyes that filter out certain wavelengths of light. Plant stress is visible earlier, at a stage when something can be done to save the plants.

  18. Corneal astigmatism after cataract surgery.

    PubMed

    Dekkers, N W; Buijs, J

    1989-08-01

    206 Consecutive cataract patients were at random divided into three groups according to the way the cataract incision was closed: virgin silk 8-0, interrupted nylon 9-0, and double running nylon 9-0. The nylon, whether interrupted or continuous, yielded in the majority of cases a postoperative astigmatism with the rule, whereas virgin silk caused in nearly all patients a postoperative astigmatism against the rule and therefore behaved like an absorbable suture. Silk is chemically non-absorbable, but in virgin silk a natural worm-produced polymer is still present, which provokes a tissue reaction. Softening of tissue diminishes the tensile strength of the suture. With respect to the postoperative astigmatism, the suture material (nylon or virgin silk) seems a more important factor than the way in which it is used (interrupted or continuous).

  19. Psychophysical Vision Simulation of Diffractive Bifocal and Trifocal Intraocular Lenses

    PubMed Central

    Brezna, Wolfgang; Lux, Kirsten; Dragostinoff, Nikolaus; Krutzler, Christian; Plank, Nicole; Tobisch, Rainer; Boltz, Agnes; Garhöfer, Gerhard; Told, Reinhard; Witkowska, Katarzyna; Schmetterer, Leopold

    2016-01-01

    Purpose The visual performance of monofocal, bifocal, and trifocal intraocular lenses was evaluated by human individuals using a vision simulator device. This allowed investigation of the visual impression after cataract surgery, without the need actually to implant the lenses. Methods The randomized, double-masked, three-way cross-over study was conducted on 60 healthy male and female subjects aged between 18 and 35 years. Visual acuity (Early Treatment Diabetic Retinopathy Study; ETDRS) and contrast sensitivity tests (Pelli-Robson) under different lighting conditions (luminosities from 0.14–55 cd/m2, mesopic to photopic) were performed at different distances. Results Visual acuity tests showed no difference for corrected distance visual acuity data of bi- and trifocal lens prototypes (P = 0.851), but better results for the trifocal than for the bifocal lenses at distance corrected intermediate (P = 0.021) and distance corrected near visual acuity (P = 0.044). Contrast sensitivity showed no differences between bifocal and trifocal lenses at the distant (P = 0.984) and at the near position (P = 0.925), but better results for the trifocal lens at the intermediate position (P = 0.043). Visual acuity and contrast sensitivity showed a strong dependence on luminosity (P < 0.001). Conclusions At all investigated distances and all lighting conditions, the trifocal lens prototype often performed better, but never worse than the bifocal lens prototype. Translational Relevance The vision simulator can fill the gap between preclinical lens development and implantation studies by providing information of the perceived vision quality after cataract surgery without implantation. This can reduce implantation risks and promotes the development of new lens concepts due to the cost effective test procedure. PMID:27777828

  20. DeepLensing: The Use of Deep Machine Learning to Find Strong Gravitational Lenses in Astronomical Surveys

    NASA Astrophysics Data System (ADS)

    Nord, Brian

    2017-01-01

    Strong gravitational lenses have potential as very powerful probes of dark energy and cosmic structure. However, efficiently finding lenses poses a significant challenge—especially in the era of large-scale cosmological surveys. I will present a new application of deep machine learning algorithms to find strong lenses, as well as the strong lens discovery program of the Dark Energy Survey (DES).Strong lenses provide unique information about the evolution of distant galaxies, the nature of dark energy, and the shapes of dark matter haloes. Current and future surveys, like DES and the Large Synoptic Survey Telescope, present an opportunity to find many thousands of strong lenses, far more than have ever been discovered. By and large, searches have heretofore relied on the time-consuming effort of human scanners. Deep machine learning frameworks, like convolutional neural nets, have revolutionized the task of image recognition, and have a natural place in the processing of astronomical images, including the search for strong lenses.Over five observing seasons, which started in August 2013, DES will carry out a wide-field survey of 5000 square degrees of the Southern Galactic Cap. DES has identified nearly 200 strong lensing candidates in the first two seasons of data. We have performed spectroscopic follow-up on a subsample of these candidates at Gemini South, confirming over a dozen new strong lenses. I will present this DES discovery program, including searches and spectroscopic follow-up of galaxy-scale, cluster-scale and time-delay lensing systems.I will focus, however, on a discussion of the successful search for strong lenses using deep learning methods. In particular, we show that convolutional neural nets present a new set of tools for efficiently finding lenses, and accelerating advancements in strong lensing science.

  1. A VidEo-Based Intelligent Recognition and Decision System for the Phacoemulsification Cataract Surgery

    PubMed Central

    Yin, Xu-Cheng; Wang, Zhi-Bin; Zhou, Fang; Hao, Hong-Wei

    2015-01-01

    The phacoemulsification surgery is one of the most advanced surgeries to treat cataract. However, the conventional surgeries are always with low automatic level of operation and over reliance on the ability of surgeons. Alternatively, one imaginative scene is to use video processing and pattern recognition technologies to automatically detect the cataract grade and intelligently control the release of the ultrasonic energy while operating. Unlike cataract grading in the diagnosis system with static images, complicated background, unexpected noise, and varied information are always introduced in dynamic videos of the surgery. Here we develop a Video-Based Intelligent Recognitionand Decision (VeBIRD) system, which breaks new ground by providing a generic framework for automatically tracking the operation process and classifying the cataract grade in microscope videos of the phacoemulsification cataract surgery. VeBIRD comprises a robust eye (iris) detector with randomized Hough transform to precisely locate the eye in the noise background, an effective probe tracker with Tracking-Learning-Detection to thereafter track the operation probe in the dynamic process, and an intelligent decider with discriminative learning to finally recognize the cataract grade in the complicated video. Experiments with a variety of real microscope videos of phacoemulsification verify VeBIRD's effectiveness. PMID:26693249

  2. Soft contact lenses

    PubMed Central

    Sutherland, R. L.; VanLeeuwen, Wm. N.

    1972-01-01

    A series of 55 patients were fitted with a new type of hydrophilic soft contact lens. These were found more comfortable than hard contact lenses and they had a protective and pain-relieving action in cases of chronic corneal disease. Vision was not as good as with hard contact lenses and a greater potential danger of infection was found. They are preferred by many patients despite the noticeable thick edge and the difficulty of obtaining an identical replacement. PMID:5042887

  3. Effect of methanolic extract of Allium sativum (AS) in delaying cataract in STZ-induced diabetic rats.

    PubMed

    Raju, T Naga; Kanth, V Rajani; Lavanya, K

    2008-03-01

    Glycemic-induced stress is a major culprit contributing to oxidative insult that has far-reaching effects in diabetic cataract worldwide. In an attempt to prevent/delay cataract, many therapeutic agents have been identified, and among these, natural dietary sources have gained pharmacological significance. Hence, we investigated the efficacy of the methanolic garlic extract against diabetic cataract in Wistar rats. Methanolic garlic extract scavenged the transition metal ion-generated H(2)O(2) with an IC(50) of 768.8 +/- 1.76 mug/ml, showing its potential ability as an antioxidant. We have noticed lenticular opacity and oxidative damage in streptozotocin (STZ)-induced hyperglycemic rats. This is evident by the elevation of Ca(2+), Cu(2+), Na(+), Mg(2+), thiobarbituric acid reacting substances (TBARS), and carbonyl content and increased activities of polyol enzymes, glutathione peroxidase (GPx), superoxide dismutase (SOD), and up regulation of iNOS transcript and protein aggregation/cross-linking followed by a decrease in reduced glutathione (GSH), K(+) content, and tryptophan fluorescence in the cataractous lenses of STZ-induced diabetic rats. Garlic administration in a dose-dependent manner attenuated the glycemia-mediated oxidative stress as all the parameters have been found normalized more or less to that of control rats and thus delaying the progression of the lens opacity. We conclude that garlic extract has hypoglycemic and anti oxidant properties that can delay the progression of cataract as revealed in this study.

  4. Cataract surgery with intraocular lens implantation in children aged 5-15 in local anaesthesia: visual outcomes and complications.

    PubMed

    Giles, Kagmeni; Christelle, Domngang; Yannick, Bilong; Fricke, Otto Herrmann; Wiedemann, Peter

    2016-01-01

    The aim of this study was to report feasibility, the visual outcomes and complications of pediatric cataract surgery with primary intraocular lens implantation in children aged 5 to15 years in local anesthesia. This retrospective interventional case series included 62 eyes from 50 children who underwent pediatrc cataract surgery with primary intraocular lens implantation at the Mana eye Clinic Nkongsamba between 2006 and 2015 Main outcome measures were: best-corrected post operative visual acuity, and intraoperative and postoperative complications. Mean age at surgery was 10.18 ± 3.21 years. Mean follow up length was 15.75 ± 3.36 weeks. Etiology included: 10 congenital cataracs (16.12%). 35 developmental cataracts (56.45%) and 17 traumatic cataracts (27.41%). The mean preoperative BCVA was logMAR 1.19 ± 0.33. (range 0.6-2.3). After cycloplegia refraction 2 weeks after surgery, the mean postoperative BCVA was log MAR 0.58 ± 0.88 ( range 0.5-1.8). The mean implanted IOL power was 22.01 ±3.16 D. IOL was succefuly implanted in 54 eyes (87.07%). Eight eyes (9.67%) were left aphakic. Increase in BCVA of 4 logMAR lines and above was recorded in 27 patients (43.55%). Intraoperative complications included: 4 posterior capsule holes with vitrous lost, 3 lenses subluxation and 1 case of iris dialyse. Late postoperative complications included: posterior capsular opacity which occurred in 16 patients, 3 posterior synechia, 2 retinal detachment. Peribulbar anaesthesia can be considered as a viable option in selected patients presenting developmental cataract undergoing cataract surgery in developing countries. Effort should be made to improve the early identification of congenital cataract and its early surgical intervention and prompt optical rehabilitation to prevent amblyopia.

  5. Cataract surgery with intraocular lens implantation in children aged 5-15 in local anaesthesia: visual outcomes and complications

    PubMed Central

    Giles, Kagmeni; Christelle, Domngang; Yannick, Bilong; Fricke, Otto Herrmann; Wiedemann, Peter

    2016-01-01

    The aim of this study was to report feasibility, the visual outcomes and complications of pediatric cataract surgery with primary intraocular lens implantation in children aged 5 to15 years in local anesthesia. This retrospective interventional case series included 62 eyes from 50 children who underwent pediatrc cataract surgery with primary intraocular lens implantation at the Mana eye Clinic Nkongsamba between 2006 and 2015 Main outcome measures were: best-corrected post operative visual acuity, and intraoperative and postoperative complications. Mean age at surgery was 10.18 ± 3.21 years. Mean follow up length was 15.75 ± 3.36 weeks. Etiology included: 10 congenital cataracs (16.12%). 35 developmental cataracts (56.45%) and 17 traumatic cataracts (27.41%). The mean preoperative BCVA was logMAR 1.19 ± 0.33. (range 0.6-2.3). After cycloplegia refraction 2 weeks after surgery, the mean postoperative BCVA was log MAR 0.58 ± 0.88 ( range 0.5-1.8). The mean implanted IOL power was 22.01 ±3.16 D. IOL was succefuly implanted in 54 eyes (87.07%). Eight eyes (9.67%) were left aphakic. Increase in BCVA of 4 logMAR lines and above was recorded in 27 patients (43.55%). Intraoperative complications included: 4 posterior capsule holes with vitrous lost, 3 lenses subluxation and 1 case of iris dialyse. Late postoperative complications included: posterior capsular opacity which occurred in 16 patients, 3 posterior synechia, 2 retinal detachment. Peribulbar anaesthesia can be considered as a viable option in selected patients presenting developmental cataract undergoing cataract surgery in developing countries. Effort should be made to improve the early identification of congenital cataract and its early surgical intervention and prompt optical rehabilitation to prevent amblyopia. PMID:27795795

  6. Lutein and cataract: from bench to bedside.

    PubMed

    Manayi, Azadeh; Abdollahi, Mohammad; Raman, Thiagarajan; Nabavi, Seyed Fazel; Habtemariam, Solomon; Daglia, Maria; Nabavi, Seyed Mohammad

    2016-10-01

    Cataract is one of the most important leading causes of blindness in the world. Extensive research showed that oxidative stress may play an important role in the initiation and progression of a cataract and other age-related eye diseases. Extra-generation of reactive oxygen and nitrogen species in the eye tissue has been shown as one of the most important risk factors for cataracts and other age-related eye diseases. With respect to this, it can be hypothesized that dietary antioxidants may be useful in the prevention and/or mitigation of cataract. Lutein is an important xanthophyll which is widely found in different vegetables such as spinach, kale and carrots as well as some other foods such as eggs. Lutein is concentrated in the macula and suppresses the oxidative stress in the eye tissues. A plethora of literature has shown that increased lutein consumption has a close correlation with reduction in the incidence of cataract. Despite this general information, there is a negligible number of review articles considering the beneficial effects of lutein on cataracts and age-related eye diseases. The present review is aimed at discussing the role of oxidative stress in the initiation and progression of a cataract and the possible beneficial effects of lutein in maintaining retinal health and fighting cataract. We also provide a perspective on the chemistry, sources, bioavailability and safety of lutein.

  7. Daily tonometric curves after cataract surgery

    PubMed Central

    Sacca, S; Marletta, A; Pascotto, A; Barabino, S; Rolando, M; Giannetti, R; Calabria, G

    2001-01-01

    AIM—To evaluate daily tonometric curves after cataract surgery in patients with cataract only and in patients with cataract and glaucoma.
METHODS—108 patients scheduled for cataract surgery were randomly allocated to two groups: 57 patients with cataract only (normal) and 51 with cataract and primary open angle glaucoma (POAG). All patients underwent extracapsular cataract extraction (ECCE) (manual technique with long wound), phacoemulsification (automated technique with short wound), or nucleus capture (manual technique with short wound). Intraocular pressure (IOP) was measured by Goldmann tonometry in all patients every 2 hours for 12 hours before the operation and at 1 and 6 months postoperatively.
RESULTS—79 patients completed the 6 month examination. ECCE resulted in greater reductions in IOP than the other procedures (ECCE: 27% and 36% in normal patients and those with POAG, respectively; nucleus capture: 20% and 31%, respectively; phacoemulsification: 19% and 22%, respectively). The fluctuations in IOP before and after surgery were not statistically significant.
CONCLUSION—Cataract surgery in normal patients reduces IOP but does not eliminate fluctuations which are directly proportional to the IOP value and result partly from circadian rhythms. This important finding might influence our approach to treatment of patients with glaucoma.

 PMID:11133707

  8. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  9. Temporal association between lens protein glycation and cataract development in diabetic rats.

    PubMed

    Turk, Z; Misur, I; Turk, N

    1997-03-01

    In an attempt to shed more light on the relation between the glycation process and structural protein alterations, we followed the formation of glycated products in the lenses of hyperglycaemic Wistar rats during a period of 5 months following alloxan diabetes inducement. The study groups included non-diabetic (control), untreated diabetic rats (D), and diabetic rats receiving insulin alone or in combination with phlorizin, an inhibitor of renal tubular glucose transport. Lenses were removed at 4 and 20 weeks, and advanced glycation products in alkalisoluble lens proteins were determined by their characteristic spectrofluorescence (emission at 385 nm with excitation of 335 nm). In 20-week untreated diabetic rats as compared to control rats, a significant increase was observed in the fluorescence level (3.25 +/- 1.02 vs 1.61 +/- 0.17 FU/mg, p < 0.001), while in 4-week animals the increase was from 1.26 +/- 0.11 FU/mg in controls to 1.80 +/- 0.25 FU/mg in diabetics (P < 0.001). Daily treatment of 20-week diabetic rats with insulin alone (2.46 +/- 0.48 FU/mg) or in combination with phlorizin (2.30 +/- 0.26 FU/mg) did not significantly influence lens fluorescence level. The amount of glucosebound ketoamine linkage was estimated after acid hydrolysis as released 5-hydroxymethylfurfural (HMF). In 20-week controls, it was slightly higher than in 4-week controls (0.57 +/- 0.31 vs 0.41 +/- 0.20 nmol HMF/mg, respectively). The diabetic group showed a significant increase, however. In 4-week diabetics, a level of 1.07 +/- 0.36 nmol HMF/mg was found, while in 20-week animals the glycated protein amount rose to 2.46 +/- 0.79 nmol HMF/mg. In addition to the increases in glycated content with continuing diabetic hyperglycaemia, significant changes in protein composition of alkali-soluble lenses developed. The SDS-PAGE pattern showed an appearance of protein polymers of heterogeneous size (C 4 weeks 3.0 +/- 1.1% vs C 20 weeks 17.9 +/- 2.9%, D 4 weeks 7.3 +/- 2.1% vs D 20 weeks 19

  10. Thermal lensing in optical fibers.

    PubMed

    Dong, Liang

    2016-08-22

    Average powers from fiber lasers have reached the point that a quantitative understanding of thermal lensing and its impact on transverse mode instability is becoming critical. Although thermal lensing is well known qualitatively, there is a general lack of a simple method for quantitative analysis. In this work, we first conduct a study of thermal lensing in optical fibers based on a perturbation technique. The perturbation technique becomes increasingly inaccurate as thermal lensing gets stronger. It, however, provides a basis for determining a normalization factor to use in a more accurate numerical study. A simple thermal lensing threshold condition is developed. The impact of thermal lensing on transverse mode instability is also studied.

  11. Cataract surgery and quality of life implications

    PubMed Central

    Morris, Daniel; Fraser, Scott G; Gray, Christopher

    2007-01-01

    Cataract surgery in the developed world has undergone a revolution over the last 20 years. An operation which used to require a stay in hospital and long visual rehabilitation is now a quick day-case procedure with immediate benefits. As with any surgery there is an associated morbidity, but there is now the potential to provide cataract surgery at an earlier stage of cataract maturation and save patients from a period of severe visual impairment. This article reviews the new techniques available to measure the impact that cataracts have not only on a patient’s visual acuity but also their general physical health, function, cognition, and emotional well-being. New research is described that takes into account these more holistic tests and how they can be used to judge the best time to refer and operate on a patient with cataracts. PMID:18044082

  12. NMR analyses of the cold cataract. III. /sup 13/C acrylamide studies

    SciTech Connect

    Lerman, S.; Megaw, J.M.; Moran, M.N.

    1985-10-01

    /sup 13/C-enriched acrylamide was employed to further delineate the action of this compound in preventing the cold cataract phenomenon when it is incorporated (in vitro) into young human and rabbit lenses. The extent of acrylamide incorporation, in the dark and with concurrent UV exposure, was monitored by /sup 13/C NMR spectroscopy. These studies provide further evidence that UV exposure causes permanent acrylamide photobinding within the lens. In such lenses, the gamma crystallin fraction of the soluble lens proteins is affected to the greatest extent. It appears to become aggregated and/or combined with the alpha and beta fractions resulting in an apparent loss of most of the gamma monomers. There is also an age-related effect with respect to the amount of acrylamide that can be incorporated into the lens. The decrease in acrylamide incorporation with age directly parallels the age-related decline in gamma crystallin levels.

  13. Dynamic contact angle analysis of silicone hydrogel contact lenses.

    PubMed

    Read, Michael Leonard; Morgan, Philip Bruce; Kelly, Jeremiah Michael; Maldonado-Codina, Carole

    2011-07-01

    Contact angle measurements are used to infer the clinical wetting characteristics of contact lenses. Such characterization has become more commonplace since the introduction of silicone hydrogel contact lens materials, which have been associated with reduced in vivo wetting due to the inclusion of siloxane-containing components. Using consistent methodology and a single investigator, advancing and receding contact angles were measured for 11 commercially available silicone hydrogel contact lens types with a dynamic captive bubble technique employing customized, fully automated image analysis. Advancing contact angles were found to range between 20° and 72° with the lenses falling into six statistically discrete groupings. Receding contact angles fell within a narrower range, between 17° and 22°, with the lenses segregated into three groups. The relationship between these laboratory measurements and the clinical performance of the lenses requires further investigation.

  14. Weak lensing and cosmology

    NASA Astrophysics Data System (ADS)

    Lombardi, Marco; Bertin, Giuseppe

    1999-02-01

    Recently, it has been shown that it is possible to reconstruct the projected mass distribution of a cluster from weak lensing provided that both the geometry of the universe and the probability distribution of galaxy redshifts are known; actually, when additional photometric data are taken to be available, the galaxy redshift distribution could be determined jointly with the cluster mass from the weak lensing analysis. In this paper we develop, in the spirit of a ``thought experiment,'' a method to constrain the geometry of the universe from weak lensing, provided that the redshifts of the source galaxies are measured. The quantitative limits and merits of the method are discussed analytically and with a set of simulations, in relation to point estimation, interval estimation, and test of hypotheses for homogeneous Friedmann-Lema\\^\\i tre models. The constraints turn out to be significant when a few thousand source galaxies are used.

  15. Contact Lenses in the Laboratory.

    ERIC Educational Resources Information Center

    Kingston, David W.

    1981-01-01

    Summarizes results of a three-item questionnaire returned by 43 Michigan institutions expressing views on wearing contact lenses in chemical laboratories. Questions focused on eye protection, type of protection, and use of contact lenses. (SK)

  16. Couching for Cataracts in China

    PubMed Central

    Chan, Chi-Chao

    2010-01-01

    Couching for cataract is one of the most ancient surgical procedures. Maharshi Sushruta, an ancient Indian surgeon, first described the procedure around 600 BC in Sushruta Samhita. The procedure, also known as jin pi shu in Mandarin, was introduced to China via the Silk Road during the late West Han Dynasty (206 BC - 9 AD), and it spread throughout China during the Tang Dynasty (618 – 907 AD). As the procedure was combined with the Chinese concept of acupuncture, jin pi shu was integrated into Chinese medical practice until the founding of the Republic of China in 1911. The government of the Republic of China considered jin pi shu to be unscientific. In 1949, the Communists established the People’s Republic of China. Jin pi shu was revitalized by Chairman Mao (1893-1976), who thought that traditional Chinese medicine, including jin pi shu, was a great treasure. After his death and the opening of China to the external world, many Chinese ophthalmologists pointed out that jin pi shu has relatively high complications and a low success rate, compared to various modern techniques for cataract surgery. This procedure is gradually fading away in China. The use of jin pi shu reflects the history, culture, and political transformation of China. PMID:20451942

  17. Couching for cataract in China.

    PubMed

    Chan, Chi-Chao

    2010-01-01

    Couching for cataract is one of the most ancient surgical procedures. Maharshi Sushruta, an ancient Indian surgeon, first described the procedure around 600 BCE in Sushruta Samhita. The procedure, also known as jin pi shu in Mandarin, was introduced to China via the Silk Road during the late West Han Dynasty (206 BCE-9 CE), and it spread throughout China during the Tang Dynasty (618-907 CE). As the procedure was combined with the Chinese concept of acupuncture, jin pi shu was integrated into Chinese medical practice until the founding of the Republic of China in 1911. The government of the Republic of China considered jin pi shu to be unscientific. In 1949, the Communists established the People's Republic of China. Jin pi shu was revitalized by Chairman Mao Zedong (1893-1976), who thought that traditional Chinese medicine, including jin pi shu, was a great treasure. After his death and the opening of China to the external world, many Chinese ophthalmologists pointed out that jin pi shu had relatively high complications and a low success rate, compared to various modern techniques for cataract surgery. This procedure is gradually fading away in China. The use of jin pi shu reflects the history, culture, and political transformation of China.

  18. Gravitational lensing of gravitational wave

    NASA Astrophysics Data System (ADS)

    Kei Wong, Wang; Ng, Kwan Yeung

    2017-01-01

    Gravitational lensing phenomena are widespread in electromagnetic astrophysics, and in principle may also be uncovered with gravitational waves. We examine gravitational wave events lensed by elliptical galaxies in the limit of geometric optics, where we expect to see multiple signals from the same event with different arrival times and amplitudes. By using mass functions for compact binaries from population-synthesis simulations and a lensing probability calculated from Planck data, we estimate the rate of lensed signals for future gravitational wave missions.

  19. Radiation Blocking Lenses

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Biomedical Optical Company of America's (BOCA) suntiger lenses, similar in principle to natural filters in the eyes of hawks and eagles, bar 99 percent of potentially harmful wavelengths, while allowing visually useful colors of light (red, orange, green) to pass through. They also improve visual acuity, night vision and haze or fog visibility. The lenses evolved from work done by James B. Stephens and Dr. Charles G. Miller of the Jet Propulsion Laboratory. They developed a formula and produced a commercial welding curtain that absorbs, filters, and scatters light. This research led to protective glasses now used by dentists, workers in hazardous environments, CRT operators and skiers.

  20. Connexin mediated cataract prevention in mice.

    PubMed

    Li, Lin; Cheng, Catherine; Xia, Chun-hong; White, Thomas W; Fletcher, Daniel A; Gong, Xiaohua

    2010-09-09

    Cataracts, named for any opacity in the ocular lens, remain the leading cause of vision loss in the world. Non-surgical methods for cataract prevention are still elusive. We have genetically tested whether enhanced lens gap junction communication, provided by increased α3 connexin (Cx46) proteins expressed from α8(Kiα3) knock-in alleles in Gja8tm1(Gja3)Tww mice, could prevent nuclear cataracts caused by the γB-crystallin S11R mutation in CrygbS11R/S11R mice. Remarkably, homozygous knock-in α8(Kiα3/Kiα3) mice fully prevented nuclear cataracts, while single knock-in α8(Kiα3/-) allele mice showed variable suppression of nuclear opacities in CrygbS11R/S11R mutant mice. Cataract prevention was correlated with the suppression of many pathological processes, including crystallin degradation and fiber cell degeneration, as well as preservation of normal calcium levels and stable actin filaments in the lens. This work demonstrates that enhanced intercellular gap junction communication can effectively prevent or delay nuclear cataract formation and suggests that small metabolites transported through gap junction channels protect the stability of crystallin proteins and the cytoskeletal structures in the lens core. Thus, the use of an array of small molecules to promote lens homeostasis may become a feasible non-surgical approach for nuclear cataract prevention in the future.

  1. [Rehabilitation methods for children with complicated cataract].

    PubMed

    Ivanov, G; Cuşnir, V; Septichina, Natalia; Cuşnir, Vitalie

    2010-01-01

    The work deals with the results of surgical treatment of 155 patients, who had uveal cataract, by method of facoemulsification with artificial crystalline lens transplanting. The age of the sick varied from 3 to 15 as a result of a complex treatment, involving determination of ethnic factor in the development of uveal cataract, before- and after-operation conservative medical treatment, surgical treatment of abscuration ambliopia 78.1% children and the keenness of sight 0.4 and 68.7% got binocularious sight. The study lot of posttraumatic cataract affected children included 189 patients, from them 68 with stationary cataract, 87 with intumescent cataract and 34 with postoperatorial aphakia. Age from 2 to 15 years. 76.3% cases of evolution without postoperatorial complications, in 13.7% intraoperatorial were observed different complications. The work presents the results of surgical treatment 196 of children, who had innate cataract, by the method of facoasoriation with soft intra-eyepiece lens transplanting from 133 patients who had two-sided cataract, 63 had monolateral cataract. All children underwent laser simulation and videocomputer auto-training in post-operation period. As a result of the treatment, 66.8% patients got the amelioration of sight with 0.4, and 58% got binocular sight. The children's age varied between 6 months and 15 years. This article presents a review of the treatment results of 213 children with posttraumatic, congenital and complicated cataracts. The rehabilitation of the patients with the lens pathology includes a complex of measures of early diagnosis, surgery, optimal correction, medical treatment before and after surgery, the prophilaxis and treatment of complications. This approach permits to increase the visual acuity in 83.8% and to restore the binocular vision in 71.4% patients.

  2. Weak lensing corrections to tSZ-lensing cross correlation

    SciTech Connect

    Tröster, Tilman; Waerbeke, Ludovic Van E-mail: waerbeke@phas.ubc.ca

    2014-11-01

    The cross correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and gravitational lensing in wide field has recently been measured. It can be used to probe the distribution of the diffuse gas in large scale structure, as well as inform us about the missing baryons. As for any lensing-based quantity, higher order lensing effects can potentially affect the signal. Here, we extend previous higher order lensing calculations to the case of tSZ-lensing cross correlations. We derive terms analogous to corrections due to the Born approximation, lens-lens coupling, and reduced shear up to order ℓ ∼> 3000.

  3. Sir Harold Ridley: innovator of cataract surgery.

    PubMed

    Sarwar, H; Modi, N

    2014-09-01

    Cataract surgery has evolved greatly over the years, from the ancient practice of 'couching' where the lens is dislodged, to the modern surgical techniques of today. Sir Harold Ridley's invention of the intraocular lens (IOL) has altered the approach towards cataract surgery, benefitting individuals worldwide. This has been his most notable contribution, it is therefore interesting to explore the build up to this event and gain an understanding of the issues faced by Sir Ridley. This paper explores the significant events and key developments that influenced one of the most valuable innovations in the context of cataract surgery--the intraocular lens.

  4. Understanding Cataract Risk in Aerospace Flight Crew And Review of Mechanisms of Cataract Formation

    NASA Technical Reports Server (NTRS)

    Jones, Jeffrey A.; McCarten, M.; Manuel, K.; Djojonegoro, B.; Murray, J.; Cucinotta, F.; Feiversen, A.; Wear, M.

    2006-01-01

    Induction of cataracts by occupational exposure in flight crew has been an important topic of interest in aerospace medicine in the past five years, in association with numerous reports of flight-associated disease incidences. Due to numerous confounding variables, it has been difficult to determine if there is increased cataract risk directly caused by interaction with the flight environment, specifically associated with added radiation exposure during flight. Military aviator records from the United States Air Force (USAF) and Navy (USN) and US astronauts at the National Aeronautics and Space Administration (NASA)/Lyndon B. Johnson Space Center (JSC) were evaluated for the presence, location and age of diagnosis of cataracts. Military aviators were found to have a statistically significant younger average age of onset of their cataracts compared with astronauts, however the incidence density of cataracts was found to be statistically higher in astronauts than in military aviators. USAF and USN aviator s cataracts were most commonly located in the posterior subcapsular region of the lens while astronauts cataracts were most likely to originate generally in the cortical zone. A prospective clinical trial which controls for confounding variables in examination technique, cataract classification, diet, exposure, and pharmacological intervention is needed to determine what percentage of the risk for cataracts are due to radiation, and how to best develop countermeasures to protect flight crews from radiation bioeffects in the future.

  5. Fresnel's Lighthouse Lenses

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

  6. Fresnel's Lighthouse Lenses

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2007-12-01

    One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

  7. Rigid lenses: an overview.

    PubMed

    Bayshore, C A

    1979-03-01

    New gas permeable rigid contact lens materials, by allowing direct transmission of oxygen, provide significant advantages over PMMA. Edema resulting from oxygen deprivation with PMMA lenses is eliminated and comfort is increased. Three types of gas permeable materials are described: CAB, silicone, and a combination of CAB and silicone.

  8. Glaucoma therapy by extended release of timolol from nanoparticle loaded silicone-hydrogel contact lenses.

    PubMed

    Jung, Hyun Jung; Abou-Jaoude, Michelle; Carbia, Blanca E; Plummer, Caryn; Chauhan, Anuj

    2013-01-10

    Glaucoma is the second major cause of blindness in the world after cataract. Glaucoma management through eye drops that reduce the intraocular pressure (IOP) has major deficiencies including low patient compliance and low bioavailability. Extended wear contact lenses that deliver glaucoma drugs for extended periods could increase patient compliance, while also increasing the bioavailability. To develop extended wear contact lenses that can also provide extended glaucoma therapy, we disperse nanoparticles of PGT (propoxylated glyceryl triacylate) that contain a glaucoma drug timolol. The particles can also be loaded into prefabricated lenses by soaking the lenses in a solution of particles in ethanol. The particle loaded gels can release timolol in phosphate buffered saline (PBS) for about a month at room temperature. The most likely rate controlling mechanism is hydrolysis of the ester bond that links timolol to the PGT matrix, but other mechanisms such as water and drug diffusion, drug dissolution, drug-polymer chain cleavage, time-dependent drug permeability within the polymeric matrix, etc. may also be important. Nanoparticle incorporation in the silicone hydrogels results in reduction in ion and oxygen permeabilities, and an increase in modulus, and the impact on each of these properties is proportional to the particle loading. A gel with 5% particle loading can deliver timolol at therapeutic doses for about a month at room temperature, with a minimal impact on critical lens properties. Preliminary animal studies in Beagle dogs conducted with lenses in which particles are loaded by soaking the lenses in ethanol show a reduction in IOP.

  9. Non-subjective cataract analysis and its application in space radiation risk assessment

    NASA Technical Reports Server (NTRS)

    Wu, B.; Medvedovsky, C.; Worgul, B. V.

    1994-01-01

    Experimental animal studies and human observations suggest that the question is not whether or not prolonged space missions will cause cataracts to appear prematurely in the astronauts, but when and to what degree. Historically the major impediment to radiation cataract follow-up has been the necessarily subjective nature of assessing the degree of lens transparency. This has spurred the development of instruments which produce video images amenable to digital analysis. One such system, the Zeiss Scheimpflug slit lamp measuring system (SLC), was incorporated into our ongoing studies of radiation cataractogenesis. It was found that the Zeiss SLC measuring system has high resolution and permits the acquisition of reproducible images of the anterior segment of the eye. Our results, based on about 650 images of the rats lens, and followed over a period of 91 weeks of radiation cataract development, showed that the Integrated Optical Density (IOD) of the lens correlated well with conventional assessment with the added advantages of objectivity, permanent and transportable records and linearity as cataracts become more severe. This continuous data acquisition, commencing with cataract onset, can proceed through more advanced stages. The SLC exhibits much greater sensitivity reflected in a continuously progressive severity despite the artifactual plateaus in staging which occur using conventional scoring methods. Systems such as the Zeiss SLC should be used to monitor astronauts frequent visits to low earth orbit to obtain a longitudinal data-base on the influence of this activity on the lens.

  10. Tryptophan and Non-Tryptophan Fluorescence of the Eye Lens Proteins Provides Diagnostics of Cataract at the Molecular Level

    PubMed Central

    Gakamsky, Anna; Duncan, Rory R.; Howarth, Nicola M.; Dhillon, Baljean; Buttenschön, Kim K.; Daly, Daniel J.; Gakamsky, Dmitry

    2017-01-01

    The chemical nature of the non-tryptophan (non-Trp) fluorescence of porcine and human eye lens proteins was identified by Mass Spectrometry (MS) and Fluorescence Steady-State and Lifetime spectroscopy as post-translational modifications (PTM) of Trp and Arg amino acid residues. Fluorescence intensity profiles measured along the optical axis of human eye lenses with age-related nuclear cataract showed increasing concentration of fluorescent PTM towards the lens centre in accord with the increased optical density in the lens nucleolus. Significant differences between fluorescence lifetimes of “free” Trp derivatives hydroxytryptophan (OH-Trp), N-formylkynurenine (NFK), kynurenine (Kyn), hydroxykynurenine (OH-Kyn) and their residues were observed. Notably, the lifetime constants of these residues in a model peptide were considerably greater than those of their “free” counterparts. Fluorescence of Trp, its derivatives and argpyrimidine (ArgP) can be excited at the red edge of the Trp absorption band which allows normalisation of the emission spectra of these PTMs to the fluorescence intensity of Trp, to determine semi-quantitatively their concentration. We show that the cumulative fraction of OH-Trp, NFK and ArgP emission dominates the total fluorescence spectrum in both emulsified post-surgical human cataract protein samples, as well as in whole lenses and that this correlates strongly with cataract grade and age. PMID:28071717

  11. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace.

  12. Clinical Detection of Pre-Cataractous Lens Protein Changes using Dynamic Light Scattering

    PubMed Central

    Datiles, Manuel B.; Ansari, Rafat R.; Suh, Kwang I.; Vitale, Susan; Reed, George F.; Zigler, J. Samuel; Ferris., Frederick L.

    2008-01-01

    Purpose To use Dynamic Light Scattering (DLS) to clinically assess early pre-cataractous lens protein changes. Methods We performed a cross sectional study in 380 eyes of 235 subjects aged 7–86 years with AREDS clinical lens nuclear grades ranging from 0–3.8. A DLS device was used to assess α-crystallin, a molecular chaperone protein shown to bind other damaged lens proteins, preventing their aggregation. The outcome measure was the α-crystallin index (ACI), a measure of unbound α-crystallin in each lens. The association of ACI with increasing nuclear opacity and aging was determined. Results There was a significant decrease in ACI associated with increasing grades of lens nuclear opacity (p<0.0001). There are significant losses of α-crystallin even in clinically clear lenses associated with aging (p<0.0001). The standard error of measurement was 3%. Conclusions DLS clinically detects loss of α-crystallin proteins even in clinically clear lenses. ACI measurements may be useful in identifying patients at high risk for developing cataract, and as an outcome variable in clinical lens studies. Clinical Relevance Our studies suggest that the ACI may be a useful measure of the protective α-crystallin molecular chaperone reserve present in a lens, analogous to creatinine clearance in estimating renal function reserve. PMID:19064850

  13. Cataracts

    MedlinePlus

    ... Plastic Surgery Center Laser Surgery Education Center Redmond Ethics Center Global Ophthalmology Guide Academy Publications EyeNet Ophthalmology Information for: International Ophthalmologists Media Medical Students Patients and Public Technicians and Nurses ...

  14. Cataracts

    MedlinePlus

    ... Courier services use: Rockville, MD 20852) 301-451-2020 Research at NEI Office of the Scientific Director ... Eye Disease Education Program Glaucoma Education Program Low Vision Education Program Hispanic/Latino Program Vision and Aging ...

  15. Preventive effect of Zea mays L. (purple waxy corn) on experimental diabetic cataract.

    PubMed

    Thiraphatthanavong, Paphaphat; Wattanathorn, Jintanaporn; Muchimapura, Supaporn; Wipawee, Thukham-mee; Wannanon, Panakaporn; Terdthai, Tong-un; Suriharn, Bhalang; Lertrat, Kamol

    2014-01-01

    Recently, substances possessing antioxidant can prevent cataractogenesis of diabetic cataract. Therefore, this study was carried out to determine the anticataract effect of Zea mays L. (purple waxy corn), a flavonoids rich plant, in experimental diabetic cataract. Enucleated rat lenses were incubated in artificial aqueous humor containing 55 mM glucose with various concentrations of Zea mays L. (purple waxy corn) ranging between 2, 10, and 50 mg/mL at room temperature for 72 h. At the end of the incubation period, the evaluation of lens opacification, MDA level, and the activities of SOD, CAT, GPx, and AR in lens were performed. The results showed that both medium and high doses of extract decreased lens opacity together with the decreased MDA level. In addition, medium dose of extract increased GPx activity while the high dose decreased AR activity. No other significant changes were observed. The purple waxy corn seeds extract is the potential candidate to protect against diabetic cataract. The mechanism of action may occur via the decreased oxidative stress and the suppression of AR. However, further research in vivo is still essential.

  16. Space radiation and cataracts in astronauts

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; Manuel, F. K.; Jones, J.; Iszard, G.; Murrey, J.; Djojonegro, B.; Wear, M.

    2001-01-01

    For over 30 years, astronauts in Earth orbit or on missions to the moon have been exposed to space radiation comprised of high-energy protons and heavy ions and secondary particles produced in collisions with spacecraft and tissue. Large uncertainties exist in the projection of risks of late effects from space radiation such as cancer and cataracts due to the paucity [corrected] of epidemiological data. Here we present epidemiological [corrected] data linking an increased risk of cataracts for astronauts with higher lens doses (>8 mSv) of space radiation relative to other astronauts with lower lens doses (<8 mSv). Our study uses historical data for cataract incidence in the 295 astronauts participating in NASA's Longitudinal Study of Astronaut Health (LSAH) and individual occupational radiation exposure data. These results, while preliminary because of the use of subjective scoring methods, suggest that relatively low doses of space radiation may predispose crew to [corrected] an increased incidence and early appearance of cataracts.

  17. Space radiation and cataracts in astronauts.

    PubMed

    Cucinotta, F A; Manuel, F K; Jones, J; Iszard, G; Murrey, J; Djojonegro, B; Wear, M

    2001-11-01

    For over 30 years, astronauts in Earth orbit or on missions to the moon have been exposed to space radiation comprised of high-energy protons and heavy ions and secondary particles produced in collisions with spacecraft and tissue. Large uncertainties exist in the projection of risks of late effects from space radiation such as cancer and cataracts due to the paucity [corrected] of epidemiological data. Here we present epidemiological [corrected] data linking an increased risk of cataracts for astronauts with higher lens doses (>8 mSv) of space radiation relative to other astronauts with lower lens doses (<8 mSv). Our study uses historical data for cataract incidence in the 295 astronauts participating in NASA's Longitudinal Study of Astronaut Health (LSAH) and individual occupational radiation exposure data. These results, while preliminary because of the use of subjective scoring methods, suggest that relatively low doses of space radiation may predispose crew to [corrected] an increased incidence and early appearance of cataracts.

  18. Cataract Surgery in Anterior Megalophthalmos: A Review

    PubMed Central

    GALVIS, Virgilio; TELLO, Alejandro; M. RANGEL, Carlos

    2015-01-01

    Anterior megalophthalmos is characterized by megalocornea associated with a very broad anterior chamber and ciliary ring elongation. It is also called X-linked megalocornea. It is accompanied by early development of cataracts, zonular anomalies, and, rarely, vitreoretinal disorders. Subluxation of a cataract can occur in cataract surgery because of zonular weakness. In addition, in most patients, standard intraocular lens (IOL) decentration is a risk because of the enlarged sulcus and capsular bag. These unique circumstances make cataract surgery challenging. To date, several approaches have been developed. Implantation of a retropupillary iris-claw aphakic intraocular lens may be a good option because it is easier than suturing the IOL and can have better and more stable anatomic and visual outcomes, compared to other techniques. PMID:27350950

  19. Serum antioxidant vitamins and risk of cataract.

    PubMed Central

    Knekt, P.; Heliövaara, M.; Rissanen, A.; Aromaa, A.; Aaran, R. K.

    1992-01-01

    OBJECTIVE--To investigate serum concentrations of alpha tocopherol, beta carotene, retinol, and selenium for their prediction of end stage cataract. DESIGN--A case-control study, nested within a cohort study, based on the linkage of records of subjects aged 40-83 from a health survey with those from the national Finnish hospital discharge register. SUBJECTS--47 patients admitted to ophthalmological wards for senile cataract over 15 years and two controls per patient individually matched for sex, age, and municipality. MAIN OUTCOME MEASURE--Concentration of serum micronutrients, development of cataract according to whether operation was performed. RESULTS--Low serum concentrations of antioxidant vitamins predicted the development of senile cataract, the odds ratio between the lowest third and the two higher thirds of the distribution of serum concentrations of alpha tocopherol and beta carotene being 1.9 (95% confidence interval 0.9 to 4.1) and 1.7 (0.8 to 3.8), respectively. Patients with both alpha tocopherol and beta carotene concentrations in the lowest third had an odds ratio of 2.6 (1.0 to 6.8) of cataract compared with subjects in the top two thirds. The associations were strengthened by adjustment for potential confounding factors such as occupation, smoking, blood pressure, serum cholesterol concentration, body mass index, and diabetes. No association was found between the serum concentrations of selenium, retinol, and retinol binding protein and the risk of cataract. CONCLUSIONS--Low serum concentrations of the antioxidant vitamins alpha tocopherol and beta carotene are risk factors for end stage senile cataract. Controlled trials of the role of antioxidant vitamins in cataract prevention are therefore warranted. PMID:1486302

  20. Cosmic Radiation and Cataracts in Airline Pilots

    NASA Astrophysics Data System (ADS)

    Rafnsson, V.; Olafsdottir, E.; Hrafnkelsson, J.; de Angelis, G.; Sasaki, H.; Arnarson, A.; Jonasson, F.

    Nuclear cataracts have been associated with ionising radiation exposure in previous studies. A population based case-control study on airline pilots has been performed to investigate whether employment as a commercial pilot and consequent exposure to cosmic radiation were associated to lens opacification, when adjusted for known risk factors for cataracts. Cases of opacification of the ocular lens were found in surveys among pilots and a random sample of the Icelandic population. Altogether 445 male subjects underwent a detailed eye examination and answered a questionnaire. Information from the airline company on the 79 pilots employment time, annual hours flown per aircraft type, the timetables and the flight profiles made calculation of individual cumulated radiation dose (mSv) possible. Lens opacification were classified and graded according to WHO simplified cataracts grading system using slit lamp. The odds ratio from logistic regression of nuclear cataracts risk among cases and controls was 3.02 (95% CI 1.44 to 6.35) for pilots compared with non-pilots, adjusted for age, smoking and sunbathing habits, whereas that of cortical cataracts risk among cases and controls was lower than unity (non significant) for pilots compared with non-pilots in a logistic regression analysis adjusted for same factors. Length of employment as a pilot and cumulated radiation dose (mSv) were significantly related to the risk of nuclear cataracts. So the association between radiation exposure of pilots and the risk of nuclear cataracts, adjusted for age, smoking and sunbathing habits, indicates that cosmic radiation may be cause of nuclear cataract among commercial pilots.

  1. Weak lensing by voids in modified lensing potentials

    SciTech Connect

    Barreira, Alexandre; Cautun, Marius; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: m.c.cautun@durham.ac.uk E-mail: c.m.baugh@durham.ac.uk

    2015-08-01

    We study lensing by voids in Cubic Galileon and Nonlocal gravity cosmologies, which are examples of theories of gravity that modify the lensing potential. We find voids in the dark matter and halo density fields of N-body simulations and compute their lensing signal analytically from the void density profiles, which we show are well fit by a simple analytical formula. In the Cubic Galileon model, the modifications to gravity inside voids are not screened and they approximately double the size of the lensing effects compared to GR. The difference is largely determined by the direct effects of the fifth force on lensing and less so by the modified density profiles. For this model, we also discuss the subtle impact on the force and lensing calculations caused by the screening effects of haloes that exist in and around voids. In the Nonlocal model, the impact of the modified density profiles and the direct modifications to lensing are comparable, but they boost the lensing signal by only ≈ 10%, compared with that of GR. Overall, our results suggest that lensing by voids is a promising tool to test models of gravity that modify lensing.

  2. Looking the cow in the eye: deletion in the NID1 gene is associated with recessive inherited cataract in Romagnola cattle.

    PubMed

    Murgiano, Leonardo; Jagannathan, Vidhya; Calderoni, Valerio; Joechler, Monika; Gentile, Arcangelo; Drögemüller, Cord

    2014-01-01

    Cataract is a known condition leading to opacification of the eye lens causing partial or total blindness. Mutations are known to cause autosomal dominant or recessive inherited forms of cataracts in humans, mice, rats, guinea pigs and dogs. The use of large-sized animal models instead of those using mice for the study of this condition has been discussed due to the small size of rodent lenses. Four juvenile-onset cases of bilateral incomplete immature nuclear cataract were recently observed in Romagnola cattle. Pedigree analysis suggested a monogenic autosomal recessive inheritance. In addition to the cataract, one of the cases displayed abnormal head movements. Genome-wide association and homozygosity mapping and subsequent whole genome sequencing of a single case identified two perfectly associated sequence variants in a critical interval of 7.2 Mb on cattle chromosome 28: a missense point mutation located in an uncharacterized locus and an 855 bp deletion across the exon 19/intron 19 border of the bovine nidogen 1 (NID1) gene (c.3579_3604+829del). RT-PCR showed that NID1 is expressed in bovine lenses while the transcript of the second locus was absent. The NID1 deletion leads to the skipping of exon 19 during transcription and is therefore predicted to cause a frameshift and premature stop codon (p.1164fs27X). The truncated protein lacks a C-terminal domain essential for binding with matrix assembly complexes. Nidogen 1 deficient mice show neurological abnormalities and highly irregular crystal lens alterations. This study adds NID1 to the list of candidate genes for inherited cataract in humans and is the first report of a naturally occurring mutation leading to non-syndromic catarct in cattle provides a potential large animal model for human cataract.

  3. Learning unit: Thin lenses

    NASA Astrophysics Data System (ADS)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  4. NMR studies in chemistry. I. Organometallic tin and geramanium compounds. II. The sorbitol pathway in intact lenses

    SciTech Connect

    Williams, W.F.

    1985-01-01

    Nuclear magnetic resonance spectroscopy has been utilized in the study of two very different chemical problems. The bonding and structure of various cyclopropyl derivatives of tin and germanium has been investigated by means of Sn-119, Ge-73, C-13, and H-1 NMR spectroscopy. Intact rabbit lenses have also been studied using NMR spectroscopy with regard to diabetic cataract formation. C-13 and P-31 NMR spectroscopies have been utilized in the study of the sorbitol pathway and aldose reductase inhibition.

  5. Tolerancing panoramic lenses

    NASA Astrophysics Data System (ADS)

    Parent, Jocelyn; Thibault, Simon

    2009-08-01

    Tolerancing a lens is a basic procedure in lens design. It consists in first defining an appropriate set of tolerances for the lens, then in adding compensators with their allowable ranges and finally in selecting an appropriate quality criterion (MTF, RMS spot size, wavefront error, boresight error...) for the given application. The procedure is straightforward for standard optical systems. However, it becomes more complex when tolerancing very wide angle lenses (larger than 150 degrees). With a large field of view, issues such as severe off-axis pupil shift, considerable distortion and low relative illumination must be addressed. The pupil shift affects the raytrace as some rays can no longer be traced properly. For high resolution imagers, particularly for robotic and security applications, the image footprint is most critical in order to limit or avoid complex calibration procedures. We studied various wide angle lenses and concluded that most of the distortion comes from the front surface of the lens. Consequently, any variation of the front surface will greatly affect the image footprint. In this paper, we study the effects on the image footprint of slightly modifying the front surface of four different lenses: a simple double-gauss for comparison, a fisheye lens, a catadioptric system (omnidirectional lens) and a Panomorph lens. We also present a method to analyze variations of the image footprint. Our analysis shows that for wide angle lenses, on which the entrance pupil is much smaller than the front surface, irregularities (amplitude, slope and location) are critical on both aspherical and spherical front surfaces to predict the image footprint variation for high resolution cameras. Finally, we present how the entrance pupil varies (location, size) with the field of view for these optical systems.

  6. A γA-Crystallin Mouse Mutant Secc with Small Eye, Cataract and Closed Eyelid

    PubMed Central

    Cheng, Man Hei; Tam, Chung Nga; Choy, Kwong Wai; Tsang, Wai Hung; Tsang, Sze Lan; Pang, Chi Pui; Song, You Qiang; Sham, Mai Har

    2016-01-01

    Cataract is the most common cause of visual loss in humans. A spontaneously occurred, autosomal dominant mouse mutant Secc, which displayed combined features of small eye, cataract and closed eyelid was discovered in our laboratory. In this study, we identified the mutation and characterized the cataract phenotype of this novel Secc mutant. The Secc mutant mice have eyelids that remain half-closed throughout their life. The mutant lens has a significant reduction in size and with opaque spots clustered in the centre. Histological analysis showed that in the core region of the mutant lens, the fiber cells were disorganized and clefts and vacuoles were observed. The cataract phenotype was evident from new born stage. We identified the Secc mutation by linkage analysis using whole genome microsatellite markers and SNP markers. The Secc locus was mapped at chromosome 1 flanked by SNPs rs3158129 and rs13475900. Based on the chromosomal position, the candidate cataract locus γ-crystallin gene cluster (Cryg) was investigated by sequencing. A single base deletion (299delG) in exon 3 of Cryga which led to a frame-shift of amino acid sequence from position 91 was identified. As a result of this mutation, the sequences of the 3rd and 4th Greek-key motifs of the γA-crystallin are replaced with an unrelated C-terminal peptide of 75 residues long. Coincidentally, the point mutation generated a HindIII restriction site, allowing the identification of the CrygaSecc mutant allele by RFLP. Western blot analysis of 3-week old lenses showed that the expression of γ-crystallins was reduced in the CrygaSecc mutant. Furthermore, in cell transfection assays using CrygaSecc mutant cDNA expression constructs in 293T, COS-7 and human lens epithelial B3 cell lines, the mutant γA-crystallins were enriched in the insoluble fractions and appeared as insoluble aggregates in the transfected cells. In conclusion, we have demonstrated that the Secc mutation leads to the generation of Cryga

  7. A γA-Crystallin Mouse Mutant Secc with Small Eye, Cataract and Closed Eyelid.

    PubMed

    Cheng, Man Hei; Tam, Chung Nga; Choy, Kwong Wai; Tsang, Wai Hung; Tsang, Sze Lan; Pang, Chi Pui; Song, You Qiang; Sham, Mai Har

    2016-01-01

    Cataract is the most common cause of visual loss in humans. A spontaneously occurred, autosomal dominant mouse mutant Secc, which displayed combined features of small eye, cataract and closed eyelid was discovered in our laboratory. In this study, we identified the mutation and characterized the cataract phenotype of this novel Secc mutant. The Secc mutant mice have eyelids that remain half-closed throughout their life. The mutant lens has a significant reduction in size and with opaque spots clustered in the centre. Histological analysis showed that in the core region of the mutant lens, the fiber cells were disorganized and clefts and vacuoles were observed. The cataract phenotype was evident from new born stage. We identified the Secc mutation by linkage analysis using whole genome microsatellite markers and SNP markers. The Secc locus was mapped at chromosome 1 flanked by SNPs rs3158129 and rs13475900. Based on the chromosomal position, the candidate cataract locus γ-crystallin gene cluster (Cryg) was investigated by sequencing. A single base deletion (299delG) in exon 3 of Cryga which led to a frame-shift of amino acid sequence from position 91 was identified. As a result of this mutation, the sequences of the 3rd and 4th Greek-key motifs of the γA-crystallin are replaced with an unrelated C-terminal peptide of 75 residues long. Coincidentally, the point mutation generated a HindIII restriction site, allowing the identification of the CrygaSecc mutant allele by RFLP. Western blot analysis of 3-week old lenses showed that the expression of γ-crystallins was reduced in the CrygaSecc mutant. Furthermore, in cell transfection assays using CrygaSecc mutant cDNA expression constructs in 293T, COS-7 and human lens epithelial B3 cell lines, the mutant γA-crystallins were enriched in the insoluble fractions and appeared as insoluble aggregates in the transfected cells. In conclusion, we have demonstrated that the Secc mutation leads to the generation of Cryga

  8. The first cataract surgeons in Latin America: 1611–1830

    PubMed Central

    Leffler, Christopher T; Wainsztein, Ricardo D

    2016-01-01

    We strove to identify the earliest cataract surgeons in Latin America. Probably by 1611, the Genovese oculist Francisco Drago was couching cataracts in Mexico City. The surgeon Melchor Vásquez de Valenzuela probably performed cataract couching in Lima by 1697. Juan Peré of France demonstrated cataract couching in Veracruz and Mexico City between 1779 and 1784. Juan Ablanedo of Spain performed couching in Veracruz in 1791. Cataract extraction might have been performed in Havana and Caracas by 1793 and in Mexico by 1797. The earliest contemporaneously documented cataract extractions in Latin America were performed in Guatemala City by Narciso Esparragosa in 1797. In addition to Esparragosa, surgeons born in the New World who established the academic teaching of cataract surgery included José Miguel Muñoz in Mexico and José María Vargas in Caracas. Although cataract surgery came quite early to Latin America, its availability was initially inconsistent and limited. PMID:27143845

  9. Radiation Blocking Lenses

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The Biomedical Optical Company of America's Eagle 475 lens absorbs 100 percent of all photowavelengths considered hazardous to eye tissue, including ultraviolet and blue light, which are considered contributors to cataract and age-related macular degeneration. The lens absorbs hazardous wavelengths, but allows a higher percentage of visually useful areas of the spectrum to pass through. Polarization blocks out irritating glint and glare and heightens visual acuity. The Eagle 475 sunglasses are the latest in a series of spinoffs that originated at the Jet Propulsion Laboratory where two scientists developed a protective, welding curtain that filtered out harmful irradiance. The result was a commercial curtain that absorbs filters and scatters light, providing protection for personnel in welding areas. Further research focused on protective industrial glasses and later on consumer products.

  10. [To guard against mistakes in selection of intraocular lenses].

    PubMed

    He, Shou-zhi

    2008-04-01

    Development of different kinds of new intraocular lenses (IOL) provide more selections to meet various clinical requirements, which may plays an active role in making cataract surgery more perfectible. But there are many misunderstandings about how to select the proper IOL. For example, "the expensive one is the best one", "new product is absolutely perfect", and so on. Some surgeons prefer more practice and ignore the summary of the experiences. Someone unilaterally exaggerates some special function of IOL When selecting the IOL, it is a common challenge for us to fully consider the patients needs, and properly manage the relationship between the basic need and special need, and to avoid fanaticism, and provide the best benefits to the patients.

  11. SPT Lensing Likelihood: South Pole Telescope CMB lensing likelihood code

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Peiris, Hiranya V.; Verde, Licia

    2014-11-01

    The SPT lensing likelihood code, written in Fortran90, performs a Gaussian likelihood based upon the lensing potential power spectrum using a file from CAMB (ascl:1102.026) which contains the normalization required to get the power spectrum that the likelihood call is expecting.

  12. Complications of foldable intraocular lenses requiring explantation or secondary intervention--2007 survey update.

    PubMed

    Mamalis, Nick; Brubaker, Jacob; Davis, Don; Espandar, Ladan; Werner, Liliana

    2008-09-01

    The tenth annual survey of complications associated with foldable intraocular lenses (IOLs) requiring explantation or secondary intervention was sent to members of the American Society of Cataract and Refractive Surgery and the European Society of Cataract and Refractive Surgeons. Preoperative data about visual acuity, patient signs and symptoms, and complications requiring IOL removal were evaluated. Complications were then tabulated for each of the following major foldable IOL groups: 1-piece (plate) silicone, 1-piece hydrophobic acrylic with haptics, 3-piece silicone, 3-piece hydrophobic acrylic, 3-piece hydrophilic acrylic (hydrogel), 3-piece unknown, multifocal acrylic, and multifocal silicone. One hundred forty-two surveys were returned for evaluation. Dislocation/decentration, incorrect IOL power, glare/optical aberrations, and IOL calcification were the most common reasons for removing foldable IOLs. Good surgical technique, accurate IOL power measurements, and high manufacturing standards for foldable IOL materials and designs are the most important factors in preventing complications.

  13. Fiber optic system for in-vivo sizing of proteins in animal eye lenses

    NASA Astrophysics Data System (ADS)

    Dhadwal, Harbans S.; Ansari, Rafat R.; DellaVecchia, Michael A.; Dubin, Stephen

    1995-05-01

    A compact fiber optic system, utilizing a lensless backscatter fiber optic probe, and a semiconductor laser is used as a non-invasive tool for in vivo characterization of the proteins in the eye lens of several animals. The system exploits the extremely sensitive technique of dynamic light scattering, which uses a laser beam to probe the temporal characteristics of the proteins present in eye lens fluid. The technique, with appropriate electronics and signal processing provides a rapid means of determining the size of the (alpha) -crystallin in the protein-water system. Changes in the size of the protein molecules can be tracked over the age of the eye lens; an abrupt increase in size is associated with the early cataractous formation. This paper describes the fiber optic system and discusses results obtained from measurements made on sedated rabbits, pigs and cats. A clear difference in the size of the (alpha) -crystallin of normal and cataractous lenses is observed.

  14. Acid phosphatase and lipid peroxidation in human cataractous lens epithelium.

    PubMed

    Vasavada, A R; Thampi, P; Yadav, S; Rawal, U M

    1993-12-01

    The anterior lens epithelial cells undergo a variety of degenerative and proliferative changes during cataract formation. Acid phosphatase is primarily responsible for tissue regeneration and tissue repair. The lipid hydroperoxides that are obtained by lipid peroxidation of polysaturated or unsaturated fatty acids bring about deterioration of biological membranes at cellular and tissue levels. Acid phosphatase and lipid peroxidation activities were studied on the lens epithelial cells of nuclear cataract, posterior subcapsular cataract, mature cataract, and mixed cataract. Of these, mature cataractous lens epithelium showed maximum activity for acid phosphatase (516.83 moles of p-nitrophenol released/g lens epithelium) and maximum levels of lipid peroxidation (86.29 O.D./min/g lens epithelium). In contrast, mixed cataractous lens epithelium showed minimum activity of acid phosphatase (222.61 moles of p-nitrophenol released/g lens epithelium) and minimum levels of lipid peroxidation (54.23 O.D./min/g lens epithelium). From our study, we correlated the maximum activity of acid phosphatase in mature cataractous lens epithelium with the increased areas of superimposed cells associated with the formation of mature cataract. Likewise, the maximum levels of lipid peroxidation in mature cataractous lens epithelium was correlated with increased permeability of the plasma membrane. Conversely, the minimum levels of lipid peroxidation in mixed cataractous lens epithelium makes us presume that factors other than lipid peroxidation may also account for the formation of mixed type of cataract.

  15. The gene of an early onset progressive cataract (cerulean cataract) maps to 17q24

    SciTech Connect

    Armitage, M.M.; Ferrell, R.E.; Kivlin, J.D.

    1994-09-01

    Cerulean cataract is an autosomal dominant, fully penetrant, early onset, progressive cataract characterized by blue or white opacifications in the nucleus and cortex of the lens. A five generation family with 44 available affected members in three generations allowed exclusion of linkage of the cerulean cataract phenotype to lens structural protein genes and to all of the chromosomal regions to which autosomal dominant cataract phenotypes have previously been mapped. Exclusion of the plausible candidate instigated a genome-wide search utilizing short tandem repeat polymorphims. The genome search localized the cerulean cataract disease gene to chromosomal region 17q24. The three markers closest to the disease gene are D17S802 [Z({theta})=9.20 at ({theta})=0.086], D17S836 [Z({theta})=4.22 at ({theta})=0.061], and AFMa238yb5 [Z({theta})=7.11 at ({theta})=0.032]. Multipoint analysis yielded a maximum lod score of Z({theta})=11.4 between D17S802 and D17S836 at recombination rates of 0.048 and 0.013 respectively. Three genes that map near the 17q24 chromosomal region and are known to contain highly polymorphic microsatellites were tested for linkage. The genes, DHP-sensitive calcium channel gamma subunit (CACNLG), human somatastatin receptor (SSTR2), and the skeletal muscle sodium channel alpha subunit (SCN4A), were all excluded [Z({theta})=-{infinity} at ({theta})=0] as the gene causing cerulean cataract. The galactokinase (GK1) gene has not been cloned, but its map location is 17q23-q25. Galactokinase deficiency is characterized by a recessive, progressive, early onset cataract. Because of the map location of galactokinase, the age-at-onset, and progressive nature of cataracts associated with galactokinase deficiency, galactokinase is being investigated as a candidate gene for the cerulean cataract phenotype.

  16. Ethanol extract of Moringa oliefera prevents in vitro glucose induced cataract on isolated goat eye lens

    PubMed Central

    Kurmi, Raghvendra; Ganeshpurkar, Aditya; Bansal, Divya; Agnihotri, Abhishek; Dubey, Nazneen

    2014-01-01

    Aim of Study: The aim of current work was to evaluate in vitro anticataract potential of Moringa oliefera extract. Materials and Methods: Goat eye lenses were divided into 4 groups; Group served as control, Group II as toxic control, Group III and Group IV were incubated in extract (250 μg/ml and 500 μg/ml of extract of M. oliefera) Group II, III and IV were incubated in 55 mM glucose in artificial aqueous humor to induce lens opacification. Estimation of total, water soluble protein, catalase, glutathione and malondialdehyde along with photographic evaluation of lens was done. Results: Group II (toxic control) lenses showed high amount of MDA (Malondialdehyde), soluble, insoluble protein, decreased catalase and glutathione levels, while lenses treated with Moringa oliefera extract (Group III and Group IV) showed significant (* P < 0.05) reduction in MDA and increased level of catalase, glutathione, total and soluble protein. Conclusion: Results of present findings suggest protective effect of Moringa oliefera in prevention of in vitro glucose induced cataract. PMID:24008789

  17. First known lenses originating in Egypt about 4600 years ago!

    PubMed

    Enoch, J

    2000-04-01

    The first lenses (ca. Vth Dynasties of the Old Kingdom of Egypt. These lenses are found in The Louvre Museum in Paris and the Egyptian Museum in Cairo. They were components of extraordinary eye constructs in statues which had unique qualities. Namely, the "eyes" appear to follow the viewer as he/she rotates about these statues in any direction. This effect can be photographed and reproduced 2620-2400 B.C., 4620-4400 Before Present=B.P.) appeared mainly during the IVth and optically. This effect has been modeled here. The lenses were ground from high quality (!) rock crystal (a form of quartz, n approximately 1.46). Each had a convex and highly polished front "corneal" surface. Thus, in a sense, these were multifocal lenses. The iris aperture may or may not have been open to a substantial posterior "vitreous" cavity formed largely by curved copper plates which extended forward to create the lid structures of these eyes. Were these a form of schematic eyes? Could such fine quality and complex (sophisticated) lenses be the first lenses? Clearly, the observer was intended to look at these eyes and follow their apparent movements. The total structure of these eyes indicated an advanced understanding of ocular anatomy and a surprising knowledge of optics. There are many questions.

  18. Can Naturoptics Vision Improvement Methods Help Clear Cataracts, as Claimed by the Member of the Naturopathic Physicians Association of Massachusetts who Stabilized and/ or Improved Vision in all the Retinitis Pigmentosa, RP, Patients Treated by him?

    NASA Astrophysics Data System (ADS)

    MacDougall, Jean; McLeod, Roger

    2006-03-01

    Mac Dougall was advised against having a single crystalline lens with a slight cataract surgically removed; it would impact her ability to reengage vision's self-correcting feedback mechanisms. Her Florida ophthalmologist removed both lenses. A Massachusetts ophthalmologist was recently de-licensed for improperly performing just those services. An optometrist says reputed vision repair can easily be tracked and evaluated; we posit that Naturoptics effects on cataracts can be similarly assessed. ``Cures'' are detectable. Naturoptics users may show glaucoma reversal. EDWARD R. ELLIS, Jr., N.D. (The Chelmsford Clinic, Massachusetts), stabilizes RP, preventing blindness.

  19. RHIC electron lenses upgrades

    SciTech Connect

    Gu, X.; Altinbas, Z.; Bruno, D.; Binello, S.; Costanzo, M.; Drees, A.; Fischer, W.; Gassner, D. M.; Hock, J.; Hock, K.; Harvey, M.; Luo, Y.; Marusic, A.; Mi, C.; Mernick, K.; Minty, M.; Michnoff, R.; Miller, T. A.; Pikin, A. I.; Robert-Demolaize, G.; Samms, T.; Shrey, T. C.; Schoefer, V.; Tan, Y.; Than, R.; Thieberger, P.; White, S. M.

    2015-05-03

    In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015, two electron lenses were used to partially compensate for the head-on beam-beam effect for the first time. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.

  20. Hollow lensing duct

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

    2000-01-01

    A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

  1. Clear Corneal Incision in Cataract Surgery

    PubMed Central

    Al Mahmood, Ammar M.; Al-Swailem, Samar A.; Behrens, Ashley

    2014-01-01

    Since the introduction of sutureless clear corneal cataract incisions, the procedure has gained increasing popularity worldwide because it offers several advantages over the traditional sutured scleral tunnels and limbal incisions. Some of these benefits include lack of conjunctival trauma, less discomfort and bleeding, absence of suture-induced astigmatism, and faster visual rehabilitation. However, an increasing incidence of postoperative endophthalmitis after clear corneal cataract surgery has been reported. Different authors have shown a significant increase up to 15-fold in the incidence of endophthalmitis following clear corneal incision compared to scleral tunnels. The aim of this report is to review the advantages and disadvantages of clear corneal incisions in cataract surgery, emphasizing on wound construction recommendations based on published literature. PMID:24669142

  2. Deprivation amblyopia and congenital hereditary cataract.

    PubMed

    Mansouri, Behzad; Stacy, Rebecca C; Kruger, Joshua; Cestari, Dean M

    2013-01-01

    Amblyopia is a neurodevelopmental disorder of vision associated with decreased visual acuity, poor or absent stereopsis, and suppression of information from one eye.(1,2) Amblyopia may be caused by strabismus (strabismic amblyopia), refractive error (anisometropic amblyopia), or deprivation from obstructed vision (deprivation amblyopia). 1 In the developed world, amblyopia is the most common cause of childhood visual impairment, 3 which reduces quality of life 4 and also almost doubles the lifetime risk of legal blindness.(5, 6) Successful treatment of amblyopia greatly depends on early detection and treatment of predisposing disorders such as congenital cataract, which is the most common cause of deprivational amblyopia. Understanding the genetic causes of congenital cataract leads to more effective screening tests, early detection and treatment of infants and children who are at high risk for hereditary congenital cataract.

  3. Cataracts induced by microwave and ionizing radiation

    SciTech Connect

    Lipman, R.M.; Tripathi, B.J.; Tripathi, R.C.

    1988-11-01

    Microwaves most commonly cause anterior and/or posterior subcapsular lenticular opacities in experimental animals and, as shown in epidemiologic studies and case reports, in human subjects. The formation of cataracts seems to be related directly to the power of the microwave and the duration of exposure. The mechanism of cataractogenesis includes deformation of heat-labile enzymes, such as glutathione peroxide, that ordinarily protect lens cell proteins and membrane lipids from oxidative damage. Oxidation of protein sulfhydryl groups and the formation of high-molecular-weight aggregates cause local variations in the orderly structure of the lens cells. An alternative mechanism is thermoelastic expansion through which pressure waves in the aqueous humor cause direct physical damage to the lens cells. Cataracts induced by ionizing radiation (e.g., X-rays and gamma rays) usually are observed in the posterior region of the lens, often in the form of a posterior subcapsular cataract. Increasing the dose of ionizing radiation causes increasing opacification of the lens, which appears after a decreasing latency period. Like cataract formation by microwaves, cataractogenesis induced by ionizing radiation is associated with damage to the lens cell membrane. Another possible mechanism is damage to lens cell DNA, with decreases in the production of protective enzymes and in sulfur-sulfur bond formation, and with altered protein concentrations. Until further definitive conclusions about the mechanisms of microwaves and ionizing radiation induced cataracts are reached, and alternative protective measures are found, one can only recommend mechanical shielding from these radiations to minimize the possibility of development of radiation-induced cataracts. 74 references.

  4. Lupeol, a pentacyclic triterpenoid isolated from Vernonia cinerea attenuate selenite induced cataract formation in Sprague Dawley rat pups.

    PubMed

    Asha, Radha; Gayathri Devi, V; Abraham, Annie

    2016-02-05

    This study investigated the inhibitory effects of active component isolated from flavonoid fraction of Vernonia cinerea (FVC), lupeol on selenite induced cataract formation. Previous reports suggest that phytochemicals or natural plant products retard the process of cataractogenesis by scavenging free oxygen radicals. Hence, the present study sought to assess the potential of lupeol on in vivo selenite induced cataract models. Lupeol, a pentacyclic triterpenoid, was isolated from the ethyl acetate fraction of methanolic extract of Vernonia cinerea, follows standard chromatographic techniques. Structural elucidation of the compound was carried out using (1)H NMR, (13)C NMR, Mass spectrometry together with other complementary techniques (UV and IR). From these, the isolated compound was identified as Lupeol (3'-hydroxylup-20(29)-ene). The antioxidant activity was comparatively studied using DPPH radical scavenging and FRAP assay. Lupeol exhibited higher DPPH radical scavenging activity as well as reducing power assay. In this study, cataract was induced by a single subcutaneous injection of sodium selenite (4 μg/g body weight) on rat pups. Lupeol was administered orally from 8th day upto 21st day at a concentration 25 μg/g body weight. Cataract was visualized on 16th day with the help of an ophthalmoscope and later on with the naked eye. On the 30th day, rats were euthanized by sodium pentothal injection, lenses were excised and the biochemical parameters such as activity of superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx), Glutathione reductase (GR), Glutathione-S-transferase (GST), Ca(2+) ATPase, glutathione content (GSH), reactive oxygen species (ROS), lipid peroxidation products (malondialdehyde) were estimated and found effective in the treatment of cataract by lupeol.

  5. [The denominations cataract and glaucoma].

    PubMed

    Tornquist, R

    1997-01-01

    Since ancient times a grey or white pupil in an nearly blind eye was thought to be caused by a mucous substance in front of the lens. It was called "hypochysis" or "hypochyma" in Greece and "suffusio" in Rome. Later the term "cataract" (=waterfall) was the most popular denomination. A surgical method was tried very early with usually good effect, when with a thin needle, introduced into the eye, the opaque material was removed from the pupillary area. In the middle of the 17th century more careful investigations showed that there was no membrane in front of the lens, but the lens itself was opaque. The final proof was delivered when an extraction of the lens was performed with good effect. In ancient times incurable blindness, which was called glaucoma, was thought to be located to the lens, which probably had a very important role in the seeing process. The name (of Greek orgin) is translated "green" or "blue-green", which was sometimes notified to be the color of the lens, seen through the pupil, in these cases. A period of great confusion followed when the removal of this very important part of the eye did not lead to blindness but rather an improved vision. As there were significant difficulties in identifying the specific color of the pupil the name glaucoma seemed to be very inadequate. In the beginning of the 19th century a disease entity (which is to-day called acute closed-angle glaucoma) seemed to eventually fullfill the demand of a greenlooking pupil. The most characteristic symptoms are pain and a high intraocular pressure causing a corneal edema and a change of the blackness of the pupil to hazy grey (and maybe a little green?).

  6. [Reliable UV-light protection in intraocular lenses--scientific rationale and quality requirements].

    PubMed

    Augustin, A J

    2014-09-01

    Since the late 1980s implantation of UV-blocker intraocular lenses during cataract surgery has become an internationally accepted standard. Last year the Kassenärztliche Vereinigung Bayern (KVB) and statutory health insurance organisations proposed for the first time quality criteria for intraocular lenses (IOL), thereby including exact parameters for the amount of UV light transmission (≤10% at 400 nm). Since then, the discussion has been raised again as to what extent IOLs should filter or block UV light. In this article, exact definitions of spectral subbands within the optical radiation band are given. Today, 400 nm is the internationally accepted standard to distinguish UV light and visible light. Moreover, exposure of the eye to UV radiation is described as well as mechanisms of photooxidative damage to the retina. Comprehensive laboratory and animal experimental studies show that light of short wave lengths, i.e., above all UV light but also blue light, may induce photochemical damage to the retina. Primary sites of such damage are both the outer segments of the photoreceptors and the retinal pigment epithelium (RPE). Physiological protective mechanisms of the eye, such as filtering properties of different ocular media are described in detail. Cornea, aqueous and vitreous absorb UV radiation below 300 nm, while the natural adult lens absorbs UV radiation between 300 and 400 nm. This protection is lost when the lens is removed by cataract surgery and thus should be restored. UV light does not contribute to vision but damages retinal structures. Therefore, UV-blocking intraocular lenses with a 10% cut-off near 400 nm should be implanted during cataract surgery. This ensures sufficient retinal protection after surgery. These theoretical considerations are supported by results from animal and clinical studies.

  7. Partially coherent interferometric biometry in cataract surgery

    NASA Astrophysics Data System (ADS)

    Drexler, Wolfgang; Findl, Oliver; Menapace, Rupert; Hitzenberger, Christoph K.; Fercher, Adolf F.

    1999-02-01

    In an earlier study we showed that precise axial eye length measurement on cataract eyes is possible with the dual beam partial coherence interferometry technique (PCI). A high correlation with the standard ultrasound technique has been obtained. Recently, in a prospective study, partially coherent interferometry and ultrasound biometry were compared in cataract surgery using the SRK II formula based on US applanation biometry. Three months after surgery PCI was repeated and refractive outcome was determined. The use of PCI would have improved refractive outcome by about 30%.

  8. Cataract - Multiple Languages: MedlinePlus

    MedlinePlus

    ... إعتام عدسة العين - العربية Bilingual PDF Health Information Translations Chinese - Simplified (简体中文) Cataract English 白内障 - 简体中文 (Chinese - ... 白内障 - 简体中文 (Chinese - Simplified) Bilingual PDF Health Information Translations Chinese - Traditional (繁體中文) Cataract English 白內障 - 繁體中文 (Chinese - ...

  9. Halo-lensing or Self-lensing? Locating the MACHO Lenses

    NASA Astrophysics Data System (ADS)

    Nelson, C. A.; Cook, K. H.; Popowski, P.; Drake, A. J.; Marshall, S. L.; Griest, K.; Vandehei, T.; Alcock, C.; Allsman, R. A.; Axelrod, T. S.; Freeman, K. C.; Peterson, B. A.; Alves, D. R.; Becker, A. C.; Stubbs, C. W.; Tomaney, A. B.; Bennett, D. P.; Geha, M.; Lehner, M. J.; Minniti, D.; Pratt, M. R.; Quinn, P. J.; Sutherland, W.; Welch, D.; MACHO Collaboration

    2000-12-01

    There are two principle geometrical arrangements which may explain Large Magellanic Cloud (LMC) microlensing: a) halo-lensing, in which the lensed object is part of the Milky Way galactic halo and b) self-lensing, in which the lensed object is part of the LMC. Self-lensing in turn may be broken into two categories: LMC-LMC self-lensing, in which both the source and the lens reside in the LMC and background self-lensing, in which the lens is a star in the LMC and the source star is drawn from some population behind the LMC. Models suggest the contribution of LMC-LMC self-lensing is small, so the nature of LMC microlensing may be estimated from the location of the microlensing source stars. If the source stars are in the LMC then microlensing is dominated by halo-lensing; conversely if the source stars are located behind the LMC then microlensing is dominated by self-lensing. Since background populations reside behind the LMC, we expect them to be both redder and fainter then the average population of the LMC. We attempt to determine if the MACHO source stars come from such a background population by comparing the HST color-magnitude diagram (CMD) of source stars to the CMD of the average population of the LMC and looking for the effects of extra reddening and extinction. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. Preliminary results suggest that halo-lensing accounts for ≳ 40% of the observed microlensing results. Support provided by NASA, DOE, NSF and NPSC.

  10. Optics of progressive addition lenses.

    PubMed

    Sheedy, J E; Buri, M; Bailey, I L; Azus, J; Borish, I M

    1987-02-01

    The optical characteristics of the major progressive addition lenses were measured using an automated lensometer with a specially designed lens holder to simulate eye rotation. Measurements were made every 3 degrees (about 1.5 mm) and graphs of isospherical equivalent lines and isocylinder lines were developed. Generally the near zone of these lenses is narrower and lower than in bifocal or trifocal lenses. Distinct differences exist between the various progressive lenses. The width of the near zone, rate of power progression, amount of unwanted cylinder (level with the distance center), and clarity of the distance zone are compared for the various lenses. The optical measurements demonstrate an apparent trade-off between the size of the cylinder-free area of the lens and the amount of the cylinder.

  11. Laminated Fresnel lenses

    SciTech Connect

    Jebens, R.W.

    1980-04-01

    A fabrication method for making plastic-on-glass laminated Fresnel lenses is discussed. These Fresnel lenses are for application in an RCA solar photovoltaic concentrator array now in the prototype stage of development. This laminated Fresnel lens fabrication method consists of making a Dow Corning J RTV silastic rubber mold of a master lens array. This mold is used to vacuum cast only the lens facets onto a low-iron tempered-glass substrate with an epoxy resin such as Hysol 0S 1000, a bisphenol-A resin with a flexibilizer that is anhydride cured. Cast acrylic Fresnel lens arrays commercialy available have potential cleaning and abrasion problems, have very large thermal expansion, and have dimensional uncertainties in their manufacture. The laminated lens is dimensionally stable with low thermal expansion, has good cleaning characteristics, and is very inexpensive in materials cost. The measured transmission of such a lens on low-iron glass is 80.4% compared with 85.1% for a cast acrylic lens, and the optical quality is good enough for application in the 100X to 200X concentration range. An approach to making large lens arrays (3 by 6 ft) on a commercial scale is explored.

  12. A 5-bp Insertion in Mip Causes Recessive Congenital Cataract in KFRS4/Kyo Rats

    PubMed Central

    Ohashi, Tomoko; Okubo, Saki; Takekuma, Kensuke; Hashizume, Ryoichi; Hayashi, Jun-Ichi; Serikawa, Tadao; Kuramoto, Takashi; Kikkawa, Yoshiaki

    2012-01-01

    We discovered a new cataract mutation, kfrs4, in the Kyoto Fancy Rat Stock (KFRS) background. Within 1 month of birth, all kfrs4/kfrs4 homozygotes developed cataracts, with severe opacity in the nuclei of the lens. In contrast, no opacity was observed in the kfrs4/+ heterozygotes. We continued to observe these rats until they reached 1 year of age and found that cataractogenesis did not occur in kfrs4/+ rats. To define the histological defects in the lenses of kfrs4 rats, sections of the eyes of these rats were prepared. Although the lenses of kfrs4/kfrs4 homozygotes showed severely disorganised fibres and vacuolation, the lenses of kfrs4/+ heterozygotes appeared normal and similar to those of wild-type rats. We used positional cloning to identify the kfrs4 mutation. The mutation was mapped to an approximately 9.7-Mb region on chromosome 7, which contains the Mip gene. This gene is responsible for a dominant form of cataract in humans and mice. Sequence analysis of the mutant-derived Mip gene identified a 5-bp insertion. This insertion is predicted to inactivate the MIP protein, as it produces a frameshift that results in the synthesis of 6 novel amino acid residues and a truncated protein that lacks 136 amino acids in the C-terminal region, and no MIP immunoreactivity was observed in the lens fibre cells of kfrs4/kfrs4 homozygous rats using an antibody that recognises the C- and N-terminus of MIP. In addition, the kfrs4/+ heterozygotes showed reduced expression of Mip mRNA and MIP protein and the kfrs4/kfrs4 homozygotes showed no expression in the lens. These results indicate that the kfrs4 mutation conveys a loss-of-function, which leads to functional inactivation though the degradation of Mip mRNA by an mRNA decay mechanism. Therefore, the kfrs4 rat represents the first characterised rat model with a recessive mutation in the Mip gene. PMID:23226368

  13. Probing gravity at large scales through CMB lensing

    NASA Astrophysics Data System (ADS)

    Pullen, Anthony R.; Alam, Shadab; Ho, Shirley

    2015-06-01

    We describe a methodology to probe gravity with the cosmic microwave background (CMB) lensing convergence κ, specifically by measuring EG, the ratio of the Laplacian of the gravitational scalar potential difference to the velocity divergence. Using CMB lensing instead of galaxy-galaxy lensing avoids intrinsic alignments while also lacking a hard limit on the lens redshift and significant uncertainties in the source plane. We model EG for general relativity and modified gravity, finding that EG for f(R) gravity should be scale dependent due to the scale dependence of the growth rate f. Next, we construct an estimator for EG in terms of the galaxy-CMB lensing and galaxy clustering angular power spectra, along with the redshift-space distortion parameter β. We also forecast statistical errors for EG from the current Planck CMB lensing map and the spectroscopic galaxy and quasar samples from the Sloan Digital Sky Survey Data Release 11, being 9 per cent with galaxies and 8 per cent when quasars are included. We also find that upcoming spectroscopic and photometric surveys, combined with the final Planck lensing map, can measure precisely the redshift- and scale dependence of EG out to redshifts z = 2 and higher, with photometric surveys having an advantage due to their high number densities. Advanced ACTPol's lensing map will increase the EG sensitivity even further. Finally, we find that Advanced ACTPol cross-correlated with spectroscopic (photometric) surveys can differentiate between general relativity and f(R) gravity at the level of 3σ (13σ). Performing a <1 per cent measurement of EG requires a 10 per cent precision in β from Euclid or Large Synoptic Survey Telescope, currently achievable with a spectroscopic survey but difficult with only a photometric survey.

  14. High-Fidelity Cataract Surgery Simulation and Third World Blindness

    PubMed Central

    Singh, Ajay

    2015-01-01

    The burden of global cataract blindness continues to rise, because the number of surgical ophthalmologists is insufficient, and they are unevenly distributed. There is an urgent need to train surgeons quickly and comprehensively in high-quality, low-cost cataract removal techniques. The authors suggest manual small-incision cataract surgery as a safe alternative to phacoemulsification cataract surgery in the developing world. They discuss the development of a novel, full-immersion, physics-based surgical training simulator as the centerpiece of a scalable, comprehensive training system for manual small-incision cataract surgery. PMID:24996918

  15. [Appropriate cataract surgery training can promote work of blindness prevention].

    PubMed

    Zhang, Mingzhi

    2014-03-01

    Cataract is the first blinding eye disease in the world and China. However, due to various reasons, cataract surgery rate (CSR) in China is much lower than in developed countries and even some developing countries. Properly and standardized training of cataract surgery for ophthalmologists from primary hospital and young eye doctors is one of the key point to improve CSR. For above, we had explored actively to establish an appropriate and suitable training model of cataract surgery. Ophthalmologist in primary hospital can provide high quality medical services to cataract patients in accordance with their own conditions after training and promote the sustainable development of blindness prevention work.

  16. High-fidelity cataract surgery simulation and third world blindness.

    PubMed

    Singh, Ajay; Strauss, Glenn H

    2015-04-01

    The burden of global cataract blindness continues to rise, because the number of surgical ophthalmologists is insufficient, and they are unevenly distributed. There is an urgent need to train surgeons quickly and comprehensively in high-quality, low-cost cataract removal techniques. The authors suggest manual small-incision cataract surgery as a safe alternative to phacoemulsification cataract surgery in the developing world. They discuss the development of a novel, full-immersion, physics-based surgical training simulator as the centerpiece of a scalable, comprehensive training system for manual small-incision cataract surgery.

  17. Roulettes: a weak lensing formalism for strong lensing: I. Overview

    NASA Astrophysics Data System (ADS)

    Clarkson, Chris

    2016-08-01

    We present a new perspective on gravitational lensing. We describe a new extension of the weak lensing formalism capable of describing strongly lensed images. By integrating the nonlinear geodesic deviation equation, the amplification matrix of weak lensing is generalised to a sum over independent amplification tensors of increasing rank. We show how an image distorted by a generic lens may be constructed as a sum over ‘roulettes’, which are the natural curves associated with the independent spin modes of the amplification tensors. Highly distorted images can be constructed even for large sources observed near or within the Einstein radius of a lens where the shear and convergence are large. The amplitude of each roulette is formed from a sum over appropriate derivatives of the lensing potential. Consequently, measuring these individual roulettes for images around a lens gives a new way to reconstruct a strong lens mass distribution without requiring a lens model. This formalism generalises the convergence, shear and flexion of weak lensing to arbitrary order, and provides a unified bridge between the strong and weak lensing regimes. This overview paper is accompanied by a much more detailed paper II, arXiv:1603.04652.

  18. Residual aniseikonia among patients fitted with one or two intraocular lenses (pseudophakic corrections)

    PubMed

    Lakshminarayanan, V; Enoch, J M; Knowles, R A

    1993-02-01

    In the presence of one or two intraocular lenses (IOL's; pseudophakic corrections) or in the presence of naturally occurring or developmental anisometropia (due to a tumescent cataract) some induced or residual refractive aniseikonia is usually encountered. We wish to call this problem to the attention of the optometric practitioner. We provide a discussion of the resultant aniseikonia and simple rules of thumb for management of such patients with refractive aniseikonia. Aniseikonia in these patients may be less important than once had been suggested, but certainly it is more significant than it is currently being considered. Use of personal computers to calculate this aniseikonia makes appropriate correction relatively easy and readily applicable.

  19. Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

    SciTech Connect

    Oguri, Masamune; Hennawi, Joseph F.; Gladders, Michael D.; Dahle, Haakon; Natarajan, Priyamvada; Dalal, Neal; Koester, Benjamin P.; Sharon, Keren; Bayliss, Matthew

    2009-01-29

    We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z = 0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the {Lambda}-dominated cold dark matter model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c{sub vir} {approx} 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster Abell 1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.

  20. LENSED: a code for the forward reconstruction of lenses and sources from strong lensing observations

    NASA Astrophysics Data System (ADS)

    Tessore, Nicolas; Bellagamba, Fabio; Metcalf, R. Benton

    2016-12-01

    Robust modelling of strong lensing systems is fundamental to exploit the information they contain about the distribution of matter in galaxies and clusters. In this work, we present LENSED, a new code which performs forward parametric modelling of strong lenses. LENSED takes advantage of a massively parallel ray-tracing kernel to perform the necessary calculations on a modern graphics processing unit (GPU). This makes the precise rendering of the background lensed sources much faster, and allows the simultaneous optimization of tens of parameters for the selected model. With a single run, the code is able to obtain the full posterior probability distribution for the lens light, the mass distribution and the background source at the same time. LENSED is first tested on mock images which reproduce realistic space-based observations of lensing systems. In this way, we show that it is able to recover unbiased estimates of the lens parameters, even when the sources do not follow exactly the assumed model. Then, we apply it to a subsample of the Sloan Lens ACS Survey lenses, in order to demonstrate its use on real data. The results generally agree with the literature, and highlight the flexibility and robustness of the algorithm.

  1. Gender and use of cataract surgical services in developing countries.

    PubMed Central

    Lewallen, Susan; Courtright, Paul

    2002-01-01

    OBJECTIVE: To determine, from the existing literature, cataract surgical coverage rates by sex and the proportion of cataract blindness that could be eliminated if women and men had equal access to cataract surgical services. METHOD: Methodologically sound population-based cataract surveys from developing countries were identified through a literature search. Cataract surgical coverage rates were extracted from the surveys and rates for women were compared to those for men. Peto odds ratios were calculated for each survey and a meta-analysis of the surveys was performed. FINDINGS: From a literature review and meta-analysis of cataract surveys in developing countries, we found that the cataract surgical coverage rate was 1.2-1.7 times higher for males than for females. For females, the odds ratio of having surgery, compared to males, was 0.67 (95% confidence interval (CI): 0.60- 0.74). Despite their lower coverage rate, females accounted for approximately 63% of all cataract cases in the study populations, and if they received surgery at the same rates as males, the prevalence of cataract blindness would be reduced by a median of 12.5% (range 4-21%). CONCLUSION: Closing the gender gap could thus significantly decrease the prevalence of cataract blindness, and gender-sensitive intervention programmes are needed to improve cataract surgical coverage among females. PMID:12075366

  2. Historical challenge of large lenses

    NASA Astrophysics Data System (ADS)

    Johnson, Kevin L.

    2002-02-01

    To present a full account of the developments in the manufacture of large lenses one needs to address wider issues rather than just provide a catalogue of technological progress. The advances in glass manufacture and improvement in optical techniques have to be considered in relation to the cultural, social and economic factors that have determined where, how and why large lens manufacture developed in specific countries. The challenge facing historians trying to tackle this technological theme, is that it is often poorly documented and little is preserved in the historical records. Until relatively recent times, opticians have concealed their methods, trade secrecy being an important economic strategy. To provide an example, it should be noted that although William Herschel produced the best optics and telescopes of the day, he published practically nothing about his methods. What has been gleaned of his techniques has only been uncovered by careful study of surviving manuscript sources and measurement of his surviving optics. Such was William's personal knowledge, that his son John had to take instruction from his father to refurbish William Herschel's 20-foot telescope. This training gave John tacit knowledge of William's methods and allowed him to successfully undertake his cape observations in the Southern Hemisphere. In spite of the shortcomings of the historical record, historians can give a measured account of the developments of lens optics by studying surviving telescopes and their optics.

  3. Surface Modification of Intraocular Lenses

    PubMed Central

    Huang, Qi; Cheng, George Pak-Man; Chiu, Kin; Wang, Gui-Qin

    2016-01-01

    Objective: This paper aimed to review the current literature on the surface modification of intraocular lenses (IOLs). Data Sources: All articles about surface modification of IOLs published up to 2015 were identified through a literature search on both PubMed and ScienceDirect. Study Selection: The articles on the surface modification of IOLs were included, but those on design modification and surface coating were excluded. Results: Technology of surface modification included plasma, ion beam, layer-by-layer self-assembly, ultraviolet radiation, and ozone. The main molecules introduced into IOLs surface were poly (ethylene glycol), polyhedral oligomeric silsesquioxane, 2-methacryloyloxyethyl phosphorylcholine, TiO2, heparin, F-heparin, titanium, titanium nitride, vinyl pyrrolidone, and inhibitors of cytokines. The surface modification either resulted in a more hydrophobic lens, a more hydrophilic lens, or a lens with a hydrophilic anterior and hydrophobic posterior surface. Advances in research regarding surface modification of IOLs had led to a better biocompatibility in both in vitro and animal experiments. Conclusion: The surface modification is an efficient, convenient, economic and promising method to improve the biocompatibility of IOLs. PMID:26830993

  4. Cat-Map: putting cataract on the map

    PubMed Central

    Bennett, Thomas M.; Hejtmancik, J. Fielding

    2010-01-01

    Lens opacities, or cataract(s), may be inherited as a classic Mendelian disorder usually with early-onset or, more commonly, acquired with age as a multi-factorial or complex trait. Many genetic forms of cataract have been described in mice and other animal models. Considerable progress has been made in mapping and identifying the genes and mutations responsible for inherited forms of cataract, and genetic determinants of age-related cataract are beginning to be discovered. To provide a convenient and accurate summary of current information focused on the increasing genetic complexity of Mendelian and age-related cataract we have created an online chromosome map and reference database for cataract in humans and mice (Cat-Map). PMID:21042563

  5. [Intraocular hydrodynamics failure as a part of age cataract etiopathogenesis].

    PubMed

    Ignat'ev, S G; Shilkin, G A; Iartseva, N S; Ignat'eva, S G; Al'-Dandan, I Kh

    2011-01-01

    59 (105 eyes) patients with initial, premature and mature cataract are studied. Besides 14 patients (19 eyes) 1-2 years after cataract phacoemulsification with IOL implantation were examined. All patients underwent routine ophthalmological examination and tonography. Average indexes of intraocular hydrodynamics coefficients differed from normal rates: in initial and premature cataract F- coefficient was lower by 34% compared to normal, in mature cataract it was higher by 8,9% than upper limit of normal, in pseudophakia by 86,8% lower. In all groups with cataract patients disbalance of intraocular hydrodynamics was revealed in more than 70% cases, and in pseudophakia group it was found in 100%. Disbalance of intraocular hydrodynamics in cataract confirms hypothesis that intraocular hydrodynamics failure is an important part of cataract etiopathogenesis.

  6. Cataract and Cognitive Impairment: A Review of the Literature

    PubMed Central

    Jefferis, Joanna M; Mosimann, Urs P; Clarke, Michael P

    2014-01-01

    Acquired cataract and cognitive impairment are both common age related problems, and ophthalmologists are increasingly likely to encounter patients who have both. Dementia types which display early visuo-perceptual impairment may present first to ophthalmology services. When these patients have coexisting cataract it may be difficult to distinguish visual complaints due to cataract from those due to dementia. The interaction between visual impairment due to cataract, and neurodegenerative disorders affecting the central visual pathways, is not fully understood. Visual impairment due to cataract may stress impaired attentional mechanisms, and cataract extraction may improve cognitive performance in some patients with early cognitive impairment; however the benefits of cataract surgery in established dementia are less clear. Here we review the literature on this subject and consider the implications for practice. PMID:20807709

  7. Erbium:YAG laser for cataract extraction

    NASA Astrophysics Data System (ADS)

    Snyder, Robert W.; Jani, Mahendra G.; Yarborough, Mike; Marcellino, George R.; Noecker, Robert J.; Kramer, Theresa R.; Vidaurri, Jesus

    1998-06-01

    The Erbium:YAG laser may be an effective laser for use in cataract surgery. At 2.94 mm the energy is maximally absorbed by water thereby efficiently disrupting tissue with minimal surrounding thermal damage. The laser may be safer to use in the eye than conventional ultrasonic emulsifiers. Preliminary clinical studies of the safety and efficacy have begun.

  8. The evolution of lenses.

    PubMed

    Land, Michael F

    2012-11-01

    Structures which bend light and so form images are present in all the major phyla. Lenses with a graded refractive index, and hence reduced spherical aberration, evolved in the vertebrates, arthropods, annelid worms, and several times in the molluscs. Even cubozoan jellyfish have lens eyes. In some vertebrate eyes, multiple focal lengths allow some correction for chromatic aberration. In land vertebrates the cornea took over the main ray-bending task, leaving accommodation as the main function of the lens. The spiders are the only other group to make use of a single cornea as the optical system in their main eyes, and some of these - the salticids - have evolved a remarkable system based on image scanning. Similar scanning arrangements are found in some crustaceans, sea-snails and insect larvae.

  9. Pulsar lensing geometry

    NASA Astrophysics Data System (ADS)

    Liu, Siqi; Pen, Ue-Li; Macquart, J.-P.; Brisken, Walter; Deller, Adam

    2016-05-01

    We test the inclined sheet pulsar scintillation model (Pen & Levin) against archival very long baseline interferometry (VLBI) data on PSR 0834+06 and show that its scintillation properties can be precisely reproduced by a model in which refraction occurs on two distinct lens planes. These data strongly favour a model in which grazing-incidence refraction instead of diffraction off turbulent structures is the primary source of pulsar scattering. This model can reproduce the parameters of the observed diffractive scintillation with an accuracy at the percent level. Comparison with new VLBI proper motion results in a direct measure of the ionized interstellar medium (ISM) screen transverse velocity. The results are consistent with ISM velocities local to the PSR 0834+06 sight-line (through the Galaxy). The simple 1-D structure of the lenses opens up the possibility of using interstellar lenses as precision probes for pulsar lens mapping, precision transverse motions in the ISM, and new opportunities for removing scattering to improve pulsar timing. We describe the parameters and observables of this double screen system. While relative screen distances can in principle be accurately determined, a global conformal distance degeneracy exists that allows a rescaling of the absolute distance scale. For PSR B0834+06, we present VLBI astrometry results that provide (for the first time) a direct measurement of the distance of the pulsar. For most of the recycled millisecond pulsars that are the targets of precision timing observations, the targets where independent distance measurements are not available. The degeneracy presented in the lens modelling could be broken if the pulsar resides in a binary system.

  10. Cross-correlating Planck CMB lensing with SDSS: lensing-lensing and galaxy-lensing cross-correlations

    NASA Astrophysics Data System (ADS)

    Singh, Sukhdeep; Mandelbaum, Rachel; Brownstein, Joel R.

    2017-01-01

    We present results from cross-correlating Planck cosmic microwave background (CMB) lensing maps with the Sloan Digital Sky Survey (SDSS) galaxy lensing shape catalogue and BOSS (Baryon Oscillation Spectroscopic Survey) galaxy catalogues. For galaxy position versus CMB lensing cross-correlations, we measure the convergence signal around the galaxies in configuration space, using the BOSS LOWZ (z ˜ 0.30) and CMASS (z ˜ 0.57) samples. With fixed Planck 2015 cosmology, doing a joint fit with the galaxy clustering measurement, for the LOWZ (CMASS) sample we find a galaxy bias bg = 1.75 ± 0.04 (1.95 ± 0.02) and galaxy-matter cross-correlation coefficient rcc = 1.0 ± 0.2 (0.8 ± 0.1) using 20 < rp < 70 h-1 Mpc, consistent with results from galaxy-galaxy lensing. Using the same scales and including the galaxy-galaxy lensing measurements, we constrain Ωm = 0.284 ± 0.024 and relative calibration bias between the CMB lensing and galaxy lensing to be b_γ =0.82^{+0.15}_{-0.14}. The combination of galaxy lensing and CMB lensing also allows us to measure the cosmological distance ratios (with zl ˜ 0.3, zs ˜ 0.5) R=D_s D_{l,*}/D_{* D_{l,s}}=2.68± 0.29, consistent with predictions from the Planck 2015 cosmology (R=2.35). We detect the galaxy position-CMB convergence cross-correlation at small scales, rp < 1 h-1 Mpc, and find consistency with lensing by NFW haloes of mass Mh ˜ 1013 h-1 M⊙. Finally, we measure the CMB lensing-galaxy shear cross-correlation, finding an amplitude of A = 0.76 ± 0.23 (zeff = 0.35, θ < 2°) with respect to Planck 2015 Λ cold dark matter predictions (1σ level consistency). We do not find evidence for relative systematics between the CMB and SDSS galaxy lensing.

  11. Galaxy cluster lensing masses in modified lensing potentials

    SciTech Connect

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; Merten, Julian; King, Lindsay; Baugh, Carlton M.; Pascoli, Silvia

    2015-10-28

    In this study, we determine the concentration–mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro–Frenk–White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentration and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ~ [2–20] Mpc/h from the cluster centre, we find that the surrounding force profiles are enhanced by ~ 20–40% in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.

  12. Galaxy cluster lensing masses in modified lensing potentials

    DOE PAGES

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; ...

    2015-10-28

    In this study, we determine the concentration–mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro–Frenk–White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentrationmore » and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ~ [2–20] Mpc/h from the cluster centre, we find that the surrounding force profiles are enhanced by ~ 20–40% in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.« less

  13. Galaxy cluster lensing masses in modified lensing potentials

    NASA Astrophysics Data System (ADS)

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; Merten, Julian; King, Lindsay; Baugh, Carlton M.; Pascoli, Silvia

    2015-12-01

    We determine the concentration-mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro-Frenk-White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentration and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ˜(2-20) Mpc h-1 from the cluster centre, we find that the surrounding force profiles are enhanced by ˜20-40 per cent in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.

  14. Relationship of cytokines and AGE products in diabetic and non-diabetic patients with cataract

    PubMed Central

    Hamid, Sadaf; Gul, Anjuman; Hamid, Qamar

    2016-01-01

    Objectives Cytokines are important mediators of inflammatory and immune responses. The aim of this study was to investigate the changes in cytokines concentration (IL-6, IL-8 and TNF-α) and serum advanced glycation end products (sAGEs) in senile diabetics with or without cataract and non-diabetic patients with cataract. Methodology The study included 124 subjects (sixty or over sixty years age), distributed as four groups thirty senile diabetic patients with cataract (Group I) (16 female and 14 male), thirty senile non-diabetic patients with cataract (Group II) (15 female and 15 male), thirty three senile diabetic patients without any complication (Group III) (16 female and 17 male), thirty one apparently normal healthy individuals (Group IV) (16 female and 15 male), age, sex and weight matched with senile control subjects were investigated. Patients were selected on clinical grounds from Eye Ward Jinnah Postgraduate Medical Centre. Results Interleukin-6 (IL-6), interleukin-8 (IL-8) and tumor necrosis factor-α (TNF-α) levels were significantly increased (P < 0.001) in Group I and III as compared to Group II and IV. Fasting blood glucose, glycosylated hemoglobin, serum fructosamine, malondialdehyde (MDA), sAGEs, IL-6, IL-8 and TNF-α levels were significantly increased (P < 0.001) in Group I as compared to Group II and the levels were almost same in Group II and IV. There was a significant decrease in serum vitamin E and total antioxidant status (p< 0.001) in Group I and Group III as compared to Group II and Group IV. Conclusion The results of the present study thus demonstrated that levels increased in both condition but are more severe in diabetic patients with cataract that may be a predictor for cataractogenesis and the levels were almost same in Group II and IV. PMID:27833515

  15. KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

    SciTech Connect

    STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

    2004-10-23

    While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

  16. CMB lensing and giant rings

    SciTech Connect

    Rathaus, Ben; Itzhaki, Nissan E-mail: ben.rathaus@gmail.com

    2012-05-01

    We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

  17. Cataract production in mice by heavy charged argon, neon, and carbon particles

    SciTech Connect

    Jose, J.G.; Ainsworth, E.J.

    1983-06-01

    The cataractogenic potential in mice of heavy charged particles from the Bevalac was examined in relation to dose, linear energy transfer (LET), and time following exposure. BALB/c x C57/bl/sub 6/(CB/sub 6/F/sub 1/) mice were exposed to graded single doses (0.05 to 0.9 Gy) of 570-MeV /sup 40/Ar, 425-MeV /sup 20/Ne, or 400-MeV /sup 12/C particles in the plateau portion of the Bragg curve. Lenses were examined by slit lamp biomicroscopy over a 21-month period. The cataract severity was scored subjectively on a scale of 0 to 4 and compared to the opacities induced by 225-kVp X rays. Both the onset and density of the lens opacities were related to dose, and opacification progressed throughout the entire period of observation. In terms of degree of opacification and rates of onset and progression, the cataractogenic response to /sup 40/Ar particles was greater than to either /sup 20/Ne or /sup 12/C particles. Discrimination between the effects of /sup 20/Ne and /sup 12/C was possible only at the higher doses employed (0.6 and 0.9 Gy) and only at some observation times. Based on average cataract density at the several observation times, the relative biological effectiveness (RBE) of /sup 40/Ar particles is estimated to be 3 to 5 over a cataract score range of about 1.5 to 3.0 (0.15 to 0.9 Gy). The RBE for /sup 20/Ne and /sup 12/C particles is probably somewhat greater than 1.0. The consistency of replicate lens examinations and challenges of the subjective scoring system are discussed.

  18. Risk Factors for Acute Endophthalmitis following Cataract Surgery: A Systematic Review and Meta-Analysis

    PubMed Central

    Li, Liping; Lo, SingKai

    2013-01-01

    Background Acute endophthalmitis is one of the most serious complications of cataract surgery and often results in severe visual impairment. Several risk factors for acute postoperative endophthalmitis (POE) following cataract surgery have been reported but the level of evidence and strength of association is varied. The purpose of this study was to critically appraise published reports on and to summarize clinical risk factors associated with acute POE which could be easily assessed by ophthalmologists for the introduction and implementation of preventive measure. Methods A systematic review and meta-analysis of observational studies was performed. Six databases were searched with no limits on the year or language of publication. Study-specific odds ratios (Ors) or relative risk (RR) of each risk factor were pooled using a random effect model. Results A total of 6 686 169 participants with 8 963 endophthalmitis in 42 studies were analyzed. Of the nine risk factors identified in our systematic review and meta-analysis, extra- or intracapsular cataract extraction, a clear corneal incision, without intracameral cefazolin (1 mg in 0.1 ml solution), without intracameral cefuroxime (1 mg in 0.1 ml solution), post capsular rupture, silicone intraocular lenses and intraoperative complications were found strongly associated with acute endophthalmitis. Other significant factors with a lower strength of association (risk estimates generally 1.5 or less) were male gender and old age (85 years and older). Conclusions Our study provides summary data on the risk factors for acute POE. Identifying patients at high risk of this sight-threatening eye disease is important from both the public health and clinical perspectives as this would facilitate detection of disease before the onset of irreversible visual loss enabling earlier intervention. PMID:23990980

  19. Prevention of cataracts in pink-eyed RCS rats by dark rearing.

    PubMed

    O'Keefe, T L; Hess, H H; Zigler, J S; Kuwabara, T; Knapka, J J

    1990-11-01

    Royal College of Surgeons rats have hereditary retinal degeneration and associated posterior subcapsular opacities (PSO) of the lens, detectable by slitlamp at 7-8 postnatal weeks in both pink- and black-eyed rats. The retinal degeneration is intensified by light, especially in pink-eyed rats. A fourth of pink-eyed rats developed mature cataracts by 9-12 months of age, but black-eyed rats whose retinas are protected from light by pigmented irises and pigment epithelium rarely have mature cataracts (3% or less), indicating light may be a factor in cataractogenesis. Prior work had shown that dark rearing reduced the rate of retinal degeneration in pink- but not black-eyed rats, but cataracts were not studied. In the present work, pregnant pink-eyed females were placed in a darkroom 1 week before parturition. Pups were removed over intervals at 20-85 postnatal days for: (a) microscopic study of fresh lenses and of fixed, stained retina and lens, and (b) counts of cells mm-2 of the web-like vitreous cortex after it had been dissected free. The macrophage-like cells are a quantitative index of immune reaction to retinal damage. At 50-53 postnatal days, in pink-eyed cyclic light reared RCS, the mean number of macrophages was 4.6-fold that in congenic controls, but in those that were dark reared it was only 1.4-fold. This was less than the increase in cyclic light reared black-eyed RCS (2.3-fold that in congenic black-eyed controls). Total absence of light reduced retinal degeneration and the number of macrophages, and prevented PSO detectable microscopically.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. HUBBLE'S TOP TEN GRAVITATIONAL LENSES

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The NASA Hubble Space Telescope serendipitous survey of the sky has uncovered exotic patterns, rings, arcs and crosses that are all optical mirages produced by a gravitational lens, nature's equivalent of having giant magnifying glass in space. Shown are the top 10 lens candidates uncovered in the deepest 100 Hubble fields. Hubble's sensitivity and high resolution allow it to see faint and distant lenses that cannot be detected with ground-based telescopes whose images are blurred by Earth's atmosphere. [Top Left] - HST 01248+0351 is a lensed pair on either side of the edge-on disk lensing galaxy. [Top Center] - HST 01247+0352 is another pair of bluer lensed source images around the red spherical elliptical lensing galaxy. Two much fainter images can be seen near the detection limit which might make this a quadruple system. [Top Right] - HST 15433+5352 is a very good lens candidate with a bluer lensed source in the form of an extended arc about the redder elliptical lensing galaxy. [Middle Far Left] - HST 16302+8230 could be an 'Einstein ring' and the most intriguing lens candidate. It has been nicknamed the 'the London Underground' since it resembles that logo. [Middle Near Left] - HST 14176+5226 is the first, and brightest lens system discovered in 1995 with the Hubble telescope. This lens candidate has now been confirmed spectroscopically using large ground-based telescopes. The elliptical lensing galaxy is located 7 billion light-years away, and the lensed quasar is about 11 billion light-years distant. [Middle Near Right] - HST 12531-2914 is the second quadruple lens candidate discovered with Hubble. It is similar to the first, but appears smaller and fainter. [Middle Far Right] - HST 14164+5215 is a pair of bluish lensed images symmetrically placed around a brighter, redder galaxy. [Bottom Left] - HST 16309+8230 is an edge-on disk-like galaxy (blue arc) which has been significantly distorted by the redder lensing elliptical galaxy. [Bottom Center] - HST 12368

  1. Fresnel lenses for ultrasonic inspection

    NASA Technical Reports Server (NTRS)

    Kammerer, C. C.

    1980-01-01

    Ultrasonic Fresnel lenses are effective focusing elements with potential applications in ultrasonic "contact" testing for defects in materials. Ultrasonic beams focused on concave lenses are used successfully with immersion transducers, for which test object is immersed in water bath. However, for large objects, objects that are already installed, objects on production lines, and objects that can be damaged by water, contact testing is more practical than immersion.

  2. Astrophysical Applications of Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, Evencio; Muñoz, Jose A.; Garzón, Francisco; Mahoney, Terence J.

    2016-10-01

    Contributors; Participants; Preface; Acknowledgements; 1. Lensing basics Sherry H. Suyu; 2. Exoplanet microlensing Andrew Gould; 3. Case studies of microlensing Veronica Motta and Emilio Falco; 4. Microlensing of quasars and AGN Joachim Wambsganss; 5. DM in clusters and large-scale structure Peter Schneider; 6. The future of strong lensing Chris Fassnacht; 7. Methods for strong lens modelling Charles Keeton; 8. Tutorial on inverse ray shooting Jorge Jimenez-Vicente.

  3. The Thirring-Lense Effect

    NASA Astrophysics Data System (ADS)

    Embacher, Franz

    The Thirring-Lense effect is the phenomenon that an observer near a rotating mass, being in a state which is non-rotating with respect to the rest of the universe, experiences extra inertial forces, i.e. becomes dizzy. The first anticipation of the effect goes back to Ernst Mach; its first quantitative prediction on the basis of general relativity was given by Hans Thirring and Joseph Lense. Almost ninety years later, the effect seems to be experimentally verified.

  4. Therapeutic uses of drug-carrier systems for imidazole-containing dipeptide compounds that act as pharmacological chaperones and have significant impact on the treatment of chronic diseases associated with increased oxidative stress and the formation of advanced glycation end products.

    PubMed

    Babizhayev, Mark A; Yegorov, Yegor E

    2010-01-01

    The purpose of this study was to determine how the naturally occurring molecules N-acetylcarnosine, L-carnosine, and carcinine, which are chemical or pharmacological chaperones, affect the cells and biomolecules of patients with skin diseases, cosmetic skin lesions, or underlying clinically significant visual impairment such as age-related cataracts, age-related retinal degeneration, and ocular complications of diabetes. We evaluated and characterized the effects of cited pharmacological chaperones on enzyme activity, protein structure in tissues, and other biomarkers of diseases in skin cells and tissues or in ocular tissues (human cataractous and normal lenses) derived from ophthalmic patients or age-matched donors. The samples were used to test imidazole-containing peptidomimetic chemical/pharmacological chaperones in relation to oxidative stress induced by reaction with lipid peroxides or advanced non-enzymatic glycation processes. Chaperone function is characterized by interaction with other proteins, mediating their folding, transport, and interaction with other molecules, lipid peroxidation products, and membranes. Although these therapies remain on hold pending further investigation, we present growing evidence demonstrating the ability of N-acetylcarnosine (lubricant eye drops) or carcinine pharmacological chaperone therapy to act as novel treatments for age-related cataracts, age-related macular degeneration, and ocular complications of diabetes. Finally, we examine strategies for identifying potential chaperone compounds and for experimentally demonstrating chaperone and transglycating (de-glycation) types of activity in in vitro and in vivo models of human age-related eye diseases, such as cataracts, and advanced glycation tissue protein-engineered systems.

  5. Laser ablation and high precision patterning of biomaterials and intraocular lenses

    NASA Astrophysics Data System (ADS)

    Serafetinides, A. A.; Spyratou, E.; Makropoulou, M.

    2010-10-01

    The use of intraocular lenses (IOL) is the most promising method for restoring excellent vision in cataract surgery. In addition, multifocal intraocular lenses for good distant and near vision are investigated. Several new materials, techniques and patterns are studied for the formation and etching of intraocular lenses in order to improve their optical properties and reduce the diffractive aberrations. As pulsed laser ablation is well established as a universal tool for surface processing of organic polymer materials, this study was focused in using laser ablation with short and ultra short laser pulses for surface modification of PMMA and intraocular lenses, instead of using other conventional techniques. The main advantage of using very short laser pulses, e.g. of ns, ps or fs duration, is that heat diffusion into the polymer material is negligible. As a result high precision patterning of the sample, without thermal damage of the surroundings, becomes possible. In this study, laser ablation was performed using commercially available hydrophobic acrylic IOLs, hydrophilic acrylic IOLs, and PMMA IOLs, with various diopters. We investigated the ablation efficiency and the phenomenology of the etched patterns by testing the ablation rate, versus laser energy fluence, at several wavelengths and the surface modification with atomic force microscopy (AFM), or scanning electron microscopy (SEM). The irradiated polymers have different optical properties, at the applied wavelengths, and therefore, present different ablation behaviour and morphology of the laser ablated crater walls and surrounding surfaces. The experimental results, some theoretical assumptions for mathematical modeling of the relevant ablation mechanisms are discussed.

  6. Prevalence of Cataract in an Older Population in India

    PubMed Central

    Vashist, Praveen; Talwar, Badrinath; Gogoi, Madhurjya; Maraini, Giovanni; Camparini, Monica; Ravindran, Ravilla D.; Murthy, Gudlavalleti V.; Fitzpatrick, Kathryn E.; John, Neena; Chakravarthy, Usha; Ravilla, Thulasiraj D.; Fletcher, Astrid E.

    2011-01-01

    Purpose To describe the prevalence of cataract in older people in 2 areas of north and south India. Design Population-based, cross-sectional study. Participants Randomly sampled villages were enumerated to identify people aged ≥60 years. Of 7518 enumerated people, 78% participated in a hospital-based ophthalmic examination. Methods The examination included visual acuity measurement, dilatation, and anterior and posterior segment examination. Digital images of the lens were taken and graded by type and severity of opacity using the Lens Opacity Classification System III (LOCS III). Main Outcome Measures Age- and gender-standardized prevalence of cataract and 95% confidence intervals (CIs). We defined type of cataract based on the LOCS III grade in the worse eye of: ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any unoperated cataract was based on these criteria or ungradable dense opacities. Any cataract was defined as any unoperated or operated cataract. Results The prevalence of unoperated cataract in people aged ≥60 was 58% in north India (95% CI, 56–60) and 53% (95% CI, 51–55) in south India (P = 0.01). Nuclear cataract was the most common type: 48% (95% CI, 46–50) in north India and 38% (95% CI, 37–40) in south India (P<0.0001); corresponding figures for PSC were 21% (95% CI, 20–23) and 17% (95% CI, 16–19; P = 0.003), respectively, and for cortical cataract 7.6% (95% CI, 7–9) and 10.2% (95% CI, 9–11; P<0.004). Bilateral aphakia/pseudophakia was slightly higher in the south (15.5%) than in the north (13.2%; P<0.03). The prevalence of any cataracts was similar in north (73.8%) and south India (71.8%). The prevalence of unoperated cataract increased with age and was higher in women than men (odds ratio [OR], 1.8). Aphakia/pseudophakia was also more common in women, either unilateral (OR, 1.2; P<0.02) or bilateral (OR, 1.3; P<0.002). Conclusions We found high rates of unoperated

  7. Cataracts and Other Common Eye Diseases | NIH MedlinePlus the Magazine

    MedlinePlus

    ... on. Feature: Treating Cataracts Cataracts and Other Common Eye Diseases Past Issues / Summer 2014 Table of Contents ... the lens. This is a cataract. Comprehensive Dilated Eye Exam A comprehensive dilated eye exam is a ...

  8. Manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts

    PubMed Central

    Yang, J; Lai, P; Wu, D; Long, Z

    2014-01-01

    Aims: To report the technique and outcomes of sutureless manual cataract extraction via a subconjunctival limbus oblique incision for mature cataracts. Materials and Methods: This retrospective study comprised of 112 eyes of 83 patients with mature cataract who all had manual cataract extraction via a subconjunctival limbus oblique incision. A transconjunctival tunnel is fashioned with a 3.0 mm keratome, 0.5 mm behind the limbal vascular arcades. A limbal tunnel, with a transverse extent of 9 mm in the cornea and 7.0 mm in the limbus, is created beneath the conjunctival/Tenon's tissue using an angled bevel-up crescent blade. Outcome measures included visual acuity, intraoperative complications, surgically induced astigmatism, endothelial cell loss rate and surgery time. Results: Self-sealing wound was achieved in 112 eyes (98.2%). The nucleus was delivered in whole in 108 eyes (96.4%). Intraoperative complications included hyphema in 3 eyes (2.7%), iridodialysis in 2 eyes 1.8%), posterior capsular rupture and zonular dialysis in 2 eyes (1.8%). At the 3-month follow-up, 91% patients achieved a best-corrected visual acuity of 20/20 or better, the mean of surgically induced astigmatism was -0.62 ± 0.41 Diopters and endothelial cell loss was 4.2%. Average surgical time was 3.75 min per case. Conclusion: This subconjunctival limbus oblique incision has the potential to serve as safe and effective technique for mature cataracts. PMID:24722270

  9. Micro-optofluidic Lenses: A review

    PubMed Central

    Nguyen, Nam-Trung

    2010-01-01

    This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field. PMID:20714369

  10. DL-3-n-butylphthalide delays the onset and progression of diabetic cataract by inhibiting oxidative stress in rat diabetic model.

    PubMed

    Wang, Fuxu; Ma, Jia; Han, Fei; Guo, Xiujin; Meng, Li; Sun, Yufeng; Jin, Cheng; Duan, Huijun; Li, Hang; Peng, Ying

    2016-01-13

    DL-3-n-butylphthalide (NBP) is a therapeutic drug used for ischemic stroke treatment. Here, we investigated the impact of NBP on the development of rat diabetic cataract induced by intraperitoneal injection of streptozotocin (STZ). NBP was then administrated by oral gavage for nine weeks. Cataract development was monitored through ophthalmoscope inspections. The levels of blood glucose and serum reactive oxygen species (ROS), malondialdehyde (MDA) and 8-Hydroxydeovexyguanosine (8-OHdG) were measured. Total and soluble protein and oxidative stress parameters, such as 2, 4- dinitrophenylhydrazone (DNP), 4-hydroxynonenal (4-HNE) and MDA in the lenses were determined by Western blot and thiobarbituric acid analyses. The expressions of NF-E2-related factor 2 (Nrf2) and its downstream antioxidant enzymes, thioredoxin (TRX), Catalase and nuclear accumulation of Nrf2 were determined by Western blot and immunohistochemistry analyses. We showed that NBP treatment significantly improved the cataract scores, the levels of DNP, 4-HNE, and MDA in the lens compared to the non-treated groups. NBP also enhanced the expressions of Nrf2, TRX and catalase in the lens of diabetic rats. In addition, NBP treatment also decreased levels of blood glucose, serum MDA and 8-OHdG. These results suggested that NBP treatment significantly delayed the onset and progression of diabetic cataract by inhibiting the oxidative stresses.

  11. Epidemiology of cataract in India: combating plans and strategies.

    PubMed

    Vajpayee, R B; Joshi, S; Saxena, R; Gupta, S K

    1999-01-01

    Blindness due to cataract presents an enormous problem in India not only in terms of human morbidity but also in terms of economic loss and social burden. The WHO/NPCB (National Programme for Control of Blindness) survey has shown that there is a backlog of over 22 million blind eyes (12 million blind people) in India, and 80.1% of these are blind due to cataract. The annual incidence of cataract blindness is about 3.8 million. The present annual level of performance is in the order of about 1.6-1.9 million cataract operations. To clear the backlog of cataract cases by the year 2000 and to tackle the rising incidence, 5-6 million cataract operations annually will have to be performed as against the present rate of 1. 7 million per year. India is undertaking a new long-term initiative to expand the capability of cataract surgery and service levels with financial assistance from the World Bank. An important feature of this initiative is the attention given to spread the cataract blindness programme in rural and tribal areas. The second feature is the emphasis placed on modern extracapsular cataract extraction with intra-ocular lens implantation as the preferred surgical technique. Another noteworthy feature is developing institutional capacity and appropriate co-ordination mechanisms for collaboration between the non-government organization and the public sector to expand coverage to the most disadvantaged populations. The fourth and the most important strategy is to carry out intensive campaigns at the state and national levels against cataract blindness in order to substantially increase the demand for cataract services. A country like India has more significance for such a plan in view of the fact that various social, economic and environmental factors contribute to cataract blindness in populations at a much younger age.

  12. Elevated Frequency of Cataracts in Birds from Chernobyl

    PubMed Central

    Mousseau, Timothy Alexander; Møller, Anders Pape

    2013-01-01

    Background Radiation cataracts develop as a consequence of the effects of ionizing radiation on the development of the lens of the eye with an opaque lens reducing or eliminating the ability to see. Therefore, we would expect cataracts to be associated with reduced fitness in free-living animals. Methodology/Principal Findings We investigated the incidence of lens opacities typical of cataracts in more than 1100 free-living birds in the Chernobyl region in relation to background radiation. The incidence of cataracts increased with level of background radiation both in analyses based on a dichotomous score and in analyses of continuous scores of intensity of cataracts. The odds ratio per unit change in the regressor was 0.722 (95% CI 0.648, 0.804), which was less than odds ratios from investigations of radiation cataracts in humans. The relatively small odds ratio may be due to increased mortality in birds with cataracts. We found a stronger negative relationship between bird abundance and background radiation when the frequency of cataracts was higher, but also a direct effect of radiation on abundance, suggesting that radiation indirectly affects abundance negatively through an increase in the frequency of cataracts in bird populations, but also through direct effects of radiation on other diseases, food abundance and interactions with other species. There was no increase in incidence of cataracts with increasing age, suggesting that yearlings and older individuals were similarly affected as is typical of radiation cataract. Conclusions/Significance These findings suggest that cataracts are an under-estimated cause of morbidity in free-living birds and, by inference, other vertebrates in areas contaminated with radioactive materials. PMID:23935827

  13. Blindness and Cataract Surgical Services in Atsinanana Region, Madagascar

    PubMed Central

    Randrianaivo, Jean-Baptiste; Anholt, R. Michele; Tendrisoa, Diarimirindra Lazaharivony; Margiano, Nestor Jean; Courtright, Paul; Lewallen, Susan

    2014-01-01

    Purpose: To assess the prevalence and causes of avoidable blindness in Atsinanana Region, Madagascar, with the Rapid Assessment of Avoidable Blindness (RAAB) survey. We analyzed the hospital records to supplement the findings for public health care planning. Materials and Methods: Only villages within a two-hour walk from a road, about half of the population of Atsinanana was included. Seventy-two villages were selected by population-proportional-to-size sampling. In each village, compact segment sampling was used to select 50 people over age 50 for eye examination using standard RAAB methods. Records at the two hospitals providing cataract surgery in the region were analyzed for information on patients who underwent cataract surgery in 2010. Cataract incidence rate and target cataract surgery rate (CSR) was modeled from age-specific prevalence of cataract. Results: The participation rate was 87% and the sample prevalence of blindness was 1.96%. Cataract was responsible for 64% and 85.7% of blindness and severe visual impairment, respectively. Visual impairment was due to cataract (69.4%) and refractive error (14.1%). There was a strong positive correlation between cataract surgical rate by district and the proportion of people living within 2 hours of a road. There were marked differences in the profiles of the cataract patients at the two facilities. The estimated incidence of cataract at the 6/18 level was 2.4 eyes per 100 people over age 50 per year. Conclusions: Although the survey included only people with reasonable access, the main cause of visual impairment was still cataract. The incidence of cataract is such that it ought to be possible to eliminate it as a cause of visual impairment, but changes in service delivery at hospitals and strategies to improve access will be necessary for this change. PMID:24791107

  14. Integrating the Advanced Human Eye Model (AHEM) and optical instrument models to model complete visual optical systems inclusive of the typical or atypical eye

    NASA Astrophysics Data System (ADS)

    Donnelly, William J., III

    2012-06-01

    PURPOSE: To present a commercially available optical modeling software tool to assist the development of optical instrumentation and systems that utilize and/or integrate with the human eye. METHODS: A commercially available flexible eye modeling system is presented, the Advanced Human Eye Model (AHEM). AHEM is a module that the engineer can use to perform rapid development and test scenarios on systems that integrate with the eye. Methods include merging modeled systems initially developed outside of AHEM and performing a series of wizard-type operations that relieve the user from requiring an optometric or ophthalmic background to produce a complete eye inclusive system. Scenarios consist of retinal imaging of targets and sources through integrated systems. Uses include, but are not limited to, optimization, telescopes, microscopes, spectacles, contact and intraocular lenses, ocular aberrations, cataract simulation and scattering, and twin eye model (binocular) systems. RESULTS: Metrics, graphical data, and exportable CAD geometry are generated from the various modeling scenarios.

  15. Cataract influence on iris recognition performance

    NASA Astrophysics Data System (ADS)

    Trokielewicz, Mateusz; Czajka, Adam; Maciejewicz, Piotr

    2014-11-01

    This paper presents the experimental study revealing weaker performance of the automatic iris recognition methods for cataract-affected eyes when compared to healthy eyes. There is little research on the topic, mostly incorporating scarce databases that are often deficient in images representing more than one illness. We built our own database, acquiring 1288 eye images of 37 patients of the Medical University of Warsaw. Those images represent several common ocular diseases, such as cataract, along with less ordinary conditions, such as iris pattern alterations derived from illness or eye trauma. Images were captured in near-infrared light (used in biometrics) and for selected cases also in visible light (used in ophthalmological diagnosis). Since cataract is a disorder that is most populated by samples in the database, in this paper we focus solely on this illness. To assess the extent of the performance deterioration we use three iris recognition methodologies (commercial and academic solutions) to calculate genuine match scores for healthy eyes and those influenced by cataract. Results show a significant degradation in iris recognition reliability manifesting by worsening the genuine scores in all three matchers used in this study (12% of genuine score increase for an academic matcher, up to 175% of genuine score increase obtained for an example commercial matcher). This increase in genuine scores affected the final false non-match rate in two matchers. To our best knowledge this is the only study of such kind that employs more than one iris matcher, and analyzes the iris image segmentation as a potential source of decreased reliability

  16. Prevalence of corneal astigmatism before cataract surgery.

    PubMed

    Mohammadi, Mehran; Naderan, Mohammad; Pahlevani, Rozhin; Jahanrad, Ali

    2016-12-01

    The purpose of this study was to describe and analyze the prevalence and pattern of corneal astigmatism in cataract surgery candidates. In a prospective cross-sectional study, preoperative demographics, and keratometric and refractive values of cataract surgery candidates were collected from January 2013 to December 2014. Axial length (AL) and flat and steep keratometry measurements were optically measured by a partial coherence interferometry device (IOLMaster). This study consisted of 2156 eyes of 1317 patients with a mean age of 64.92 ± 11.48 (SD) (30-88 years). The mean of AL was 23.33 ± 1.37 mm, and the mean of corneal astigmatism was 1.12 ± 1.10 diopter (D) (range 0.0-7.00), in all patients. Furthermore, the mean of flat and steep keratometry were 43.70 ± 1.70 and 44.83 ± 1.79 D, respectively. Corneal astigmatism was 1.50 D or less in 1590 eyes (73.7 %), more than 1.50 D in 566 eyes (26.2 %), 3.00 D or more in 161 eyes (7.4 %), WTR in 796 eyes (36.9 %), ATR in 1010 eyes (46.8 %), and oblique in 350 eyes (16.2 %). ATR astigmatism axis significantly increased with the increase in age. Corneal astigmatism of most cataract surgery candidates fell between 0.50 and 1.50 D. The results of our study however is confined to our demographics might provide useful data for cataract patients, surgeons, and intraocular lens manufacturers for different purposes.

  17. Combined surgery versus cataract surgery alone for eyes with cataract and glaucoma

    PubMed Central

    Zhang, Mingjuan Lisa; Hirunyachote, Phenpan; Jampel, Henry

    2016-01-01

    Background Cataract and glaucoma are leading causes of blindness worldwide, and their co-existence is common in elderly people. Glaucoma surgery can accelerate cataract progression, and performing both surgeries may increase the rate of postoperative complications and compromise the success of either surgery. However, cataract surgery may independently lower intraocular pressure (IOP), which may allow for greater IOP control among patients with co-existing cataract and glaucoma. The decision between undergoing combined glaucoma and cataract surgery versus cataract surgery alone is complex. Therefore, it is important to compare the effectiveness of these two interventions to aid clinicians and patients in choosing the better treatment approach. Objectives To assess the relative effectiveness and safety of combined surgery versus cataract surgery (phacoemulsification) alone for co-existing cataract and glaucoma. The secondary objectives include cost analyses for different surgical techniques for co-existing cataract and glaucoma. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 10), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2014), EMBASE (January 1980 to October 2014), PubMed (January 1948 to October 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to October 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 3 October 2014. We checked the reference lists of the included trials to identify further relevant trials. We used the Science

  18. Assessing the elasticity change of cataract lens with OCE

    NASA Astrophysics Data System (ADS)

    Wu, Chen; Liu, Chih-Hao; Raghunathan, Raksha; Singh, Manmohan; Li, Jiasong; Han, Zhaolong; Larin, Kirill V.

    2016-03-01

    Cataract is one of the most common degenerative diseases that causes blindness. Careful quantification of lens biomechanical properties can greatly assist in early detection of the disease as well as personalization of treatment procedures. In this study, we utilize a phase-sensitive optical coherence elastography (OCE) system to assess the effects of the cold cataract on the biomechanical properties of porcine crystalline lens in vitro. Relaxation rates of air puff induced elastic waves were measured on the same crystalline lens with and without cold cataract. Results demonstrate that the relaxation rate and, thus, associated elasticity of the porcine lens, increased due to the presence of cold cataract.

  19. Global Challenges in the Management of Congenital Cataract

    PubMed Central

    Lenhart, Phoebe D.; Courtright, Paul; Wilson, M. Edward; Taylor, David Samuel; Lewallen, Susan; Ventura, Marcelo C.; Bowman, Richard; Woodward, Lee; Ditta, Lauren C.; Kruger, Stacey; Haddad, Danny; El Shakankiri, Nihal; Rai, Salma KC; Bailey, Tehara; Lambert, Scott R.

    2015-01-01

    Summary Childhood cataracts have become a leading cause of preventable childhood blindness in many areas of the world. Here we summarize regional focus group discussions from the 4th Annual International Congenital Cataract Symposium on the current situation, challenges, and recommendations for the management of congenital cataracts in sub-Saharan Africa, the Middle East and North Africa, South Asia, Central America, South America, and developed nations. Strategies for managing congenital cataracts must be adapted and developed according to regional conditions. A basic framework for acceptable outcomes must focus on developing systems to address the critical components of education, access, quality care, and good follow-up. PMID:25892047

  20. Hollow needle cataract aspiration in antiquity.

    PubMed

    Pérez-Cambrodí, Rafael J; Ascaso, Francisco J; Diab, Fathi; Alzamora-Rodríguez, Antonio; Grzybowski, Andrzej

    2015-12-01

    The dislocation of the crystalline lens or couching technique was the predominant procedure to surgically remove cataracts until the 18th century A.D. However, in the Middle Ages, some Arab physicians tried to aspirate the opaque lens by means of a glass tube following a paracentesis. Some literary sources attributed the origins of this technique to Antyllus of Alexandria, a Greek surgeon who lived in the 2nd century A.D. in the Roman Empire. Nevertheless, this statement remains unclear and is probably the consequence of posterior interpretations or incorrect translations of the manuscripts. In recent years, the discovery of the hollow needles from Montbellet (France) and Viladamat (Spain), in archaeological settlements dated between the 1st century and 3rd century A.D., has reopened the possibility of cataract extraction as an option in the surgical management of soft cataracts in the antiquity. In any case, these findings are exceptional, and thus, probably this technique was not widely practised and very likely disparaged by the medical community.

  1. Lens Position Parameters as Predictors of Intraocular Pressure Reduction After Cataract Surgery in Nonglaucomatous Patients With Open Angles

    PubMed Central

    Hsu, Chi-Hsin; Kakigi, Caitlin L.; Lin, Shuai-Chun; Wang, Yuan-Hung; Porco, Travis; Lin, Shan C.

    2015-01-01

    Purpose To evaluate the relationship between lens position parameters and intraocular pressure (IOP) reduction after cataract surgery in nonglaucomatous eyes with open angles. Methods The main outcome of the prospective study was percentage of IOP change, which was calculated using the preoperative IOP and the IOP 4 months after cataract surgery in nonglaucomatous eyes with open angles. Lens position (LP), defined as anterior chamber depth (ACD) + 1/2 lens thickness (LT), was assessed preoperatively using parameters from optical biometry. Preoperative IOP, central corneal thickness, ACD, LT, axial length (AXL), and the ratio of preoperative IOP to ACD (PD ratio) were also evaluated as potential predictors of percentage of IOP change. The predictive values of the parameters we found to be associated with the primary outcome were compared. Results Four months after cataract surgery, the average IOP reduction was 2.03 ± 2.42 mm Hg, a 12.74% reduction from the preoperative mean of 14.5 ± 3.05 mm Hg. Lens position was correlated with IOP reduction percentage after adjusting for confounders (P = 0.002). Higher preoperative IOP, shallower ACD, shorter AXL, and thicker LT were significantly associated with percentage of IOP decrease. Although not statistically significant, LP was a better predictor of percentage of IOP change compared to PD ratio, preoperative IOP, and ACD. Conclusions The percentage of IOP reduction after cataract surgery in nonglaucomatous eyes with open angles is greater in more anteriorly positioned lenses. Lens position, which is convenient to compute by basic ocular biometric data, is an accessible predictor with considerable predictive value for postoperative IOP change. PMID:26650901

  2. Hyperacuity test to evaluate vision through dense cataracts: research preliminary to a clinical study in India

    NASA Astrophysics Data System (ADS)

    Enoch, Jay M.; Giraldez, Maria J.; Huang, Doahua; Hirose, Hiroshi; Knowles, Richard A.; Namperumalsamy, P.; LaBree, Lauri; Azen, Stanley P.

    1995-03-01

    Using high luminance point-of-light stimuli, Vernier judgments can be made in the presence of markedly degraded retinal imagery. Without coaching, observers perform center-of-gravity assessments of relative locations of degraded point images. We seek to defined, presurgery, individuals who will derive the most benefit from advanced cataract removal (a form of triage), and to determine which of two cataractous eyes has the better postsurgical visual prognosis. There are incredible and growing backlogs of patients with severe cataracts (and other dense media opacities) in the developing world, and generally, limited resources are available for provision of health care. Postcataract surgical failure rates for good visual function are often high, and only one eye is operated on in over 95% of indigent patients treated. Prior to initiating advanced studies in the developing world, at Berkeley we conducted preliminary research on Vernier acuity test techniques on normal adult subjects. We sought to determine the number of repeat trials necessary; to compare a two-point and a three-point Vernier display; to determine the shape of the measured response function at large gap separations between test points (required when testing advanced cataract patients); to assess the effect(s) of a broad range of uncorrected refractive errors on outcomes; and to consider means to minimize refraction-based errors. From these and prior data and analyses, we defined a protocol for use in the developing world. Using a newly designed and rugged precision instrument, these tests were repeated on an advanced cataract population at Aravind Eye Hospital in Madurai, India. Although we had much prior experience in India, the initial protocol required major revision on site. Necessary changes in test methods and analytical approaches were made, and next stages in this program were planned. And a new and simple gap `visual acuity' (gap `VA') test was added to the protocol, which greatly facilitated

  3. Thermal lensing in ocular media

    NASA Astrophysics Data System (ADS)

    Vincelette, Rebecca Lee

    2009-12-01

    This research was a collaborative effort between the Air Force Research Laboratory (AFRL) and the University of Texas to examine the laser-tissue interaction of thermal lensing induced by continuous-wave, CW, near-infrared, NIR, laser radiation in the eye and its influence on the formation of a retinal lesion from said radiation. CW NIR laser radiation can lead to a thermal lesion induced on the retina given sufficient power and exposure duration as related to three basic parameters; the percent of transmitted energy to, the optical absorption of, and the size of the laser-beam created at the retina. Thermal lensing is a well-known phenomenon arising from the optical absorption, and subsequent temperature rise, along the path of the propagating beam through a medium. Thermal lensing causes the laser-beam profile delivered to the retina to be time dependent. Analysis of a dual-beam, multidimensional, high-frame rate, confocal imaging system in an artificial eye determined the rate of thermal lensing in aqueous media exposed to 1110, 1130, 1150 and 1318-nm wavelengths was related to the power density created along the optical axis and linear absorption coefficient of the medium. An adaptive optics imaging system was used to record the aberrations induced by the thermal lens at the retina in an artificial eye during steady-state. Though the laser-beam profiles changed over the exposure time, the CW NIR retinal damage thresholds between 1110--1319-nm were determined to follow conventional fitting algorithms which neglected thermal lensing. A first-order mathematical model of thermal lensing was developed by conjoining an ABCD beam propagation method, Beer's law of attenuation, and a solution to the heat-equation with respect to radial diffusion. The model predicted that thermal lensing would be strongest for small (< 4-mm) 1/e2 laser-beam diameters input at the corneal plane and weakly transmitted wavelengths where less than 5% of the energy is delivered to the retina

  4. Breeding gravitational lenses

    NASA Astrophysics Data System (ADS)

    Liesenborgs, J.; de Rijcke, S.; Dejonghe, H.; Bekaert, P.

    2011-03-01

    Gravitational lenses are a spectacular astrophysical phenomenon, a cosmic mirage caused by the gravitational deflection of light in which multiple images of a same background object can be seen. Their beauty is only exceeded by their usefulness, as the gravitational lens effect is a direct probe of the total mass of the deflecting object. Furthermore, since the image configuration arising from the gravitational lens effect depends on the exact gravitational potential of the deflector, it even holds the promise of learning about the distribution of the mass. In this presentation, a method for extracting the information encoded in the images and reconstructing the mass distribution is presented. Being a non-parametric method, it avoids making a priori assumptions about the shape of the mass distribution. At the core of the procedure lies a genetic algorithm, an optimization strategy inspired by Darwin's principle of ``survival of the fittest''. One only needs to specify a criterion to decide if one particular trial solution is deemed better than another, and the genetic algorithm will ``breed'' appropriate solutions to the problem. In a similar way, one can create a multi-objective genetic algorithm, capable of optimizing several fitness criteria at the same time. This provides a very flexible way to incorporate all the available information in the gravitational lens system: not only the positions and shapes of the multiple images are used, but also the so-called ``null space'', i.e. the area in which no such images can be seen. The effectiveness of this approach is illustrated using simulated data, which allows one to compare the reconstruction to the true mass distribution.

  5. [Intraocular lenses for the correction of refraction errors. Part II. Phakic posterior chamber lenses and refractive lens exchange with posterior chamber lens implantation].

    PubMed

    Kohnen, T; Kasper, T; Terzi, E

    2005-11-01

    In this overview, the current status of intraocular lens surgery to correct refractive error is reviewed. The interventions are divided into additive surgery with intraocular lens implantation without extraction of the crystalline lens (phakic intraocular lens, PIOL) or removal of the crystalline lens with implantation of an IOL (refractive lens exchange, RLE). Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and posterior chamber lenses which are fixated in the ciliary sulcus. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and differ for the three types of PIOL; for posterior chamber lenses these are mainly cataract formation and pigment dispersion. RLE is preferable in cases of high ametropia in which the natural lens has lost its accommodative effect. The main complications for myopic RLA include retinal detachment, while hyperopic refractive lens exchange may be associated with surgical problems in the narrower anterior eye segment.

  6. Surface gravity-wave lensing.

    PubMed

    Elandt, Ryan B; Shakeri, Mostafa; Alam, Mohammad-Reza

    2014-02-01

    Here we show that a nonlinear resonance between oceanic surface waves caused by small seabed features (the so-called Bragg resonance) can be utilized to create the equivalent of lenses and curved mirrors for surface gravity waves. Such gravity wave lenses, which are merely small changes to the seafloor topography and therefore are surface noninvasive, can focus or defocus the energy of incident waves toward or away from any desired focal point. We further show that for a broadband incident wave spectrum (i.e., a wave group composed of a multitude of different-frequency waves), a polychromatic topography (occupying no more than the area required for a monochromatic lens) can achieve a broadband lensing effect. Gravity wave lenses can be utilized to create localized high-energy wave zones (e.g., for wave energy harvesting or creating artificial surf zones) as well as to disperse waves in order to create protected areas (e.g., harbors or areas near important offshore facilities). In reverse, lensing of oceanic waves may be caused by natural seabed features and may explain the frequent appearance of very high amplitude waves in certain bodies of water.

  7. Heat shock protein concentration and clarity of porcine lenses incubated at elevated temperatures

    PubMed Central

    Dzialoszynski, T. M.; Milne, K.J.; Trevithick, J.R.

    2016-01-01

    Purpose To quantify the concentration of heat shock proteins in lenses in lens organ culture at elevated temperatures, and to examine the relation between elevated temperature and lens clarity. Methods Pig lenses obtained from a local abattoir were dissected aseptically and incubated in medium M199 without serum for 4 days to stabilize, and lenses with protein leakage of less than 10 mg/l were obtained for heat shock exposure. Heat shock was performed by incubation for 1 h in M199 without serum at various temperatures ranging from 37 °C to 55 °C. After incubation for 24 h, cataract blurring of the images was assessed using Scantox™ and Scion Image analysis of the lens photographs. Lens homogenates were subsequently analyzed for Hsp70 and Hsp27 with western blotting. Results The degree of cataract blurring of the images increased with increasing temperature, but the two functional measures provided different results. Focal length inconsistency, as assessed with the back vertex distance standard error of the mean (BVD SEM; the variability in focal lengths measured at 20 equally spaced locations across the lens, Scantox™), increased nearly linearly with the heat treatment temperature. In contrast, decreased clarity, evident by a fuzzy image with lower contrast, was not markedly altered as the temperature rose until a threshold of approximately 47.5 °C. The inducible isoform of the Hsp70 family (Hsp70) of heat shock proteins was increased at all temperatures above the control except those above 50 °C. Changes in Hsp27 were less clear as the protein content increased only at the incubation temperatures of 39 °C and 48.5 °C. Conclusions The porcine lens demonstrates subtle changes in the variability of the focal length, and the variability increases as the incubation temperature rises. In contrast, lens clarity is relatively stable at temperatures up to 47.5 °C, above which dramatic changes, indicative of the formation of cataracts, occur. The lens content

  8. The M31 pixel lensing plan campaign: MACHO lensing and self-lensing signals

    SciTech Connect

    Calchi Novati, S.; Scarpetta, G.; Bozza, V.; Bruni, I.; Gualandi, R.; Dall'Ora, M.; De Paolis, F.; Ingrosso, G.; Nucita, A.; Strafella, F.; Dominik, M.; Jetzer, Ph.; Mancini, L.; Safonova, M.; Subramaniam, A.; Sereno, M.; Gould, A.; Collaboration: PLAN Collaboration

    2014-03-10

    We present the final analysis of the observational campaign carried out by the PLAN (Pixel Lensing Andromeda) collaboration to detect a dark matter signal in form of MACHOs through the microlensing effect. The campaign consists of about 1 month/year observations carried out over 4 years (2007-2010) at the 1.5 m Cassini telescope in Loiano (Astronomical Observatory of BOLOGNA, OAB) plus 10 days of data taken in 2010 at the 2 m Himalayan Chandra Telescope monitoring the central part of M31 (two fields of about 13' × 12.'6). We establish a fully automated pipeline for the search and the characterization of microlensing flux variations. As a result, we detect three microlensing candidates. We evaluate the expected signal through a full Monte Carlo simulation of the experiment completed by an analysis of the detection efficiency of our pipeline. We consider both 'self lensing' and 'MACHO lensing' lens populations, given by M31 stars and dark matter halo MACHOs, in M31 and the Milky Way, respectively. The total number of events is consistent with the expected self-lensing rate. Specifically, we evaluate an expected signal of about two self-lensing events. As for MACHO lensing, for full 0.5(10{sup –2}) M {sub ☉} MACHO halos, our prediction is for about four (seven) events. The comparatively small number of expected MACHO versus self-lensing events, together with the small number statistics at our disposal, do not enable us to put strong constraints on that population. Rather, the hypothesis, suggested by a previous analysis, on the MACHO nature of OAB-07-N2, one of the microlensing candidates, translates into a sizeable lower limit for the halo mass fraction in form of the would-be MACHO population, f, of about 15% for 0.5 M {sub ☉} MACHOs.

  9. Cataract induction by protons and HZE particles is suppressed by dietary supplements

    NASA Astrophysics Data System (ADS)

    Ware, Jeffrey; Kennedy, Ann; Davis, James

    The present study was undertaken to investigate the ability of dietary supplements to reduce the formation and severity of cataracts in mice irradiated with protons or iron ions, which are important components of the radiation encountered by astronauts during spaceflight. The mice were exposed to proton or iron ion radiation and fed with control diet or diets supplemented with an antioxidant formulation or with Bowman-Birk Inhibitor Concentrate (BBIC) both before and after the radiation exposure. The antioxidant formulation contained L-selenomethionine, N-acetyl cysteine, ascorbic acid, co-enzyme Q10, alpha-lipoic acid and vitamin E succinate. This mixture is highly effective at reducing space radiation induced oxidative stress in both in vivo and in vitro systems, space radiation induced cytotoxicity and malignant transformation in vitro. BBIC is a soybean extract with high levels of the Bowman-Birk Inhibitor, an 8-KD soybean-derived protease inhibitor with anticarcinogenic, anti-inflammatory and radioprotection properties. At approximately two years after the radiation exposure, the animals were killed and lenses were harvested post-mortem and characterized using an established classifi- cation system that assigns discrete scores based on the severity of the lens opacifications. The results showed that exposure to 1-GeV/n proton (300 cGy) or iron ion (50 cGy) radiation significantly increased the cataract prevalence and severity in CBA/J mice to levels above the baseline levels of age-induced cataract formation in this mouse strain. Treatment with BBIC or the antioxidant formulation significantly reduced the prevalence and severity of the lens opaci- fications in the mice exposed to iron ion radiation. Treatment with BBIC or the antioxidant formulation also decreased the severity of the lens opacifications in the mice exposed to proton radiation; however, the decrease did not reach statistical significance. These results indicate that BBIC and the antioxidant

  10. Cataract Blindness in Osun State, Nigeria: Results of a Survey

    PubMed Central

    Kolawole, Olubayo U.; Ashaye, Adeyinka O.; Mahmoud, Abdulraheem O.; Adeoti, Caroline O.

    2012-01-01

    Purpose: To estimate the burden of blindness and visual impairment due to cataract in Egbedore Local Government Area of Osun State, Nigeria. Materials and Methods: Twenty clusters of 60 individuals who were 50 years or older were selected by systematic random sampling from the entire community. A total of 1,183 persons were examined. Results: The age- and sex-adjusted prevalence of bilateral cataract-related blindness (visual acuity (VA) < 3/60) in people of 50 years and older was 2.0% (95% confidence interval (CI): 1.6–2.4%). The Cataract Surgical Coverage (CSC) (persons) was 12.1% and Couching Coverage (persons) was 11.8%. The age- and sex-adjusted prevalence of bilateral operable cataract (VA < 6/60) in people of 50 years and older was 2.7% (95% CI: 2.3–3.1%). In this last group, the cataract intervention (surgery + couching) coverage was 22.2%. The proportion of patients who could not attain 6/60 vision after surgery were 12.5, 87.5, and 92.9%, respectively, for patients who underwent intraocular lens (IOL) implantation, cataract surgery without IOL implantation and those who underwent couching. “Lack of awareness” (30.4%), “no need for surgery” (17.6%), cost (14.6%), fear (10.2%), “waiting for cataract to mature” (8.8%), AND “surgical services not available” (5.8%) were reasons why individuals with operable cataract did not undergo cataract surgery. Conclusions: Over 600 operable cataracts exist in this region of Nigeria. There is an urgent need for an effective, affordable, and accessible cataract outreach program. Sustained efforts have to be made to increase the number of IOL surgeries, by making IOL surgery available locally at an affordable cost, if not completely free. PMID:23248537

  11. Lensing smoothing of BAO wiggles

    NASA Astrophysics Data System (ADS)

    Di Dio, Enea

    2017-03-01

    We study non-perturbatively the effect of the deflection angle on the BAO wiggles of the matter power spectrum in real space. We show that from redshift z~2 this introduces a dispersion of roughly 1 Mpc at BAO scale, which corresponds approximately to a 1% effect. The lensing effect induced by the deflection angle, which is completely geometrical and survey independent, smears out the BAO wiggles. The effect on the power spectrum amplitude at BAO scale is about 0.1 % for z~2 and 0.2 % for z~4. We compare the smoothing effects induced by the lensing potential and non-linear structure formation, showing that the two effects become comparable at z ~ 4, while the lensing effect dominates for sources at higher redshifts. We note that this effect is not accounted through BAO reconstruction techniques.

  12. Beam bending via plasmonic lenses.

    PubMed

    Zhao, Yanhui; Lin, Sz-Chin Steven; Nawaz, Ahmad Ahsan; Kiraly, Brian; Hao, Qingzhen; Liu, Yanjun; Huang, Tony Jun

    2010-10-25

    We have designed and characterized three different types of plasmonic lenses that cannot only focus, but can also bend electromagnetic (EM) waves. The bending effect is achieved by constructing an asymmetric phase front caused by varying phase retardations in EM waves as they pass through a plasmonic lens. With an incident wave normal to the lens surface, light bends up to 8° off the axial direction. The optical wave propagation was numerically investigated using the finite-difference time-domain (FDTD) method. Simulation results show that the proposed plasmonic lenses allow effective beam bending under both normal and tilted incidence. With their relatively large bending range and capability to perform in the far field, the plamsonic lenses described in this article could be valuable in applications such as photonic communication and plasmonic circuits.

  13. Contact lenses for infant aphakia.

    PubMed Central

    Amaya, L G; Speedwell, L; Taylor, D

    1990-01-01

    We prospectively studied for three years the optical correction by contact lenses of 83 aphakic infants (141 eyes) who generally also had systemic and other ocular anomalies: 85% of the patients tolerated the lens wear for the whole study period. Complications occurred in 46 eyes and led to cessation of lens wear in two cases. Ten patients abandoned the lenses for other reasons. Thirty-four eyes needed subsequent intraocular surgery, mostly minor, and nine patients had strabismus surgery. Contact lenses are a versatile, safe, successful, and cost effective treatment for aphakia in infancy against which, before their widespread introduction for primary optical correction of infant aphakia, other methods of aphakic treatment need to be compared. PMID:2322512

  14. Tuning Gravitationally Lensed Standard Sirens

    NASA Astrophysics Data System (ADS)

    Jönsson, J.; Goobar, A.; Mörtsell, E.

    2007-03-01

    Gravitational waves emitted by chirping supermassive black hole binaries could in principle be used to obtain very accurate distance determinations. Provided they have an electromagnetic counterpart from which the redshift can be determined, these standard sirens could be used to build a high-redshift Hubble diagram. Errors in the distance measurements will most likely be dominated by gravitational lensing. We show that the (de)magnification due to inhomogeneous foreground matter will increase the scatter in the measured distances by a factor of ~10. We propose to use optical and IR data of the foreground galaxies to minimize the degradation from weak lensing. We find that the net effect of correcting the estimated distances for lensing is comparable to increasing the sample size by a factor of 3 when using the data to constrain cosmological parameters.

  15. Effects of Cataract Surgery on Endothelium in Transplanted Corneal Grafts: Comparison of Extracapsular Cataract Extraction and Phacoemulsification for Complicated Cataract after Penetrating Keratoplasty

    PubMed Central

    Zhou, Hong-Wei; Xie, Li-Xin

    2016-01-01

    Background: The endothelium should be carefully evaluated when choosing a surgical technique for cataract removal. Therefore, we aimed to study the effects of different cataract surgery techniques on endothelial cell loss in transplanted corneal grafts. Methods: A total of 54 patients who received complicated cataract surgery in post-penetrating keratoplasty (PKP) eyes at the Shandong Eye Institute between February 2001 and June 2014 were included, and clinical records were reviewed. Baseline demographic details, clinical characteristics, endothelial cell density (ECD), and best-corrected visual acuity (BCVA) were recorded. Wilcoxon rank-sum test and Wilcoxon signed-rank test were used to test the equality of medians. A regression model was constructed to compare the reduced rate of ECD. Results: Of the 54 eyes included in this study, extracapsular cataract extraction (ECCE) was performed in 34 eyes of 33 patients (ECCE group) whereas phacoemulsification was performed in 20 eyes of 20 patients (phacoemulsification group). There was no significant difference in the median age (P = 0.081) or preoperative ECD (P = 0.585) between the two groups. At 6 months after cataract surgery, ECD in ECCE group was significantly higher than that in phacoemulsification group (P = 0.043). In addition, the endothelial cell loss rate in ECCE group was significantly lower than that in phacoemulsification group at 2 months (P = 0.018), 4 months (P < 0.001), and 6 months (P < 0.001) after cataract surgery. Endothelial cell loss rate after cataract surgery increased over the 6-month study duration in both ECCE group (P < 0.001) and phacoemulsification group (P < 0.001), but phacoemulsification resulted in a greater reduction in ECD than that of ECCE in transplanted corneal grafts (P < 0.001). There was no significant difference in postoperative BCVA between the two groups (P = 0.065). Conclusion: ECCE is more suitable than phacoemulsification in cataract surgery in complicated cataract

  16. Fabrication of nanoscale electrostatic lenses

    NASA Astrophysics Data System (ADS)

    Sinno, I.; Sanz-Velasco, A.; Kang, S.; Jansen, H.; Olsson, E.; Enoksson, P.; Svensson, K.

    2010-09-01

    The fabrication of cylindrical multi-element electrostatic lenses at the nanoscale presents a challenge; they are high-aspect-ratio structures that should be rotationally symmetric, well aligned and freestanding, with smooth edges and flat, clean surfaces. In this paper, we present the fabrication results of a non-conventional process, which uses a combination of focused gallium ion-beam milling and hydrofluoric acid vapor etching. This process makes it possible to fabricate nanoscale electrostatic lenses down to 140 nm in aperture diameter and 4.2 µm in column length, with a superior control of the geometry as compared to conventional lithography-based techniques.

  17. Barriers to Cataract Surgery in Africa: A Systematic Review

    PubMed Central

    Aboobaker, Shaheer; Courtright, Paul

    2016-01-01

    Cataract remains the leading cause of blindness in Africa. We performed a systematic literature search of articles reporting barriers to cataract surgery in Africa. PubMed and Google Scholar databases were searched with the terms “barriers, cataract, Africa, cataract surgery, cataract surgical coverage (CSC), and rapid assessment of avoidable blindness (RAAB).” The review covered from 1999 to 2014. In RAAB studies, barriers related to awareness and access were more commonly reported than acceptance. Other type of studies reported cost as the most common barrier. Some qualitative studies tended to report community and family dynamics as barriers to cataract surgery. CSC was lower in females in 88.2% of the studies. The variability in outcomes of studies of barriers to cataract surgery could be due to context and the type of data collection. It is likely that qualitative data will provide a deeper understanding of the complex social, family, community, financial and gender issues relating to barriers to uptake of cataract surgery in Africa. PMID:26957856

  18. Exploiting ensemble learning for automatic cataract detection and grading.

    PubMed

    Yang, Ji-Jiang; Li, Jianqiang; Shen, Ruifang; Zeng, Yang; He, Jian; Bi, Jing; Li, Yong; Zhang, Qinyan; Peng, Lihui; Wang, Qing

    2016-02-01

    Cataract is defined as a lenticular opacity presenting usually with poor visual acuity. It is one of the most common causes of visual impairment worldwide. Early diagnosis demands the expertise of trained healthcare professionals, which may present a barrier to early intervention due to underlying costs. To date, studies reported in the literature utilize a single learning model for retinal image classification in grading cataract severity. We present an ensemble learning based approach as a means to improving diagnostic accuracy. Three independent feature sets, i.e., wavelet-, sketch-, and texture-based features, are extracted from each fundus image. For each feature set, two base learning models, i.e., Support Vector Machine and Back Propagation Neural Network, are built. Then, the ensemble methods, majority voting and stacking, are investigated to combine the multiple base learning models for final fundus image classification. Empirical experiments are conducted for cataract detection (two-class task, i.e., cataract or non-cataractous) and cataract grading (four-class task, i.e., non-cataractous, mild, moderate or severe) tasks. The best performance of the ensemble classifier is 93.2% and 84.5% in terms of the correct classification rates for cataract detection and grading tasks, respectively. The results demonstrate that the ensemble classifier outperforms the single learning model significantly, which also illustrates the effectiveness of the proposed approach.

  19. Outcomes of Cataract Surgery Following Treatment for Retinoblastoma

    PubMed Central

    Kim, Hyeong Min; Lee, Byung Joo; Kim, Jeong Hun

    2017-01-01

    Purpose To evaluate the long-term visual outcomes and complications of cataract surgery in eyes previously treated for retinoblastoma. Methods We reviewed the medical records of patients who underwent cataract extraction and intraocular lens implantation at Seoul National University Children's Hospital for a secondary cataract that developed after retinoblastoma treatment. Results During the period between 1990 and 2014, 208 eyes of 147 patients received eye-salvaging treatment (radiotherapy, chemotherapy, and local therapy) for retinoblastoma at Seoul National University Children's Hospital. Among these eyes, a secondary cataract was detected in 17 eyes of 14 patients, and five eyes of five patients underwent cataract surgery. The median age of cataract formation was 97 months (range, 38 to 153 months). The medial interval between the diagnosis of retinoblastoma and cataract formation was 79 months (range, 29 to 140 months). All patients received posterior chamber intraocular lens insertion after irrigation and aspiration of the lens through a scleral tunnel incision. Anterior vitrectomy and posterior capsulotomy were performed in two eyes and a laser capsulotomy was subsequently performed in one eye. No intraoperative and postoperative complications occurred. The median follow-up after surgery was 36 months (range, 14 to 47 months). The final best corrected visual acuities were improved in all five eyes. No intraocular tumor recurrences or metastases occurred. Conclusions After retinoblastoma regression, cataract extraction in our series was not associated with tumor recurrence or metastasis. Visual improvement was noted in every patient. PMID:28243024

  20. Barriers to Cataract Surgery in Africa: A Systematic Review.

    PubMed

    Aboobaker, Shaheer; Courtright, Paul

    2016-01-01

    Cataract remains the leading cause of blindness in Africa. We performed a systematic literature search of articles reporting barriers to cataract surgery in Africa. PubMed and Google Scholar databases were searched with the terms "barriers, cataract, Africa, cataract surgery, cataract surgical coverage (CSC), and rapid assessment of avoidable blindness (RAAB)." The review covered from 1999 to 2014. In RAAB studies, barriers related to awareness and access were more commonly reported than acceptance. Other type of studies reported cost as the most common barrier. Some qualitative studies tended to report community and family dynamics as barriers to cataract surgery. CSC was lower in females in 88.2% of the studies. The variability in outcomes of studies of barriers to cataract surgery could be due to context and the type of data collection. It is likely that qualitative data will provide a deeper understanding of the complex social, family, community, financial and gender issues relating to barriers to uptake of cataract surgery in Africa.

  1. Lensing signals from spin-2 perturbations

    SciTech Connect

    Adamek, Julian; Durrer, Ruth; Tansella, Vittorio E-mail: ruth.durrer@unige.ch

    2016-01-01

    We compute the angular power spectra of the E-type and B-type lensing potentials for gravitational waves from inflation and for tensor perturbations induced by scalar perturbations. We derive the tensor-lensed CMB power spectra for both cases. We also apply our formalism to determine the linear lensing potential for a Bianchi I spacetime with small anisotropy.

  2. Cataract extraction after brachytherapy for malignant melanoma of the choroid

    SciTech Connect

    Fish, G.E.; Jost, B.F.; Snyder, W.I.; Fuller, D.G.; Birch, D.G. )

    1991-05-01

    Thirteen eyes of 55 consecutive patients treated with brachytherapy for malignant melanoma of the choroid developed postirradiation cataracts. Cataract development was more common in older patients and in patients with larger and more anterior tumors. Eleven eyes had extracapsular cataract extraction and intraocular lens implantation. Initial visual improvement occurred in 91% of eyes, with an average improvement of 5.5 lines. Visual acuity was maintained at 20/60 or better in 55% of the eyes over an average period of follow-up of 24 months (range, 6 to 40 months). These data suggest that, visually, cataract extraction can be helpful in selected patients who develop a cataract after brachytherapy for malignant melanoma of the choroid.

  3. Cataracts in retired actinide-exposed radiation workers.

    PubMed

    Jacobson, Baruch S

    2005-01-01

    Radiation-induced cataracts are predominantly of the posterior sub-capsular (PSC) type, whereas about 90% of age-related cataracts are of other types. Retired workers, likely to have transuranic body burdens, from three DOE-supported installations were questioned regarding their eye-care history and asked for permission to contact their eye-care providers regarding any cataracts. In 97 cases with lifetime exposure records 20 cases (20.6%) were reported to have PSC cataracts. However, of 24 individuals with recorded lifetime doses of 200-600 mSv, nine (37.5%) had PSC cataracts, compared with 15.1% of 73 cases with doses of less than 200 mSv. This difference is statistically significant at the 5% level.

  4. Changing trends in barriers to cataract surgery in India.

    PubMed Central

    Vaidyanathan, K.; Limburg, H.; Foster, A.; Pandey, R. M.

    1999-01-01

    Cataract is a major cause of blindness in Asia. Efforts in India to provide cataract surgical services have had limited success in reaching the cataract-blind population. Earlier studies identified the major barriers to cataract surgery as poverty, lack of transportation or felt need, or sex related; and the critical barriers in rural areas as lack of awareness, difficult access, and cost. Compared with these earlier data, the results of the present study in Karnataka State indicate a shift in the character of the barriers. They now appear to be more related to case selection and service provision. These shifts are analysed and alternative strategies to increase the uptake to cataract surgery are recommended. PMID:10083707

  5. N-body lensed CMB maps: lensing extraction and characterization

    NASA Astrophysics Data System (ADS)

    Antolini, Claudia; Fantaye, Yabebal; Martinelli, Matteo; Carbone, Carmelita; Baccigalupi, Carlo

    2014-02-01

    We reconstruct shear maps and angular power spectra from simulated weakly lensed total intensity (TT) and polarised (EB) maps of the Cosmic Microwave Background (CMB) anisotropies, obtained using Born approximated ray-tracing through the N-body simulated Cold Dark Matter (CDM) structures in the Millennium Simulations (MS). We compare the recovered signal with the ΛCDM prediction, on the whole interval of angular scales which is allowed by the finite box size, extending from the degree scale to the arcminute, by applying a quadratic estimator in the flat sky limit; we consider PRISM-like instrumental specification for future generation CMB satellites, corresponding to arcminute angular resolution of 3.2' and sensitivity of 2.43 μK-arcmin. The noise contribution in the simulations closely follows the estimator prediction, becoming dominated by limits in the angular resolution for the EB signal, at l simeq 1500. The recovered signal shows no visible departure from predictions of the weak lensing power within uncertainties, when considering TT and EB data singularly. In particular, the reconstruction precision reaches the level of a few percent in bins with Δl simeq 100 in the angular multiple interval 1000lesssimllesssim2000 for T, and about 10% for EB. Within the adopted specifications, polarisation data do represent a significant contribution to the lensing shear, which appear to faithfully trace the underlying N-body structure down to the smallest angular scales achievable with the present setup, validating at the same time the latter with respect to semi-analytical predictions from ΛCDM cosmology at the level of CMB lensing statistics. This work demonstrates the feasibility of CMB lensing studies based on large scale simulations of cosmological structure formation in the context of the current and future high resolution and sensitivity CMB experiment.

  6. N-body lensed CMB maps: lensing extraction and characterization

    SciTech Connect

    Antolini, Claudia; Martinelli, Matteo; Baccigalupi, Carlo; Fantaye, Yabebal; Carbone, Carmelita E-mail: y.t.fantaye@astro.uio.no E-mail: carmelita.carbone@brera.inaf.it

    2014-02-01

    We reconstruct shear maps and angular power spectra from simulated weakly lensed total intensity (TT) and polarised (EB) maps of the Cosmic Microwave Background (CMB) anisotropies, obtained using Born approximated ray-tracing through the N-body simulated Cold Dark Matter (CDM) structures in the Millennium Simulations (MS). We compare the recovered signal with the ΛCDM prediction, on the whole interval of angular scales which is allowed by the finite box size, extending from the degree scale to the arcminute, by applying a quadratic estimator in the flat sky limit; we consider PRISM-like instrumental specification for future generation CMB satellites, corresponding to arcminute angular resolution of 3.2' and sensitivity of 2.43 μK-arcmin. The noise contribution in the simulations closely follows the estimator prediction, becoming dominated by limits in the angular resolution for the EB signal, at ℓ ≅ 1500. The recovered signal shows no visible departure from predictions of the weak lensing power within uncertainties, when considering TT and EB data singularly. In particular, the reconstruction precision reaches the level of a few percent in bins with Δℓ ≅ 100 in the angular multiple interval 1000∼<ℓ∼<2000 for T, and about 10% for EB. Within the adopted specifications, polarisation data do represent a significant contribution to the lensing shear, which appear to faithfully trace the underlying N-body structure down to the smallest angular scales achievable with the present setup, validating at the same time the latter with respect to semi-analytical predictions from ΛCDM cosmology at the level of CMB lensing statistics. This work demonstrates the feasibility of CMB lensing studies based on large scale simulations of cosmological structure formation in the context of the current and future high resolution and sensitivity CMB experiment.

  7. Manual Suture Less Small Incision Cataract Surgery in Patients with Uveitic Cataract

    PubMed Central

    Bhargava, Rahul; Kumar, Prachi; Bashir, Hafsa; Sharma, Shiv Kumar; Mishra, Anurag

    2014-01-01

    Purpose: The purpose of this study is to evaluate the outcome of manual small incision cataract surgery (SICS) in eyes with uveitic cataract. Setting: Medical college hospital of the subcontinent. Design: Retrospective case series. Materials and Methods: In this retrospective study, patients who underwent SICS with posterior chamber intraocular lens implantation for uveitic cataract from 2006 to 2009 were evaluated. Patients with less than 3 months follow-up were excluded. Post-operative vision and complications were analyzed. Results: A total of 54 patients completed the study. The mean age was 52.3 ± 9.3 years. The mean follow-up was 11.53 ± 5.05 months. The mean surgical time was (10.2 ± 3.8 min). Etiological diagnosis was possible in 31.41% (17/54) of patients. There was a statistically significant improvement in vision after surgery (P < 0.001). When uveitis was well-controlled, pre-operative corticosteroids did not change post-operative inflammation (P = 0.796). However, pre-operative corticosteroids were statistically significantly associated to final best corrected visual acuity (BCVA) (P = 0.010). Conclusion: SICS with posterior chamber intraocular lens implantation is safe in most cataracts due to uveitis and improves BCVA at 6 months. Inflammation should be well-controlled pre-operatively for at least 3 months. Posterior capsule opacification, macular edema and persistent uveitis were the main factors affecting visual outcome. SICS requires minimal instrumentation, surgical time is short and can also be performed in rural clinics and eye-camps, where phacoemulsification machines are unavailable. SICS may be a more practical and cost-effective technique for uveitic cataract, in such circumstances. PMID:24669151

  8. Comparison of Perioperative Ranibizumab Injections for Diabetic Macular Edema in Patients Undergoing Cataract Surgery

    PubMed Central

    2016-01-01

    Purpose. To compare the efficacy of perioperative ranibizumab injections on diabetic macular edema (DME) in patients undergoing cataract surgery. Methods. This study included 59 eyes of 59 patients. All patients had advanced cataract with DME and underwent an uneventful phacoemulsification surgery. There were 3 subgroups. The first group received intravitreal ranibizumab injection 2 weeks preoperatively, the second group received intraoperatively, and the third group received 2 weeks postoperatively. Follow-up examinations were performed at 1 week as well as at 1 and 3 months. Results. Baseline visual acuity showed a significant increase in all groups at 1 month. In group 1, compared to baseline value, foveal thickness (FT) increased significantly at 1 month and showed a significant decrease up to month 3. In group 2, FT increased at month 1 and this continued up to month 3. In group 3, FT increased at month 1 and was almost stable up to month 3. There were not any significant differences for visual acuity and FT between the groups. Conclusions. Although intrapostoperative ranibizumab injection for DME seems to be more effective than preoperative injections in patients undergoing cataract surgery, the treatment still needs to be continued following surgery. PMID:27493795

  9. Internal wave structures in abyssal cataract flows

    NASA Astrophysics Data System (ADS)

    Makarenko, Nikolay; Liapidevskii, Valery; Morozov, Eugene; Tarakanov, Roman

    2014-05-01

    We discuss some theoretical approaches, experimental results and field data concerning wave phenomena in ocean near-bottom stratified flows. Such strong flows of cold water form everywhere in the Atlantic abyssal channels, and these currents play significant role in the global water exchange. Most interesting wave structures arise in a powerful cataract flows near orographic obstacles which disturb gravity currents by forced lee waves, attached hydraulic jumps, mixing layers etc. All these effects were observed by the authors in the Romanche and Chain fracture zones of Atlantic Ocean during recent cruises of the R/V Akademik Ioffe and R/V Akademik Sergei Vavilov (Morozov et al., Dokl. Earth Sci., 2012, 446(2)). In a general way, deep-water cataract flows down the slope are similar to the stratified flows examined in laboratory experiments. Strong mixing in the sill region leads to the splitting of the gravity current into the layers having the fluids with different densities. Another peculiarity is the presence of critical layers in shear flows sustained over the sill. In the case under consideration, this critical level separates the flow of near-bottom cold water from opposite overflow. In accordance with known theoretical models and laboratory measurements, the critical layer can absorb and reflect internal waves generated by the topography, so the upward propagation of these perturbations is blocked from above. High velocity gradients were registered downstream in the vicinity of cataract and it indicates the existence of developed wave structures beyond the sill formed by intense internal waves. This work was supported by RFBR (grants No 12-01-00671-a, 12-08-10001-k and 13-08-10001-k).

  10. Are Entry Criteria for Cataract Surgery Justified?

    PubMed Central

    Böhringer, Daniel; Vach, Werner; Hagenlocher, Kai; Eberwein, Philipp; Maier, Philip; Reinhard, Thomas

    2014-01-01

    Purpose The German Ophthalmological Society (GOS) recently proposed surgical entry criteria, i.e. 300 cataract surgeries. We herein correlate the surgical hands-on experience with the risk of posterior capsule ruptures in order to assess whether this number is appropriate. Methods We identified all cataract operations that had been performed at the University Eye Hospital Freiburg since 1995. For each surgeon, we assigned a running number to his/her procedures in the order they had been performed. Thereafter, we excluded all combined procedures and the second eyes. We then selected the 5475 surgical reports between November 2008 and November 2012 for detailed review. We additionally classified each surgery into low- vs. high- à priori risk for posterior capsule ruptures. We fitted a multifactorial logistic regression model to assess the GOS recommendation of 300 surgeries under supervision. In the low-risk group, we additionally visualized the 'typical' learning curve by plotting the posterior capsule ruptures against the respective rank numbers. Results The odds ratio for posterior capsule ruptures of 'learning-mode' (one of the respective surgeon's 300 first procedures) vs. the non-learning-mode was 3.8 (p<0.0001). By contrast, classification into the low-risk group lowered the risk of posterior capsule ruptures three fold (p<0.0001). According to the low-risk plot, the surgeons started with a complication rate of 4% and continuously improved towards 0.5% after 1500 operations. Thereafter, the rate increased again and stabilized around one percent. Conclusion The learning curve with respect to posterior capsule ruptures is surprisingly flat. The GOS entry criterion of 300 cataract procedures is therefore most likely justified. Careful selection of low-risk patients for the training surgeons may help in reducing the rate of posterior capsule ruptures during training. PMID:25401738

  11. Liquefied after cataract and its surgical treatment

    PubMed Central

    Bhattacharjee, Harsha; Bhattacharjee, Kasturi; Bhattacharjee, Pankaj; Das, Dipankar; Gogoi, Krishna; Arati, Diyali

    2014-01-01

    Aims: To describe liquefied after cataract (LAC) and its surgical management following an uneventful phacoemulsification with posterior chamber in-the-bag intraocular lens (IOL) implantation and continuous curvilinear capsulorrhexis (CCC). Design: Interventional case series. Materials and Methods: Eleven patients with LAC, following uneventful phacoemulsification with CCC and in-the-bag IOL implantation were enrolled. After the basic slit lamp examination, each case was investigated with Scheimpflug photography and ultrasound biomicroscopy (UBM). Each case was treated with capsular lavage. Biochemical composition of the milky fluid was evaluated and ring of anterior capsular opacity (ACO) was examined under electron microscope. Results: All 11 cases presented with blurring of vision after 6-8 years of cataract surgery with IOL implantation. All cases had IOL microvacuoles, 360° anterior capsule, and anterior IOL surface touch along with ACO, ring of Soemmering, and posterior capsule distension filled with opalescent milky fluid with whitish floppy or crystalline deposits. Biochemically, the milky fluid contained protein (800 mg/dl), albumin (100 mg/dl), sugar (105 mg/dl), and calcium (0.13%) and was bacteriologically sterile. Histologically, the dissected ACO showed fibrous tissue. All cases were successfully treated with capsular lavage with good visual recovery and with no complication. There was no recurrence of LAC during 2 years postoperative follow-up in any of the cases. Conclusions: LAC is a late complication of standard cataract surgery. It may be a spectrum of capsular bag distension syndrome (CBDS) without shallow anterior chamber and secondary glaucoma. Capsular bag lavage is a simple and effective treatment for LAC and a safe alternative to neodymium-doped yttrium aluminum garnet (Nd-YAG) capsulotomy. PMID:24881605

  12. The Safety and Efficacy of Day Care Cataract Surgery

    PubMed Central

    Cabric, Emir; Zvornicanin, Jasmin; Jusufovic, Vahid

    2014-01-01

    ABSTRACT Purpose: To evaluate safety and efficacy of day care cataract surgery in developing country. Patients and Methods: This prospective study included 200 patients planned for cataract surgery during October and November 2012 divided in to two groups, day care cataract surgery (DCCS) and inpatient cataract surgery (ICS), with same number of male and female patients right and left eyes. All patients had same operative conditions and postoperative follow up. Results: The average age of patients in this study was 68.4 ± 7.47 years. Visual acuity before cataract extraction was 0.1754 where 44.5% of patients had severe visual impairment and another 23% had complicated cataract. Posterior capsule rupture was noted in 4.5% of cases. The main risk factors in both groups were: higher age, female gender, left side, complicated cataract, higher dioptric power of IOL and ECCE. Regular control opthalmologic examinations 30, 90 and 180 days after the cataract extraction did not reveal signs bullous keratopathy, wound dehiscence, cystoid macular edema and endophtalmitis in any of patients. Postoperative visual acuity 180 days after the operation in DCCS was 0.920 ± 0.154 and 0.928 ± 0.144 in ICS. Visual acuity less than 0.5 was noted in 4.5% due to posterior eye segment changes. Patients in DCCS group had 30 control examinations more and 95 days of hospitalization less than ICS with 16.5% cost reduction. Conclusion: The concept of day care cataract surgery is equally safe and more cost effective than inpatient cataract surgery. PMID:24937936

  13. Long term management of congenital cataracts.

    PubMed Central

    Burns, E C; Jones, R B

    1985-01-01

    Presentation and outcome, particularly in terms of development, nursery, and school placement of 55 children with treated congenital cataracts was studied. Results indicate that although most children have satisfactory vision many of their parents would have welcomed more support at the time of the diagnosis, an opportunity to talk to parents of similarly affected children, and further advice on their child's early development and educational placement. It is suggested that improved communications between clinicians, therapists, and teachers, and parents' support groups would be helpful to these families. PMID:3923944

  14. Optics Demonstrations Using Cylindrical Lenses

    ERIC Educational Resources Information Center

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  15. Towards noiseless gravitational lensing simulations

    NASA Astrophysics Data System (ADS)

    Angulo, Raul E.; Chen, Ruizhu; Hilbert, Stefan; Abel, Tom

    2014-11-01

    The microphysical properties of the dark matter (DM) particle can, in principle, be constrained by the properties and abundance of substructures in galaxy clusters, as measured through strong gravitational lensing. Unfortunately, there is a lack of accurate theoretical predictions for the lensing signal of these substructures, mainly because of the discreteness noise inherent to N-body simulations. Here, we present a method, dubbed as Recursive-TCM, that is able to provide lensing predictions with an arbitrarily low discreteness noise. This solution is based on a novel way of interpreting the results of N-body simulations, where particles simply trace the evolution and distortion of Lagrangian phase-space volume elements. We discuss the advantages and limitations of this method compared to the widely used density estimators based on cloud-in-cells and adaptive-kernel smoothing. Applying the new method to a cluster-sized DM halo simulated in warm and cold DM scenarios, we show how the expected differences in their substructure population translate into differences in convergence and magnification maps. We anticipate that our method will provide the high-precision theoretical predictions required to interpret and fully exploit strong gravitational lensing observations.

  16. Gravitational Lenses in the Classroom

    ERIC Educational Resources Information Center

    Ros, Rosa M.

    2008-01-01

    It is not common to introduce current astronomy in school lessons. This article presents a set of experiments about gravitational lenses. It is normal to simulate them by means of computers, but it is very simple to simulate similar effects using a drinking glass full of liquid or using only the glass base. These are, of course, cheap and easy…

  17. The Optical Gravitational Lensing Experiment

    NASA Technical Reports Server (NTRS)

    Udalski, A.; Szymanski, M.; Kaluzny, J.; Kubiak, M.; Mateo, Mario

    1992-01-01

    The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

  18. Gravitational Lensing of Supernova Neutrinos

    SciTech Connect

    Mena, Olga; Mocioiu, Irina; Quigg, Chris; /Fermilab

    2006-10-01

    The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

  19. Magnified Weak Lensing Cross Correlation Tomography

    SciTech Connect

    Ulmer, Melville P., Clowe, Douglas I.

    2010-11-30

    This project carried out a weak lensing tomography (WLT) measurement around rich clusters of galaxies. This project used ground based photometric redshift data combined with HST archived cluster images that provide the WLT and cluster mass modeling. The technique has already produced interesting results (Guennou et al, 2010,Astronomy & Astrophysics Vol 523, page 21, and Clowe et al, 2011 to be submitted). Guennou et al have validated that the necessary accuracy can be achieved with photometric redshifts for our purposes. Clowe et al titled "The DAFT/FADA survey. II. Tomographic weak lensing signal from 10 high redshift clusters," have shown that for the **first time** via this purely geometrical technique, which does not assume a standard rod or candle, that a cosmological constant is **required** for flat cosmologies. The intent of this project is not to produce the best constraint on the value of the dark energy equation of state, w. Rather, this project is to carry out a sustained effort of weak lensing tomography that will naturally feed into the near term Dark Energy Survey (DES) and to provide invaluable mass calibration for that project. These results will greatly advance a key cosmological method which will be applied to the top-rated ground-based project in the Astro2020 decadal survey, LSST. Weak lensing tomography is one of the key science drivers behind LSST. CO-I Clowe is on the weak lensing LSST committee, and senior scientist on this project, at FNAL James Annis, plays a leading role in the DES. This project has built on successful proposals to obtain ground-based imaging for the cluster sample. By 1 Jan, it is anticipated the project will have accumulated complete 5-color photometry on 30 (or about 1/3) of the targeted cluster sample (public webpage for the survey is available at http://cencos.oamp.fr/DAFT/ and has a current summary of the observational status of various clusters). In all, the project has now been awarded the equivalent of over 60

  20. Immersion Meta-Lenses at Visible Wavelengths for Nanoscale Imaging.

    PubMed

    Chen, Wei Ting; Zhu, Alexander Y; Khorasaninejad, Mohammadreza; Shi, Zhujun; Sanjeev, Vyshakh; Capasso, Federico

    2017-04-13

    Immersion objectives can focus light into a spot smaller than what is achievable in free space, thereby enhancing the spatial resolution for various applications such as microscopy, spectroscopy, and lithography. Despite the availability of advanced lens polishing techniques, hand-polishing is still required to manufacture the front lens of a high-end immersion objective, which poses major constraints for lens design. This limits the shape of the front lens to spherical. Therefore, several other lenses need to be cascaded to correct for spherical aberration, resulting in significant challenges for miniaturization and adding design complexity for different immersion liquids. Here, by using metasurfaces, we demonstrate liquid immersion meta-lenses free of spherical aberration at various design wavelengths in the visible spectrum. We report water and oil immersion meta-lenses of various numerical apertures (NA) up to 1.1 and show that their measured focal spot sizes are diffraction-limited with Strehl ratios of approximately 0.9 at 532 nm. By integrating the oil immersion meta-lens (NA = 1.1) into a commercial scanning confocal microscope, we achieve an imaging spatial resolution of approximately 200 nm. These meta-lenses can be easily adapted to focus light through multilayers of different refractive indices and mass-produced using modern industrial manufacturing or nanoimprint techniques, leading to cost-effective high-end optics.

  1. Dynamic wettability of pHEMA-based hydrogel contact lenses.

    PubMed

    Maldonado-Codina, Carole; Efron, Nathan

    2006-07-01

    Standard methods of contact angle analysis include sessile drop, captive bubble and Wilhelmy plate techniques; however, these methodologies are not particularly well suited for assessing the wettability of the surfaces of formed hydrogel contact lenses. This paper describes two methodologies that are adaptations of previously described techniques. The maximum adherent force method is an adaptation of the dynamic Wilhelmy plate technique that allows the assessment of whole, finished contact lenses. The dynamic photographic method allows the simultaneous assessment of the front and back surfaces of strip samples for the assessment of advancing and receding contact angles. Lenses investigated were made from polyhydroxyethyl methacrylate, hydroxyethyl methacrylate/methacrylic acid and hydroxyethyl methacrylate/glycerol methacrylate. The lenses were manufactured by lathing, spin-casting or cast-moulding techniques. Overall, both techniques demonstrated few differences between the wettability of different lens materials and no differences between materials of the 'same' lens type but manufactured by different methods. These findings are consistent with the results of clinical studies, which have shown little difference between contact lens surface wettability in vivo, which may be due to the apparent natural surface wettability-enhancing properties of the pre-lens tear film.

  2. Thermal lensing of laser materials

    NASA Astrophysics Data System (ADS)

    Davis, Mark J.; Hayden, Joseph S.

    2014-10-01

    This paper focuses on the three main effects that can induce wave-front distortion due to thermal lensing in laser gain media: 1) thermo-optic (dn/dT); 2) stress-optic; and 3) surface deformation (e.g., "end-bulging" of a laser rod). Considering the simple case of a side-pumped cylindrical rod which is air- or water-cooled along its length, the internal temperature distribution has long been known to assume a simple parabolic profile. Resulting from this are two induced refractive index variations due to thermo-optic and stress-optic effects that also assume a parabolic profile, but generally not of the same magnitude, nor even of the same sign. Finally, a small deformation on the rod ends can induce a small additional lensing contribution. We had two goals in this study: a) use finite-element simulations to verify the existing analytical expressions due to Koechner1 and Foster and Osterink; and b) apply them to glasses from the SCHOTT laser glass portfolio. The first goal was a reaction to more recent work by Chenais et al. who claimed Koechner made an error in his analysis with regard to thermal stress, throwing into doubt conclusions within studies since 1970 which made use of his equations. However, our re-analysis of their derivations, coupled with our FE modeling, confirmed that the Koechner and Foster and Osterink treatments are correct, and that Chenais et al. made mistakes in their derivation of the thermally-induced strain. Finally, for a nominal laser rod geometry, we compared the thermally-induced optical distortions in LG-680, LG-750, LG-760, LG-770, APG-1, and APG-2. While LG-750, -760, and -770 undergo considerable thermo-optic lensing, their stress-optic lensing is nearly of the same magnitude but of opposite sign, leading to a small total thermal lensing signature.

  3. On seeing yellow: the case for, and against, short-wavelength light-absorbing intraocular lenses.

    PubMed

    Simunovic, Matthew P

    2012-07-01

    The normal human crystalline lens absorbs UV and short-wavelength visible electromagnetic radiation. Early intraocular lenses (IOLs) permitted the transmission of such radiation to the retina following cataract extraction. Experimental studies of the absorption profile of the crystalline lens and animal studies demonstrating the deleterious effects of short-wavelength radiation on the retina led to the development of UV-absorbing, and later, short-wavelength light-absorbing (SLA) IOLs. Short-wavelength light-absorbing IOLs were designed to mimic the absorption properties of the normal crystalline lens by absorbing some short-wavelength light in addition to UV radiation; however, debate continues regarding the relative merits of such lenses over UV-absorbing IOLs. Advocates of SLA IOLs suggest that they may theoretically offer increased photoprotection and decreased glare sensitivity and draw on in vitro, animal, and limited clinical studies that infer possible benefits. Detractors suggest that there is no direct evidence supporting a role for SLA IOLs in preventing retinal dysfunction in humans and suggest that they may have negative effects on color perception, scotopic vision, and circadian rhythms. This article examines the theoretical and empirical evidence for, and against, such lenses.

  4. Bifocal contact lenses: History, types, characteristics, and actual state and problems

    PubMed Central

    Toshida, Hiroshi; Takahashi, Kozo; Sado, Kazushige; Kanai, Atsushi; Murakami, Akira

    2008-01-01

    Since people who wear contact lenses (CL) often continue using CL even when they develop presbyopia, there are growing expectations for bifocal CL. To understand actual state and problems, history, types, and their characteristics are summarized in this review. Bifocal CL have a long history over 70 years. Recently, bifocal CL have achieved remarkable progress. However, there still is an impression that prescription of bifocal CL is not easy. It should also be remembered that bifocal CL have limits, including limited addition for near vision, as well as the effects of aging and eye diseases in the aged, such as dry eye, astigmatism, cataract, etc. Analysis of the long-term users of bifocal CL among our patients has revealed the disappearance of bifocal CL that achieved unsatisfactory vision and poor contrast compared with those provided by other types of CL. Changing the prescription up to 3 times for lenses of the same brand may be appropriate. Lenses that provide poor contrast sensitivity, suffer from glare, or give unsatisfactory vision have been weeded out. The repeated replacement of products due to the emergence of improved or new products will be guessed. PMID:19668441

  5. Femtosecond laser-assisted keratoplasty combined with cataract extraction in a patient with keratoconus and oculocutaneous albinism

    PubMed Central

    Pásztor, Dorottya; Kolozsvári, Bence Lajos; Losonczy, Gergely; Fodor, Mariann

    2016-01-01

    In this study, we present a case of a 58-year-old male patient with oculocutaneous albinism, keratoconus, total cataract, and glaucoma originating from father-daughter incest. He underwent femtosecond laser-assisted keratoplasty with “open-sky” cataract extraction and posterior chamber intraocular lens implantation. One week after surgery his uncorrected visual acuity improved from hand motion to 20/200. Six months later corneal K values were 49.1 D in the flat and 50.0 D in the steep meridian. The graft had a central corneal thickness of 488 µm and was well fitted. The patient's quality of life improved substantially due to the surgery. To the best of our knowledge, this is the first report on the association of albinism with advanced keratoconus, total cataract, and glaucoma. Moreover, no previous report on femtosecond laser-assisted keratoplasty using VisuMax femtosecond laser system with “open-sky” cataract extraction is available in the literature. The VisuMax femtosecond laser-assisted keratoplasty ensures fast patient rehabilitation in such challenging cases. PMID:27146942

  6. Posterior Corneal Characteristics of Cataract Patients with High Myopia

    PubMed Central

    Jing, Qinghe; Tang, Yating; Qian, Dongjin; Lu, Yi; Jiang, Yongxiang

    2016-01-01

    Purpose To evaluate the characteristics of the posterior corneal surface in patients with high myopia before cataract surgery. Methods We performed a cross-sectional study at the Eye and ENT Hospital of Fudan University, Shanghai, China. Corneal astigmatism and axial length were measured with a rotating Scheimpflug camera (Pentacam) and partial coherence interferometry (IOLMaster) in a high-myopia study group of 167 eyes (axial length ≥ 26 mm) and a control group of 150 eyes (axial length > 20 mm and < 25 mm). Results Total corneal astigmatism and anterior corneal astigmatism values were higher in the high-myopia group than in the control group. There was no significant difference in posterior corneal astigmatism between the high-myopia study group and the control group. In the study group, the mean posterior corneal astigmatism (range 0 – −0.9 diopters) was –0.29 diopters (D) ± 0.17 standard deviations (SD). The steep corneal meridian was aligned vertically (60°–120°) in 87.43% of eyes for the posterior corneal surface, and did not change with increasing age. There was a significant correlation (r = 0.235, p = 0.002) between posterior corneal astigmatism and anterior corneal astigmatism, especially when the anterior corneal surface showed with-the-rule (WTR) astigmatism (r = 0.452, p = 0.000). There was a weak negative correlation between posterior corneal astigmatism and age (r = –0.15, p = 0.053) in the high-myopia group. Compared with total corneal astigmatism values, the anterior corneal measurements alone overestimated WTR astigmatism by a mean of 0.27 ± 0.18 D in 68.75% of eyes, underestimated against-the-rule (ATR) astigmatism by a mean of 0.41 ± 0.28 D in 88.89% of eyes, and underestimated oblique astigmatism by a mean of 0.24 ± 0.13 D in 63.64% of eyes. Conclusions Posterior corneal astigmatism decreased with age and remained as ATR astigmatism in most cases of high myopia. There was a significant correlation between posterior corneal

  7. [Research progress in relative crystallin genes of congenital cataract].

    PubMed

    Wang, D D; Yang, H J; Yi, J L

    2016-02-01

    Congenital cataract is the common cause of visual disability in children. Nearly one third of congenital cataract cases may have a related genetic mutation. With the development of molecular genetics, especially gentechnik, more and more genes, such as crystallin genes, membrane protein genes, eytoskeletal protein genes and regulatory protein genes have been confirmed to participate in the process of congenital cataract. Furthermore, crystallin genes account for most of these genes and the crystallin has the highest amount of the whole protein in lens.It has been found that nearly one hundred mutations in crystallin genes are associated with the onset of congenital cataract. Researchers are exploring how these mutations further affect the function of cellular biology and eventually lead to cataract. Although more and more research results gradually reveal the pathogenesis of congenital cataract from the level of gene and protein, the specific pathogenesis is still unclear. The recent progression about inherited congenital cataract related with crysallin genes is summarized in this review.

  8. Global prevalence of childhood cataract: a systematic review.

    PubMed

    Sheeladevi, S; Lawrenson, J G; Fielder, A R; Suttle, C M

    2016-09-01

    Childhood cataract is an avoidable cause of visual disability worldwide and is a priority for VISION 2020: The Right to Sight. There is a paucity of information about the burden of cataract in children and the aim of this review is to assess the global prevalence of childhood cataract. The methodology for the review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We performed a literature search for studies reporting estimates of prevalence or incidence of cataract among children (aged<18 years) at any global location using the Cochrane Library, Medline and Embase up to January 2015. No restrictions were imposed based on language or year of publication. Study quality was assessed using a critical appraisal tool designed for systematic reviews of prevalence. Twenty prevalence and four incidence studies of childhood cataract from five different geographical regions were included. The overall prevalence of childhood cataract and congenital cataract was in the range from 0.32 to 22.9/10000 children (median=1.03) and 0.63 to 9.74/10000 (median=1.71), respectively. The incidence ranged from 1.8 to 3.6/10000 per year. The prevalence of childhood cataract in low-income economies was found to be 0.42 to 2.05 compared with 0.63 to 13.6/10000 in high-income economies. There was no difference in the prevalence based on laterality or gender. This review highlights substantial gaps in the epidemiological knowledge of childhood cataract worldwide, particularly from low and lower middle-income economies. More studies are needed using standard definitions and case ascertainment methods with large enough sample sizes.

  9. Increasing incidence of cataract surgery: Population-based study

    PubMed Central

    Gollogly, Heidrun E.; Hodge, David O.; St. Sauver, Jennifer L.; Erie, Jay C.

    2015-01-01

    PURPOSE To estimate the incidence of cataract surgery in a defined population and to determine longitudinal cataract surgery patterns. SETTING Mayo Clinic, Rochester, Minnesota, USA. DESIGN Cohort study. METHODS Rochester Epidemiology Project (REP) databases were used to identify all incident cataract surgeries in Olmsted County, Minnesota, between January 1, 2005, and December 31, 2011. Age-specific and sex-specific incidence rates were calculated and adjusted to the 2010 United States white population. Data were merged with previous REP data (1980 to 2004) to assess temporal trends in cataract surgery. Change in the incidence over time was assessed by fitting generalized linear models assuming a Poisson error structure. The probability of second-eye cataract surgery was calculated using the Kaplan-Meier method. RESULTS Included were 8012 cataract surgeries from 2005 through 2011. During this time, incident cataract surgery significantly increased (P < .001), peaking in 2011 with a rate of 1100 per 100 000 (95% confidence interval, 1050–1160). The probability of second-eye surgery 3, 12, and 24 months after first-eye surgery was 60%, 76%, and 86%, respectively, a significant increase compared with the same intervals in the previous 7 years (1998 to 2004) (P < .001). When merged with 1980 to 2004 REP data, incident cataract surgery steadily increased over the past 3 decades (P < .001). CONCLUSION Incident cataract surgery steadily increased over the past 32 years and has not leveled off, as reported in Swedish population-based series. Second-eye surgery was performed sooner and more frequently, with 60% of residents having second-eye surgery within 3-months of first-eye surgery. PMID:23820302

  10. Effect of four different intraocular lenses on posterior capsule opacification

    PubMed Central

    Duman, Rahmi; Karel, Fatih; Özyol, Pelin; Ateş, Can

    2015-01-01

    AIM To evaluate the impact of 4 different intraocular lenses (IOLs) on posterior capsule opacification (PCO) by comparing the neodymium: yttrium-aluminum-garnet (Nd:YAG) laser capsulotomy rates. METHODS This retrospective study included 4970 eyes of 4013 cataract patients who underwent phacoemulsification and IOL implantation between January 2000 and January 2008 by the same surgeon at one clinic. Four different IOLs were assessed. The outcome parameter was the incidence of Nd:YAG laser posterior capsulotomies. RESULTS An Nd:YAG laser posterior capsulotomy was performed in 153 (3.07%) of the 4970 eyes. The mean follow-up time was 84mo for all of the IOL groups. The percentage of eyes developing PCO was significantly greater for the acrylic hydrophilic IOLs than for the hydrophobic IOLs, although eyes with acrylic hydrophilic IOLs did not require Nd:YAG laser capsulotomy as soon as eyes with acrylic hydrophobic IOLs. There was no difference between the long-term PCO rates when 1- and 3-piece acrylic hydrophobic IOLs were compared or when IOLs made of the same material but with different haptic angles were compared. CONCLUSION In this study, eyes with acrylic hydrophilic IOLs were more likely to develop PCO than those with acrylic hydrophobic IOLs. The lens design (1-piece versus 3-piece and varying haptic angles) did not affect the PCO rate. PMID:25709920

  11. Visual Acuity after Cataract Surgery in Patients with Age-Related Macular Degeneration. Age-Related Eye Disease Study 2 Report No. 5

    PubMed Central

    Huynh, Nancy; Nicholson, Benjamin P.; Agrón, Elvira; Clemons, Traci E.; Bressler, Susan B.; Rosenfeld, Philip J.; Chew, Emily Y.

    2014-01-01

    Objective To evaluate visual acuity outcomes after cataract surgery in persons with varying severity of age-related macular degeneration (AMD). Design Cohort study. Participants A total of 1232 eyes of 793 participants who underwent cataract surgery during the Age-Related Eye Disease Study 2 (AREDS2), a prospective, multicenter, randomized controlled trial of nutritional supplements for treatment of AMD. Methods Preoperative and postoperative characteristics of participants who underwent cataract extraction during the 5 year trial were analyzed. Both clinical data and standardized red-reflex lens and fundus photographs were obtained at baseline and annually. Photographs were graded by a centralized reading center for cortical and posterior subcapsular lens opacities and for AMD severity. Cataract surgery was documented at annual study visits or by history during the 6 month telephone calls. Analyses were conducted using multivariate repeated-measures regression. Main Outcome Measures Change in best-corrected visual acuity (BCVA) after cataract surgery compared with preoperative BCVA. Results Adjusting for age at time of surgery, gender, interval between preoperative and postoperative visits, and type and severity of cataract, the mean changes in visual acuity were as follows: eyes with mild AMD (n=30) gained 11.2 letters (95% confidence interval (CI), 6.9-15.5), eyes with moderate AMD (n=346) gained 11.1 letters (95% CI, 9.1-13.2), eyes with severe AMD (n=462) gained 8.7 letters (95% CI, 6.7-10.7), eyes with non-central geographic atrophy (n=70) gained 8.9 letters (95% CI, 5.8-12.1), and eyes with advanced AMD (central geographic atrophy and/or neovascular) AMD (n=324) gained 6.8 letters (95% CI, 4.9-8.8). The visual acuity gain across all AMD severity groups was statistically significant from pre-operative state (P<0.0001). Conclusions Mean visual acuities improved significantly after cataract surgery across varying degrees of AMD severity. PMID:24613825

  12. Ocular safety limits for 1030nm femtosecond laser cataract surgery

    NASA Astrophysics Data System (ADS)

    Wang, Jenny; Sramek, Christopher; Paulus, Yannis M.; Lavinsky, Daniel; Schuele, Georg; Anderson, Dan; Dewey, David; Palanker, Daniel V.

    2013-03-01

    Application of femtosecond lasers to cataract surgery has added unprecedented precision and reproducibility but ocular safety limits for the procedure are not well-quantified. We present an analysis of safety during laser cataract surgery considering scanned patterns, reduced blood perfusion, and light scattering on residual bubbles formed during laser cutting. Experimental results for continuous-wave 1030 nm irradiation of the retina in rabbits are used to calibrate damage threshold temperatures and perfusion rate for our computational model of ocular heating. Using conservative estimates for each safety factor, we compute the limits of the laser settings for cataract surgery that optimize procedure speed within the limits of retinal safety.

  13. Femtosecond laser cataract surgery: technology and clinical practice.

    PubMed

    Roberts, Timothy V; Lawless, Michael; Chan, Colin Ck; Jacobs, Mark; Ng, David; Bali, Shveta J; Hodge, Chris; Sutton, Gerard

    2013-03-01

    The recent introduction of femtosecond lasers to cataract surgery has generated much interest among ophthalmologists around the world. Laser cataract surgery integrates high-resolution anterior segment imaging systems with a femtosecond laser, allowing key steps of the procedure, including the primary and side-port corneal incisions, the anterior capsulotomy and fragmentation of the lens nucleus, to be performed with computer-guided laser precision. There is emerging evidence of reduced phacoemulsification time, better wound architecture and a more stable refractive result with femtosecond cataract surgery, as well as reports documenting an initial learning curve. This article will review the current state of technology and discuss our clinical experience.

  14. Femtosecond laser assisted cataract surgery, beginning of a new era in cataract surgery

    PubMed Central

    Ali, Muhammad Hassaan; Javaid, Mamoona; Jamal, Samreen; Butt, Nadeem Hafeez

    2015-01-01

    The purpose of this article is to analyze and understand the mechanism of action, effectiveness, cost and time benefits, advantages and disadvantages of the femtosecond laser (FSL) assisted cataract surgery. A PubMed search was done using the topic and the keywords. Research shows considerable improvements in corneal incisions, anterior capsulotomy, and phacofragmentation using FSL. We will also discuss and compare FSL with conventional cataract extraction techniques in terms of both short-term and long-term advantages and disadvantages. Limitations of the studies reviewed include small sample size and short-term follow-up. The major dilemma is still considered to be its heavy financial feasibility to date. PMID:26903717

  15. Parabolic single-crystal diamond lenses for coherent x-ray imaging

    NASA Astrophysics Data System (ADS)

    Terentyev, Sergey; Blank, Vladimir; Polyakov, Sergey; Zholudev, Sergey; Snigirev, Anatoly; Polikarpov, Maxim; Kolodziej, Tomasz; Qian, Jun; Zhou, Hua; Shvyd'ko, Yuri

    2015-09-01

    We demonstrate parabolic single-crystal diamond compound refractive lenses designed for coherent x-ray imaging resilient to extreme thermal and radiation loading expected from next generation light sources. To ensure the preservation of coherence and resilience, the lenses are manufactured from the highest-quality single-crystalline synthetic diamond material grown by a high-pressure high-temperature technique. Picosecond laser milling is applied to machine lenses to parabolic shapes with a ≃ 1 μ m precision and surface roughness. A compound refractive lens comprised of six lenses with a radius of curvature R = 200 μ m at the vertex of the parabola and a geometrical aperture A = 900 μ m focuses 10 keV x-ray photons from an undulator source at the Advanced Photon Source facility to a focal spot size of ≃ 20 × 90 μ m 2 with a gain factor of ≃ 50 - 100 .

  16. Our warped universe: the power of gravitational lensing for probing the cosmos

    NASA Astrophysics Data System (ADS)

    Nord, Brian

    2017-01-01

    Gravitational lensing epitomizes a maxim of Einstein's General Relativity: space tells energy how to move and energy tells space how to curve. Through lensing, massive objects magnify and distort the shapes of distant objects, likes galaxies and quasars. The connection between the lens's mass distribution and the degree of distortion in the images allows us to observe faint, distant objects, and to infer the matter distribution and cosmic expansion in the nearby universe. Current and future surveys, both ground- and space-based, will provide data sets unprecedented in size and precision with which to probe dark energy, dark matter and the early universe through gravitational lensing. I will discuss recent advances in observations and analysis techniques in both weak and strong lensing, and the burgeoning potential of these techniques to derive important and competitive cosmological constraints from surveys of large-scale structure.

  17. The shape of the CMB lensing bispectrum

    SciTech Connect

    Lewis, Antony; Challinor, Anthony; Hanson, Duncan E-mail: adc1000@ast.cam.ac.uk

    2011-03-01

    Lensing of the CMB generates a significant bispectrum, which should be detected by the Planck satellite at the 5-sigma level and is potentially a non-negligible source of bias for f{sub NL} estimators of local non-Gaussianity. We extend current understanding of the lensing bispectrum in several directions: (1) we perform a non-perturbative calculation of the lensing bispectrum which is ∼ 10% more accurate than previous, first-order calculations; (2) we demonstrate how to incorporate the signal variance of the lensing bispectrum into estimates of its amplitude, providing a good analytical explanation for previous Monte-Carlo results; and (3) we discover the existence of a significant lensing bispectrum in polarization, due to a previously-unnoticed correlation between the lensing potential and E-polarization as large as 30% at low multipoles. We use this improved understanding of the lensing bispectra to re-evaluate Fisher-matrix predictions, both for Planck and cosmic variance limited data. We confirm that the non-negligible lensing-induced bias for estimation of local non-Gaussianity should be robustly treatable, and will only inflate f{sub NL} error bars by a few percent over predictions where lensing effects are completely ignored (but note that lensing must still be accounted for to obtain unbiased constraints). We also show that the detection significance for the lensing bispectrum itself is ultimately limited to 9 sigma by cosmic variance. The tools that we develop for non-perturbative calculation of the lensing bispectrum are directly relevant to other calculations, and we give an explicit construction of a simple non-perturbative quadratic estimator for the lensing potential and relate its cross-correlation power spectrum to the bispectrum. Our numerical codes are publicly available as part of CAMB and LensPix.

  18. Tomography and weak lensing statistics

    SciTech Connect

    Munshi, Dipak; Coles, Peter; Kilbinger, Martin E-mail: peter.coles@astro.cf.ac.uk

    2014-04-01

    We provide generic predictions for the lower order cumulants of weak lensing maps, and their correlators for tomographic bins as well as in three dimensions (3D). Using small-angle approximation, we derive the corresponding one- and two-point probability distribution function for the tomographic maps from different bins and for 3D convergence maps. The modelling of weak lensing statistics is obtained by adopting a detailed prescription for the underlying density contrast that involves hierarchal ansatz and lognormal distribution. We study the dependence of our results on cosmological parameters and source distributions corresponding to the realistic surveys such as LSST and DES. We briefly outline how photometric redshift information can be incorporated in our results. We also show how topological properties of convergence maps can be quantified using our results.

  19. Seeing Patients Through Genetic Lenses

    PubMed Central

    FELCONE, LINDA HULL

    2005-01-01

    Biotechnology is changing how doctors ‘see’ patients and disease processes. Optical probes and computer-assisted genetic screening tools let researchers peer into the structure and functions of cellular proteins on a molecular level. Soon, this clearer vision of individual patients will be available in the clinic, making drug and biologic treatments safer. These new lenses will push medicine toward risk prediction and away from acute intervention. PMID:23393472

  20. Biomimetic Gradient Index (GRIN) Lenses

    DTIC Science & Technology

    2006-01-01

    optics include single lenses inspired by cephalopod (octopus) eyes and a three-lens, wide field of view, optical system for a surveillance sensor...camera. Details are easily resolv- able with the polymer lens. This lens system was installed on an Evolution unmanned aerial vehicle (UAV) with a...lens system was installed in an NRL Evolution UAV and used to record video images at a height of up to 1000 ft. The index gradients in the polymer

  1. RELICS: Reionization Lensing Cluster Survey

    NASA Astrophysics Data System (ADS)

    Coe, Dan A.; RELICS Team

    2017-01-01

    Hubble and Spitzer imaging programs observing galaxy cluster lenses have delivered some of the highest redshift galaxy candidates to date (z ~ 9 - 11, or 540 - 410 Myr after the Big Bang). These magnified galaxies are intrinsically faint, and thus more representative of the sources believed to be primarily responsible for reionization. Magnified galaxies are also observed brightly enough to be prime targets for detailed follow-up study with current and future observatories, including JWST. Building on the successes of CLASH and the Frontier Fields, we have begun RELICS, the Reionization Lensing Cluster Survey. By observing 41 massive clusters for the first time at infrared wavelengths, RELICS will deliver more of the best and brightest high-redshift candidates to the community in time for the November 2017 JWST GO Cycle 1 call for proposals. I will present our early results. I will also discuss prospects for JWST to follow-up known candidates and discover new galaxies at even higher redshifts (z > 11). The discovery efficiency gains from lensing will be even more pronounced at z > 11 if luminosity function faint end slopes are steeper than alpha ~ -2, as suggested by current models and observational extrapolations.

  2. Gravitational lensing in plasmic medium

    SciTech Connect

    Bisnovatyi-Kogan, G. S. Tsupko, O. Yu.

    2015-07-15

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  3. Gravitational lensing in plasmic medium

    NASA Astrophysics Data System (ADS)

    Bisnovatyi-Kogan, G. S.; Tsupko, O. Yu.

    2015-07-01

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  4. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  5. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  6. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  7. The Age-Related Eye Disease Study (AREDS) System for Classifying Cataracts From Photographs: AREDS Report No. 4

    PubMed Central

    2006-01-01

    • PURPOSE: To describe the system for grading cataracts from photographs in the Age-Related Eye Disease Study (AREDS). • METHODS: The system for grading cataracts in AREDS uses photographs taken in a standardized fashion with specially modified cameras at 11 clinical centers. The photographs are evaluated by graders for quality and cataract severity at a central reading center. The area of lens involvement is used to assess the severity of cortical and posterior subcapsular opacities. Optical density of nuclear opacity is graded against a series of seven standard photographs. Contemporaneous variability in grading is evaluated periodically by having a second examiner regrade a subset of the photographs. Temporal variability is assessed by annually regrading a subset of photographs. • RESULTS: Photographs of 925 eyes, most with no or early lens opacities, were regraded to assess intergrader reliability. For cortical opacities, there was an absolute difference of 10% or greater of area involved in 1.9% of the replicate gradings. For posterior subcapsular opacities an absolute difference of 5% of area involved was noted in 2.8% of the regraded photographs. For nuclear opacities, absolute differences of 1.5 or more steps were observed in 0.6% of eyes. There was little evidence of temporal drift in grading any of the three types of opacity during four annual regrades. • CONCLUSIONS: We have demonstrated a high degree of reliability in grading the severity of lens opacities in a large study cohort with mostly early lens changes, the type of cohort most likely to be entered in clinical trials involving cataract prevention. The Age-Related Eye Disease Study System for Classifying Cataracts From Photographs could be useful in studies where there is a need to standardize data collection over time and across different data collection sites. Limitations of the system include the cost of implementation and, currently, the limited amount of data on grading

  8. Experimental imaging properties of immersion microscale spherical lenses

    PubMed Central

    Ye, Ran; Ye, Yong-Hong; Ma, Hui Feng; Cao, Lingling; Ma, Jun; Wyrowski, Frank; Shi, Rui; Zhang, Jia-Yu

    2014-01-01

    Using the immersion lensing technique, the resolution of a conventional spherical lens can be improved by a factor of 1/n over its value in air (n, the refractive index of the immersion medium). Depending on the relative position between an object and a lens, either a real or a virtual image is formed. Here we report a new physical phenomenon experimentally observed in the microscale lens imaging. We find that when a microscale spherical lens is semi-immersed in a medium, the resolution of the lens is improved as it can intercept more fine details of the object. However, the microscale lens has two image channels for the fine and coarse details and two images corresponding to the two components can be formed simultaneously. Our findings will advance the understanding of the super-resolution imaging mechanisms in microscale lenses. PMID:24442126

  9. A multiple methods approach: radiation associated cataracts and occupational radiation safety practices in interventionalists in South Africa.

    PubMed

    Rose, A; Rae, W I D; Chikobvu, P; Marais, W

    2017-03-02

    Ionising radiation is a modality used in diagnostic and therapeutic medicine. The technology has improved and resulted in lower dose exposure but there has been an escalation in the quantity of procedures, their duration and complexity. These factors have meant increased occupational radiation exposure for interventionalists. Ionising radiation exposure can have detrimental health effects and includes radiation skin burns, various carcinomas, genetic and chromosomal aberrations and cataractogenesis of the lenses of the eye. The lenses of the eye are of the most radiosensitive organs and the risk of cataracts is high despite low radiation dose exposures. The use of personal protective equipment (PPE) is a method that can be used to mitigate the risk for developing lens opacifications. The consistent and effective utilisation of PPE is marred by availability, proper fit and ease of use when performing procedures. Radiation safety training is imperative to enforce a culture of radiation safety among interventionalists. The aim of this study was to quantify and describe cataracts among South African interventionalists and to understand their radiation safety practices. For this purpose, a cross sectional study was designed using multiple methods. A survey was conducted to determine the demographics and the risk factors of doctors exposed to radiation to doctors not exposed. The radiation workload and radiation safety practices of interventionalists were explored. Both groups had slit lamp examinations. The data were analysed analytically and a regression model developed looking at the outcomes and the risk factors. Qualitative in-depth interviews and group interviews were conducted to explore the perceptions of interventionalists regarding radiation safety. Deductive and inductive thematic analysis was done. Interdisciplinary research is challenging but offers tremendous opportunity for exploring and tackling complex issues related to securing a safe radiation work

  10. Clinical outcomes after cataract surgery with implantation of the Tecnis ZMB00 multifocal intraocular lens

    PubMed Central

    Lubiński, Wojciech; Gronkowska-Serafin, Jolanta; Podborączyńska-Jodko, Karolina

    2014-01-01

    Background The aim of this study was to evaluate visual performance, contrast sensitivity, and patient satisfaction in patients undergoing cataract surgery with bilateral implantation of the Tecnis ZMB00 diffractive multifocal IOL (intraocular lens). Material/Methods This was a prospective study of 40 eyes of 20 patients with an age range from 48 to 67 years and undergoing cataract surgery with implantation of the diffractive 1-piece IOL Tecnis ZMB00 (Abbott Medical Optics) in 1 eye and 3 weeks later in the other eye. The following parameters were evaluated at 3 and 6 months after the operation: binocular uncorrected distance, intermediate and near visual acuity (UDVA, UIVA, UNVA), uncorrected binocular photopic and mesopic distance and photopic near contrast sensitivity (CSV-1000), subjective symptoms, and patient satisfaction (VF-14). Results No significant change was observed in logMAR UDVA between 3 and 6 months postoperatively (−0.11±0.14 vs. −0.10±0.13, p>0.05). In contrast, UNVA (0.06±0.12 vs. −0.02±0.12, p=0.004) and UIVA (0.12±0.15 vs. 0.07±0.11, p=0.005) in this period improved significantly. At 3 and 6 months after surgery, 85% of patients no longer needed to wear corrective lenses. Contrast sensitivity under different conditions was within normal age-matched limits, with significant improvements for some spatial frequencies at 3 and 6 months after surgery (p<0.04). Mean overall patient satisfaction was 9.39±1.06 and 9.19±1.20 (scale from 1 to 10, with 10 being the best score) at 3 and 6 months, respectively. Low level of halo perception was reported in 75% of patients. Conclusions The Tecnis ZMB00 IOL provides an effective restoration of the distance, intermediate, and near visual function, allowing patients to be totally free of need to wear corrective lenses and providing high levels of patient satisfaction. PMID:25022700

  11. Gravitational lenses and dark matter - Theory

    NASA Technical Reports Server (NTRS)

    Gott, J. Richard, III

    1987-01-01

    Theoretical models are presented for guiding the application of gravitational lenses to probe the characteristics of dark matter in the universe. Analytical techniques are defined for quantifying the mass associated with lensing galaxies (in terms of the image separation), determining the quantity of dark mass of the lensing bodies, and estimating the mass density of the lenses. The possibility that heavy halos are made of low mass stars is considered, along with the swallowing of central images of black holes or cusps in galactic nuclei and the effects produced on a lensed quasar image by nonbaryonic halos. The observable effects of dense groups and clusters and the characteristics of dark matter strings are discussed, and various types of images which are possible due to lensing phenomena and position are described.

  12. Inflatable lenses for space photovoltaic concentrator arrays

    SciTech Connect

    O`Neill, M.J.; Piszczor, M.F.

    1997-12-31

    For 12 years, ENTECH and NASA Lewis have been developing Fresnel lens concentrator technology for space power applications. ENTECH provided the point-focus mini-dome lenses for the PASP+ array, launched in 1994. These silicone lenses performed well on orbit, with only about 3% optical performance loss after 1 year in elliptical orbit, with high radiation, atomic oxygen, and ultraviolet exposure. The only protection for these silicone lenses was a thin-film coating provided by OCLI. ENTECH also provided the line-focus lenses for the SCARLET 1 and SCARLET 2 arrays in 1995 and 1997, respectively. These lenses are laminated assemblies, with protective ceria glass superstrates over the silicone lens. In March 1997, ENTECH and NASA Lewis began development of inflatable Fresnel lenses, to achieve lower weight, smaller launch volume, reduced cost, less fragility, and other advantages. This paper summarizes the new concentrator approach, including key program results to date.

  13. Lens Position Parameters as Predictors of Intraocular Pressure Reduction After Cataract Surgery in Glaucomatous Versus Nonglaucomatous Eyes

    PubMed Central

    Coh, Paul; Moghimi, Sasan; Chen, Rebecca I.; Hsu, Chi-Hsin; Masís Solano, Marissé; Porco, Travis; Lin, Shan C.

    2016-01-01

    Purpose To evaluate the relationship between lens position parameters and intraocular pressure (IOP) reduction after cataract surgery in patients with primary open-angle glaucoma (POAG) and in nonglaucomatous patients. Methods The main outcomes of this prospective study were percent and absolute IOP change, which were calculated using the preoperative IOP and the IOP 4 months after cataract surgery in POAG and nonglaucomatous eyes. Lens position (LP), defined as anterior chamber depth (ACD) + one-half lens thickness (LT), was assessed preoperatively using parameters from optical biometry. Preoperative IOP, axial length (AL), ACD, LT, relative lens position (RLP), and the ratio of preoperative IOP to ACD (PD ratio) were also evaluated as potential predictors of IOP change. Results Four months postoperatively, the average IOP reduction was 2.80 ± 3.83 mm Hg (15.79%) from the preoperative mean of 14.73 ± 2.89 mm Hg for nonglaucomatous eyes. The average IOP reduction was 2.66 ± 2.07 mm Hg (16.98%) from the preoperative mean of 14.86 ± 2.97 mm Hg for POAG eyes. Preoperative IOP, sex, AL, ACD, PD ratio, and LP predicted IOP change in nonglaucomatous eyes. Preoperative IOP and PD ratio predicted IOP change in POAG eyes. Conclusions Intraocular pressure reduction after phacoemulsification cataract surgery in nonglaucomatous eyes is significantly greater in more anteriorly positioned lenses. Though it did not reach statistical significance in patients with glaucoma, the association of LP with IOP reduction is in the same direction as in nonglaucomatous patients where smaller LP appears to predict greater IOP reduction. Lens position is a simple, easily calculable, accurate, and widely available parameter, which clinicians can potentially utilize in managing glaucoma. PMID:27163773

  14. Atm heterozygous mice are more sensitive to radiation-induced cataracts than are their wild-type counterparts

    NASA Technical Reports Server (NTRS)

    Worgul, Basil V.; Smilenov, Lubomir; Brenner, David J.; Junk, Anna; Zhou, Wei; Hall, Eric J.

    2002-01-01

    It is important to know whether the human population includes genetically predisposed radiosensitive subsets. In vitro studies have shown that cells from individuals homozygous for ataxia telangiectasia (A-T) are much more radiosensitive than cells from unaffected individuals. Although cells heterozygous for the ATM gene (ATM(+/-)) may be slightly more radiosensitive in vitro, it remained to be determined whether the greater susceptibility of ATM(+/-) cells translates into an increased sensitivity for late effects in vivo, though there is a suggestion that radiotherapy patients that are heterozygous for the ATM gene may be more at risk of developing late normal tissue damage. We chose cataractogenesis in the lens as a means to assay for the effects of ATM deficiency in a late-responding tissue. One eye of wild-type, Atm heterozygous and homozygous knockout mice was exposed to 0.5-, 1.0-, 2.0-, or 4.0-Gy x rays. The animals were followed weekly for cataract development by conventional slit-lamp biomicroscopy. Cataract development in the animals of all three groups was strongly dependent on dose. The lenses of homozygous mice were the first to opacify at any given dose. Most important in the present context is that cataracts appeared earlier in the heterozygous versus wild-type animals. The data suggest that ATM heterozygotes in the human population may also be radiosensitive. This may influence the choice of individuals destined to be exposed to higher than normal doses of radiation, such as astronauts, and may also suggest that radiotherapy patients who are ATM heterozygotes could be predisposed to increased late normal tissue damage.

  15. Early acute aseptic iritis after cataract extraction.

    PubMed

    Allen, H F; Grove, A S

    1976-01-01

    Severe iritis which occurs within the first five days after cataract extraction may be categorized as (1) bacterial endophthalmitis, (2) toxic iritis, or (3) aseptic iritis. These entities can sometimes be distinguished because of their clinical features. If bacterial endophthalmitis is suspected, anterior chamber paracentesis should be considered and appropriate antibiotic treatment should be initiated. Acute iritis may result from the introduction of toxic agents into the eye, and may follow the use of products sterilized with ethylene oxide. Early acute aseptic iritis probably occurs more often than has previously been recognized. Response to intensive anti-inflammatory treatment is usually prompt and dramatic. The judicious use of cryoextraction and the careful manipulation of intraocular tissues may minimize the incidence and the severity of postoperative inflammation.

  16. Unfolded-protein response-associated stabilization of p27(Cdkn1b) interferes with lens fiber cell denucleation, leading to cataract.

    PubMed

    Lyu, Lei; Whitcomb, Elizabeth A; Jiang, Shuhong; Chang, Min-Lee; Gu, Yumei; Duncan, Melinda K; Cvekl, Ales; Wang, Wei-Lin; Limi, Saima; Reneker, Lixing W; Shang, Fu; Du, Linfang; Taylor, Allen

    2016-03-01

    Failure of lens fiber cell denucleation (LFCD) is associated with congenital cataracts, but the pathobiology awaits elucidation. Recent work has suggested that mechanisms that direct the unidirectional process of LFCD are analogous to the cyclic processes associated with mitosis. We found that lens-specific mutations that elicit an unfolded-protein response (UPR) in vivo accumulate p27(Cdkn1b), show cyclin-dependent kinase (Cdk)-1 inhibition, retain their LFC nuclei, and are cataractous. Although a UPR was not detected in lenses expressing K6W-Ub, they also accumulated p27 and showed failed LFCD. Induction of a UPR in human lens epithelial cells (HLECs) also induced accumulation of p27 associated with decreased levels of S-phase kinase-associated protein (Skp)-2, a ubiquitin ligase that regulates mitosis. These cells also showed decreased lamin A/C phosphorylation and metaphase arrest. The suppression of lamin A/C phosphorylation and metaphase transition induced by the UPR was rescued by knockdown of p27. Taken together, these data indicate that accumulation of p27, whether related to the UPR or not, prevents the phosphorylation of lamin A/C and LFCD in maturing LFCs in vivo, as well as in dividing HLECs. The former leads to cataract and the latter to metaphase arrest. These results suggest that accumulation of p27 is a common mechanism underlying retention of LFC nuclei.

  17. 3. COPY OF A PHOTOGRAPH OF THE CATARACT MILLS, NEWBURGH, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. COPY OF A PHOTOGRAPH OF THE CATARACT MILLS, NEWBURGH, OHIO. Date unknown. Photographer: Berni Rich, Score Photographers, September 1986 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH

  18. Cataract surgery in a case of carotid cavernous fistula

    PubMed Central

    Nair, Akshay Gopinathan; Praveen, Smita Vittal; Noronha, Veena Olma

    2014-01-01

    A carotid-cavernous fistula (CCF) is an abnormal communication between the cavernous sinus and the carotid arterial system. The ocular manifestations include conjunctival chemosis, proptosis, globe displacement, raised intraocular pressure and optic neuropathy. Although management of CCF in these patients is necessary, the ophthalmologist may also have to treat other ocular morbidities such as cataract. Cataract surgery in patients with CCF may be associated with many possible complications, including suprachoroidal hemorrhage. We describe cataract extraction surgery in 60-year-old female with bilateral spontaneous low-flow CCF. She underwent phacoemulsification via a clear corneal route under topical anesthesia and had an uneventful postoperative phase and recovered successfully. Given the various possible ocular changes in CCF, one must proceed with an intraocular surgery with caution. In this communication, we wish to describe the surgical precautions and the possible pitfalls in cataract surgery in patients with CCF. PMID:25370401

  19. Treating Cataracts | NIH MedlinePlus the Magazine

    MedlinePlus

    ... her experience recently with NIH MedlinePlus magazine. What did you notice about your vision that told you ... how long it would take to recover. Where did you go for information about cataracts and surgery? ...

  20. Detection of TORCH pathogens in children with congenital cataracts

    PubMed Central

    Lu, Bin; Yang, Yabo

    2016-01-01

    The aim of the present study was to investigate the correlation between infection rates with TORCH pathogens including toxoplasma, rubella virus, cytomegalovirus, and herpes simplex virus (HSV) I and II and congenital cataracts. In total, the data from 69 children with congenital cataract treated at the Children's Hospital of the Zhejiang University School of Medicine between May 2006 and September 2013 were examined, including the complete serum test results for immunoglobulin (Ig)G and IgM that target TORCH pathogenic antibodies. These results were compared with the antibody levels of 5,914 children in a control group. Using SPSS 19.0 software, variance equation Levene tests, mean equation t tests, and completely randomized design of four tables χ2 tests were applied. The HSV II IgG positivity rates significantly differed between the cataract and control groups. These results suggested that HSV may be one of the pathogenic viruses that leads to congenital cataracts. PMID:27446337

  1. Diabetes mellitus and bilateral cataracts in a kitten.

    PubMed

    Thoresen, S I; Bjerkås, E; Aleksandersen, M; Peiffer, R L

    2002-06-01

    An 18-week-old male domestic long-hair kitten was presented with a history of polyuria and polydipsia for several weeks. The general condition was unremarkable, but the kitten was considerably smaller than expected for the age and showed cataracts in both eyes. Serum glucose concentrations were persistently elevated and based on clinical findings and an elevated serum fructosamine concentration, a diagnosis of diabetes mellitus was established. Diabetes mellitus is not commonly diagnosed in young kittens, nor are cataracts recognised as a frequent feature of this disease in cats. The cataracts progressed in spite of the insulin therapy and the kitten was euthanised 10 weeks after referral. Histopathological examination of the pancreas revealed few and small islets of Langerhans compared to the examination of pancreas from a healthy kitten of the same age. Histopathological changes in the eyes included cataracts affecting both cortex and nucleus.

  2. [Iritis following cataract operations. Historical retrospective with critical comments on a so-called "toxic lens" syndrome].

    PubMed

    Wenzel, M

    1990-06-01

    Postoperative inflammation is one of the oldest complications of cataract surgery. It was described by the Indian Susruta as early as 500 BC. Following the introduction of cataract extraction by Daviel in 1745, these operations attracted increasing interest. In 1786 de Wenzel distinguished two types of postoperative inflammation. In the dangerous type there was involvement of the entire eye and severe pain; in the benign type, which began in the first few postoperative days, the conjunctiva and lids were not involved, and even if hypopyon developed there was no severe pain. During the 19th century, the possible causes of the benign type of iritis were discussed, including infection, phacoanaphylaxis, trauma, toxicity of irrigation solutions etc. In the early days of implantation of intraocular lenses, from 1949 onward, postoperative inflammation was common. However, it was not until 1980 that the term "toxic lens syndrome" was introduced. The clinical descriptions do not differ much from other descriptions of benign iritis published during the last 200 years. Therefore, it does not seem that there is any great advantage to be gained by using this new term.

  3. Anterior chamber bacterial contamination in cataract surgery

    PubMed Central

    2014-01-01

    Background The incidence of postoperative endophthalmitis has reduced during last several years to <0.01%; however, its associated complications continue to be devastating. Several sources of infection, including contamination by air, solutions, surgical instruments, intraocular lens, and wound leakage have been identified. The objective of this study was to evaluate the surgical technique, antibiotics, and asepsis that are used to reduce the risk of infection during cataract surgery. Methods This was a transversal prospective study, in which 64 cataract surgeries were evaluated from 32 patients, with 1 month recovery time; and cultures from preoperative and postoperative aspirates were analyzed. Two groups were established based on whether preoperative antibiotics were given or not. The analysis employed descriptive statistics. Results Of the 32 patients whose aspirates were obtained, three (9.37%) and 10 (31.25%) yielded positive cultures preoperative and postoperatively respectively. Staphylococcus species was the most common contaminating bacteria. The isolation of Staphylococcus species may indicate its potential as exogenous contaminant at time of wound closure. The cultures obtained from patients using preoperative antibiotics were positive for S. aureus in 10% (n = 2) of cases, and positive in 8.33% (n = 1) of cases not using antibiotics. The mean transoperative time with positive growth was 67 ± 17.8 minutes, and with negative growth was 76.3 ± 25.2 minutes. Two surgical techniques were evaluated: phacoemulsification and extracapsular extraction. The extracapsular technique showed a contamination rate of 33.33% (n = 8) compared to phacoemulsification with a rate of 25% (n = 2) (RR = 1.33). Conclusions Common contaminating microorganisms included the Staphylococcus species, which was isolated from the eyelids and ocular annexes at the time of wound closure. The isolation of microorganisms postoperatively could have been

  4. Aberrations of sphero-cylindrical ophthalmic lenses.

    PubMed

    Malacara, Z; Malacara, D

    1990-04-01

    The authors have presented in two previous articles the graphic solutions resembling Tscherning ellipses, for spherical as well as for aspherical ophthalmic lenses free of astigmatism or power error. These solutions were exact, inasmuch as they were based on exact ray tracing, and not third-order theory as frequently done. In this paper sphero-cylindrical lenses are now analyzed, also using exact ray tracing. The functional dependence of the astigmatism and the power error for these lenses is described extensively.

  5. The Alvarez and Lohmann refractive lenses revisited.

    PubMed

    Barbero, Sergio

    2009-05-25

    Alvarez and Lohmann lenses are variable focus optical devices based on lateral shifts of two lenses with cubic-type surfaces. I analyzed the optical performance of these types of lenses computing the first order optical properties (applying wavefront refraction and propagation) without the restriction of the thin lens approximation, and the spot diagram using a ray tracing algorithm. I proposed an analytic and numerical method to select the most optimum coefficients and the specific configuration of these lenses. The results show that Lohmann composite lens is slightly superior to Alvarez one because the overall thickness and optical aberrations are smaller.

  6. Ion exchange tempering of glass ophthalmic lenses.

    PubMed

    Keeney, A H; Duerson, H L

    1975-08-01

    We performed low velocity drop-ball tests using 5/8-, 7/8-, and 1-inch diameter steel balls on ophthalmic crown glass lenses chemically tempered by the ion exchange process. Four representative dioptric strengths (+ 2.50 spherical, - 2.50 spherical, -2.50 cylindrical, and plano) were studied with the isolated lenses mounted, convex side up, on the American National Standards Institute Z80 test block. New ion exchange lenses exhibited a 100 to 350% greater capacity for attenuation of energy from low velocity, large size missiles than matched lenses of similar strength prepared by the conventional heat-treating and air-quenching process.

  7. Bilateral congenital cataracts in an infant with Klinefelter syndrome.

    PubMed

    Nur, Banu Güzel; Altıok-Clark, Özden; İlhan, Hatice Deniz; Sayar, Ersin; Yücel, İclal; Mıhçı, Ercan

    2014-01-01

    Congenital cataract is one of the most treatable causes of visual impairment and blindness during infancy, with an estimated prevalence of approximately 2.5:10,000 infants under the age of 1 year. Congenital cataract can be observed with certain chromosomal abnormalities, such as trisomies, deletions, translocations and Turner syndrome. In Klinefelter syndrome, however, ocular complications and cataract are not commonly encountered, so reports in the literature are very rare. In this manuscript, we present a 3-month-old male infant who had congenital cataracts. Chromosomal analysis revealed that his karyotype was 47,XXY. He did not show any of the main clinical signs of Klinefelter syndrome because of his very young age. To the best of our knowledge, our patient is only the second-ever case reported in the literature in which congenital cataracts have been found in an infant with a nonmosaic 47,XXY karyotype. The aim of the present report is to both describe the ocular abnormalities that can sometimes be found in Klinefelter syndrome and to emphasize the importance of performing a karyotype analysis in order to rule out chromosome abnormalities in patients with congenital cataracts.

  8. Cataract blindness--challenges for the 21st century.

    PubMed Central

    Brian, G.; Taylor, H.

    2001-01-01

    Cataract prevalence increases with age. As the world's population ages, cataract-induced visual dysfunction and blindness is on the increase. This is a significant global problem. The challenges are to prevent or delay cataract formation, and treat that which does occur. Genetic and environmental factors contribute to cataract formation. However, reducing ocular exposure to UV-B radiation and stopping smoking are the only interventions that can reduce factors that affect the risk of cataract. The cure for cataract is surgery, but this is not equally available to all, and the surgery which is available does not produce equal outcomes. Readily available surgical services capable of delivering good vision rehabilitation must be acceptable and accessible to all in need, no matter what their circumstances. To establish and sustain these services requires comprehensive strategies that go beyond a narrow focus on surgical technique. There must be changes in government priorities, population education, and an integrated approach to surgical and management training. This approach must include supply of start-up capital equipment, establishment of surgical audit, resupply of consumables, and cost-recovery mechanisms. Considerable innovation is required. Nowhere is this more evident than in the pursuit of secure funding for ongoing services. PMID:11285671

  9. Ultraviolet or blue-filtering intraocular lenses: what is the evidence?

    PubMed Central

    Downes, S M

    2016-01-01

    Cataract surgery was revolutionised by the introduction of modern intraocular lenses in the late 1940's. By the late 1960's to 1970's evidence had emerged that short-wavelength light caused phototoxicity at the retina and retinal pigment epithelium. By the early 1980's ultraviolet filters had been incorporated into intraocular lenses. This caused intense controversy, as there was concern that the UV-filtering chromophore might leach out into the eye causing toxicity. With the arrival of blue-filtering intraocular lenses (BFIOLs) in 1990's, a further debate was ignited as to their safety and potential disadvantages. Selecting the optimal performing intraocular lens to obtain the best visual performance with the fewest potential drawbacks has become complex and challenging for cataract surgeons and their patients with the wide choice of lenses available. Choosing a personalised lens to address astigmatism, presbyopia, spherical aberration, chromatic aberration, and potentially to shield the retina from short-wavelength light is now possible. The potential benefits and possible side effects of these different innovations emphasise the importance of assessing the evidence for their clinical utility, allowing the surgeon and the patient to weigh-up the risk benefit ratio and make an informed decision. The BFIOLs were developed to reduce cyanopsia, address chromatic aberration, and improve contrast sensitivity in different lighting conditions, as well as to prevent short-wavelength light reaching the retina thus potentially reducing the risk of developing age-related macular degeneration. Further design development of the BFIOLs was to mimic the natural crystalline lens absorption and transmittance properties in adulthood. Multiple publications have reported on the potential benefits and pitfalls of implanting a blue-filtering lens. The potential disadvantages raised in the literature over the last 25 years since their introduction, regarding compromise of visual

  10. Methylglyoxal induces endoplasmic reticulum stress and DNA demethylation in the Keap1 promoter of human lens epithelial cells and age-related cataracts.

    PubMed

    Palsamy, Periyasamy; Bidasee, Keshore R; Ayaki, Masahiko; Augusteyn, Robert C; Chan, Jefferson Y; Shinohara, Toshimichi

    2014-07-01

    Age-related cataracts are a leading cause of blindness. Previously, we have demonstrated the association of the unfolded protein response with various cataractogenic stressors. However, DNA methylation alterations leading to suppression of lenticular antioxidant protection remains unclear. Here, we report the methylglyoxal-mediated sequential events responsible for Keap1 promoter DNA demethylation in human lens epithelial cells, because Keap1 is a negative regulatory protein that regulates the Nrf2 antioxidant protein. Methylglyoxal induces endoplasmic reticulum stress and activates the unfolded protein response leading to overproduction of reactive oxygen species before human lens epithelial cell death. Methylglyoxal also suppresses Nrf2 and DNA methyltransferases but activates the DNA demethylation pathway enzyme TET1. Bisulfite genomic DNA sequencing confirms the methylglyoxal-mediated Keap1 promoter DNA demethylation leading to overexpression of Keap1 mRNA and protein. Similarly, bisulfite genomic DNA sequencing shows that human clear lenses (n = 15) slowly lose 5-methylcytosine in the Keap1 promoter throughout life, at a rate of 1% per year. By contrast, diabetic cataractous lenses (n = 21) lose an average of 90% of the 5-methylcytosine regardless of age. Overexpressed Keap1 protein is responsible for decreasing Nrf2 by proteasomal degradation, thereby suppressing Nrf2-dependent stress protection. This study demonstrates for the first time the associations of unfolded protein response activation, Nrf2-dependent antioxidant system failure, and loss of Keap1 promoter methylation because of altered active and passive DNA demethylation pathway enzymes in human lens epithelial cells by methylglyoxal. As an outcome, the cellular redox balance is altered toward lens oxidation and cataract formation.

  11. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced

    NASA Astrophysics Data System (ADS)

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per

    2015-01-01

    The damage mechanism for near-infrared radiation (IRR) induced cataract is unclear. Both a photochemical and a thermal mechanism were suggested. The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity. Groups of 20 rats were unilaterally exposed to 96-W/cm2 IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, and 344 kJ/cm2, respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was quantitatively measured. The average maximum temperature increases for exposure times of 10, 18, 33, and 60 min were expressed as 7.0±1.1, 6.8±1.1, 7.6±1.3, and 7.4±1.1°C [CI (0.95)] at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not-exposed eyes was 0.00±0.02, 0.01±0.03, -0.01±0.02, and -0.01±0.03 transformed equivalent diazepam concentration (tEDC), respectively, and no apparent morphological changes in the lens were observed. An exposure to 96-W/cm2 1090-nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm2 does not induce cataract if the temperature rise at the limbus is <8°C. This is consistent with a thermal damage mechanism for IRR-induced cataract.

  12. Temperature-controlled in vivo ocular exposure to 1090-nm radiation suggests that near-infrared radiation cataract is thermally induced.

    PubMed

    Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per

    2015-01-01

    The damage mechanism for near-infrared radiation (IRR) induced cataract is unclear. Both a photochemical and a thermal mechanism were suggested. The current paper aims to elucidate a photochemical effect based on investigation of irradiance-exposure time reciprocity. Groups of 20 rats were unilaterally exposed to 96-W/cm(2) IRR at 1090 nm within the dilated pupil accumulating 57, 103, 198, and 344 kJ/cm(2), respectively. Temperature was recorded at the limbus of the exposed eye. Seven days after exposure, the lenses were macroscopically imaged and light scattering was quantitatively measured. The average maximum temperature increases for exposure times of 10, 18, 33, and 60 min were expressed as 7.0 ± 1.1, 6.8 ± 1.1, 7.6 ± 1.3, and 7.4 ± 1.1 °C [CI (0.95)] at the limbus of the exposed eye. The difference of light scattering in the lenses between exposed and contralateral not-exposed eyes was 0.00 ± 0.02, 0.01 ± 0.03, -0.01 ± 0.02, and -0.01 ± 0.03 transformed equivalent diazepam concentration (tEDC), respectively, and no apparent morphological changes in the lens were observed. An exposure to 96-W/cm(2) 1090-nm IRR projected on the cornea within the dilated pupil accumulating radiant exposures up to 344 kJ/cm(2) does not induce cataract if the temperature rise at the limbus is <8 °C. This is consistent with a thermal damage mechanism for IRR-induced cataract.

  13. The Melaka Hospital cataract complications study analysis of 12,992 eyes

    PubMed Central

    Thevi, Thanigasalam; Maizura, Zin; Abas, Adinegara Lutfi

    2017-01-01

    Introduction: As in all surgeries, complications during cataract surgery are unavoidable and cause distress to the surgeon and the patient. This study was conducted to know the factors contributing to complications in our settings, to be able to counsel patients about complications and outcomes and to reduce litigations. Materials and Methods: The secondary data analysis was conducted using the National Eye Database from 2007 to 2014. Demographic features, ocular comorbidities, technique of surgery, grade of surgeons, types of intraoperative complications, and reasons for not obtaining good visual acuity following intraoperative complications were studied. Statistics was done using Statistical Package for Social Sciences version 20. Results: Out of 12,992 eyes, 6.1% had intraoperative complications. The highest rate of complications was when more trainees (medical officers [MOs] and gazetting specialists) operated. Posterior capsule rupture (PCR) was the most common complication followed by vitreous loss and zonular dehiscence. Those aged below 40 years had more complications (P < 0.05), and females had more complications. Ethnicity did not affect complications. Pseudoexfoliation was the only comorbidity causing complications (P < 0.05). Phacolytic lenses had 8.118 times the odds of getting intraoperative complications. MOs and gazetting specialists got more complications. Good outcomes were obtained in cases without complications and those operated by specialists. High astigmatism was the main reason for poorer outcomes. Conclusion: Intraoperative complications were caused mostly by less experienced doctors and had poorer outcomes. Age below 40 years, females, the presence of pseudoexfoliation and phacolytic lenses had more complications. PCR was the most common complication. PMID:28300736

  14. Overview of the current attempts toward the medical treatment of cataract

    SciTech Connect

    Kador, P.F.

    1983-04-01

    A variety of agents are currently available that claim to either prevent, delay, or reverse cataracts associated with aging (senile cataracts), radiation, or diabetes and galactosemia (sugar cataracts). Senile cataract therapy includes formulation containing inorganic salts, nutritional supplements, natural product extracts, sulfhydryl, and sulfonic acid containing compounds and miscellaneous redox and nonsteroidal anti-inflammatory compounds. Agents associated with the treatment of radiation cataracts include antioxidants and free radial scavengers. Aldose reductase inhibitors have been effective in the prevention of sugar cataracts. A summary of these agents and their potential ocular effects are presented.

  15. Regulatory effect of chrysin on expression of lenticular calcium transporters, calpains, and apoptotic-cascade components in selenite-induced cataract

    PubMed Central

    Sundararajan, Mahalingam; Thomas, Philip A.; Teresa, P. Archana; Anbukkarasi, Muniyandi

    2016-01-01

    Purpose Selenite-induced cataract is associated with oxidative stress, loss of calcium homeostasis, activation of calpain enzymes, and apoptotic cell death in the lens. An evaluation of naturally occurring antioxidants that also restrict calcium influx into the lens and calpain activation and thus prevent lenticular cell death may lead to the development of safe and effective anticataractogenic drugs. This study focuses on a naturally occurring flavone, chrysin, and its efficacy in preventing cataractogenic changes in in vitro cultured Wistar rat lenses. Methods Lenses from Wistar rats incubated for 24 h at 37 °C in Dulbecco’s modified Eagle’s medium (DMEM) were categorized into four main groups: Group I (control, incubated in DMEM alone); Group II (selenite-challenged and untreated, incubated in DMEM that contained 100 µM/ml of sodium selenite only); Group III (selenite-challenged and chrysin-treated, incubated in DMEM that contained sodium selenite [100 µM/ml of DMEM] and chrysin [200 µM/ml of DMEM]); and Group IV (chrysin-treated, incubated in DMEM that contained chrysin [200 µM/ml of DMEM] only). The Group III (selenite-challenged and chrysin-treated) lenses were further categorized into five sub-groups: Group IIIa (incubated for 24 h in DMEM that contained sodium selenite and chrysin added simultaneously), Group IIIb (first incubated for 2 h in DMEM that contained chrysin only and then for up to 24 h in fresh DMEM that contained sodium selenite only), Group IIIc (first incubated for 30 min in DMEM that contained sodium selenite only and subsequently for up to 24 h in DMEM that contained chrysin only), and Groups IIId and IIIe (first incubated for 1 h and 2 h, respectively, in DMEM that contained sodium selenite only and subsequently for up to 24 h in DMEM that contained chrysin only). Results Gross morphological assessment revealed dense opacification (Grade +++) in the selenite-challenged, untreated lenses (Group II); however, seven of the eight

  16. Evaluating the Biostability of Yellow and Clear Intraocular Lenses with a System Simulating Natural Intraocular Environment

    PubMed Central

    Hayashi, Rijo; Hayashi, Shimmin; Arai, Kiyomi; Yoshida, Shinichirou; Chikuda, Makoto; Machida, Shigeki

    2016-01-01

    Purpose Blue light–filtering intraocular lenses (IOLs) are thought to protect the retina from blue light damage after cataract surgery, and the implantation of yellow-tinted IOLs has been commonly used in cataract surgery. To our knowledge, this is the first investigation measuring the long-term biostability of yellow-tinted IOLs using an in vitro system simulating natural intraocular environment. Methods Six hydrophobic acrylic IOLs, three clear IOLs, and three yellow-tinted IOLs were included in the study. Each yellow-tinted IOL was a matching counterpart of a clear IOL, with the only difference being the lens color. The IOLs were kept in conditions replicating the intraocular environment using a perfusion culture system for 7 months. Resolution, light transmittance rate, and the modulation transfer function (MTF) were measured before and after culturing. Surface roughness of the anterior and posterior surfaces was also measured. Results After culturing for 7 months, there were no changes in the resolution, the light transmittance rate, and MTF. The surface roughness of the anterior and posterior surfaces increased after culturing; however, this increase was clinically insignificant. There were no differences in surface roughness between the clear and yellow-tinted IOLs, either before or after culturing. Conclusions A novel in vitro system replicating intraocular environment was used to investigate the biostability of yellow-tinted IOLs. The surface roughness showed no clinically significant increase after culturing for 7 months. Translational Relevance This system is useful for evaluating the biostability of IOLs. PMID:27933221

  17. Severe Adverse Events Following Cataract Surgery Among Medicare Beneficiaries

    PubMed Central

    Stein, Joshua D.; Grossman, Daniel S.; Mundy, Kevin M.; Sugar, Alan; Sloan, Frank A.

    2012-01-01

    Purpose To determine rates and risk factors associated with severe post-operative complications following cataract surgery and whether they have been changing over the past decade. Design Retrospective longitudinal cohort study Participants 221,594 Medicare beneficiaries who underwent cataract surgery during 1994–2006. Methods Beneficiaries were stratified into 3 cohorts, those who underwent initial cataract surgery during 1994-5, 1999–2000, or 2005-6. One year rates of post-operative severe adverse events (endophthalmitis, suprachoroidal hemorrhage, retinal detachment) were determined for each cohort. Cox regression analyses determined the hazard of developing severe adverse events for each cohort with adjustment for demographic factors, ocular and medical conditions, and surgeon case-mix. Main Outcome Measures Time period rates of development of severe post-operative adverse events. Results Among the 221,594 individuals who underwent cataract surgery, 0.5% (1,086) had at least one severe post-operative complication. After adjustment for confounders, individuals who underwent cataract surgery during 1994-5 had a 21% increased hazard of being diagnosed with a severe post-operative complication (Hazard Ratio (HR): 1.21; [95% Confidence Interval (CI): 1.05–1.41]) relative to individuals who underwent cataract surgery during 2005-6. Those who underwent cataract surgery during 1999–2000 had a 20% increased hazard of experiencing a severe complication (HR: 1.20 [95% CI: 1.04–1.39]) relative to the 2005-6 cohort. Risk factors associated with severe adverse events include a prior diagnosis of proliferative diabetic retinopathy (HR: 1.62 [95% CI: 1.07–2.45]) and cataract surgery combined with another intraocular surgical procedure on the same day (HR: 2.51 [95% CI: 2.07–3.04]). Individuals receiving surgery by surgeons with the case-mix least prone to developing a severe adverse event (HR: 0.52 [95% CI: 0.44–0.62]) had a 48% reduced hazard of a severe

  18. Ultraviolet (UV) transmittance characteristics of daily disposable and silicone hydrogel contact lenses.

    PubMed

    Moore, Linda; Ferreira, Jannie T

    2006-07-01

    The ultraviolet (UV) transmittance spectra of daily wear hydrogel and disposable silicone hydrogel contact lenses were measured. Average transmittance percentages were calculated for each lens for the entire UV spectrum and individually for the UVC, UVB and UVA portions of the spectrum. The significance of the differences in transmittance spectra obtained for the lenses was analysed using a one-way ANOVA planned comparisons test (alpha=0.05). The transmittance data were then used to calculate a UV protection factor (PF) for each contact lens brand tested. The PFs for 1-DAY ACUVUE MOIST (6.22), ACUVUE ADVANCE (10.02) and ACUVUE OASYS (11.96) contact lenses show that these contact lenses have superior UV-blocking capabilities. The PFs for Focus DAILIES (1.79), SofLens 1-day disposables (1.72), NIGHT & DAY (1.84), O2 Optix (1.99) and Purevision (2.62) show that these contact lenses posses more modest UV-blocking characteristics. This paper reviews the importance of protection of the anterior ocular surface from UV damage and quantifies the protection afforded by selected commercially available disposable contact lenses.

  19. The impact of cataract surgery on vision-related quality of life for bilateral cataract patients in Ho Chi Minh City, Vietnam: a prospective study

    PubMed Central

    2014-01-01

    Background To determine the impact of cataract surgery on vision-related quality of life (VRQOL) and examine the association between objective visual measures and change in VRQOL after surgery among bilateral cataract patients in Ho Chi Minh City, Vietnam. Methods A cohort of older patients with bilateral cataract was assessed one week before and one to three months after first eye or both eye cataract surgery. Visual measures including visual acuity, contrast sensitivity and stereopsis were obtained. Vision-related quality of life was assessed using the NEI VFQ-25. Descriptive analyses and a generalized linear estimating equation (GEE) analysis were undertaken to measure change in VRQOL after surgery. Results Four hundred and thirteen patients were assessed before cataract surgery and 247 completed the follow-up assessment one to three months after first or both eye cataract surgery. Overall, VRQOL significantly improved after cataract surgery (p < 0.001) particularly after both eye surgeries. Binocular contrast sensitivity (p < 0.001) and stereopsis (p < 0.001) were also associated with change in VRQOL after cataract surgery. Visual acuity was not associated with VRQOL. Conclusions Cataract surgery significantly improved VRQOL among bilateral cataract patients in Vietnam. Contrast sensitivity as well as stereopsis, rather than visual acuity significantly affected VRQOL after cataract surgery. PMID:24499481

  20. Gravitational Lensing Extends SETI Range

    NASA Astrophysics Data System (ADS)

    Factor, Richard

    Microwave SETI (The Search for Extraterrestrial Intelligence) focuses on two primary strategies, the "Targeted Search" and the "All-Sky Survey." Although the goal of both strategies is the unequivocal discovery of a signal transmitted by intelligent species outside our solar system, they pursue the strategies in very different manners and have vastly different requirements. This chapter introduces Gravitational Lensing SETI (GL-SETI), a third strategy. Its goal is the unequivocal discovery of an extraterrestrial signal, with equipment and data processing requirements that are substantially different from the commonly-used strategies. This strategy is particularly suitable for use with smaller radio telescopes and has budgetary requirements suitable for individual researchers.

  1. Contact Lenses Wettability In Vitro: Effect of Surface-Active Ingredients

    PubMed Central

    Lin, Meng C.; Svitova, Tatyana F.

    2010-01-01

    Purpose To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses and their influence on the lens surface wettability in vitro. Methods Surface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel (SiH) soft contact lenses (SCLs) were evaluated in a dynamic-cycling regime using a modified captive-bubble tensiometer-goniometer. Measurements were performed immediately after removal from blister packs, and after soaking in a glass vial filled with a surfactant-free solution, which was replaced daily for one week. Lens surface wettability was expressed as adhesion energy (AE) according to Young’s equation. Results STs of all blister pack solutions were lower than the reference ST of pure water (72.5 mN/m), indicating the presence of surfactants. When lenses were depleted of surfactants by soaking, the STs of all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12° ± 5° and were not affected by the presence of surfactants. For most of the conventional lenses, the surface wettability was largely dependent on surfactants, and reduced significantly after surfactant depletion. In contrast, most SiH lenses exhibited stable and self-sustained surface wettability in vitro. Conclusions The manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees. PMID:20400924

  2. Offset lenses add versatility to phototypesetting machine

    NASA Technical Reports Server (NTRS)

    James, A. M.

    1966-01-01

    Offset lenses facilitate the composition of inputs of other than straight baseline characters on the Photon phototypesetting machine. A number of lenses in the turret are mounted in an offset pattern that causes characters projected through them to fall on the photographic paper in the magazine above and below the baseline.

  3. BAYESIAN INFERENCE OF CMB GRAVITATIONAL LENSING

    SciTech Connect

    Anderes, Ethan; Wandelt, Benjamin D.; Lavaux, Guilhem

    2015-08-01

    The Planck satellite, along with several ground-based telescopes, has mapped the cosmic microwave background (CMB) at sufficient resolution and signal-to-noise so as to allow a detection of the subtle distortions due to the gravitational influence of the intervening matter distribution. A natural modeling approach is to write a Bayesian hierarchical model for the lensed CMB in terms of the unlensed CMB and the lensing potential. So far there has been no feasible algorithm for inferring the posterior distribution of the lensing potential from the lensed CMB map. We propose a solution that allows efficient Markov Chain Monte Carlo sampling from the joint posterior of the lensing potential and the unlensed CMB map using the Hamiltonian Monte Carlo technique. The main conceptual step in the solution is a re-parameterization of CMB lensing in terms of the lensed CMB and the “inverse lensing” potential. We demonstrate a fast implementation on simulated data, including noise and a sky cut, that uses a further acceleration based on a very mild approximation of the inverse lensing potential. We find that the resulting Markov Chain has short correlation lengths and excellent convergence properties, making it promising for applications to high-resolution CMB data sets in the future.

  4. Lenses and Perception: Investigations with Light

    ERIC Educational Resources Information Center

    Akcay, Hakan

    2005-01-01

    The main goals of these activities are to help students learn how a convex lens can serve as a magnifying lens and how light travels and creates images. These explorations will introduce middle school students to different types of lenses and how they work. Students will observe and describe how lenses bend light that passes through them and how…

  5. Phakic Intraocular Lenses and their Special Indications

    PubMed Central

    Pineda, Roberto; Chauhan, Tulika

    2016-01-01

    Phakic intraocular lenses revolutionize refractive surgery and continue to serve as an excellent option for vision correction in patients who are not ideal candidates for laser vision correction. This article will review special indications of phakic intraocular lenses in the clinical practice. PMID:27994811

  6. Galactic Internet made possible by star gravitational lensing

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2013-02-01

    In this paper we study how to create a radio bridge between the Sun and any other star made up by both the gravitational lenses of the Sun and that star. The alignment for this radio bridge to work is very strict, but the power-saving is enormous, due to the huge contributions of the two stars' lenses to the overall antenna gain of the system. In particular, we study in detail: The Sun-Alpha Centauri A radio bridge. The Sun-Barnard's star radio bridge. The Sun-Sirius A radio bridge. The radio bridge between the Sun and any Sun-like star located in the Galactic Bulge. The radio bridge between the Sun and a similar Sun-like star located inside the Andromeda galaxy (M31). Finally, we find the information channel capacity for each of the above radio bridges, putting thus a physical constraint to the maximum information transfer that will be enabled even by exploiting the stars as gravitational lenses. The conclusion is that a Galactic Internet is indeed physically possible. May be the Galactic Internet already is in existence, and was created long ago by civilizations more advanced than ours. But the potential for creating such a system has only recently been realized by Humans.

  7. Weak gravitational lensing theory and data analysis

    NASA Astrophysics Data System (ADS)

    Hirata, Christopher Michael

    2005-12-01

    This thesis describes methodology for analysis of weak gravitational lensing data. Weak lensing, i.e. the perturbative distortion of the images of distant objects by the gravitational deflection of light, is an important tool for understanding the distribution of matter in the universe. This is interesting because a number of extentions to the standard cosmological model, including dynamical dark energy and neutrino masses, affect the growth of structure and hence may be detectable using weak lensing. Studies of weak lensing are also motivated by lensing's ability to affect the modes in the cosmic microwave background (CMB) polarization that are sensitive to primordial gravitational waves. Both lensing of galaxies and lensing of the CMB are considered here. The section devoted to galaxies is principally concerned with measuring the lensing-induced shape distortions from galaxy images in the Sloan Digital Sky Survey (SDSS), although the methodology will be applicable to future projects. We investigate in detail the problem of separating lensing from other shape distortions such as those induced by the atmosphere, the telescope, and photon Poisson noise. Since the intrinsic shapes of observed galaxies are not known, weak lensing observations always attempt some sort of statistical averaging over galaxies that presumably have independent orientations. We investigate the extent to which this process "averages down" the intrinsic shapes and identify a new type of bias that can affect the weak lensing power spectrum. Selection biases are considered and their importance in SDSS estimated. We present some recent cosmological results using the SDSS analysis, including new upper limits on the neutrino mass. Lensing of the CMB has not yet been detected, nevertheless several experiments are being built that should have the sensitivity to see it. The statistical problem of extracting lensing information from the distortion of the CMB anisotropy is considered, and in the case of

  8. [Use of rigid gas permeable contact lenses].

    PubMed

    Habela, M

    1992-01-01

    By application of contact lenses destined for a extended wearing, for preservation of a normal structure and metabolism of the cornea a considerable permeability of the contact lens for oxygen is necessary (Dk/L 75-80). The actually most popular in the world soft contact lenses have no such parameters. The application of rigid lenses produced from materials of high permeability for oxygen enables the extended wearing without substantial disturbances of the corneal metabolism. The paper presents a new generation of fluoro-silicone acrylates used for the production of contact lenses permeable for oxygen. Discussed are the problems connected with the adjusting of these lenses, their tolerance and influence on the corneal metabolism.

  9. The effect of lens aging and cataract surgery on circadian rhythm

    PubMed Central

    Yan, Shen-Shen; Wang, Wei

    2016-01-01

    Many organisms have evolved an approximately 24-hour circadian rhythm that allows them to achieve internal physiological homeostasis with external environment. Suprachiasmatic nucleus (SCN) is the central pacemaker of circadian rhythm, and its activity is entrained to the external light-dark cycle. The SCN controls circadian rhythm through regulating the synthesis of melatonin by pineal gland via a multisynaptic pathway. Light, especially short-wavelength blue light, is the most potent environmental time cue in circadian photoentrainment. Recently, the discovery of a novel type of retinal photoreceptors, intrinsically photosensitive retinal ganglion cells, sheds light on the mechanism of circadian photoentrainment and raises concerns about the effect of ocular diseases on circadian system. With age, light transmittance is significantly decreased due to the aging of crystalline lens, thus possibly resulting in progressive loss of circadian photoreception. In the current review, we summarize the circadian physiology, highlight the important role of light in circadian rhythm regulation, discuss about the correlation between age-related cataract and sleep disorders, and compare the effect of blue light- filtering intraocular lenses (IOLs) and ultraviolet only filtering IOLs on circadian rhythm. PMID:27500118

  10. Switching to instant black coffee modulates sodium selenite-induced cataract in rats

    PubMed Central

    El Okda, E. A.; Mohamed, M. M.; Shaheed, E. B.; Abdel-Moemin, A. R.

    2016-01-01

    The influence of daily consumption of some common beverages on the development of cataract in rats was investigated. Total phenol content was determined in the beverages and an oral standardized dose of total phenols from each beverage was given to the treated rats. Weaned male albino rats were used and divided into five groups (n=7). Rats were fed Ain 93G and administered the standardized dose of instant coffee, black tea and hibiscus beverages for 30 days. On day 14 all rats were injected with a single dose of sodium selenite (Na2SeO3) 15 µmol/kg bodyweight, except the control groups NC (negative control, did not receive Na2SeO3) and PC (positive control, was already injected on day 1 of the study). The rats were continued on Ain 93G and the standardized dose for another 16 days. Positive control rats were used. Total phenols were 210, 40, and 44 mg/g dry weight gallic acid equivalent in black coffee, black tea, and hibiscus, respectively. Decreased levels (statistically significant P<0.05) of malondialdehyde, total nitric oxide, Ca-ATPase, tumor necrosis factor-α, interleukin-1β, superoxide dismutase, and conversely, increased levels (statistically significant P<0.05) of total protein, reduced glutathione, catalase were found in the lenses of the coffee group compared to PC. There are co-phenol substances in the instant black coffee that promoted coffee to be the most effective beverage. PMID:27158251

  11. Switching to instant black coffee modulates sodium selenite-induced cataract in rats.

    PubMed

    El Okda, E A; Mohamed, M M; Shaheed, E B; Abdel-Moemin, A R

    2016-01-01

    The influence of daily consumption of some common beverages on the development of cataract in rats was investigated. Total phenol content was determined in the beverages and an oral standardized dose of total phenols from each beverage was given to the treated rats. Weaned male albino rats were used and divided into five groups (n=7). Rats were fed Ain 93G and administered the standardized dose of instant coffee, black tea and hibiscus beverages for 30 days. On day 14 all rats were injected with a single dose of sodium selenite (Na2SeO3) 15 µmol/kg bodyweight, except the control groups NC (negative control, did not receive Na2SeO3) and PC (positive control, was already injected on day 1 of the study). The rats were continued on Ain 93G and the standardized dose for another 16 days. Positive control rats were used. Total phenols were 210, 40, and 44 mg/g dry weight gallic acid equivalent in black coffee, black tea, and hibiscus, respectively. Decreased levels (statistically significant P<0.05) of malondialdehyde, total nitric oxide, Ca-ATPase, tumor necrosis factor-α, interleukin-1β, superoxide dismutase, and conversely, increased levels (statistically significant P<0.05) of total protein, reduced glutathione, catalase were found in the lenses of the coffee group compared to PC. There are co-phenol substances in the instant black coffee that promoted coffee to be the most effective beverage.

  12. The effect of lens aging and cataract surgery on circadian rhythm.

    PubMed

    Yan, Shen-Shen; Wang, Wei

    2016-01-01

    Many organisms have evolved an approximately 24-hour circadian rhythm that allows them to achieve internal physiological homeostasis with external environment. Suprachiasmatic nucleus (SCN) is the central pacemaker of circadian rhythm, and its activity is entrained to the external light-dark cycle. The SCN controls circadian rhythm through regulating the synthesis of melatonin by pineal gland via a multisynaptic pathway. Light, especially short-wavelength blue light, is the most potent environmental time cue in circadian photoentrainment. Recently, the discovery of a novel type of retinal photoreceptors, intrinsically photosensitive retinal ganglion cells, sheds light on the mechanism of circadian photoentrainment and raises concerns about the effect of ocular diseases on circadian system. With age, light transmittance is significantly decreased due to the aging of crystalline lens, thus possibly resulting in progressive loss of circadian photoreception. In the current review, we summarize the circadian physiology, highlight the important role of light in circadian rhythm regulation, discuss about the correlation between age-related cataract and sleep disorders, and compare the effect of blue light- filtering intraocular lenses (IOLs) and ultraviolet only filtering IOLs on circadian rhythm.

  13. Syringic Acid Extracted from Herba dendrobii Prevents Diabetic Cataract Pathogenesis by Inhibiting Aldose Reductase Activity

    PubMed Central

    Wei, Xiaoyong; Chen, Dan; Yi, Yanchun; Qi, Hui; Gao, Xinxin; Fang, Hua; Gu, Qiong; Wang, Ling; Gu, Lianquan

    2012-01-01

    Objective. Effects of Syringic acid (SA) extracted from dendrobii on diabetic cataract (DC) pathogenesis were explored. Methods. Both in vitro and in vivo DC lens models were established using D-gal, and proliferation of HLEC exposed to SA was determined by MMT assay. After 60-day treatment with SA, rat lens transparency was observed by anatomical microscopy using a slit lamp. SA protein targets were extracted and isolated using 2-DE and MALDI TOF/TOF. AR gene expression was investigated using qRT-PCR. Interaction sites and binding characteristics were determined by molecule-docking techniques and dynamic models. Results. Targeting AR, SA provided protection from D-gal-induced damage by consistently maintaining lens transparency and delaying lens turbidity development. Inhibition of AR gene expression by SA was confirmed by qRT-PCR. IC50 of SA for inhibition of AR activity was 213.17 μg/mL. AR-SA binding sites were Trp111, His110, Tyr48, Trp20, Trp79, Leu300, and Phe122. The main binding modes involved hydrophobic interactions and hydrogen bonding. The stoichiometric ratio of non-covalent bonding between SA and AR was 1.0 to 13.3. Conclusion. SA acts to prevent DC in rat lenses by inhibiting AR activity and gene expression, which has potential to be developed into a novel drug for therapeutic management of DC. PMID:23365598

  14. Development of cataract and corneal opacity in mice due to radon exposure

    NASA Astrophysics Data System (ADS)

    Abdelkawi, S. A.; Abo-Elmagd, M.; Soliman, H. A.

    This work investigates the radiation damage on the eye of albino mice exposed to effective radon doses ranging from 20.92 to 83.68 mSv. These doses were taken over 2-8 weeks using a radon chamber constructed by the National Institute for Standard (Egypt). The guidance on the quality assurance program for radon measurements was followed. Therefore, the estimated doses received by the laboratory animals meet the requirements of national standardE The refractive index(RI) and protein concentration were measured for soluble proteins of both corneas and lenses. In addition, the sodium dodecyle sulfate polyacrylamide gel electrophoresis (SDSPAGE) technique was used. The results show increasing of the RI of both cornea and lens proteins and decreasing in total protein concentration of exposed animals. These results were accompanied with changes in the SDSPAGE profile for both cornea and lens. Therefore, radon exposure produces substantial hazards to the cornea and lens of experimental animals and has a crucial role in the development of cataract and corneal opacity.

  15. The effect of simulated cataract light scatter on retinal vessel oximetry.

    PubMed

    Patel, Sunni R; Hudson, Chris; Flanagan, John G; Heitmar, Rebekka

    2013-11-01

    To assess the impact of light scatter, similar to that introduced by cataract on retinal vessel blood oxygen saturation measurements using poly-bead solutions of varying concentrations. Eight healthy, young, non-smoking individuals were enrolled for this study. All subjects underwent digital blood pressure measurements, assessment of non-contact intraocular pressure, pupil dilation and retinal vessel oximetry using dual wavelength photography (Oximetry Module, Imedos Systems, Germany). To simulate light scatter, cells comprising a plastic collar and two plano lenses were filled with solutions of differing concentrations (0.001, 0.002 and 0.004%) of polystyrene microspheres (Polysciences Inc., USA). The adopted light scatter model showed an artifactual increase in venous optical density ratio (p = 0.036), with the 0.004% condition producing significantly higher venous optical density ratio values when compared to images without a cell in place. Spectrophotometric analysis, and thus retinal vessel oximetry of the retinal vessels, is altered by artificial light scatter.

  16. The Search for Lensed Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-01-01

    Type Ia supernovae that have multiple images due to gravitational lensing can provide us with a wealth of information both about the supernovae themselves and about our surrounding universe. But how can we find these rare explosions?Clues from Multiple ImagesWhen light from a distant object passes by a massive foreground galaxy, the galaxys strong gravitational pull can bend the light, distorting our view of the backgroundobject. In severe cases, this process can cause multiple images of the distant object to appear in the foreground lensing galaxy.An illustration of gravitational lensing. Light from the distant supernova is bent as it passes through a giant elliptical galaxy in the foreground, causing multiple images of the supernova to appear to be hosted by the elliptical galaxy. [Adapted from image by NASA/ESA/A. Feild (STScI)]Observations of multiply-imaged Type Ia supernovae (explosions that occur when white dwarfs in binary systems exceed their maximum allowed mass) could answer a number of astronomical questions. Because Type Ia supernovae are standard candles, distant, lensed Type Ia supernovae can be used to extend the Hubble diagram to high redshifts. Furthermore, the lensing time delays from the multiply-imaged explosion can provide high-precision constraints on cosmological parameters.The catch? So far, weve only found one multiply-imaged Type Ia supernova: iPTF16geu, discovered late last year. Were going to need a lot more of them to develop a useful sample! So how do we identify themutiply-imaged Type Ias among the many billions of fleeting events discovered in current and future surveys of transients?Searching for AnomaliesAbsolute magnitudes for Type Ia supernovae in elliptical galaxies. None are expected to be above -20 in the B band, so if we calculate a magnitude for a Type Ia supernova thats larger than this, its probably not hosted by the galaxy we think it is! [Goldstein Nugent 2017]Two scientists from University of California, Berkeley and

  17. Excessive hydrogen peroxide enhances the attachment of amyloid β1-42 in the lens epithelium of UPL rats, a hereditary model for cataracts.

    PubMed

    Nagai, Noriaki; Ito, Yoshimasa

    2014-01-06

    Several studies have reported that hydrogen peroxide (H2O2) is related to the toxicity of amyloid β (Aβ), and that the accumulation of Aβ in the lenses of humans causes lens opacification. In this study, we investigate the accumulation of Aβ1-42 in the lenses of UPL rats, which then leads to lens opacification. In addition, we demonstrate the effect of disulfiram eye drops (DSF), a potent radical scavenger, on Aβ1-42 accumulation in the lenses of UPL rats. The H2O2 levels in 46- to 60-day-old UPL rat lenses are significantly higher than in normal rats, and the Aβ1-42 levels in 53- and 60-day-old UPL rats are also increased only in lens epithelium containing capsules (capsule-epithelium), not in the lens cortex and nucleus. However, no increases in amyloid precursor protein (APP), β- or γ-secretase mRNA were observed in lenses of the corresponding ages. It has been thought that Aβ1-42 that accumulates in the lenses of UPL rats is actually produced in another tissue containing neuronal cells, such as brain or retina. Aβ1-42 levels in the brain and retina rise with aging, and the levels of APP, β- and γ-secretase mRNA in the retinas of 53-day-old UPL rats with opaque lenses are significantly higher than in 25-day-old UPL rats with transparent lenses. In contrast to the results in retinas, the levels of APP, β- and γ-secretase mRNA in the brains of 25- and 53-day-old UPL rats are similar. On the other hand, in an in vitro study, Aβ1-42 attachment in the lens capsule-epithelium of UPL rats was found to increase in H2O2. In addition, in an in vivo study, the inhibition of H2O2 by DSF was found to attenuate the increase in Aβ1-42 in the lens capsule-epithelium of 60-day-old UPL rats. Taken together, we hypothesize that excessive H2O2 in the lens enhances the attachment of Aβ1-42 in the lens capsule-epithelium of UPL rats, and that the instillation of DSF has the ability to attenuate the attachment of Aβ1-42 by inhibiting H2O2 production in lens. These

  18. Coated with nanomaterials intraocular lenses, ophthalmic and human body implantable devices with high catalytic antioxidant activities: a new nanotechnology strategy of peroxidase cellular enzyme mimics increasing the biocompatibility and therapeutic deployment of the medical prosthetic device.

    PubMed

    Babizhayev, Mark A

    2013-04-01

    While cataract surgery is generally recognized as being one of the safest operations, there is still a significant complication rate. From 30 to 50% of all patients in the United States having cataract extraction develop opacification of the posterior lens capsule within two years and require laser treatment with its own significant risk of complications. Of the patients having cataract surgery, 0.8% develop retinal detachments, from 0.6% to 1.3% were rehospitalized for corneal edema or required corneal transplantation and about 0.1% presented with endophthalmitis . Thus, aside from secondary cataract, about 2% of 1.3 million people, or 26,000 individuals in the United States annually develop serious complications as a result of cataract surgery. The aim of this investigation was to increase the safety and effectiveness of an individual intraocular lens (IOL) preventing an impairment in peroxide metabolism of the mature human cataractous lenses compared to normal lenses employing the specific nanotechnology coating which substitutes the inhibitory effect of the implantable device towards the active species of oxygen and the ability of IOL to regulate the H2O2 and lipid hydroperoxides levels in the surrounding medium. The implantation of IOLs with metabolic activity improves the capability of the surrounding ocular tissues to withstand oxidative stress induced in ocular humors by the photochemical and other metabolic reactions. The coated implantable medical device with thin film of platinum applied with magnetron sputtering, reacts as a body enzyme with deleterious peroxide compounds and free radical oxygen species in body fluids and tissue when said device is implanted into human body. The IOL having haptics coated with thin film of platinum, catalyzes the reduction of peroxide compounds to decrease their levels within the aqueous humor. Further, the coatings also scavenge toxic free radicals of oxygen, thus preventing cellular dysfunction resulting from oxidative

  19. Planck 2015 results. XV. Gravitational lensing

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; White, M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-09-01

    We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40σ), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator, we detect lensing at a significance of 5σ. We cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. Public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40 ≤ L ≤ 400, and an associated likelihood for cosmological parameter constraints. We find good agreement between our measurement of the lensing potential power spectrum and that found in the ΛCDM model that best fits the Planck temperature and polarization power spectra. Using the lensing likelihood alone we obtain a percent-level measurement of the parameter combination σ8Ω0.25m = 0.591 ± 0.021. We combine our determination of the lensing potential with the E-mode polarization, also measured by Planck, to generate an estimate of the lensing B-mode. We show that this lensing B-mode estimate is correlated with the B-modes observed directly by Planck at the expected level and with a statistical significance of 10σ, confirming Planck's sensitivity to this known sky signal. We also correlate our lensing potential estimate with the large-scale temperature anisotropies, detecting a cross-correlation at the 3σ level, as expected because of dark energy in the concordance ΛCDM model.

  20. Ionizing radiation induced cataracts: Recent biological and mechanistic developments and perspectives for future research.

    PubMed

    Ainsbury, Elizabeth A; Barnard, Stephen; Bright, Scott; Dalke, Claudia; Jarrin, Miguel; Kunze, Sarah; Tanner, Rick; Dynlacht, Joseph R; Quinlan, Roy A; Graw, Jochen; Kadhim, Munira; Hamada, Nobuyuki

    The lens of the eye has long been considered as a radiosensitive tissue, but recent research has suggested that the radiosensitivity is even greater than previously thought. The 2012 recommendation of the International Commission on Radiological Protection (ICRP) to substantially reduce the annual occupational equivalent dose limit for the ocular lens has now been adopted in the European Union and is under consideration around the rest of the world. However, ICRP clearly states that the recommendations are chiefly based on epidemiological evidence because there are a very small number of studies that provide explicit biological, mechanistic evidence at doses <2Gy. This paper aims to present a review of recently published information on the biological and mechanistic aspects of cataracts induced by exposure to ionizing radiation (IR). The data were compiled by assessing the pertinent literature in several distinct areas which contribute to the understanding of IR induced cataracts, information regarding lens biology and general processes of cataractogenesis. Results from cellular and tissue level studies and animal models, and relevant human studies, were examined. The main focus was the biological effects of low linear energy transfer IR, but dosimetry issues and a number of other confounding factors were also considered. The results of this review clearly highlight a number of gaps in current knowledge. Overall, while there have been a number of recent advances in understanding, it remains unknown exactly how IR exposure contributes to opacification. A fuller understanding of how exposure to relatively low doses of IR promotes induction and/or progression of IR-induced cataracts will have important implications for prevention and treatment of this disease, as well as for the field of radiation protection.

  1. Strong gravitational lensing of gravitational waves from double compact binaries—perspectives for the Einstein Telescope

    SciTech Connect

    Biesiada, Marek; Ding, Xuheng; Zhu, Zong-Hong; Piórkowska, Aleksandra E-mail: dingxuheng@mail.bnu.edu.cn E-mail: zhuzh@bnu.edu.cn

    2014-10-01

    Gravitational wave (GW) experiments are entering their advanced stage which should soon open a new observational window on the Universe. Looking into this future, the Einstein Telescope (ET) was designed to have a fantastic sensitivity improving significantly over the advanced GW detectors. One of the most important astrophysical GW sources supposed to be detected by the ET in large numbers are double compact objects (DCO) and some of such events should be gravitationally lensed by intervening galaxies. We explore the prospects of observing gravitationally lensed inspiral DCO events in the ET. This analysis is a significant extension of our previous paper [1]. We are using the intrinsic merger rates of the whole class of DCO (NS-NS,BH-NS,BH-BH) located at different redshifts as calculated by [2] by using StarTrack population synthesis evolutionary code. We discuss in details predictions from each evolutionary scenario. Our general conclusion is that ET would register about 50–100 strongly lensed inspiral events per year. Only the scenario in which nascent BHs receive strong kick gives the predictions of a few events per year. Such lensed events would be dominated by the BH-BH merging binary systems. Our results suggest that during a few years of successful operation ET will provide a considerable catalog of strongly lensed events.

  2. Altitude Adaptation: A Glimpse Through Various Lenses

    PubMed Central

    2015-01-01

    Abstract Simonson, Tatum S. Altitude adaptation: A glimpse through various lenses. High Alt Med Biol 16:125–137, 2015.—Recent availability of genome-wide data from highland populations has enabled the identification of adaptive genomic signals. Some of the genomic signals reported thus far among Tibetan, Andean, and Ethiopian are the same, while others appear unique to each population. These genomic findings parallel observations conveyed by decades of physiological research: different continental populations, resident at high altitude for hundreds of generations, exhibit a distinct composite of traits at altitude. The most commonly reported signatures of selection emanate from genomic segments containing hypoxia-inducible factor (HIF) pathway genes. Corroborative evidence for adaptive significance stems from associations between putatively adaptive gene copies and sea-level ranges of hemoglobin concentration in Tibetan and Amhara Ethiopians, birth weights and metabolic factors in Andeans and Tibetans, maternal uterine artery diameter in Andeans, and protection from chronic mountain sickness in Andean males at altitude. While limited reports provide mechanistic insights thus far, efforts to identify and link precise genetic variants to molecular, physiological, and developmental functions are underway, and progress on the genomics front continues to provide unprecedented movement towards these goals. This combination of multiple perspectives is necessary to maximize our understanding of orchestrated biological and evolutionary processes in native highland populations, which will advance our understanding of both adaptive and non-adaptive responses to hypoxia. PMID:26070057

  3. Altitude Adaptation: A Glimpse Through Various Lenses.

    PubMed

    Simonson, Tatum S

    2015-06-01

    Simonson, Tatum S. Altitude adaptation: A glimpse through various lenses. High Alt Med Biol 16:125-137, 2015.--Recent availability of genome-wide data from highland populations has enabled the identification of adaptive genomic signals. Some of the genomic signals reported thus far among Tibetan, Andean, and Ethiopian are the same, while others appear unique to each population. These genomic findings parallel observations conveyed by decades of physiological research: different continental populations, resident at high altitude for hundreds of generations, exhibit a distinct composite of traits at altitude. The most commonly reported signatures of selection emanate from genomic segments containing hypoxia-inducible factor (HIF) pathway genes. Corroborative evidence for adaptive significance stems from associations between putatively adaptive gene copies and sea-level ranges of hemoglobin concentration in Tibetan and Amhara Ethiopians, birth weights and metabolic factors in Andeans and Tibetans, maternal uterine artery diameter in Andeans, and protection from chronic mountain sickness in Andean males at altitude. While limited reports provide mechanistic insights thus far, efforts to identify and link precise genetic variants to molecular, physiological, and developmental functions are underway, and progress on the genomics front continues to provide unprecedented movement towards these goals. This combination of multiple perspectives is necessary to maximize our understanding of orchestrated biological and evolutionary processes in native highland populations, which will advance our understanding of both adaptive and non-adaptive responses to hypoxia.

  4. Prognostic Factors for Visual Outcome in Traumatic Cataract Patients

    PubMed Central

    Zhang, Yan F.; Zhu, Yu; Wan, Ming G.; Du, Shan S.; Yue, Zhen Z.

    2016-01-01

    Purpose. To investigate the prognostic factors for visual outcome in traumatic cataract patients. Methods. The demographic features of traumatic cataract patients in Central China were studied. The factors that might influence the visual outcome were analyzed. The sensitivity and specificity of OTS (ocular trauma score) in predicting VA were calculated. Results. The study enrolled 480 cases. 65.5% of patients achieved VA at >20/60. The factors associated with the final VA were initial VA, injury type, wound location, the way of cataract removal, and IOL implantation. The sensitivities of OTS in predicting the VA at NLP (nonlight perception), LP/HM (light perception/hand motion), and ≥20/40 were 100%. The specificity of OTS to predict the final VA at 1/200-19/200 and 20/200-20/50 was 100%. Conclusion. The prognostic factors were initial VA, injury type, wound location, cataract removal procedure, and the way of IOL implantation. The OTS has good sensitivity and specificity in predicting visual outcome in traumatic cataract patients in long follow-up. PMID:27595014

  5. Development of appropriateness explicit criteria for cataract extraction by phacoemulsification

    PubMed Central

    Ma Quintana, José; Escobar, Antonio; Aróstegui, Inmaculada

    2006-01-01

    Background Consensus development techniques were used in the late 1980s to create explicit criteria for the appropriateness of cataract extraction. We developed a new appropriateness of indications tool for cataract following the RAND method. We tested the validity of our panel results. Methods Criteria were developed using a modified Delphi panel judgment process. A panel of 12 ophthalmologists was assembled. Ratings were analyzed regarding the level of agreement among panelists. We studied the influence of all variables on the final panel score using linear and logistic regression models. The explicit criteria developed were summarized by classification and regression tree analysis. Results Of the 765 indications evaluated by the main panel in the second round, 32.9% were found appropriate, 30.1% uncertain, and 37% inappropriate. Agreement was found in 53% of the indications and disagreement in 0.9%. Seven variables were considered to create the indications and divided into three groups: simple cataract, with diabetic retinopathy, or with other ocular pathologies. The preoperative visual acuity in the cataractous eye and visual function were the variables that best explained the panel scoring. The panel results were synthesized and presented in three decision trees. Misclassification error in the decision trees, as compared with the panel original criteria, was 5.3%. Conclusion The parameters tested showed acceptable validity for an evaluation tool. These results support the use of this indication algorithm as a screening tool for assessing the appropriateness of cataract extraction in field studies and for the development of practice guidelines. PMID:16512906

  6. The First Cataract Surgeons in Anglo-America

    PubMed Central

    Leffler, Christopher T.; Schwartz, Stephen G.; Grzybowski, Andrzej; Braich, Puneet S.

    2014-01-01

    We tried to identify the earliest cataract surgeons in the English-speaking areas of America. In 1751, couching was performed on the Caribbean island of Montserrat by John Morphy. William Stork of England, who couched cataracts, practiced in Jamaica in 1760 and then in cities from Annapolis to Boston between 1761 and 1764. Frederick William Jericho of Germany, upon completion of his training at Utrecht, published his 1767 treatise on his preferred surgical technique of extracapsular cataract extraction. Jericho had practiced in the Leeward Islands by 1776 and then in cities from Charleston to Boston between 1783 and 1785. The French surgeon Lewis Leprilete was the first to advertise cataract extraction in the United States in 1782 and probably passed on the skill to his protégé, Nathaniel Miller of Massachusetts. Leprilete was also the first to publicize Benjamin Franklin's invention of bifocals.. These pioneers exposed American doctors and the public to cataract surgery. Shortly after their arrival, evidence emerges of other surgeons performing these procedures in America. PMID:25444521

  7. Not only Gravitational Lensing, but in general Medium Lensing

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2013-05-01

    According to the General Theory of Relativity the gravity curves the spacetime and everything over there follows a curved path. The space being curved near massive cosmic bodies is just a metaphor, not a fact. We dough that gravity is only geometry. The deflection of light (Gravitational Lensing) near massive cosmic bodies is not due because of a ``curved space'', but because of the medium composition (medium that could be formed by waves, particles, plasma, dust, gaseous, fluids, solids, etc.), to the medium density, medium heterogeneity, and to the electromagnetic and gravitational fields contained in that medium that light passes through. This medium deviates the light direction, because of the interactions of photons with other particles. The space is not empty; it has various nebulae and fields and corpuscles, etc. Light bends not only because of the gravity but also because of the medium gradient and refraction index, similarly as light bends when it leaves or enters a liquid, a plastic, a glass, or a quartz. The inhomogeneous medium may act as an optical lens such that its refractive index varies in a fashion, alike the Gradient-Index Lens. We talk about a Medium Lensing, which means that photons interact with other particles in the medium. For example, the interaction between a photon of electromagnetic radiation with a charged particle (let's say with a free electron), which is known as Compton Effect, produces an increase in the photon's wavelength. In the Inverse Compton Effect the low-energy photons gain energy because they were scattered by much-higher energy free electrons.

  8. Phakic Intraocular Lenses for the Treatment of Refractive Errors

    PubMed Central

    2009-01-01

    BSCVA ranging from 20/70 to 20/160, one study estimated that 35.6 per 10,000 people in Canada have low vision. The 2001 Participation and Activity Limitation Survey (PALS) found that 594,350 (2.5%) Canadians had “difficulty seeing ordinary newsprint or clearly seeing the face of someone from 4 m,” and the Canadian National Institute for the Blind (CNIB) registry classified 105,000 (.35%) Canadians as visually disabled. Phakic Intraocular Lenses (pIOL) A phakic intraocular lens (pIOL) is a supplementary lens that is inserted into the anterior or posterior chamber of the eye to correct refractive errors (myopia, hyperopia, and astigmatism). Unlike in cataract surgery, the eye’s natural crystalline lens is not removed when the pIOL is inserted, so the eye retains its accommodative ability. In Canada and the United States, iris-fixated (anterior chamber lenses that are anchored to the iris with a claw) and posterior chamber lenses are the only types of pIOLs that are licensed by Health Canada and the Food and Drug Administration, respectively. Evidence-Based Analysis Method Research Questions & Methodology What are the effectiveness, cost-effectiveness, and safety of pIOLs for the treatment of myopia, hyperopia, and astigmatism? Do certain subgroups (e.g. high myopia and low vision) benefit more from pIOLs? How do pIOLs compare with alternative surgical treatment options (LASIK, PRK, and CLE)? Using appropriate keywords, a literature search was conducted up to January 2009. Systematic reviews, meta-analyses, randomized controlled trials, and observational studies with more than 20 eyes receiving pIOLs were eligible for inclusion. The primary outcomes of interest were uncorrected visual acuity (UCVA), predictability of manifest refraction spherical equivalent (MRSE), and adverse events. The GRADE approach was used to systematically and explicitly evaluate the quality of evidence. Summary of Findings The search identified 1,131 citations published between January 1

  9. 42 CFR 1001.1701 - Billing for services of assistant at surgery during cataract operations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... cataract operations. 1001.1701 Section 1001.1701 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE... PROGRAMS Permissive Exclusions § 1001.1701 Billing for services of assistant at surgery during cataract... surgery during a cataract operation, or (ii) Charges that include a charge for an assistant at...

  10. 42 CFR 1001.1701 - Billing for services of assistant at surgery during cataract operations.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... cataract operations. 1001.1701 Section 1001.1701 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE... PROGRAMS Permissive Exclusions § 1001.1701 Billing for services of assistant at surgery during cataract... surgery during a cataract operation, or (ii) Charges that include a charge for an assistant at...

  11. 42 CFR 1001.1701 - Billing for services of assistant at surgery during cataract operations.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... cataract operations. 1001.1701 Section 1001.1701 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE... PROGRAMS Permissive Exclusions § 1001.1701 Billing for services of assistant at surgery during cataract... surgery during a cataract operation, or (ii) Charges that include a charge for an assistant at...

  12. 42 CFR 1001.1701 - Billing for services of assistant at surgery during cataract operations.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... cataract operations. 1001.1701 Section 1001.1701 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE... PROGRAMS Permissive Exclusions § 1001.1701 Billing for services of assistant at surgery during cataract... surgery during a cataract operation, or (ii) Charges that include a charge for an assistant at...

  13. 42 CFR 1001.1701 - Billing for services of assistant at surgery during cataract operations.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... cataract operations. 1001.1701 Section 1001.1701 Public Health OFFICE OF INSPECTOR GENERAL-HEALTH CARE... PROGRAMS Permissive Exclusions § 1001.1701 Billing for services of assistant at surgery during cataract... surgery during a cataract operation, or (ii) Charges that include a charge for an assistant at...

  14. Scanning Miniature Microscopes without Lenses

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  15. X-ray imaging in advanced studies of ophthalmic diseases

    SciTech Connect

    Antunes, Andrea; Safatle, Angelica M. V.; Barros, Paulo S. M.; Morelhao, Sergio L.

    2006-07-15

    Microscopic characterization of pathological tissues has one major intrinsic limitation, the small sampling areas with respect to the extension of the tissues. Mapping possible changes on vast tissues and correlating them with large ensembles of clinical cases is not a feasible procedure for studying most diseases, as for instance vision loss related diseases and, in particular, the cataract. Although intraocular lens implants are successful treatments, cataract still is a leading public-health issue that grows in importance as the population increases and life expectancy is extended worldwide. In this work we have exploited the radiation-tissue interaction properties of hard x-rays--very low absorption and scattering--to map distinct lesions on entire eye lenses. At the used synchrotron x-ray photon energy of 20 keV (wavelength {lambda}=0.062 nm), scattering and refraction are angular resolved effects. It allows the employed x-ray image technique to efficiently characterize two types of lesions in eye lenses under cataractogenesis: distributions of tiny scattering centers and extended areas of fiber cell compaction. The data collection procedure is relatively fast; allowing dozens of samples to be totally imaged (scattering, refraction, and mass absorption images) in a single day of synchrotron beam time. More than 60 cases of canine cataract, not correlated to specific causes, were investigated in this first application of x-rays to image entire lenses. Cortical opacity cases, or partial opacity, could be related to the presence of calcificated tissues at the cortical areas, clearly visible in the images, whose elemental contents were verified by micro x-ray fluorescence as very rich in calcium. Calcificated tissues were also observed at nuclear areas in some cases of hypermature cataract. Total opacity cases without distinguishable amount of scattering centers consist in 70% of the analyzed cases, where remarkable fissure marks owing to extended areas of fiber

  16. Evaluation of Different Power of Near Addition in Two Different Multifocal Intraocular Lenses

    PubMed Central

    Unsal, Ugur; Baser, Gonen

    2016-01-01

    Purpose. To compare near, intermediate, and distance vision and quality of vision, when refractive rotational multifocal intraocular lenses with 3.0 diopters or diffractive multifocal intraocular lenses with 2.5 diopters near addition are implanted. Methods. 41 eyes of 41 patients in whom rotational +3.0 diopters near addition IOLs were implanted and 30 eyes of 30 patients in whom diffractive +2.5 diopters near addition IOLs were implanted after cataract surgery were reviewed. Uncorrected and corrected distance visual acuity, intermediate visual acuity, near visual acuity, and patient satisfaction were evaluated 6 months later. Results. The corrected and uncorrected distance visual acuity were the same between both groups (p = 0.50 and p = 0.509, resp.). The uncorrected intermediate and corrected intermediate and near vision acuities were better in the +2.5 near vision added intraocular lens implanted group (p = 0.049, p = 0.005, and p = 0.001, resp.) and the uncorrected near vision acuity was better in the +3.0 near vision added intraocular lens implanted group (p = 0.001). The patient satisfactions of both groups were similar. Conclusion. The +2.5 diopters near addition could be a better choice in younger patients with more distance and intermediate visual requirements (driving, outdoor activities), whereas the + 3.0 diopters should be considered for patients with more near vision correction (reading). PMID:27340560

  17. CONSTRAINING SOURCE REDSHIFT DISTRIBUTIONS WITH GRAVITATIONAL LENSING

    SciTech Connect

    Wittman, D.; Dawson, W. A.

    2012-09-10

    We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that {approx}40 massive ({sigma}{sub v} = 1200 km s{sup -1}) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to {approx}11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20%-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as N{sub lens}{sup -1/2}, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens-mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

  18. Investigations of galaxy clusters using gravitational lensing

    NASA Astrophysics Data System (ADS)

    Wiesner, Matthew P.

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  19. Investigations of Galaxy Clusters Using Gravitational Lensing

    SciTech Connect

    Wiesner, Matthew P.

    2014-08-01

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  20. Adherence of Pseudomonas aeruginosa to contact lenses

    SciTech Connect

    Miller, M.J.

    1988-01-01

    The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens.

  1. Three Gravitational Lenses for the Price of One: Enhanced Strong Lensing Through Galaxy Clustering

    SciTech Connect

    Fassnacht, Chris D.; McKean, J.P.; Koopmans, L.V.E.; Treu, T.; Blandford, R.D.; Auger, M.W.; Jeltema, T.E.; Lubin, L.M.; Margoniner, V.E.; Wittman, D.; /UC, Davis /Kapteyn Astron. Inst., Groningen /UC, Santa Barbara /KIPAC, Menlo Park /Carnegie Inst. Observ.

    2006-04-03

    We report the serendipitous discovery of two strong gravitational lens candidates (ACS J160919+6532 and ACS J160910+6532) in deep images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope, each less than 40'' from the previously known gravitational lens system CLASS B1608+656. The redshifts of both lens galaxies have been measured with Keck and Gemini: one is a member of a small galaxy group at z {approx} 0.63, which also includes the lensing galaxy in the B1608+656 system, and the second is a member of a foreground group at z {approx} 0.43. By measuring the effective radii and surface brightnesses of the two lens galaxies, we infer their velocity dispersions based on the passively evolving Fundamental Plane (FP) relation. Elliptical isothermal lens mass models are able to explain their image configurations within the lens hypothesis, with a velocity dispersion compatible with that estimated from the FP for a reasonable source-redshift range. Based on the large number of massive early-type galaxies in the field and the number-density of faint blue galaxies, the presence of two additional lens systems around CLASS B1608+656 is not unlikely in hindsight. Gravitational lens galaxies are predominantly early-type galaxies, which are clustered, and the lensed quasar host galaxies are also clustered. Therefore, obtaining deep high-resolution images of the fields around known strong lens systems is an excellent method of enhancing the probability of finding additional strong gravitational lens systems.

  2. Two new cataract loci, Ccw and To3, and further mapping of the Npp and Opj cataracts in the mouse

    SciTech Connect

    Kerscher, S.; Glenister, P.H.; Lyon, M.F.; Favor, J.

    1996-08-15

    Many types of inherited early onset cataract are known in both human and mouse. Here we describe the mapping of two novel dominant cataract loci in the mouse genome. Cataract and curly whiskers, Ccw, maps to Chromosome 4, 3.1 {+-} 1.1 cM distal to the b (brown) locus. Total opacity 3, To3, maps to Chromosome 7, 7.1 {+-} 1.8 cM proximal top (pink-eyed dilution). The map positions of two other dominant cataract mutants have now been refined by three-point crosses. Nuclear and posterior polar cataract, Npp, maps to the central part of Chromosome 5,1.4 {+-} 0.5 cM distal to W{sup e} (dominant spotting-extreme, an allele at the Kit locus), and Opaque secondary fiber cell junctions, Opj, maps to the proximal region of Chromosome 16, 9.1 {+-} 1.5 cM distal to the marker md (mahoganoid). While there are no obvious candidate genes in the vicinity of the Ccw, Npp, and Opj mutations, To3 lies remarkably close to the recently mapped Lim2 locus, which encodes lens intrinsic membrane protein 2. also called MP19. 24 refs., 1 fig., 4 tabs.

  3. Natural wormholes as gravitational lenses

    SciTech Connect

    Cramer, J.G.; Forward, R.L.; Morris, M.S.; Visser, M.; Benford, G.; Landis, G.A. Forward Unlimited, P.O. Box 2783, Malibu, California 90265 Department of Physics and Astronomy, Butler University, Indianapolis, Indiana 46208 Physics Department, Washington University, St. Louis, Missouri 63130-4899 Physics Department, University of California at Irvine, Irvine, California 92717-4575 NASA Lewis Research Center, Mail Code 302-1, Cleveland, Ohio 44135-3191 )

    1995-03-15

    Once quantum mechanical effects are included, the hypotheses underlying the positive mass theorem of classical general relativity fail. As an example of the peculiarities attendant upon this observation, a wormhole mouth embedded in a region of high mass density might accrete mass, giving the other mouth a net [ital negative] mass of unusual gravitational properties. The lensing of such a gravitationally negative anomalous compact halo object (GNACHO) will enhance background stars with a time profile that is observable and qualitatively different from that recently observed for massive compact halo objects (MACHO's) of positive mass. While the analysis is discussed in terms of wormholes, the observational test proposed is more generally a search for compact negative mass objects of any origin. We recommend that MACHO search data be analyzed for GNACHO's.

  4. Cataract production in mice by heavy charged particles

    NASA Technical Reports Server (NTRS)

    Ainsworth, E. J.; Jose, U.; Yang, V. V.; Barker, M. E.

    1981-01-01

    The cataractogenic effects of heavy charged particles are evaluated in mice in relation to dose and ionization density. The relative biological effectiveness in relation to linear energy transfer for various particles is considered. Results indicated that low single doses (5 to 20 rad) of Fe 56 or Ar 40 particles are cataractogenic at 11 to 18 months after irradiation; onset and density of the opacification are dose related and cataract density (grade) at 9, 11, 13, and 16 months after irradiation shows partial linear energy transfer dependence. The severity of cataracts is reduced significantly when 417 rad of Co 60 gamma radiation is given in 24 weekly 17 rad fractions compared to giving this radiation as a single dose, but cataract severity is not reduced by fractionation of C12 doses over 24 weeks.

  5. Congenital cataracts in an Ayrshire herd: a herd case report

    PubMed Central

    2014-01-01

    An Ayrshire dairy herd was investigated for occurrence of ocular abnormalities in new-born calves. Ophthalmic examinations were performed on all the animals in the herd and 26% of them were diagnosed with bilateral cataracts. Cataracts varied in extent and severity but the majority were restricted to the lens nucleus. Epidemiological analysis showed the prevalence was higher in male animals and lower in animals born to heifers. A family tree was designed but no genetic impact of dam lines was evident. Sire data was incomplete and could therefore not be included. Based on the information provided by the farmer there was no obvious environmental or nutritional cause of these cataracts. However, data records were incomplete and further investigation/monitoring of the herd would be needed to establish a cause and enable a better insight into the aetiology of this disease in cattle. PMID:24460638

  6. Pros and cons of immediately sequential bilateral cataract surgery (ISBCS).

    PubMed

    Grzybowski, Andrzej; Wasinska-Borowiec, Weronika; Claoué, Charles

    2016-01-01

    Immediately sequential bilateral cataract surgery (ISBCS) is currently a "hot topic" in ophthalmology. There are well-documented advantages in terms of quicker visual rehabilitation and reduced costs. The risk of bilateral simultaneous endophthalmitis and bilateral blindness is now recognized to be minuscule with the advent of intracameral antibiotics and modern management of endophthalmitis. Refractive surprises are rare for normal eyes and with the use of optical biometry. Where a general anesthetic is indicated for cataract surgery, the risk of death from a second anesthetic is much higher than the risk of blindness. A widely recognized protocol from the International Society of Bilateral Cataract Surgeons needs to be adhered to if surgeons wish to start practicing ISBCS.

  7. Bimatoprost Induced Serous Macular Detachment after Cataract Surgery

    PubMed Central

    Kaliaperumal, Subashini; Deb, Amit Kumar; Babu, K. Ramesh; Srinivasan, Renuka

    2016-01-01

    We report a case of bimatoprost induced serous macular detachment and choroidal folds following uneventful cataract surgery. A 66-year-old male using topical bimatoprost in both eyes for open angle glaucoma underwent uneventful cataract surgery in the right eye. Postoperatively, he was restarted on topical bimatoprost and antibiotic-steroids combination drops. One week after surgery, he presented with conjunctival hyperemia, serous macular detachment, and choroidal folds at the posterior pole. Fundus fluorescein angiography showed perifoveal leaks in early stage with pooling of dye in late stage. Discontinuation of bimatoprost led to resolution of serous detachment and choroidal folds within 3 weeks with significant improvement in visual acuity. Occurrence of serous macular detachment and choroidal folds in this case could be probably related to the proinflammatory property of bimatoprost. Hence, it should be used with caution in the immediate postoperative period after cataract surgery. PMID:27957367

  8. Corneoscleral abscess resulting from a broken suture after cataract surgery.

    PubMed

    Cameron, J A; Huaman, A

    1994-01-01

    An 82-year-old man had pain and decreased vision in his right eye 15 months after uncomplicated cataract surgery. Examination revealed a large corneoscleral abscess with a 2 mm x 1 mm area of fluorescein staining at the base of a broken protruding 10-0 nylon suture. Streptococcus pneumoniae was isolated from both the suture and base of the ulcer. Despite intensive topical, subconjunctival, and systemic antibiotics, a large corneal perforation developed, necessitating a 10 mm tectonic penetrating keratoplasty. Long-term follow-up of patients after cataract surgery is important and should include an inspection of the limbal wound and removal of loose or broken exposed sutures. Suture-related complications will be eliminated if clinical studies prove the safety and efficacy of sutureless cataract surgery.

  9. [Correction of keratoconus with soft contact lenses].

    PubMed

    Koos, D; Bitea, M J

    1989-01-01

    The authors present their experience in using soft contact lenses in 33 eyes with keratoconus (18 patients). Adaptation was possible only when the doctor-patient collaboration was good. Visual acuity (VA) of 0.4-1 was obtained in 85% cases versus 42.5% when glasses were used. In the period under observation no case of VA decrease was recorded. The subjects tolerated well the contact lenses. The specialty literature contains data indicating not only the optical role of the contact lenses but also their therapeutic, tectorial role.

  10. Flexibility of hard gas permeable contact lenses.

    PubMed

    Stevenson, R W

    1988-11-01

    Gas permeable (GP) lenses can flex on some eyes producing unpredictable clinical results. A method of measuring the flexibility of hard GP materials has been developed and shown to be repeatable. Materials in the form of flats rather than lenses were used. Differences between materials were found and in general a linear relation was shown to exist between maximum flexing and quoted oxygen permeability (r = 0.78, p less than 0.05). It is recommended that flexibility be measured and reported in the data presented with all new GP polymers. The term "hard" rather than "rigid" in describing GP lenses is suggested.

  11. Tevatron Electron Lenses: Design and Operation

    SciTech Connect

    Shiltsev, Vladimir; Bishofberger, Kip; Kamerdzhiev, Vsevolod; Kozub, Sergei; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; /Fermilab /SLAC /Fermilab /Serpukhov, IHEP /Novosibirsk, IYF /Serpukhov, IHEP /Fermilab

    2008-08-01

    The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

  12. Wettability and silicone hydrogel lenses: a review.

    PubMed

    Keir, Nancy; Jones, Lyndon

    2013-01-01

    One of the major breakthroughs in the development of silicone hydrogel contact lenses has related to the ability of manufacturers to overcome the surface hydrophobicity that occurred with silicone elastomer lenses. However, the wettability of silicone hydrogel lenses continues to be of interest as a potential link between in vivo lens performance and contact lens-related comfort. This article will review some of the knowledge we have gained in the area of contact lens wettability over the past decade and will discuss some of the challenges related to its measurement.

  13. Twin axial vortices generated by Fibonacci lenses.

    PubMed

    Calatayud, Arnau; Ferrando, Vicente; Remón, Laura; Furlan, Walter D; Monsoriu, Juan A

    2013-04-22

    Optical vortex beams, generated by Diffractive Optical Elements (DOEs), are capable of creating optical traps and other multi-functional micromanipulators for very specific tasks in the microscopic scale. Using the Fibonacci sequence, we have discovered a new family of DOEs that inherently behave as bifocal vortex lenses, and where the ratio of the two focal distances approaches the golden mean. The disctintive optical properties of these Fibonacci vortex lenses are experimentally demonstrated. We believe that the versatility and potential scalability of these lenses may allow for new applications in micro and nanophotonics.

  14. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    SciTech Connect

    Kleiman, Norman Jay

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  15. Gender and cataract--the role of estrogen.

    PubMed

    Zetterberg, Madeleine; Celojevic, Dragana

    2015-02-01

    There is evidence from epidemiologic data that cataract is more common in women than men. This is not solely due to a higher rate of cataract extraction in women, as is the case in the western world, but several population-based studies show that females have a higher prevalence of lens opacities, especially cortical. There is no firm evidence that lifestyle-related factors are the cause of this gender discrepancy. Focus has therefore been directed towards the role of estrogen in cataract formation. Although data on endogenous and exogenous estrogen involvement in cataractogenesis are conflicting, some studies have indicated that hormone therapy may decrease the risk of cataract and thus be protective. It has been hypothesized that the decrease in estrogen at menopause cause increased risk of cataract in women, i.e. not strictly the concentration of estrogen, but more the withdrawal effect. Estrogens are known to exert several anti-aging effects that may explain the longer lifespan in women, including metabolically beneficial effects, neuroprotection, preservation of telomeres and anti-oxidative properties. Since oxidative stress is considered important in cataractogenesis, studies have investigated the effects of estrogens on lens epithelial cells in culture or in animal models. Several investigators have found protection by physiological concentrations of 17β-estradiol against oxidative stress induced by H2O2 in cultured lens epithelial cells. Although both main types of estrogen receptors, ERα and ERβ, have been demonstrated in lens epithelium, most studies so far indicate that the estrogen-mediated protection in the lens is exerted through non-genomic, i.e. receptor-independent mechanisms, possibly through phosphorylation of extracellular signal-regulated kinase (ERK1/ERK2), a member of the mitogen-activated protein kinase (MAPK)-signaling pathway. Further studies are needed, both epidemiologic as to the role of hormone therapies, and laboratory studies

  16. ["Cataract of metallurgists" in workers of the oxygen-converter production].

    PubMed

    Dorozhkin, A V

    2003-01-01

    The condition of the lens was studied in 1210 workers of steel industry: in 455 workers of an open-hearth shop (OHS) and in 755 workers of oxygen-converter shops (OCS). The intensity of infra-red irradiation was measured at working places in both shops by non-selective radiometer ARGUS-03. A higher level of automation and more advanced technological processes in the OCS ensure a better protection of the organ of vision of the OCS workers from the impact of infrared irradiation. Thus, the OCS workers had a lower occurrence of cataract development and a less intensity in changes of the lens as compared to the similar parameters registered in the OHS workers. The cataract development was proven to be directly dependant on a labor record length: changes in the posterior capsule and opacifications of the lens posterior cortical segments (stages I and II) were observed in those, whose labor record ranged from 10 to 15 years; brown changes in the nucleus and dystrophic changes in the anterior capsule (degree III) were found in those, whose labor record exceeded 15 years.

  17. Development of cataract caused by diabetes mellitus: Raman study

    NASA Astrophysics Data System (ADS)

    Furić, Krešimir; Mohaček-Grošev, Vlasta; Hadžija, Mirko

    2005-06-01

    Diabetes mellitus succeeded by diabetic cataract was induced to experimental animals (Wistar rats) by applying an Alloxan injection. Eye properties deterioration were monitored from clinical standpoint and using Raman and infrared spectroscopies. All cases of developed cataract were followed by important changes in vibrational spectra, but Raman spectroscopy proved to be more useful because of larger number of resolved bands. Each kth Raman spectrum of diseased lens (in our notation k denotes disease age and cataract degree as described in chapter Alloxan diabetes) can be expressed as a sum of the Raman spectrum of healthy lens, I R, multiplied by a suitable constant ck, and the fluorescent background spectrum, I FB. We introduce the ratio of integrated intensities IFB and ck* IR as a physical parameter called fluorescent background index F FB. It turns out that FFB grows as cataract progresses and has its maximum at approx. 4, whence it decreases. FFB values are larger for 200-1800 cm -1 spectral interval than for 2500-4000 cm -1 interval. In the same manner another quantity called water band index FW is defined for each Raman spectrum of diseased lens in the 2800-3730 cm -1 interval. It is the ratio of the integrated intensity from 3100 to 3730 cm -1 (water band interval) divided by the integrated intensity of the 2800-3100 cm -1 interval (C-H stretching region). FW increases monotonously with cataract progression with maximum at the end of monitored period (5 months). These two indices helped us to formulate a model describing disease development from the earliest molecular changes to its macroscopic manifestation. As glucose and other small saccharide molecules enter the lens tissue, they bind to crystallin and other proteins via O- and S-glycosidic linkages which occur probably at tyrosine and cystein sites. In Raman spectrum this corresponds to broad bands at 540 and 1100 cm -1 which grow together with the fluorescent background, because both contributions

  18. Wound construction in manual small incision cataract surgery

    PubMed Central

    Haldipurkar, S S; Shikari, Hasanain T; Gokhale, Vishwanath

    2009-01-01

    The basis of manual small incision cataract surgery is the tunnel construction for entry to the anterior chamber. The parameters important for the structural integrity of the tunnel are the self-sealing property of the tunnel, the location of the wound on the sclera with respect to the limbus, and the shape of the wound. Cataract surgery has gone beyond just being a means to get the lens out of the eye. Postoperative astigmatism plays an important role in the evaluation of final outcome of surgery. Astigmatic consideration, hence, forms an integral part of incisional considerations prior to surgery. PMID:19075401

  19. A kindred with alopecia, keratosis, pilaris, cataracts, and psoriasis.

    PubMed

    Appell, M L; Sherertz, E F

    1987-01-01

    Three members of a family with numerous ectodermal abnormalities are described. These anomalies primarily include patchy alopecia beginning in childhood, premature cataracts, widespread keratosis pilaris, and psoriasis. The alopecia and premature cataracts appear to follow an autosomal dominant inheritance pattern with incomplete penetrance and appear to be linked. Psoriasis also occurs in several members of this family and probably represents a separate but possibly related genodermatosis. This kindred has features of both keratosis follicularis spinulosa decalvans and ichthyosis follicularis, and the disorder seems to fit into the group of follicular hyperkeratosis disorders.

  20. An analytical approach to gravitational lensing by an ensemble of axisymmetric lenses

    NASA Technical Reports Server (NTRS)

    Lee, Man Hoi; Spergel, David N.

    1990-01-01

    The problem of gravitational lensing by an ensemble of identical axisymmetric lenses randomly distributed on a single lens plane is considered and a formal expression is derived for the joint probability density of finding shear and convergence at a random point on the plane. The amplification probability for a source can be accurately estimated from the distribution in shear and convergence. This method is applied to two cases: lensing by an ensemble of point masses and by an ensemble of objects with Gaussian surface mass density. There is no convergence for point masses whereas shear is negligible for wide Gaussian lenses.

  1. TANGENTIAL VELOCITY OF THE DARK MATTER IN THE BULLET CLUSTER FROM PRECISE LENSED IMAGE REDSHIFTS

    SciTech Connect

    Molnar, Sandor M.; Broadhurst, Tom; Zitrin, Adi; Rephaeli, Yoel; Shimon, Meir

    2013-09-01

    We show that the fast-moving component of the ''Bullet Cluster'' (1E0657-56) can induce potentially resolvable redshift differences between multiply lensed images of background galaxies. This moving cluster effect, due to the tangential peculiar velocity of the lens, can be expressed as the scalar product of the lensing deflection angle with the tangential velocity of the mass components; the effect is maximal for clusters colliding in the plane of the sky with velocities boosted by their mutual gravity. The Bullet Cluster is likely to be the best candidate for the first measurement of this effect due to the large collision velocity and because the lensing deflection and the cluster fields can be calculated in advance. We derive the deflection field using multiply lensed background galaxies detected with the Hubble Space Telescope. The velocity field is modeled using self-consistent N-body/hydrodynamical simulations constrained by the observed X-ray and gravitational lensing features of this system. We predict that the triply lensed images of systems ''G'' and ''H'' straddling the critical curve of the bullet component will show the largest frequency shifts up to {approx}0.5 km s{sup -1}. These shifts are within the range of the Atacama Large Millimeter/Submillimeter Array for molecular emission, and are near the resolution limit of the new generation high-throughput optical-IR spectrographs. The detection of this effect measures the tangential motion of the subclusters directly, thereby clarifying the tension with {Lambda}CDM, which is inferred from the gas motion less directly. This method may be extended to smaller redshift differences using the Ly{alpha} forest toward QSOs lensed by more typical clusters of galaxies. More generally, the tangential component of the peculiar velocities of clusters derived by our method complements the radial component determined by the kinematic Sunyaev-Zel'dovich effect, providing a full three-dimensional description of

  2. Tear exchange and contact lenses: a review.

    PubMed

    Muntz, Alex; Subbaraman, Lakshman N; Sorbara, Luigina; Jones, Lyndon

    2015-01-01

    Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses.

  3. Tear exchange and contact lenses: A review

    PubMed Central

    Muntz, Alex; Subbaraman, Lakshman N.; Sorbara, Luigina; Jones, Lyndon

    2015-01-01

    Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses. PMID:25575892

  4. Thermal lensing in a supercritical water medium.

    PubMed

    Rodriguez, Rene G; Mezyk, Stephen P; Stewart, Charlynn; Rollins, Harry W; Mincher, Bruce J; Fox, Robert V; Phillips, BarJean; Brey, Richard

    2007-01-25

    A pulsed, two-beam, thermal lensing experiment was performed to determine the concentration of aqueous solutes above the critical point of water. Despite a very significant mirage effect due to thermal gradients in the cell and absorption by water itself, the thermal lensing signal strength for aqueous benzoic acid in supercritical water was found to be linear with concentration in the sub-millimolar range. Although thermal lensing experiments in aqueous media are notoriously insensitive, the sharp density gradient near the critical point considerably improves the signal intensity. In this study a short-pulse pump 266 nm YAG laser and continuous low-power probe Ar ion beam were both focused into a supercritical water cell, giving a lensing signal whose strength could be maximized by changing the overlap of the two beams.

  5. Light diffraction by concentrator Fresnel lenses.

    PubMed

    Hornung, Thorsten; Nitz, Peter

    2014-05-05

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as primary optical elements focusing sunlight onto small solar cells or onto entrance apertures of secondary optical elements attached to the solar cells. Calculations using the Young-Maggi-Rubinowicz theory of diffraction yield analytical expressions for the amount of light spilling outside these target areas due to diffraction at the edges of the concentrator Fresnel lenses. Explicit equations are given for the diffraction loss due to planar Fresnel lenses with small prisms and due to arbitrarily shaped Fresnel lenses. Furthermore, the cases of illumination by monochromatic, polychromatic, totally spatially coherent and partially spatially coherent light (e.g. from the solar disc) are treated, resulting in analytical formulae. Examples using realistic values show losses due to diffraction of up to several percent.

  6. Strongly lensed gravitational waves from intrinsically faint double compact binaries—prediction for the Einstein Telescope

    SciTech Connect

    Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong E-mail: marek.biesiada@us.edu.pl

    2015-12-01

    With a fantastic sensitivity improving significantly over the advanced GW detectors, Einstein Telescope (ET) will be able to observe hundreds of thousand inspiralling double compact objects per year. By virtue of gravitational lensing effect, intrinsically unobservable faint sources can be observed by ET due to the magnification by intervening galaxies. We explore the possibility of observing such faint sources amplified by strong gravitational lensing. Following our previous work, we use the merger rates of DCO (NS-NS,BH-NS,BH-BH systems) as calculated by Dominik et al.(2013). It turns out that tens to hundreds of such (lensed) extra events will be registered by ET. This will strongly broaden the ET's distance reach for signals from such coalescences to the redshift range z = 2 − 8. However, with respect to the full inspiral event catalog this magnification bias is at the level of 0.001 and should not affect much cosmological inferences.

  7. Feedback control of thermal lensing in a high optical power cavity.

    PubMed

    Fan, Y; Zhao, C; Degallaix, J; Ju, L; Blair, D G; Slagmolen, B J J; Hosken, D J; Brooks, A F; Veitch, P J; Munch, J

    2008-10-01

    This paper reports automatic compensation of strong thermal lensing in a suspended 80 m optical cavity with sapphire test mass mirrors. Variation of the transmitted beam spot size is used to obtain an error signal to control the heating power applied to the cylindrical surface of an intracavity compensation plate. The negative thermal lens created in the compensation plate compensates the positive thermal lens in the sapphire test mass, which was caused by the absorption of the high intracavity optical power. The results show that feedback control is feasible to compensate the strong thermal lensing expected to occur in advanced laser interferometric gravitational wave detectors. Compensation allows the cavity resonance to be maintained at the fundamental mode, but the long thermal time constant for thermal lensing control in fused silica could cause difficulties with the control of parametric instabilities.

  8. [Therapeutic approach in patients with age-related macular degeneration and cataract].

    PubMed

    Tomi, Anca; Moldoveanu, A; Marin, Irina

    2011-01-01

    Management of the patient with coexisting cataract and AMD presents unique challenges to the cataract surgeon, the retina specialist, and the patient. A common clinical scenario is the patient in whom both the cataract and macular pathology appear to be contributing to decreased visual acuity. As with any surgery, the expectations from cataract removal must be evaluated thoroughly and understood clearly by both the patient and the cataract surgeon. Most patients with AMD who undergo cataract surgery feel that the surgery is worthwhile, and they report improvement of visual function and quality of life. In patients with mild AMD, improvement in central visual acuity and attainment of driving vision are realistic and achievable goals. In an eye with central disciform scarring or geographic atrophy there may be potential for improvement in color discrimination, contrast, or clarity of peripheral vision. In cases of dense cataract obscuring macular detail, cataract removal may be necessary to allow for adequate biomicroscopy and angiography, especially in an eye that may be at high risk for the development of choroidal neovascularization. It is often challenging to estimate the relative impact on visual impairment made by the lens opacities and the macular changes and the benefits and risks of cataract surgery in eyes with AMD should be carefully evaluated. Is cataract surgery justified in these patients? Does cataract surgery aggravate AMD in some patients?

  9. Revised Unfilling Procedure for Solid Lithium Lenses

    SciTech Connect

    Leveling, A.; /Fermilab

    2003-06-03

    A procedure for unfilling used lithium lenses to has been described in Pbar Note 664. To date, the procedure has been used to disassemble lenses 20, 21, 17, 18, and 16. As a result of this work, some parts of the original procedure were found to be time consuming and ineffective. Modifications to the original procedure have been made to streamline the process and are discussed in this note. The revised procedure is included in this note.

  10. Measuring neutrino masses with weak lensing

    SciTech Connect

    Wong, Yvonne Y. Y.

    2006-11-17

    Weak gravitational lensing of distant galaxies by large scale structure (LSS) provides an unbiased way to map the matter distribution in the low redshift universe. This technique, based on the measurement of small distortions in the images of the source galaxies induced by the intervening LSS, is expected to become a key cosmological probe in the future. We discuss how future lensing surveys can probe the sum of the neutrino masses at the 0 05 eV level.

  11. Simulating HST observations of strong lensing clusters

    NASA Astrophysics Data System (ADS)

    Meneghetti, Massimo

    2014-10-01

    The Frontier Fields {FF} are using galaxy cluster gravitational lensing to boost the powers of Hubble and Spitzer to reveal the faintest galaxies yet observed. Accurate gravitational lensing models with uncertainty estimates are required to study some of the physical parameters of the lensed galaxies. Simulated HST observations of lensing clusters with known mass distributions are ideal to determine the accuracies of these modeling methods. Our team has begun performing these tests, demonstrating that integrated quantities such as lensed number counts are accurately recovered, enabling luminosity functions to be constrained. We have also begun to quantify magnification uncertainties for individual galaxies, but additional tests are needed. Here we propose to create a set of simulated osbervations of clusters selected to be analogs of the CLASH and FF clusters. They will include lensing effects and they will be delivered to the Mikulski Archive for Space Telescopes as a legacy product for others to analyze. They will be usable to extend our tests for robustly determine the accuracies in model magnification and mass measurements. Mass uncertainties will be a key ingredient in efforts to use galaxy clusters to constrain cosmology and theories of structure formation. Results from this program will also be useful to improve lens modeling methods toward more optimal use of the large numbers of lensing constraints available in deep FF imaging. This program will help astronomers realize the full potential of the large investments of Hubble, Spitzer, Chandra, and ground-based observing time in the FF, CLASH, and other past and future cluster lensing observations.

  12. Electron lenses for particle collimation in LHC

    SciTech Connect

    Shiltsev, v.; /Fermilab

    2007-12-01

    Electron Lenses built and installed in Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam-beam effects [1], DC beam removal from abort gaps [2], as a diagnostic tool. In this presentation we - following original proposal [3] - consider in more detail a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC.

  13. Mimicking cataract-induced visual dysfunction by means of protein denaturation in egg albumen

    NASA Astrophysics Data System (ADS)

    Mandracchia, B.; Finizio, A.; Ferraro, P.

    2016-03-01

    As the world's population ages, cataract-induced visual dysfunction and blindness is on the increase. This is a significant global problem. The most common symptoms of cataracts are glared and blurred vision. Usually, people with cataract have trouble seeing and reading at distance or in low light and also their color perception is altered. Furthermore, cataract is a sneaky disease as it is usually a very slow but progressive process, which creates adaptation so that patients find it difficult to recognize. All this can be very difficult to explain, so we built and tested an optical device to help doctors giving comprehensive answers to the patients' symptoms. This device allows visualizing how cataract impairs vision mimicking the optical degradation of the crystalline related cataracts. This can be a valuable optical tool for medical education as well as to provide a method to illustrate the patients how cataract progression process will affect their vision.

  14. Global challenges in the management of congenital cataract: proceedings of the 4th International Congenital Cataract Symposium held on March 7, 2014, New York, New York.

    PubMed

    Lenhart, Phoebe D; Courtright, Paul; Wilson, M Edward; Lewallen, Susan; Taylor, David Samuel; Ventura, Marcelo C; Bowman, Richard; Woodward, Lee; Ditta, Lauren C; Kruger, Stacey; Haddad, Danny; El Shakankiri, Nihal; Rai, Salma Kc; Bailey, Tehara; Lambert, Scott R

    2015-04-01

    Childhood cataracts have become a leading cause of preventable childhood blindness in many areas of the world. Here we summarize regional focus group discussions from the 4th Annual International Congenital Cataract Symposium on the current situation, challenges, and recommendations for the management of congenital cataracts in sub-Saharan Africa, the Middle East and North Africa, South Asia, Central America, South America, and developed nations. Strategies for managing congenital cataracts must be adapted and developed according to regional conditions. A basic framework for acceptable outcomes must focus on developing systems to address the critical components of education, access, quality care, and good follow-up.

  15. Surface analysis of polished fused-silica laser lenses by ion-scattering spectrometry

    SciTech Connect

    Orvek, K.; Steward, S.A.

    1982-10-11

    New advances in high-powered glass lasers, particularly the NOVA system, have resulted in a need for lenses having higher damage threshold values than those now available. It is currently thought that surface contaminants on the lenses are responsible for initiating part of the damage. These contaminants are apparently introduced during the final polishing stages. In this study, we used ion-scattering spectrometry (ISS) to identify contaminants arising through the use of different polishing techniques. Five lenses were studied, each having undergone different polishing procedures. The first lens was not polished after receiving it from the manfacturer (No. 381). Ion microprobe data were available for this lens, and they were compared to ISS results. The second lens had been polished with rouge, a polishing compound no longer in use (No. 796). This sample served as a further check on the ISS results. The third lens was studied as received from the manufacturer - with no handling or cleaning (No. 802). The final two lenses had both been polished using high-purity ceria, cerium oxide (No. 800 and No. 801). The difference between these two was that No. 800 was polished using a nylon lap, and No. 801 was polished using pitch as a lap. The 800-series lenses were all made from the same batch, and constituted the major part of the investigation.

  16. Equatorial potassium currents in lenses.

    PubMed

    Wind, B E; Walsh, S; Patterson, J W

    1988-02-01

    Earlier work with the vibrating probe demonstrated the existence of outward potassium currents at the equator and inward sodium currents at the optical poles of the lens. By adding microelectrodes to the system, it is possible to relate steady currents (J) to the potential difference (PD) measured with a microelectrode. By injecting an outward current (I), it is possible to determine resistances and also the PD at which the steady outward potassium current becomes zero (PDJ = 0). At this PD the concentration gradient for potassium efflux and the electrical gradient for potassium influx are balanced so that there is no net flow of potassium across the membranes associated with the production of J. The PDJ = 0 for 18 rat lenses was 86 mV and that for 12 frogs lenses was -95 mV. This agrees with the potassium equilibrium potential and provides strong evidence to support the view that the outward equatorial current, J, is a potassium current. With the injection of outward current, I, the PD becomes more negative, the outward equatorial current, J, decreases, and the inward current at the optical poles increases. This suggests that there are separate electrical loops for K+ and Na+ that are partially linked by the Na, K-pump. Using Ohm's law, it is possible to calculate the input resistance (R = delta PD/I), the resistance related to the production of J (RJ = delta PD/delta J), and the effect of the combined resistances (delta J/I). The driving force for J can be estimated (PDJ = 0-PD). The relationships among currents, voltages and resistance can be used to determine the characteristics of the membranes that are associated with the outward potassium current observed at the equator. The effects of graded deformation of the lens were determined. The effects were reversible. The sites of inward and outward currents were not altered. Following deformation, the equatorial current, J, increased, and the PD became less negative. The PDJ = 0 remains the same so the ratio of K

  17. Monitoring visual outcome of cataract surgery in India.

    PubMed Central

    Limburg, H.; Foster, A.; Vaidyanathan, K.; Murthy, G. V.

    1999-01-01

    Two simple methods of assessing visual outcome following cataract surgery were evaluated in India. The first used data obtained from standardized patient records of cataract surgery. The second used data from population-based rapid epidemiological assessments. Analysis of 4168 hospital and eye camp records showed that, with the available standard correction, a good outcome (visual acuity > or = 6/18) was achieved in 37.8%, a borderline outcome (visual acuity 6/246-6/60) in 45.6% and a poor outcome (visual acuity 6/60) in 16.6% of instances. Of 2401 aphakic/pseudophakic eyes examined in a cross-sectional population-based study, outcome was good in 43.5% and poor in 26.4%. For 776 eyes examined in a similar study in a different state, outcome was good in 49.9% and poor in 23.9%. These assessments indicate that outcome with available correction was poor in 15-25% of eyes following cataract surgery. Visual outcome is likely to improve when better correction for aphakia can be provided. Further assessment of the causes of poor visual outcome is needed. The visual outcome following cataract surgery could be monitored on a regular basis by ophthalmologists, using either of the methods evaluated, an exercise which in itself is likely to improve the outcome of surgery. When the proportion of poor outcomes is high (> 10%) further investigation into the causes is warranted. PMID:10427929

  18. Cataract production in mice by heavy charged particles

    SciTech Connect

    Ainsworth, E.H.; Jose, J.; Yang, V.V.; Barker, M.E.

    1981-03-01

    The cataractogenic effects of heavy charged particles have been evaluated in mice in relation to dose and ionization density (LET/sub infinity/). The study was undertaken due to the high potential for eye exposures to HZE particles among SPS personnel working in outer space. This has made it imperative that the relative biological effectiveness (RBE) in relation to LET/sub infinity/ for various particles be defined so that appropriate quality factors (Q) could be assigned for estimation of risk. Although mice and men differ in susceptibility to radiation-induced cataracts, the results from this project should assist in defining appropriate quality factors in relation to LET/sub infinity/, particle mass, charge, or velocity. Evaluation of results indicated that : (1) low single doses (5 to 20 rad) of iron (/sup 56/Fe) or argon (/sup 40/Ar) particles are cataractogenic at 11 to 18 months after irradiation; (2) onset and density of the opacification are dose related; (3) cataract density (grade) at 9, 11, 13, and 16 months after irradiation shows partial LET/sub infinity/-dependence; and (4) the severity of cataracts is reduced significantly when 417 rad of /sup 60/Co gamma radiation is given in 24 weekly 17 rad fractions compared to giving this radiation as a single dose, but cataract severity is not reduced by fractionation of /sup 12/C doses over 24 weeks.

  19. A prospective study on postoperative pain after cataract surgery

    PubMed Central

    Porela-Tiihonen, Susanna; Kaarniranta, Kai; Kokki, Merja; Purhonen, Sinikka; Kokki, Hannu

    2013-01-01

    Purpose To evaluate postoperative pain and early recovery in cataract patients. Patients and methods A total of 201 patients who underwent elective first eye cataract extraction surgery were enrolled, and 196 were included in the final analysis. The study design was a single-center, prospective, follow-up study in a tertiary hospital in eastern Finland. Postoperative pain was evaluated with the Brief Pain Inventory at four time points: at baseline, and at 24 hours, 1 week, and 6 weeks postsurgery. Results Postoperative pain was relatively common during the first hours after surgery, as it was reported by 67 (34%) patients. After hospital discharge, the prevalence decreased; at 24 hours, 1 week, and 6 weeks, 18 (10%), 15 (9%) and 12 (7%) patients reported having ocular pain, respectively. Most patients with eye pain reported significant pain, with a score of ≥4 on a pain scale of 0–10, but few had taken analgesics for eye pain. Those who had used analgesics rated the analgesic efficacy of paracetamol and ibuprofen as good or excellent. Other ocular irritation symptoms were common after surgery; as a new postoperative symptom, foreign-body sensation was reported by 40 patients (22%), light sensitivity by 29 (16%), burning by 15 (8%), and itching by 15 (8%). Conclusion Moderate or severe postoperative pain was relatively common after cataract surgery. Thus, all patients undergoing cataract surgery should be provided appropriate counseling on pain and pain management after surgery. PMID:23885165

  20. Emerging issues in radiogenic cataracts and cardiovascular disease

    PubMed Central

    Hamada, Nobuyuki; Fujimichi, Yuki; Iwasaki, Toshiyasu; Fujii, Noriko; Furuhashi, Masato; Kubo, Eri; Minamino, Tohru; Nomura, Takaharu; Sato, Hitoshi

    2014-01-01

    In 2011, the International Commission on Radiological Protection issued a statement on tissue reactions (formerly termed non-stochastic or deterministic effects) to recommend lowering the threshold for cataracts and the occupational equivalent dose limit for the crystalline lens of the eye. Furthermore, this statement was the first to list circulatory disease (cardiovascular and cerebrovascular disease) as a health hazard of radiation exposure and to assign its threshold for the heart and brain. These changes have stimulated various discussions and may have impacts on some radiation workers, such as those in the medical sector. This paper considers emerging issues associated with cataracts and cardiovascular disease. For cataracts, topics dealt with herein include (i) the progressive nature, stochastic nature, target cells and trigger events of lens opacification, (ii) roles of lens protein denaturation, oxidative stress, calcium ions, tumor suppressors and DNA repair factors in cataractogenesis, (iii) dose rate effect, radiation weighting factor, and classification systems for cataracts, and (iv) estimation of the lens dose in clinical settings. Topics for cardiovascular disease include experimental animal models, relevant surrogate markers, latency period, target tissues, and roles of inflammation and cellular senescence. Future research needs are also discussed. PMID:24824673

  1. Cataract Section Across Temporary Stainless-Steel Sutures

    PubMed Central

    MacDonald, R. Keith

    1965-01-01

    The purpose of the technique described was to combine the advantages of a cleanedged Graefe-knife incision with those of safety and near-perfect apposition offered by preplaced sutures: a preliminary to cataract extraction. Uncuttable preplaced 2-mm. stainless steel sutures were finally replaced after completion of the incision by attached braided silk for closure purposes. PMID:14291461

  2. Arachnodactyly, aminoaciduria, congenital cataracts, cerebellar ataxia, and delayed developmental milestones

    PubMed Central

    Bhaskar, P. A.; Jagannathan, K.; Valmikinathan, K.

    1974-01-01

    Two male cousins are reported with arachnodactyly, selective aminoaciduria, congenital cataracts, cerebellar ataxia, and delayed developmental milestones, and a distant female relative with similar abnormalities. The syndrome is thought to be previously undescribed, though it has resemblances to Marinesco-Sjögren and Marfan's syndromes. Images PMID:4448994

  3. Treatment of congenital aniridia associated with subluxated infantile cataract.

    PubMed

    Jusufovic, Vahid; Cabric, Emir; Popovic-Beganovic, Allen; Musanovic, Zlatko; Zvornicanin, Jasmin

    2014-01-01

    A 5 year old boy was presented at Eye clinic University clinical center Tuzla with congenital aniridia in both eyes. Clinical examination revealed visual acuity of 0.08 without correction in right and 0.7 with -5.0 Dsph and -1.0 Dcyl Axx 109 degrees in left eye. Opthalmologic examination showed bilateral aniridia associated with moderate cataract in the right and incipient cataract in the left eye. In the right eye, zonular weakness with incipient capsular displacement and esotropia of delta6 degrees, were noted. The patient underwent phacoemulsification, implantation of capsular tension ring and Artificial Iris implant in the capsular bag. Phacoemulsification went uneventful and early postoperative recovery was successful with no signs of aniridia-associated keratopathy development and normal values of intra ocular pressure. Patient was not motivated for operation of the left eye and it was corrected with soft contact lens. Six month after the operation visual acuity in the right eye improved to 0.9 with +1.25 Dsph and maintained stable in left eye, with complete elimination of esotropia and signs of binocular vision restoration. Small incision cataract extraction with IOL and Artificial Iris implantation in one procedure can be used to correct congenital aniridia and cataract with significant visual function improvement.

  4. Treatment of congenital aniridia associated with subluxated infantile cataract.

    PubMed

    Jusufovic, Vahid; Cabric, Emir; Popovic-Beganovic, Allen; Musanovic, Zlatko; Zvornicanin, Jasmin

    2014-06-01

    A 5 year old boy was presented at Eye clinic University clinical center Tuzla with congenital aniridia in both eyes. Clinical examination revealed visual acuity of 0,08 without correction in right and 0.7 with -5.0 Dsph and -1.0 Dcyl Axx 109° in left eye. Opthalmologic examination showed bilateral aniridia associated with moderate cataract in the right and incipient cataract in the left eye. In the right eye, zonular weakness with incipient capsular displacement and esotropia of Δ6º, were noted. The patient underwent phacoemulsification, implantation of capsular tension ring and Artificial Iris implant in the capsular bag. Phacoemulsification went uneventful and early postoperative recovery was successful with no signs of aniridia-associated keratopathy development and normal values of intra ocular pressure. Patient was not motivated for operation of the left eye and it was corrected with soft contact lens. Six month after the operation visual acuity in the right eye improved to 0.9 with +1.25Dsph and maintained stable in left eye, with complete elimination of esotropia and signs of binocular vision restoration. Small incision cataract extraction with IOL and Artificial Iris implantation in one procedure can be used to correct congenital aniridia and cataract with significant visual function improvement.

  5. Preclinical cataract masquerading as post-LASIK regression

    PubMed Central

    Shetty, Rohit; Negalur, Nikhil; Kurian, Mathew; Shroff, Rushad

    2016-01-01

    The purpose of this case report is to bring forth a rare clinical scenario where preclinical cataract mimics post-LASIK regression and to describe the role of aberrometry in detecting higher order aberrations (HOAs) and early lens changes. A 36-year-old female presented with blurring of vision since 1 year after having undergone an uneventful LASIK surgery 3 years prior. Corneal topography and aberrometry were within normal limits. Although the lens was morphologically normal on slit lamp examination, increased HOAs and lenticular density were detected. Since there were no cataractous changes, the patient was advised regular follow-up. A year later, the patient had developed lenticular changes along with a further increase in aberrations and worsening of scatter on densitometry. Increase in aberrations and lenticular density may serve as a marker for cataract development before clinically detectable lenticular changes. This report shows how preclinical cataract can mimic post-LASIK regression with a change in spherical and cylindrical power of the eye. This could result in patients undergoing re-correction in eyes where the primary pathology is in the lens. PMID:27843230

  6. Posterior Iris Fixated Intraocular Lens for Pediatric Traumatic Cataract

    PubMed Central

    Kavitha, V.; Balasubramanian, Preethi; Heralgi, Mallikarjun M.

    2016-01-01

    Purpose: To evaluate the postoperative visual outcomes and complications of posterior iris fixated intraocular lens (IFIOL) implantation for pediatric traumatic cataract. Methods: A retrospective clinical audit was performed of all the pediatric traumatic cataract patients who underwent lens removal and iris fixated lens implantation due to inadequate capsular support with or without corneal tear repair between January 2009 and December 2013. Data were collected and analyzed on the preoperative and postoperative visual outcomes and complications. Results: Twenty-five children (25 eyes; 21 males and 4 females) were enrolled with the mean age of 11 ± 4.0 years. There were 72% of eyes that underwent primary cataract removal with IFIOL implantation. Twenty-eight percent of eyes underwent corneal tear repair prior to intraocular lens (IOL) implantation. Preoperative best corrected visual acuity (BCVA) was hand motion in 32% eyes, counting fingers in 24%, and perception of light in 44%. Postoperative BCVA of 0-0.2 logarithm of minimum angle of resolution was reported in the 64% of eyes. One eye developed secondary glaucoma, one eye underwent re-enclavation, and none developed retinal complications. Conclusion: Posterior IFIOL implantation resulted in an improved visual outcome, low incidence of postoperative complications, and is a good alternative to other IOL, in the cases of pediatric traumatic cataract without adequate capsular support. PMID:27162456

  7. Gas-permeable cellulose acetate butyrate (CAB) contact lenses.

    PubMed

    Hales, R H

    1977-09-01

    Gas-permeable cellulose acetate butyrate (CAB) contact lenses may often be worn succesfully by aphakic and other patients who are unable to wear hard contact lenses. The comfort characteristics of the CAB lenses are betweeen those of hard and soft contact lenses. They are much more permeable to O2 and CO2 than soft lenses and thus are less apt to cause edema. They are more flexible and more wettable than hard lenses. This study presents 50 patients who, having had to discontinue wearing hard contact lenses because of discomfort, diffuse central corneal edema, or visual problems, were fitted with CAB contact lenses. Thirty of the fifty were able to wear the CAB lenses successfully.

  8. Route visualization using detail lenses.

    PubMed

    Karnick, Pushpak; Cline, David; Jeschke, Stefan; Razdan, Anshuman; Wonka, Peter

    2010-01-01

    We present a method designed to address some limitations of typical route map displays of driving directions. The main goal of our system is to generate a printable version of a route map that shows the overview and detail views of the route within a single, consistent visual frame. Our proposed visualization provides a more intuitive spatial context than a simple list of turns. We present a novel multifocus technique to achieve this goal, where the foci are defined by points of interest (POI) along the route. A detail lens that encapsulates the POI at a finer geospatial scale is created for each focus. The lenses are laid out on the map to avoid occlusion with the route and each other, and to optimally utilize the free space around the route. We define a set of layout metrics to evaluate the quality of a lens layout for a given route map visualization. We compare standard lens layout methods to our proposed method and demonstrate the effectiveness of our method in generating aesthetically pleasing layouts. Finally, we perform a user study to evaluate the effectiveness of our layout choices.

  9. Multi-wavelength applications of gravitational lensing

    NASA Astrophysics Data System (ADS)

    Fadely, Ross

    2010-12-01

    Using an array of multi-wavelength data, we examine a variety of astrophysical problems with gravitational lensing. First, we seek to understand the mass distribution of an early-type galaxy with an analysis of the lens Q0957+561. We dissect the lens galaxy into luminous and dark components, and model the environment using results from weak lensing. Combining constraints from newly-discovered lensed images and stellar population models, we find the lens has a density profile which is shallower than isothermal, unlike those of typical early-type galaxies. Finally, using the measured time delay between the quasar images we find the Hubble constant to be H 0 = 79.3+6.7-8.5 km s-1 Mpc-1 . One intriguing application of lensing is to exploit the lens magnification boost to study high-redshift objects in greater detail than otherwise possible. Here, we analyze the mid-infrared properties of two lensed z ˜ 2 star-forming galaxies, SDSS J120602.09+514229.5 and SDSS J090122.37+181432.3, using Spitzer /IRS spectra to study their rest-frame ˜ 5-12 μm emission. Both systems exhibit strong polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicating strong star formation and the absence of significant AGN activity. For SDSS J090122.37+181432.3, this detection belies that inferred from optical measurements, indicating mid-IR spectroscopy provides key information needed to understand the properties of high-redshift star-forming galaxies. While lensing provides measurements of the macroscopic properties of lens systems, it can also shed light on small-scale structure of galaxies. To identify and understand lens substructure, we examine the multi-wavelength properties of flux ratios for six lenses. Variations of the flux ratios with wavelength can be used to study the lensed quasars and the small-scale mass distribution of lens galaxies. We detect strong multi-wavelength variations in the lenses HE 0435-1223 and SDSS 0806+2006. For HE 0435-1223, we study its

  10. Are hard lenses superior to soft? The advantages of soft lenses.

    PubMed

    Yamane, S J

    1990-01-01

    Soft lenses now account for 85% of all lens sales in the United States and 74% of all sales worldwide. Several factors account for their popularity with patients, practitioners, and lens manufacturers. For patients, soft lenses offer easier adaptation, greater comfort, better appearance, less nighttime flare and spectacle blur, more flexibility in wearing schedule, and less chance of lens loss than polymethylmethacrylate (PMMA) or rigid gas-permeable lenses. Soft lenses also provide the options of disposability and of iris color change. Practitioners prefer soft lenses because they are less likely than hard lenses to cause epithelial staining, corneal molding, corneal edema, corneal desensitivity, or lens overwear syndrome. Furthermore, soft lenses present fewer fitting problems, satisfy therapeutic needs, are easier to stock for replacement purposes, and generally require no in-office modifications. Practitioners also welcome the benefits of disposable lenses: a simple lens care regimen, a decreased potential for deposit buildup, and adaptability to many different lifestyles. Manufacturers like the fact that hydrogels can be stock molded, and that their fitting is easier to teach.

  11. Observation of Influence of Cataract Surgery on the Ocular Surface

    PubMed Central

    Park, Yuli; Hwang, Hyung Bin; Kim, Hyun Seung

    2016-01-01

    Introduction To evaluate meibomian gland function, changes of lacrimal tears and ocular surface parameters and tear inflammatory mediators following cataract surgery. Methods 48 eyes of 34 patients who underwent uncomplicated phacoemulsification were involved and divided into 2 groups with those who had preexisting dry-eye before cataract surgery and those who did not. Ocular symptom score, Schirmer I test, tear film break-up time (TBUT), corneal sensitivity threshold, corneal staining, inflammatory cytokine activities, lid margin abnormalities, meibum expressibility, meibum quality and meibomian gland imaging were evaluated preoperatively, at 1 day, 1 and 2 months postoperatively. Results Ocular symptom scores were worse at 1 and 2 months postoperatively but, TBUT, corneal staining score and corneal sensitivity threshold showed gradual improvements at 1 month and 2 months postoperatively (p<0.05, respectively). Interestingly there were statistically significant improvements in TBUT, corneal staining score and corneal sensitivity threshold at 1 month postoperatively when topical eye drops were used compared to the period without topical therapy which is the months 2 postoperatively. There were statistically significant decreases in IL-1β, IL-6, IL-8, MCP-1, TNF-α and IFN-γ concentrations at 1 and 2 months postoperatively. Lid margin abnormalities, meibum quality and expressibility scores increased significantly (p < 0.05, respectively) at postoperative period. Compared with the no dry eye group, dry eye group revealed significantly higher ocular symptom scores, lower TBUT, higher lid margin abnormalities, meibum quality and expressibility scores after cataract surgery. There were significant correlations between IL-6 and parameters of dry eye, and between MGD parameters and ocular symptom scores. Conclusions Our study revealed that meibomian gland function is influenced after cataract surgery accompanying structural changes and these were correlated with

  12. On the delights of being an ex-cataract patient: Visual experiences before and after cataract operations; what they indicate

    NASA Astrophysics Data System (ADS)

    van Nes, Floris L.

    2014-02-01

    This paper is about changes in the author's visual perception over most of his lifetime, but in particular in the period before and after cataract operations. The author was myopic (-3D) until the operations, and emmetropic afterwards - with mild astigmatic aberrations that can be compensated with cylindrical spectacles, but in his case rarely are, because of the convenience of not needing to wear distance glasses in daily life anymore. The perceptual changes concern color vision, stereopsis and visual acuity. The post-cataract changes were partly expected, for example less yellow and more blue images, but partly wholly unexpected, and accompanied by feelings of excitement and pleasure; even delight. These unexpected changes were a sudden, strongly increased depth vision and the sensation of seeing suddenly sharper than ever before, mainly at intermediate viewing distances. The visual acuity changes occur after, exceptionally, his distance glasses are put on. All these sensations lasted or last only for a short time. Those concerning stereopsis were dubbed 'super depth', and were confined to the first two months after the second cataract operation. Those concerning acuity were termed 'super-sharpness impression'; SSI. These can be elicited more or less at will, by putting on the spectacles described; but will then disappear again, although the spectacles are kept on. Ten other ex-cataract patients have been interviewed on their post-operation experiences. The 'super-depth' and SSI experiences may be linked to assumed neurophysiological mechanisms such as the concept of Bayesian reweighting of perceptual criteria.

  13. Precision cosmology with weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Hearin, Andrew P.

    In recent years, cosmological science has developed a highly predictive model for the universe on large scales that is in quantitative agreement with a wide range of astronomical observations. While the number and diversity of successes of this model provide great confidence that our general picture of cosmology is correct, numerous puzzles remain. In this dissertation, I analyze the potential of planned and near future galaxy surveys to provide new understanding of several unanswered questions in cosmology, and address some of the leading challenges to this observational program. In particular, I study an emerging technique called cosmic shear, the weak gravitational lensing produced by large scale structure. I focus on developing strategies to optimally use the cosmic shear signal observed in galaxy imaging surveys to uncover the physics of dark energy and the early universe. In chapter 1 I give an overview of a few unsolved mysteries in cosmology and I motivate weak lensing as a cosmological probe. I discuss the use of weak lensing as a test of general relativity in chapter 2 and assess the threat to such tests presented by our uncertainty in the physics of galaxy formation. Interpreting the cosmic shear signal requires knowledge of the redshift distribution of the lensed galaxies. This redshift distribution will be significantly uncertain since it must be determined photometrically. In chapter 3 I investigate the influence of photometric redshift errors on our ability to constrain dark energy models with weak lensing. The ability to study dark energy with cosmic shear is also limited by the imprecision in our understanding of the physics of gravitational collapse. In chapter 4 I present the stringent calibration requirements on this source of uncertainty. I study the potential of weak lensing to resolve a debate over a long-standing anomaly in CMB measurements in chapter 5. Finally, in chapter 6 I summarize my findings and conclude with a brief discussion of my

  14. Breaking the imaging symmetry in negative refraction lenses.

    PubMed

    Ma, Changbao; Liu, Zhaowei

    2012-01-30

    Optical lenses are pervasive in various areas of sciences and technologies. It is well known that conventional lenses have symmetrical imaging properties along forward and backward directions. In this letter, we show that hyperbolic plasmonic metamaterial based negative refraction lenses perform as either converging lenses or diverging lenses depending on the illumination directions. New imaging equations and properties that are different from those of all the existing optical lenses are also presented. These new imaging properties, including symmetry breaking as well as the super resolving power, significantly expand the horizon of imaging optics and optical system design.

  15. In vitro water wettability of silicone hydrogel contact lenses determined using the sessile drop and captive bubble techniques.

    PubMed

    Maldonado-Codina, Carole; Morgan, Philip B

    2007-11-01

    This study investigated the water contact angles of five commercially available silicone hydrogel contact lenses (Acuvue Advance, Acuvue Oasys, Focus Night & Day, O2 Optix, and PureVision) using sessile drop and captive bubble techniques. The only lens type that showed a significant difference in water contact angle when measured by sessile drop direct from the blister compared with after 48 h of soaking/washing in saline was the Acuvue Advance lens (from 66 degrees to 96 degrees, respectively) (p=0.0002), presumably because of surface active agents within the blister solution. The water contact angle data split the lenses into two distinct groups (pAdvance, Acuvue Oasys, and PureVision lenses demonstrated relatively high sessile drop measures and relatively low captive bubble values (thereby displaying significant hysteresis) whereas the Focus Night & Day and O2 Optix lenses showed relatively low sessile drop measures and relatively high captive bubble values (with little hysteresis). Contact angle analysis of hydrogel lens surfaces is highly methodologically dependent and may be able to predict the clinical performance of contact lenses in vivo.

  16. Novel phenotypes and loci identified through clinical genomics approaches to pediatric cataract.

    PubMed

    Patel, Nisha; Anand, Deepti; Monies, Dorota; Maddirevula, Sateesh; Khan, Arif O; Algoufi, Talal; Alowain, Mohammed; Faqeih, Eissa; Alshammari, Muneera; Qudair, Ahmed; Alsharif, Hadeel; Aljubran, Fatimah; Alsaif, Hessa S; Ibrahim, Niema; Abdulwahab, Firdous M; Hashem, Mais; Alsedairy, Haifa; Aldahmesh, Mohammed A; Lachke, Salil A; Alkuraya, Fowzan S

    2017-02-01

    Pediatric cataract is highly heterogeneous clinically and etiologically. While mostly isolated, cataract can be part of many multisystem disorders, further complicating the diagnostic process. In this study, we applied genomic tools in the form of a multi-gene panel as well as whole-exome sequencing on unselected cohort of pediatric cataract (166 patients from 74 families). Mutations in previously reported cataract genes were identified in 58% for a total of 43 mutations, including 15 that are novel. GEMIN4 was independently mutated in families with a syndrome of cataract, global developmental delay with or without renal involvement. We also highlight a recognizable syndrome that resembles galactosemia (a fulminant infantile liver disease with cataract) caused by biallelic mutations in CYP51A1. A founder mutation in RIC1 (KIAA1432) was identified in patients with cataract, brain atrophy, microcephaly with or without cleft lip and palate. For non-syndromic pediatric cataract, we map a novel locus in a multiplex consanguineous family on 4p15.32 where exome sequencing revealed a homozygous truncating mutation in TAPT1. We report two further candidates that are biallelically inactivated each in a single cataract family: TAF1A (cataract with global developmental delay) and WDR87 (non-syndromic cataract). In addition to positional mapping data, we use iSyTE developmental lens expression and gene-network analysis to corroborate the proposed link between the novel candidate genes and cataract. Our study expands the phenotypic, allelic and locus heterogeneity of pediatric cataract. The high diagnostic yield of clinical genomics supports the adoption of this approach in this patient group.

  17. Management of advanced corneal ectasias.

    PubMed

    Maharana, Prafulla K; Dubey, Aditi; Jhanji, Vishal; Sharma, Namrata; Das, Sujata; Vajpayee, Rasik B

    2016-01-01

    Corneal ectasias include a group of disorders characterised by progressive thinning, bulging and distortion of the cornea. Keratoconus is the most common disease in this group. Other manifestations include pellucid marginal degeneration, Terrien's marginal degeneration, keratoglobus and ectasias following surgery. Advanced ectasias usually present with loss of vision due to high irregular astigmatism. Management of these disorders is difficult due to the peripheral location of ectasia and associated severe corneal thinning. Newer contact lenses such as scleral lenses are helpful in a selected group of patients. A majority of these cases requires surgical intervention. This review provides an update on the current treatment modalities available for management of advanced corneal ectasias.

  18. Numerical simulation of gravitational lenses

    NASA Astrophysics Data System (ADS)

    Cherniak, Yakov

    Gravitational lens is a massive body or system of bodies with gravitational field that bends directions of light rays propagating nearby. This may cause an observer to see multiple images of a light source, e.g. a star, if there is a gravitational lens between the star and the observer. Light rays that form each individual image may have different distances to travel, which creates time delays between them. In complex gravitational fields generated by the system of stars, analytical calculation of trajectories and light intensities is virtually impossible. Gravitational lens of two massive bodies, one behind another, are able to create four images of a light source. Furthermore, the interaction between the four light beams can form a complicated interference pattern. This article provides a brief theory of light behavior in a gravitational field and describes the algorithm for constructing the trajectories of light rays in a gravitational field, calculating wave fronts and interference pattern of light. If you set gravitational field by any number of transparent and non- transparent objects (stars) and set emitters of radio wave beams, it is possible to calculate the interference pattern in any region of space. The proposed method of calculation can be applied even in the case of the lack of continuity between the position of the emitting stars and position of the resulting image. In this paper we propose methods of optimization, as well as solutions for some problems arising in modeling of gravitational lenses. The simulation of light rays in the sun's gravitational field is taken as an example. Also caustic is constructed for objects with uniform mass distribution.

  19. Pixelation Effects in Weak Lensing

    NASA Technical Reports Server (NTRS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-01-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, and Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09' for a 0.14' FWHM point-spread function (PSF). The pixel scale could be increased to 0.16' if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  20. The structural alteration and aggregation propensity of glycated lens crystallins in the presence of calcium: Importance of lens calcium homeostasis in development of diabetic cataracts

    NASA Astrophysics Data System (ADS)

    ZM, Sara Zafaranchi; Khoshaman, Kazem; Masoudi, Raheleh; Hemmateenejad, Bahram; Yousefi, Reza

    2017-01-01

    The imbalance of the calcium homeostasis in the lenticular tissues of diabetic patients is an important risk factor for development of cataract diseases. In the current study, the impact of elevated levels of calcium ions were investigated on structure and aggregation propensity of glycated lens crystallins using gel electrophoresis and spectroscopic assessments. The glycated proteins indicated significant resistance against calcium-induced structural insults and aggregation. While, glycated crystallins revealed an increased conformational stability; a slight instability was observed for these proteins upon interaction with calcium ions. Also, in the presence of calcium, the proteolytic pattern of native crystallins was altered and that of glycated protein counterparts remained almost unchanged. According to results of this study it is suggested that the structural alteration of lens crystallins upon glycation may significantly reduce their calcium buffering capacity in eye lenses. Therefore, under chronic hyperglycemia accumulation of this cataractogenic metal ion in the lenticular tissues may subsequently culminate in activation of different pathogenic pathways, leading to development of lens opacity and cataract diseases.