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Sample records for laser induced glaucoma

  1. Pattern-evoked potentials and optic nerve fiber loss in monocular laser-induced glaucoma

    SciTech Connect

    Johnson, M.A.; Drum, B.A.; Quigley, H.A.; Sanchez, R.M.; Dunkelberger, G.R.

    1989-05-01

    ERG and VEP responses to counterphase checkerboard stimuli were obtained from cynomolgus monkeys with monocular glaucoma induced by laser photocoagulation of the trabecular meshwork. The glaucomatous eyes showed reductions of PERG amplitude that were directly related to the histologically defined nerve damage. VEP amplitudes were also reduced in the glaucomatous eyes, but were more variable and less affected by damage than the PERG responses. An acute increase in eye pressure to 40 mm Hg in eyes without damage had no detectable effect on PERG amplitudes.

  2. Ultrastructural and pharmacologic studies on laser-induced glaucoma in primates and rabbits

    SciTech Connect

    March, W.F.; Gherezghiher, T.; Koss, M.; Nordquist, R.

    1984-01-01

    Sustained high intraocular pressure resulting in optic nerve cupping and loss of ganglion cells was produced in five rhesus monkeys and eight pigmented rabbits by applying argon laser energy to the trabecular meshwork. In addition, the rabbits manifested buphthalmus. Flow of carbon particles subsequently injected into the anterior chamber was obstructed at the trabecular meshwork by a wound-healing response that closed the intratrabecular spaces. Besides this sustained high intraocular pressure as a result of late scarring, an acute hypertensive response was seen in all rabbits which may correspond to the acute hypertension seen after laser trabeculoplasty in humans. The acute hypertensive response could be only partially blocked by prostaglandin inhibitors and the authors believe that prostaglandins are not primarily responsible for this effect. Medications known to lower intraocular pressure were systematically tested in both glaucoma models.

  3. Glaucoma.

    PubMed

    Gupta, Divakar; Chen, Philip P

    2016-04-15

    Glaucoma is a set of irreversible, progressive optic neuropathies that can lead to severe visual field loss and blindness. The two most common forms of glaucoma, primary open-angle glaucoma and primary angle-closure glaucoma, affect more than 2 million Americans and are increasing in prevalence. Many patients with glaucoma are asymptomatic and do not know they have the disease. Risk factors for primary open-angle glaucoma include older age, black race, Hispanic origin, family history of glaucoma, and diabetes mellitus. Risk factors for primary angle-closure glaucoma include older age, Asian descent, and female sex. Advanced disease at initial presentation and treatment nonadherence put patients with glaucoma at risk of disease progression to blindness. The U.S. Preventive Services Task Force has concluded that the evidence is insufficient to assess the potential benefits and harms of screening for glaucoma in the primary care setting. Regular eye examinations for adults are recommended by the American Academy of Ophthalmology, with the interval depending on patient age and risk factors. Diagnosis of glaucoma requires careful optic nerve evaluation and functional studies assessing a patient's visual field. The goal of treatment with eye drops, laser therapy, or surgery is to slow visual field loss by lowering intraocular pressure. Family physicians can contribute to lowering morbidity from glaucoma through early identification of high-risk patients and by emphasizing treatment adherence in patients with glaucoma. PMID:27175839

  4. Non-steroidal drug-induced glaucoma

    PubMed Central

    Razeghinejad, M R; Pro, M J; Katz, L J

    2011-01-01

    Numerous systemically used drugs are involved in drug-induced glaucoma. Most reported cases of non-steroidal drug-induced glaucoma are closed-angle glaucoma (CAG). Indeed, many routinely used drugs that have sympathomimetic or parasympatholytic properties can cause pupillary block CAG in individuals with narrow iridocorneal angle. The resulting acute glaucoma occurs much more commonly unilaterally and only rarely bilaterally. CAG secondary to sulfa drugs is a bilateral non-pupillary block type and is due to forward movement of iris–lens diaphragm, which occurs in individuals with narrow or open iridocorneal angle. A few agents, including antineoplastics, may induce open-angle glaucoma. In conclusion, the majority of cases with glaucoma secondary to non-steroidal medications are of the pupillary block closed-angle type and preventable if the at-risk patients are recognized and treated prophylactically. PMID:21637303

  5. Lasers in the treatment of glaucoma

    NASA Astrophysics Data System (ADS)

    Kecik, Tadeusz

    1995-03-01

    The task of the laser methods of glaucoma treatment used up to the present day is to reduce the intraocular pressure. They are the modification of the surgical procedures. The radiation of the laser is the tool that enables us to perform the procedure in a more precise and safe manner. Most of the procedures are ambulatory, thus, making the expenses for the treatment lower. The results of the treatment are satisfactory, and in many cases, enable the patient to avoid surgical procedures. In practice, for the anti-glaucoma procedures the argon laser, YAG Nd+3, of free generation, and Q-switch, Holm laser, are being used. The perspectives to use other lasers also exist.

  6. Copper vapor laser prospects in glaucoma treatment

    NASA Astrophysics Data System (ADS)

    Egorov, E. A.; Nesterov, Arcady P.; Novoderezhkin, Vladimir I.; Egorov, Alexey E.; Shaban, Naim; Ponomarev, Igor V.

    1996-05-01

    New advances of copper vapor laser (CVL-laser) have been studied. Two wavelength radiation of the laser (511 nm and 578 nm) gives deeper permeability into organic tissues. Besides, the short pulse prevents the warm relaxation of small vessels. The technical data of CVL-laser: operating regime -- pulse, pulse duration -- 20 ns, pulse frequency 15000 pulse/sec. The shutter works in intervals from 0.05 to 2.0 sec. The power varies in accordance with wavelength: 511 nm (green) -- 1.5 W, 578 nm (yellow) -- 1, 2 W. The diameter of coagulate may be different: 100, 150, 400, 1000 mkm. We chose CVL-laser 'Femta,' created by P. N. Lebedev Physical Institute of RAS, for ophthalmological use. Thirty eight eyes of 37 patients with different types and stages of glaucoma were studied and treated with CVL-laser. The operations of photomydriasis, gonioplasty and trabeculoplasty have been performed. CVL- laser demonstrated efficient application in treatment of interior eye segment of glaucoma patients. The advantages and disadvantages of the CVL-laser application in glaucoma surgery were discussed.

  7. Glaucoma

    MedlinePlus

    ... version of this page please turn Javascript on. Glaucoma What is Glaucoma? Glaucoma is a group of diseases that can ... is much greater for people over 60. How Glaucoma Develops There are several different types of glaucoma. ...

  8. Glaucoma

    PubMed Central

    2009-01-01

    Introduction Glaucoma is characterised by progressive optic neuropathy and peripheral visual field loss. It affects 1% to 2% of white people aged over 40 years and accounts for 8% of new blind registrations in the UK. The main risk factor for glaucoma is raised intraocular pressure, but 40% of people with glaucoma have normal intraocular pressure and only 10% of people with raised intraocular pressure are at risk of optic-nerve damage. Glaucoma is more prevalent, presents earlier, and is more difficult to control in black people than in white populations. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for established primary open-angle glaucoma, ocular hypertension, or both? What are the effects of lowering intraocular pressure in people with normal-tension glaucoma? What are the effects of treatment for acute angle-closure glaucoma? We searched: Medline, Embase, The Cochrane Library, and other important databases up to November 2007 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 20 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: laser trabeculoplasty (alone or plus topical medical treatment); topical medical treatments; and surgical trabeculectomy.

  9. Glaucoma

    PubMed Central

    2011-01-01

    Introduction Glaucoma is characterised by progressive optic neuropathy and peripheral visual field loss. It affects 1% to 2% of white people aged over 40 years and accounts for 8% of new blind registrations in the UK. The main risk factor for glaucoma is raised intraocular pressure, but 40% of people with glaucoma have normal intraocular pressure and only 10% of people with raised intraocular pressure are at risk of optic-nerve damage. Glaucoma is more prevalent, presents earlier, and is more difficult to control in black people than in white populations. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for established primary open-angle glaucoma, ocular hypertension, or both? What are the effects of lowering intraocular pressure in people with normal-tension glaucoma? What are the effects of treatment for acute angle-closure glaucoma? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 12 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: laser trabeculoplasty (alone or plus topical medical treatment), topical medical treatments, and surgical trabeculectomy. PMID:21658300

  10. Experimental Contact Lens to Prevent Glaucoma-Induced Blindness

    MedlinePlus

    ... Articles | Inside Life Science Home Page An Experimental Contact Lens to Prevent Glaucoma-Induced Blindness By Sharon Reynolds Posted January 23, 2014 An experimental contact lens design releases a glaucoma medicine at a ...

  11. Ocular-specific ER stress reduction rescues glaucoma in murine glucocorticoid-induced glaucoma

    PubMed Central

    Zode, Gulab S.; Sharma, Arti B.; Lin, Xiaolei; Searby, Charles C.; Bugge, Kevin; Kim, Gun Hee; Clark, Abbot F.; Sheffield, Val C.

    2014-01-01

    Administration of glucocorticoids induces ocular hypertension in some patients. If untreated, these patients can develop a secondary glaucoma that resembles primary open-angle glaucoma (POAG). The underlying pathology of glucocorticoid-induced glaucoma is not fully understood, due in part to lack of an appropriate animal model. Here, we developed a murine model of glucocorticoid-induced glaucoma that exhibits glaucoma features that are observed in patients. Treatment of WT mice with topical ocular 0.1% dexamethasone led to elevation of intraocular pressure (IOP), functional and structural loss of retinal ganglion cells, and axonal degeneration, resembling glucocorticoid-induced glaucoma in human patients. Furthermore, dexamethasone-induced ocular hypertension was associated with chronic ER stress of the trabecular meshwork (TM). Similar to patients, withdrawal of dexamethasone treatment reduced elevated IOP and ER stress in this animal model. Dexamethasone induced the transcriptional factor CHOP, a marker for chronic ER stress, in the anterior segment tissues, and Chop deletion reduced ER stress in these tissues and prevented dexamethasone-induced ocular hypertension. Furthermore, reduction of ER stress in the TM with sodium 4-phenylbutyrate prevented dexamethasone-induced ocular hypertension in WT mice. Our data indicate that ER stress contributes to glucocorticoid-induced ocular hypertension and suggest that reducing ER stress has potential as a therapeutic strategy for treating glucocorticoid-induced glaucoma. PMID:24691439

  12. Current and Future of Laser Therapy in the Management of Glaucoma

    PubMed Central

    Ekici, Feyzahan; Waisbourd, Michael; Katz, L. Jay

    2016-01-01

    There has been tremendous progress in the past decades in the utilization of lasers for treating patients with glaucoma. This article reviews the use of lasers in different areas of glaucoma, including the shift from argon laser trabeculoplasty (ALT) to selective laser trabeculoplasty (SLT), laser trabeculoplasty as an initial treatment for glaucoma, new laser trabeculoplasty procedures under investigation, and other recent laser treatment modalities such as endoscopic cyclophotocoagulation and laser-assisted deep sclerectomy. PMID:27014388

  13. Experimentally Induced Mammalian Models of Glaucoma

    PubMed Central

    Yoshitomi, Takeshi; Zorumski, Charles F.; Izumi, Yukitoshi

    2015-01-01

    A wide variety of animal models have been used to study glaucoma. Although these models provide valuable information about the disease, there is still no ideal model for studying glaucoma due to its complex pathogenesis. Animal models for glaucoma are pivotal for clarifying glaucoma etiology and for developing novel therapeutic strategies to halt disease progression. In this review paper, we summarize some of the major findings obtained in various glaucoma models and examine the strengths and limitations of these models. PMID:26064891

  14. Glaucoma

    MedlinePlus

    ... vision Nausea and vomiting Rainbow-like halos around lights Red eye Eye feels swollen CONGENITAL GLAUCOMA Symptoms are most ... Enlargement of 1 eye or both eyes Red eye Sensitivity to light Tearing SECONDARY GLAUCOMA Symptoms are most often related ...

  15. Glaucoma

    MedlinePlus

    Glaucoma is a group of diseases that can damage the eye's optic nerve. It is a leading ... no symptoms at first. Without treatment, people with glaucoma will slowly lose their peripheral, or side vision. ...

  16. Transscleral laser cyclocoagulation in treatment of noncompensated glaucoma

    NASA Astrophysics Data System (ADS)

    Bakutkin, Valery V.; Karimov, Ravil N.; Tcherviakova, Olga V.

    2001-05-01

    The object of the present study is to estimate the impact of transscleral laser cyclocoagulation as a treatment for patients with non-compensated glaucoma and low visual functions. The effectiveness of the given treatment is estimated by the use of multiple statistical methods, including correlation, multiple regression and discriminant analysis. The results meaningfully confirm the effectiveness of laser surgery in non-compensated open-angle (stage III) glaucoma treatment, whilst the developed mathematical model of correlation between intra-eye liquid production and key operation parameters can be successfully used to control the process of liquid production.

  17. Laser Activated Flow Regulator for Glaucoma Drainage Devices

    PubMed Central

    Olson, Jeffrey L.; Velez-Montoya, Raul; Bhandari, Ramanath

    2014-01-01

    Purpose To assess the capabilities of a new glaucoma drainage device regulator in controlling fluid flow as well as to demonstrate that this effect may be titratable by noninvasive means. Methods A rigid eye model with two main ports was used. On the first port, we placed a saline solution column. On the second, we placed a glaucoma shunt. We then measured the flow and flow rate through the system. After placing the regulator device on the tip of the tube, we measured again with the intact membrane and with the membrane open 50% and 100%. For the ex vivo testing we used a similar setting, using a cadaveric porcine eye, we measured again the flow and flow rate. However, this time we opened the membrane gradually using laser shots. A one-way analysis of variance and a Fisher's Least Significant Difference test were used for statistical significance. We also calculated the correlation between the numbers of laser shots applied and the main outcomes. Results The flow through the system with the glaucoma drainage device regulator (membrane intact and 50% open) was statistically lower than with the membrane open 100% and without device (P < 0.05). The flow was successfully controlled by the number of laser shots applied, and showed a positive correlation (+ 0.9). The flow rate was almost doubled every 10 shots and statistically lower than without device at all time (P < 0.05). Conclusions The glaucoma drainage device regulator can be controlled noninvasively with laser, and allows titratable control of aqueous flow. Translational Relevance Initial results and evidence from this experiment will justify the initiation of in vivo animal trials with the glaucoma drainage device regulator; which brings us closer to possible human trials and the chance to significantly improve the existing technology to treat glaucoma surgically. PMID:25374772

  18. Glaucoma

    MedlinePlus Videos and Cool Tools

    ... Funding Division of Extramural Activities Division of Extramural Science Programs Funding Opportunity Announcements Funding Mechanisms Supported by ... Amaurosis Low Vision Refractive Errors Retinopathy of Prematurity Science Spanish Videos Webinars NEI YouTube Videos: Glaucoma NEI ...

  19. Comparison of selective laser trabeculoplasty (SLT) in primary open angle glaucoma and pseudoexfoliation glaucoma

    PubMed Central

    Ayala, Marcelo; Chen, Enping

    2011-01-01

    Background and objective The aim of the present study was to compare intraocular pressure (IOP) reduction and inflammation after selective laser trabeculoplasty (SLT) treatment in patients suffering from primary open angle (POAG) vs pseudoexfoliative (PXFG) glaucoma. Study design/patients and methods Sixty patients (60 eyes) participated in the study. Glaucoma patients (POAG or PXFG) scheduled for treatment with SLT were included. Inflammation was measured with a laser flare meter (Kowa FM-500). Measurements were made before SLT and 2 hours, 1 week, and 1 month after SLT treatment. IOP was also checked at the same time intervals. Results Inflammation after SLT showed no significant difference between the groups (t-test, before: P = 0.16; 2 hours: P = 0.14; 1 week: P = 0.12; and 1 month: P = 0.36). IOP reduction was the same in both groups (t-test, P = 0.27). Conclusion SLT safely reduces IOP in both POAG and PXFG. Pseudoexfoliation does not seem to be a risk factor for post-laser complications. PMID:22069348

  20. Glaucoma

    MedlinePlus

    ... and angle. Anything that slows or blocks the flow of this fluid will cause pressure to build up in the ... a painless laser to open the channels where fluid flows out. If drops and laser treatment do not ...

  1. Drug-Induced Ocular Hypertension and Angle-Closure Glaucoma.

    PubMed

    Badhu, Badri P; Bhattarai, Balkrishna; Sangraula, Himal P

    2013-01-01

    The objective of this study was to review the available literature on the drugs causing ocular hypertension and glaucoma. Electronic literature search was carried out using the Web sites www.pubmed.gov and www.google.com published through the year 2011. The search words were "drug induced ocular hypertension" and "drug induced glaucoma" used in combination. The articles published or translated into English were studied. Quite a significant number of drugs commonly prescribed by various physicians of different specialties can induce ocular hypertension or glaucoma. A brief account of various drugs that can induce ocular hypertension has been given in this article. Those drugs are parasympatholytics; steroids; anticholinergics, adrenergics, and antidepressants; cholinomimetics; antineoplastic agents; antipsychotic and antiparkinsonism agents; H1 and H2 receptor blockers; botulinum toxin, cardiac agents, and anticoagulants; silicone oil; sulfa drugs; and anesthetic agents. Rational use of these drugs and knowledge of their potential adverse effects can help prevent the devastating complications resulting in loss of vision and compromised quality of life. PMID:26108110

  2. Selective Laser Trabeculoplasty as Primary Treatment for Open-Angle Glaucoma.

    PubMed

    Kadasi, Laith M; Wagdi, Safa; Miller, Kimberly V

    2016-01-01

    Open-angle glaucoma is a silent, chronic disorder which results in progressive and permanent vision loss. Designing the optimal treatment regimen can be particularly challenging in the management of high-risk patients with frequent loss to follow-up or a longstanding history of medication noncompliance. In this article we aim to review fundamental techniques in glaucoma diagnosis and treatment with emphasis on the strengths and weaknesses of selective laser trabeculoplasty, a technique in modern therapy which may mold the future of primary treatment in open angle glaucoma management. [Full article available at http://rimed.org/rimedicaljournal-2016-06.asp, free with no login]. PMID:27247968

  3. Interface Fluid Syndrome Induced by Uncontrolled Intraocular Pressure Without Triggering Factors After LASIK in a Glaucoma Patient

    PubMed Central

    Shoji, Nobuyuki; Ishida, Akira; Haruki, Takahiro; Matsumura, Kazuhiro; Kasahara, Masayuki; Shimizu, Kimiya

    2015-01-01

    Abstract This study sought to describe a glaucoma patient with interface fluid syndrome (IFS) induced by uncontrolled intraocular pressure (IOP) without triggering factors after laser in situ keratomileusis (LASIK). Case report and review of the literature. A 23-year-old man with open-angle glaucoma underwent bilateral LASIK for myopia in 2009. Two years later, the patient reported sudden vision loss. The IOP in the right eye was not measurable using Goldmann applanation tonometry (GAT), but was determined to be 33.7 mm Hg using a noncontact tonometer. IFS was diagnosed based on the presence of space-occupying interface fluid on anterior segment optical coherence tomography images. After a trabeculectomy was performed, the IOP decreased to 10 mm Hg, and GAT measurement became possible. However, the corneal fold remained visible in the flap interface. Six months later, the IOP in the left eye increased, and a trabeculectomy was performed during the early stages of this increase in IOP. Following this procedure, the IOP decreased, and visual acuity remained stable. In glaucoma cases that involve a prior increase in IOP, IOP can continue to increase during the disease course even if temporary control of IOP has been achieved. If LASIK is performed in such cases, the treatment of glaucoma becomes insufficient because of underestimation of the typical IOP. In fact, the measurement of IOP can become difficult because of high-IOP levels. Therefore, LASIK should not be performed on patients with glaucoma who are at high risk of elevated IOP. PMID:26426645

  4. Interface Fluid Syndrome Induced by Uncontrolled Intraocular Pressure Without Triggering Factors After LASIK in a Glaucoma Patient: A Case Report.

    PubMed

    Shoji, Nobuyuki; Ishida, Akira; Haruki, Takahiro; Matsumura, Kazuhiro; Kasahara, Masayuki; Shimizu, Kimiya

    2015-09-01

    This study sought to describe a glaucoma patient with interface fluid syndrome (IFS) induced by uncontrolled intraocular pressure (IOP) without triggering factors after laser in situ keratomileusis (LASIK). Case report and review of the literature. A 23-year-old man with open-angle glaucoma underwent bilateral LASIK for myopia in 2009. Two years later, the patient reported sudden vision loss. The IOP in the right eye was not measurable using Goldmann applanation tonometry (GAT), but was determined to be 33.7 mm Hg using a noncontact tonometer. IFS was diagnosed based on the presence of space-occupying interface fluid on anterior segment optical coherence tomography images. After a trabeculectomy was performed, the IOP decreased to 10 mm Hg, and GAT measurement became possible. However, the corneal fold remained visible in the flap interface. Six months later, the IOP in the left eye increased, and a trabeculectomy was performed during the early stages of this increase in IOP. Following this procedure, the IOP decreased, and visual acuity remained stable. In glaucoma cases that involve a prior increase in IOP, IOP can continue to increase during the disease course even if temporary control of IOP has been achieved. If LASIK is performed in such cases, the treatment of glaucoma becomes insufficient because of underestimation of the typical IOP. In fact, the measurement of IOP can become difficult because of high-IOP levels. Therefore, LASIK should not be performed on patients with glaucoma who are at high risk of elevated IOP. PMID:26426645

  5. Bilateral, Simultaneous, Acute Angle Closure Glaucoma in Pseudophakia Induced by Chlorthalidone

    PubMed Central

    Durai, Indra; Mohan Dhavalikar, Mrunali; Anand, Chandran Prem; Ganesh, Venkatraman; Krishnadas, Ramaswami

    2016-01-01

    Purpose. To report two persons with acute, bilateral, and simultaneous angle closure glaucoma in pseudophakia secondary to uveal effusions induced by administration of chlorthalidone. Methods. Case reports. Results. Bilateral shallow anterior chambers and high intraocular pressure with decline in visual acuity were reported in two patients within days of intake of chlorthalidone for systemic hypertension. Gonioscopy confirmed appositional angle closure while choroidal detachment and ciliochoroidal detachment were revealed on ultrasonographic studies. Discontinuing chlorthalidone and institution of aqueous suppressants to reduce IOP and cycloplegics reversed angle closure and glaucoma. Conclusions. Reports of angle closure glaucoma in pseudophakic eyes induced by idiosyncratic reaction to chlorthalidone confirms that osmotic changes in the crystalline lens has no role in the pathogenesis of drug induced glaucoma and reaffirms that glaucoma is secondary to ciliochoroidal detachment and ciliary body rotation and edema. PMID:27274878

  6. Scanning laser polarimetry of the peripapillar retinal nerve fiber layer in glaucoma cases

    NASA Astrophysics Data System (ADS)

    Janiec, Slawomir; Rzendkowski, Marek; Gierek-Ciaciura, Stanislawa; Szymkowiak, Monika; Momot-Kawalska, Barbara

    1998-10-01

    Scanning laser polarimetry is the method of evaluating the thickness of the retinal nerve fiber layer. Different pathologies damage retinal fibers, but in glaucoma the damage is present very often before other symptoms reveal. As the earliest possible diagnosis of glaucoma is essential for treatment results, scanning laser polarimetry offers a very useful diagnostic tool for ophthalmology. This paper describes the principles of the method and discusses the results obtained in 50 glaucomatous eyes in conjunction with 2- and 3-D topographical parameters of the optic disc.

  7. Femtosecond laser for glaucoma treatment: the comparison between simulation and experimentation results on ocular tissue removal

    NASA Astrophysics Data System (ADS)

    Hou, Dong Xia; Ngoi, Bryan K. A.; Hoh, Sek Tien; Koh, Lee Huat K.; Deng, Yuan Zi

    2005-04-01

    In ophthalmology, the use of femtosecond lasers is receiving more attention than ever due to its extremely high intensity and ultra short pulse duration. It opens the highly beneficial possibilities for minimized side effects during surgery process, and one of the specific areas is laser surgery in glaucoma treatment. However, the sophisticated femtosecond laser-ocular tissue interaction mechanism hampers the clinical application of femtosecond laser to treat glaucoma. The potential contribution in this work lies in the fact, that this is the first time a modified moving breakdown theory is applied, which is appropriate for femtosecond time scale, to analyze femtosecond laser-ocular tissue interaction mechanism. Based on this theory, energy deposition and corresponding thermal increase are studied by both simulation and experimentation. A simulation model was developed using Matlab software, and the simulation result was validated through in-vitro laser-tissue interaction experiment using pig iris. By comparing the theoretical and experimental results, it is shown that femtosecond laser can obtain determined ocular tissue removal, and the thermal damage is evidently reduced. This result provides a promising potential for femtosecond laser in glaucoma treatment.

  8. Laser Cyclophotocoagulation Enhances the Regulative Capacity of Retinal Vessels in Glaucoma

    PubMed Central

    Kremmer, Stephan; Anastassiou, Gerasimos; Schallenberg, Maurice; Steuhl, Klaus-Peter; W, Vilser; J, Michael Selbach

    2014-01-01

    Purpose: To determine the effects of laser surgical IOP reduction by means of transscleral cyclophotocoagulation (CPC) on retinal blood flow parameters in glaucoma patients using Dynamic Vessel Analysis (DVA). Materials and Methodology: 26 patients (average age: 70 years) with a long history of primary open angle glaucoma underwent CPC. The effect on the reactive capacity of retinal vessels was assessed before and 6-8 weeks after CPC by means of the Dynamic Vessel Analyzer (DVA) using flicker light provocation. Results: In our group of POAG patients, IOP was significantly reduced about approximately 20% by CPC while systemic blood pressure and heart rate were not changed. The most obvious differences between the pre- and postoperative DVA measurements could be observed in the maximal dilation of the retinal arteries which increased from 0.75 % (+/- 0.6) to 3.17 % (+/- 0.5) with an average increase of 2.4 % (p<0.01). In addition, the ability of the arteries for constriction improved significantly (p<0.05) while the dynamic responses of the veins and the initial baseline values (MU) of the vessel diameters did not change. Conclusions: Our results of DVA measurements after an IOP-lowering laser surgical intervention (CPC) reveal a significant recovery of the regulative capacity of retinal arteries in glaucoma patients that has up to now neither been properly documented nor appreciated. Future studies with long-term follow-up must determine the clinical importance of these findings for the treatment of glaucoma patients. PMID:25067978

  9. Inflammatory glaucoma

    PubMed Central

    Bodh, Sonam A.; Kumar, Vasu; Raina, Usha K.; Ghosh, B.; Thakar, Meenakshi

    2011-01-01

    Glaucoma is seen in about 20% of the patients with uveitis. Anterior uveitis may be acute, subacute, or chronic. The mechanisms by which iridocyclitis leads to obstruction of aqueous outflow include acute, usually reversible forms (e.g., accumulation of inflammatory elements in the intertrabecular spaces, edema of the trabecular lamellae, or angle closure due to ciliary body swelling) and chronic forms (e.g., scar formation or membrane overgrowth in the anterior chamber angle). Careful history and follow-up helps distinguish steroid-induced glaucoma from uveitic glaucoma. Treatment of combined iridocyclitis and glaucoma involves steroidal and nonsteroidal antiinflammatory agents and antiglaucoma drugs. However, glaucoma drugs can often have an unpredictable effect on intraocular pressure (IOP) in the setting of uveitis. Surgical intervention is required in case of medical failure. Method of Literature Search: Literature on the Medline database was searched using the PubMed interface. PMID:21713239

  10. Glaucoma-inducing Procedure in an In Vivo Rat Model and Whole-mount Retina Preparation.

    PubMed

    Gossman, Cynthia A; Linn, David M; Linn, Cindy

    2016-01-01

    Glaucoma is a disease of the central nervous system affecting retinal ganglion cells (RGCs). RGC axons making up the optic nerve carry visual input to the brain for visual perception. Damage to RGCs and their axons leads to vision loss and/or blindness. Although the specific cause of glaucoma is unknown, the primary risk factor for the disease is an elevated intraocular pressure. Glaucoma-inducing procedures in animal models are a valuable tool to researchers studying the mechanism of RGC death. Such information can lead to the development of effective neuroprotective treatments that could aid in the prevention of vision loss. The protocol in this paper describes a method of inducing glaucoma - like conditions in an in vivo rat model where 50 µl of 2 M hypertonic saline is injected into the episcleral venous plexus. Blanching of the vessels indicates successful injection. This procedure causes loss of RGCs to simulate glaucoma. One month following injection, animals are sacrificed and eyes are removed. Next, the cornea, lens, and vitreous are removed to make an eyecup. The retina is then peeled from the back of the eye and pinned onto sylgard dishes using cactus needles. At this point, neurons in the retina can be stained for analysis. Results from this lab show that approximately 25% of RGCs are lost within one month of the procedure when compared to internal controls. This procedure allows for quantitative analysis of retinal ganglion cell death in an in vivo rat glaucoma model. PMID:27023167

  11. Laser sclerectomy and 5-FU controlled-drug-release biodegradable implant for glaucoma therapy

    NASA Astrophysics Data System (ADS)

    Villain, Franck L.; Parel, Jean-Marie A.; Kiss, Katalin; Parrish, Richard K.; Kuhne, Francois; Takesue, Yoshiko; Hostyn, Patrick

    1993-06-01

    Laser sclerectomy, a simple filtering procedure performed to alleviate high intraocular pressure in glaucoma patients, was taught to offer longer lasting effect and therefore improve the patient's outcome when compared with the standard trabeculectomy procedure. Recent clinical trials have shown that this was not the case and pharmacologic wound healing modulation is also required with this new procedure. Five-Fluorouracil (5-FU) is useful as an adjunct treatment for glaucoma filtering surgery. However, efficacy depends upon maintaining sustained drug levels, currently achieved by repeated daily injection of the drug for several weeks. To overcome this limitation, we designed a biodegradable implant for the sustained release of 5-FU. After laser sclerectomy, the implant is inserted through the same 1 mm wide conjunctival snip incision and positioned below the open channel. Implantation takes less than a minute. The implant releases the drug for over 15 days and totally biodegrades in less than 100 days. The combined laser surgery and implantation procedure show great potentials for the treatment of glaucoma.

  12. Question on clinical efficiency and principles of diode laser radiation activity at a primary open-angle glaucoma

    NASA Astrophysics Data System (ADS)

    Bolshunov, A. V.; Litvinova, G. G.; Ilyina, O. S.; Easakiva, A. L.; Fyodorov, A. A.; Poleva, R. P.

    1999-07-01

    The efficiency of a diode laser with a wavelength 0,81 microns in treatment of an open-angle glaucoma is investigated. The diode LTP is a pathogenesis oriented method of treatment of an open angle glaucoma: it gives in improvement of outflow of an intraocular fluid, stabilization and improvement of visual functions for patients with initial and developed stages of disease at term of observation up to 12 months.

  13. Selective laser trabeculoplasty in patients with pseudoexfoliative glaucoma vs primary open angle glaucoma: a one-year comparative study

    PubMed Central

    Miraftabi, Arezoo; Nilforushan, Naveed; Nassiri, Nariman; Nouri-Mahdavi, Kouros

    2016-01-01

    AIM To compare the efficacy of single-session 360-degree selective laser trabeculoplasty (SLT) for reduction of intraocular pressure (IOP) in patients with pseudoexfoliative glaucoma (PXFG) and primary open angle glaucoma (POAG). METHODS This is a single-center, prospective, nonrandomized comparative study. Patients older than 18 years of age with uncontrolled PXFG or POAG eyes requiring additional therapy while on maximally tolerated IOP-lowering medications were included. The primary outcome measure changed in IOP from baseline. Success was defined as IOP reduction ≥20% from baseline without any additional IOP-lowering medication. All patients were examined at 1d, 1wk, 1, 3, 6, 9, 12mo after SLT. RESULTS Nineteen patients (20 eyes) with PXFG and 27 patients (28 eyes) with POAG were included in the study. In the visual fields mean deviation was -2.88 (±1.67) in the POAG and -3.1 (±1.69) in the PXFG groups (P=0.3). The mean (±SD) IOP was 22.9 (±3.7) mm Hg in the POAG group and 25.7 (±4.4) mm Hg in the PXFG group at baseline and decreased to 18.4 (±3.2) and 18.0 (±3.9) mm Hg in the POAG group (P<0.001 and P=0.02), and to 17.9 (±4.0) and 21.0 (±6.6) mm Hg in the PXFG group (P<0.001 and P=0.47) at 6 and 12mo, respectively. The number of medications was 2.6 (±0.8) in the POAG group and 2.5 (±0.8) in the PXFG group at baseline, and did not change at all follow-up visits in both groups (P=0.16 in POAG and 0.57 in PXFG). Based on Kaplan-Meier survival analysis, the success rate was 75% in the POAG group compared to 94.1% in the PXFG group (P=0.08; log rank test) at 6mo, and 29.1% and 25.0% at 12mo, respectively (P=0.9; log rank). CONCLUSION The 360-degree SLT is an effective and well-tolerated therapeutic modality in patients with POAG and PXFG by reducing IOP without any change in number of medications. The response was more pronounced early in the postoperative period in patients with PXFG whereas there was no statistically significant difference at 12

  14. Controlled five-year follow-up study of laser trabeculoplasty as primary therapy for open-angle glaucoma

    SciTech Connect

    Tuulonen, A.; Niva, A.K.; Alanko, H.I.

    1987-10-15

    We followed up 32 eyes of 32 patients with early glaucoma (22 with capsular glaucoma and ten with simple glaucoma) who received laser trabeculoplasty as a primary therapy. These eyes were compared with a matched control group of 32 eyes treated with medication initially. The success rate (intraocular pressure below 22 mm Hg with laser alone or medication alone) at five years was 50% (16 of 32 eyes) in the laser-treated group and 22% (seven of 32 eyes) in the control group (P less than .02). The control group required more modifications of their therapy to control intraocular pressure. The neuroretinal rim area in the control eyes decreased 2.5 times as much as in the laser group (P = .017). Changes in the Friedmann visual fields did not differ significantly between the two groups.

  15. Trans-scleral diode laser cyclophotocoagulation for refractory glaucoma after high-risk penetrating keratoplasty.

    PubMed

    Rodríguez-García, Alejandro; González-González, Luis Alonso; Carlos Alvarez-Guzmán, J

    2016-06-01

    To analyze the intraocular pressure reduction, number of anti-glaucoma medications needed, and post-operative complications of trans-scleral diode laser cyclophotocoagulation (DCPC) in patients with high-risk penetrating keratoplasty (PKP) and secondary refractory glaucoma. Prospective interventional, longitudinal, non-comparative series of cases, including 16 eyes of 15 patient's post-PKP on maximal anti-glaucoma medical therapy with intraocular pressures above 22 mmHg. All patients received 18 shots, 360° peri-limbal (avoiding the long posterior ciliary nerves and arteries at 3 and 9 o'clock positions) of trans-scleral DCPC (2000 mW, time: 2.0 s/shot). There was a 55.5 % reduction (total of 14.0 mmHg) of the mean pre-operative IOP (31.5 mmHg) after the first diode laser application (p = 0.0020). Re-treatment was required in 31.2 % of eyes over a mean period of 10.7 months. In these five eyes, the mean pre-operative IOP was 40.4 mmHg, which decreased to 15.0 mmHg post-therapy, and a mean IOP reduction of 25.4 mmHg (p = 0.0218). There was a 51.0 % reduction in the mean number of medications used after the first, and a 57.1 % reduction after a second laser application. The incidence of failure (IOP ≥ 22 mmHg or need of additional medical therapy) from initial intervention to loss of follow-up was 1.3 % per person-month. DCPC effectively reduces the intraocular pressure and the number of anti-glaucoma medications with few complications in patients after high-risk PKP and secondary glaucoma. Only, one-third of the eyes needed a second intervention to control the intraocular pressure. Post-DCPC complications were limited to phthisis bulbi and endothelial dysfunction, one eye each. Please check and confirm the author names and initials are correct. Also, kindly confirm the details in the metadata are correct. PMID:26419547

  16. Transscleral photodisruption for the treatment of glaucoma

    NASA Astrophysics Data System (ADS)

    Sacks, Zachary S.; Loesel, Frieder H.; Durfee, Charles G., III; Kurtz, Ron M.; Juhasz, Tibor; Mourou, Gerard A.

    1999-03-01

    To evaluate transscleral glaucoma surgery techniques using ultrashort pulsed lasers, we attempted to produce photodisruption on the inner surface of the sclera without damaging the overlying tissue. We identified two methods, using pulses centered at 1700 nm and a transparency inducing drug, to produce the spatial and temporal confinement of the pulse necessary to produce photodisruption in the highly scattering sclera. When fully developed these concepts may help address the longstanding limitations of current glaucoma surgical techniques.

  17. A review of drug-induced acute angle closure glaucoma for non-ophthalmologists

    PubMed Central

    Ah-kee, Elliott Yann; Egong, Eric; Shafi, Ahad; Lim, Lik Thai; Yim, James Li

    2015-01-01

    Acute angle closure glaucoma is an ophthalmic emergency and can lead to blindness if left untreated. Several types of drugs have the potential to precipitate acute angle closure glaucoma. These include adrenergic, cholinergic and anticholinergic, antidepressants, anticoagulants and sulfa-based agents. This article provides a basic overview of the risk factors and pathophysiologic mechanisms involved in angle closure glaucoma and focuses on drug-induced angle closure glaucoma for the non-ophthalmologist. A PubMed search limited to the English language was conducted to find relevant literature for the purpose of this article. Most attacks occur in subjects unaware that they are at risk due to innately narrow iridocorneal angles. Clinicians should always review medications in patients presenting with symptoms of acute angle closure glaucoma. The aim of this article is to bring this ophthalmic condition to the attention of clinicians, particularly those outside the field of ophthalmology who commonly prescribe these medications or see these patients prior to referring to ophthalmologists. PMID:26535174

  18. A review of drug-induced acute angle closure glaucoma for non-ophthalmologists.

    PubMed

    Ah-Kee, Elliott Yann; Egong, Eric; Shafi, Ahad; Lim, Lik Thai; Yim, James Li

    2015-01-01

    Acute angle closure glaucoma is an ophthalmic emergency and can lead to blindness if left untreated. Several types of drugs have the potential to precipitate acute angle closure glaucoma. These include adrenergic, cholinergic and anticholinergic, antidepressants, anticoagulants and sulfa-based agents. This article provides a basic overview of the risk factors and pathophysiologic mechanisms involved in angle closure glaucoma and focuses on drug-induced angle closure glaucoma for the non-ophthalmologist. A PubMed search limited to the English language was conducted to find relevant literature for the purpose of this article. Most attacks occur in subjects unaware that they are at risk due to innately narrow iridocorneal angles. Clinicians should always review medications in patients presenting with symptoms of acute angle closure glaucoma. The aim of this article is to bring this ophthalmic condition to the attention of clinicians, particularly those outside the field of ophthalmology who commonly prescribe these medications or see these patients prior to referring to ophthalmologists. PMID:26535174

  19. Selective laser trabeculoplasty in treating post-trabeculectomy advanced primary open-angle glaucoma

    PubMed Central

    ZHANG, HONGYANG; YANG, YANGFAN; XU, JIANGANG; YU, MINBIN

    2016-01-01

    The aim of this study was to investigate the safety and efficacy of selective laser trabeculoplasty (SLT) treatment of patients with primary open-angle glaucoma (POAG) who could not obtain target intraocular pressure (IOP) through post-trabeculectomy medication. Sixteen patients with POAG (18 eyes), who could not obtain target IOP following medication and surgery, were treated with 360° SLT. The IOP, anterior chamber inflammation, and daytime and long-term IOP fluctuations before and 2 h, 1 day, 7 days, 1 month, 3 months, 6 months and 9 months after SLT were documented. SLT treatment success was defined as >20% IOP reduction compared with the baseline IOP at 6 and 9 months after the laser treatment date. Prior to SLT, the patients were administered different types (average, 2.8±0.8) of anti-glaucoma drugs and had an average IOP of 21.3±3.4 mmHg. Following SLT, the average IOP decreased to 16.2±3.0 mmHg and the success rate was 77.7%. The pre-SLT daytime IOP fluctuation was 4.1±1.4 mmHg, which decreased to 2.6±1.1 mmHg following the laser treatment (P<0.05). In conclusion, this study demonstrated that SLT could reduce the IOP in post-trabeculectomy patients with POAG, and reduce the daytime IOP fluctuations. PMID:26998042

  20. Regional Image Features Model for Automatic Classification between Normal and Glaucoma in Fundus and Scanning Laser Ophthalmoscopy (SLO) Images.

    PubMed

    Haleem, Muhammad Salman; Han, Liangxiu; Hemert, Jano van; Fleming, Alan; Pasquale, Louis R; Silva, Paolo S; Song, Brian J; Aiello, Lloyd Paul

    2016-06-01

    Glaucoma is one of the leading causes of blindness worldwide. There is no cure for glaucoma but detection at its earliest stage and subsequent treatment can aid patients to prevent blindness. Currently, optic disc and retinal imaging facilitates glaucoma detection but this method requires manual post-imaging modifications that are time-consuming and subjective to image assessment by human observers. Therefore, it is necessary to automate this process. In this work, we have first proposed a novel computer aided approach for automatic glaucoma detection based on Regional Image Features Model (RIFM) which can automatically perform classification between normal and glaucoma images on the basis of regional information. Different from all the existing methods, our approach can extract both geometric (e.g. morphometric properties) and non-geometric based properties (e.g. pixel appearance/intensity values, texture) from images and significantly increase the classification performance. Our proposed approach consists of three new major contributions including automatic localisation of optic disc, automatic segmentation of disc, and classification between normal and glaucoma based on geometric and non-geometric properties of different regions of an image. We have compared our method with existing approaches and tested it on both fundus and Scanning laser ophthalmoscopy (SLO) images. The experimental results show that our proposed approach outperforms the state-of-the-art approaches using either geometric or non-geometric properties. The overall glaucoma classification accuracy for fundus images is 94.4% and accuracy of detection of suspicion of glaucoma in SLO images is 93.9 %. PMID:27086033

  1. Guiding glaucoma laser surgery using Fourier-domain optical coherence tomography at 1.3 μm

    NASA Astrophysics Data System (ADS)

    Bayleyegn, Masreshaw D.; Makhlouf, Houssine; Crotti, Caroline; Plamann, Karsten; Dubois, Arnaud

    2012-06-01

    Glaucoma is a disease of the optic nerve that is usually associated with an increased internal pressure of the eye and can lead to a decreased vision and eventually blindness. It is the second leading cause of blindness worldwide with more than 80 million people affected and approximately 6 million blind. The standard clinical treatment for glaucoma, after unsuccessful administration of eyedrops and other treatments, is performing incisional surgery. However, due to post-surgical complications like scarring and wound healing, this conventional method has a global success rate of only about 60%. In comparison, as femtosecond laser surgery may be performed in volume and is a priori less invasive and less susceptible of causing scarring, glaucoma laser surgery could be a novel technique to supplement the conventional glaucoma surgery. We have been working on the development of a new tool for glaucoma treatment that uses an optimized femtosecond laser source centered at 1.65 μm wavelength for making the surgery and an imaging system based on optical coherence tomography (OCT) for guiding the laser surgery. In this proceeding, we present the results obtained so far on the development and utilization of Fourier-domain OCT imaging system working at 1.3 μm center wavelength for guiding the laser incision. Cross-sectional OCT image of pathological human cornea showing the Schlemm's canal, where the surgery is intended to be done, is presented. By coupling OCT imaging system with the laser incision system, we also demonstrate real-time imaging of femtosecond laser incision of cornea.

  2. A Magnetic Microbead Occlusion Model to Induce Ocular Hypertension-Dependent Glaucoma in Mice

    PubMed Central

    Cueva Vargas, Jorge L.; Di Polo, Adriana

    2016-01-01

    The use of rodent models of glaucoma has been essential to understand the molecular mechanisms that underlie the pathophysiology of this multifactorial neurodegenerative disease. With the advent of numerous transgenic mouse lines, there is increasing interest in inducible murine models of ocular hypertension. Here, we present an occlusion model of glaucoma based on the injection of magnetic microbeads into the anterior chamber of the eye using a modified microneedle with a facetted bevel. The magnetic microbeads are attracted to the iridocorneal angle using a handheld magnet to block the drainage of aqueous humour from the anterior chamber. This disruption in aqueous dynamics results in a steady elevation of intraocular pressure, which subsequently leads to the loss of retinal ganglion cells, as observed in human glaucoma patients. The microbead occlusion model presented in this manuscript is simple compared to other inducible models of glaucoma and also highly effective and reproducible. Importantly, the modifications presented here minimize common issues that often arise in occlusion models. First, the use of a bevelled glass microneedle prevents backflow of microbeads and ensures that minimal damage occurs to the cornea during the injection, thus reducing injury-related effects. Second, the use of magnetic microbeads ensures the ability to attract most beads to the iridocorneal angle, effectively reducing the number of beads floating in the anterior chamber avoiding contact with other structures (e.g., iris, lens). Lastly, the use of a handheld magnet allows flexibility when handling the small mouse eye to efficiently direct the magnetic microbeads and ensure that there is little reflux of the microbeads from the eye when the microneedle is withdrawn. In summary, the microbead occlusion mouse model presented here is a powerful investigative tool to study neurodegenerative changes that occur during the onset and progression of glaucoma. PMID:27077732

  3. Correlation between Lamina Cribrosa Tilt Angles, Myopia and Glaucoma Using OCT with a Wide Bandwidth Femtosecond Mode-Locked Laser

    PubMed Central

    Shoji, Takuhei; Kuroda, Hiroto; Suzuki, Masayuki; Baba, Motoyoshi; Hangai, Masanori; Araie, Makoto; Yoneya, Shin

    2014-01-01

    Purpose To measure horizontal and vertical lamina cribrosa (LC) tilt angles and investigate associated factors using prototype optical coherence tomography (OCT) with a broad wavelength laser light source. Design Cross sectional study. Methods Twenty-eight no glaucoma eyes (from 15 subjects) and 25 glaucoma eyes (from 14 patients) were enrolled. A total of 300 optic nerve head B-scans were obtained in 10 µm steps and the inner edge of Bruch's membrane opening (BMO) was identified as the reference plane. The vertical and horizontal angles between BMO line and approximate the best-fitting line for the surface of the LC were measured and potential associated factors were estimated with univariate and multivariate logistic regression analyses. Results The median (interquartile range) horizontal and vertical tilt angles were 7.10 (2.43–11.45) degrees and 4.15 (2.60–6.85) degrees in eyes without glaucoma and 8.50 (4.40–14.10) degrees and 9.30 (6.90–14.15) degrees in glaucoma eyes, respectively. The refractive errors had a statistically significant association with horizontal LC tilt angles (coefficients, −1.53 per diopter) and glaucoma had a significant correlation with vertical tilt angles (coefficients, 6.56) using multiple logistic regression analysis (p<0.001). Conclusions OCT allowed evaluation of the internal tilting of the LC compared with the BMO. The horizontal internal LC tilt angle was correlated with refractive errors, corresponding to myopic physiological changes, and vertical internal LC tilt was correlated with glaucoma, corresponding to glaucomatous pathological changes. These parameters have important implications for investigation of the correlation between myopia, glaucoma and LC morphological features. PMID:25551632

  4. 193 nm excimer laser sclerostomy in pseudophakic patients with advanced open angle glaucoma.

    PubMed Central

    Allan, B D; van Saarloos, P P; Cooper, R L; Constable, I J

    1994-01-01

    A modified open mask system incorporating an en face air jet to dry the target area during ablation and a conjunctival plication mechanism, which allows ab externo delivery of the 193 nm excimer laser without prior conjunctival dissection, has been developed to form small bore sclerostomies accurately and atraumatically. Full thickness sclerostomies, and sclerostomies guarded by a smaller internal ostium can be created. A pilot therapeutic trial was conducted in pseudophakic patients with advanced open angle glaucoma. Six full thickness sclerostomies (200 microns and 400 microns diameter) and three guarded sclerostomies were created in nine patients by 193 nm excimer laser ablation (fluence per pulse 400 mJ/cm2, pulse rate 16 Hz, air jet pressure intraocular pressure +25 mm Hg). After 6 months' follow up, intraocular pressure was controlled (< or = 16 mm Hg) in eight of the nine patients (6/9 without medication). Early postoperative complications included hyphaema (trace--2.5 mm) (6/9), temporary fibrinous sclerostomy occlusion (4/9), profound early hypotony (all patients without fibrinous occlusion), and suprachoroidal haemorrhage in one case. Conjunctival laser wounds were self sealing. Small bore laser sclerostomy procedures are functionally equivalent to conventional full thickness procedures, producing early postoperative hypotony, with an increased risk of suprachoroidal haemorrhage in association with this. Further research is required to improve control over internal guarding in excimer laser sclerostomy before clinical trials of this technique can safely proceed. Images PMID:8148335

  5. Reproducibility of retinal circulation measurements obtained using laser speckle flowgraphy-NAVI in patients with glaucoma

    PubMed Central

    Aizawa, Naoko; Yokoyama, Yu; Chiba, Naoki; Omodaka, Kazuko; Yasuda, Masayuki; Otomo, Takaaki; Nakamura, Masahiko; Fuse, Nobuo; Nakazawa, Toru

    2011-01-01

    Background: Laser speckle flowgraphy (LSFG) enables noninvasive quantification of the retinal circulation in glaucoma patients. In this study, we tested the intrasession reproducibility of LSFG-NAVI, a modified LSFG technique. Methods: Sixty-five eyes from 33 subjects (male (M):female (F) = 17:16) with a mean age of 49.4 ± 11.2 years were examined in this study. Two parameters indicating reproducibility – the coefficient of variation (COV) and the intraclass correlation coefficient (ICC) – were analyzed three times on the same day that mean blur rate (MBR) was measured using LSFG-NAVI. The sites analyzed were the retinal artery and vein, the optic disk, and the choroid. Following classification according to the Glaucoma Hemifield Test (GHT; SITA-Standard 30-2 program), the COV and ICC were examined in patients with (GHT+; 38 eyes, M:F = 20:18, average age 48.9 ± 12.8 years) and without (GHT−; 27 eyes, M:F = 13:14, average age 50.1 ± 8.7 years) abnormal glaucomatous visual fields. Results: For all subjects, the intrasession reproducibility of MBR in the optic disk (COV: 3.4 ± 2.0; ICC: 0.95) and choroid (COV: 4.7 ± 3.4; ICC: 0.98) was excellent. The reproducibility for the retinal vein (COV: 8.4 ± 5.6, ICC: 0.90) and retinal artery (COV: 10.9 ± 9.9, ICC: 0.9) was moderate. MBRs in the optic disk had good reproducibility in both the GHT+ group (COV: 3.8 ± 2.0; ICC: 0.97) and the GHT− group (COV: 2.9 ± 2.1; ICC: 0.95). Local assessment of the optic disk in normal or glaucoma patients showed that the COVs of the quadrant optic disk areas were best in the temporal area of MBR (3.4%, 4.2%, respectively). Conclusion: LSFG-NAVI showed favorable reproducibility in evaluation of retinal circulation of glaucoma patients, particularly in the optic disk and choroid. PMID:21887100

  6. Incidence, severity and factors related to drug-induced keratoepitheliopathy with glaucoma medications

    PubMed Central

    Fukuchi, Takeo; Wakai, Kimiko; Suda, Kieko; Nakatsue, Tomoko; Sawada, Hideko; Hara, Hiroaki; Ueda, Jun; Tanaka, Takayuki; Yamada, Akiko; Abe, Haruki

    2010-01-01

    Purpose To evaluate the incidence, severity, and factors related to drug-induced keratoepitheliopathy in eyes using antiglaucoma eye drops. Patients and methods In a cross-sectional study, 749 eyes from 427 patients who had used one or more antiglaucoma eye drops were examined at Niigata University Medical and Dental Hospital or related facilities. The incidence and severity of superficial punctate keratitis (SPK), patient gender and age, type of glaucoma, and type of eye drops were recorded. SPK was graded according to the AD (A, area; D, density) classification. The severity score (SS) was calculated from A × D. Results SPK was observed in 382 (51.0%) of 749 eyes that had received any type of antiglaucoma eye drops. While 254 eyes (33.9%) were classified as A1D1 (SS 1), 34 eyes (4.6%) had severe SPK with SS 4 or more. The number of eye drops and the total dosing frequency per day were significantly greater in SPK-positive eyes than in eyes without SPK. The number of eye drops was proportional to the frequency and severity of SPK. Among eyes that were treated with three or more eye drops, SPK was more severe and more frequent in older patients (≥71 years). In addition, a considerable difference was detected for each type of glaucoma. Conclusion Drug-induced keratoepitheliopathy is often observed in eyes that have received recent antiglaucoma eye drops. The number of eye drops, the total dose frequency per day, patient age, and type of glaucoma may affect this condition. We have to consider not only the effects on intraocular pressure but also the incidence and severity of drug-induced keratoepitheliopathy as a frequent side effect of glaucoma medications. PMID:20463785

  7. VEGF induces TGF-β1 expression and myofibroblast transformation after glaucoma surgery.

    PubMed

    Park, Hae-Young L; Kim, Jie Hyun; Park, Chan Kee

    2013-06-01

    Subconjunctival fibrosis at the surgical site determines the outcome of glaucoma surgery. Myofibroblast transformation has a significant role in fibrosis, and vascular endothelial growth factor (VEGF) is reported to trigger myofibroblast transformation by inducing transforming growth factor (TGF)-β1. In the present study, we used IHC, Western blot analysis, enzyme-linked immunosorbent assay, and electron microscopy to determine the contribution of VEGF to myofibroblast transformation in subconjunctival fibrosis after glaucoma surgery. A rabbit trabeculectomy model was generated, and VEGF stimulation or VEGF inhibition was performed during surgery. VEGF stimulation induced TGF-β1 expression in a dose-dependent manner. Down-regulation of epithelial markers (E-cadherin and β-catenin) and up-regulation of mesenchymal marker (α-smooth muscle actin) were observed in the subconjunctival layers after trabeculectomy with VEGF stimulation. Up-regulations of Smad and Snail, which play a central role in myofibroblast transformation, were observed in the conjunctival and subconjunctival layers at the site of trabeculectomy. Electron microscopy revealed changes of the conjunctival epithelial cells, especially the presence of myofilaments and increased rough endoplasmic reticulum in the cytoplasm. Myofibroblast transformation was activated by VEGF stimulation and decreased by VEGF inhibition. These findings suggest that VEGF potentially affected the TGF-β1/Smad/Snail pathway, thereby triggering myofibroblast transformation. Therapeutic approaches modulating VEGF may control myofibroblast transformation and reduce subconjunctival fibrosis after glaucoma surgery. PMID:23684430

  8. Two-Year Clinical Results After Selective Laser Trabeculoplasty for Normal Tension Glaucoma

    PubMed Central

    Lee, Jacky W.Y.; Shum, Jennifer J.W.; Chan, Jonathan C.H.; Lai, Jimmy S.M.

    2015-01-01

    Abstract This article aims to investigate the clinical results at 2 years after selective laser trabeculoplasty (SLT) for normal tension glaucoma (NTG). This prospective cohort study recruited NTG patients taking antiglaucoma medication. Subjects were excluded if they had previous glaucoma surgery/laser or corneal pathologies. All subjects underwent a 1-month washout. A single session of SLT was performed to 360° of the trabecular meshwork. Medication was resumed at 1 month to achieve a targeted 30% intraocular pressure (IOP) reduction from the post-washout/pre-SLT IOP. IOP was measured every 3 months and medication use was recorded at 3, 6, 12, and 24 months. Subjects with a secondary SLT or cataract extraction were excluded from IOP and medication analyses. At 24 months, 34 of the initial 45 right eyes were eligible for analyses. There were significant IOP reductions at all time intervals (except at 1 week) following SLT when compared to the prestudy (without medication) or pre-SLT (post-washout) IOP (P < 0.0001). Medications were likewise significantly reduced at all time intervals following SLT (P < 0.0001). At 24 months, the IOP was 11.5% lower than the prestudy IOP, 22.0% lower than the pre-SLT IOP, and medication use was reduced by 41.1% (P < 0.0001). Six out of 45 eyes (13.3%) required a secondary SLT. Absolute success (IOP reduction >20% from pre-SLT, without medication) was achieved in 11.1% (5/45). Reductions in IOP and medication use were evident at 2 years following SLT for the treatment of NTG whereas 11% remained medication free. Trial Registrations: The Clinical Trials Register of the University of Hong Kong HKCTR1847. The European Clinical Trials Database 2014-003305-15 (August 11, 2014).

  9. Selective laser trabeculoplasty for primary open angle glaucoma: six-year follow up

    NASA Astrophysics Data System (ADS)

    Koev, Krassimir

    2005-04-01

    In order to establish the long-term efficacy of selective laser trabeculoplasty for primary open-angle glaucoma [POAG], trabecular meshwork of 34 eyes (21 patients) with POAG was treated with Q-switched frequency doubled Nd-YAG laser with wavelength of 532 nm Coherent Selecta 7000 (SLT). The eyes were divided in two groups: group 1-18 eyes with pigmentation degree in the frontal chamber angle of 1 and 2; group 2-16 eyes with pigmentation degree of 3 and 4. An average of 104 spots on 360 degrees was applied stepwise to the trabecular meshwork of every eye. The treatment and follow up period lasted 6 years. The mean prepoerative intraocular pressure [IOP] in group 1 was 25,5+/-1,5 mmHg, and in group 2-26+/-1 mmHg. During the last visit 6 years after SLT, the mean IOP in group 1 was 18,7+/-1.4 mmHg. Statistically significant decrease of IOP [p<0.001] was observed after SLT by an average of 6,8 mmHg [26.7%]. During the last visit 6 years after SLT in group 2, the mean IOP was 18.8+/-1.2 mmHg. Statistically significant IOP decrase method for POAG treatment and that IOP decrase in treated eyes is preserved for several years.

  10. Laser induced nuclear reactions

    SciTech Connect

    Ledingham, Ken; McCanny, Tom; Graham, Paul; Fang Xiao; Singhal, Ravi; Magill, Joe; Creswell, Alan; Sanderson, David; Allott, Ric; Neely, David; Norreys, Peter; Santala, Marko; Zepf, Matthew; Watts, Ian; Clark, Eugene; Krushelnick, Karl; Tatarakis, Michael; Dangor, Bucker; Machecek, Antonin; Wark, Justin

    1998-12-16

    Dramatic improvements in laser technology since 1984 have revolutionised high power laser technology. Application of chirped-pulse amplification techniques has resulted in laser intensities in excess of 10{sup 19} W/cm{sup 2}. In the mid to late eighties, C. K. Rhodes and K. Boyer discussed the possibility of shining laser light of this intensity onto solid surfaces and to cause nuclear transitions. In particular, irradiation of a uranium target could induce electro- and photofission in the focal region of the laser. In this paper it is shown that {mu}Ci of {sup 62}Cu can be generated via the ({gamma},n) reaction by a laser with an intensity of about 10{sup 19} Wcm{sup -2}.

  11. Neodymium-YAG laser iridotomy in the treatment and prevention of angle closure glaucoma. A review of 373 eyes.

    PubMed

    Tomey, K F; Traverso, C E; Shammas, I V

    1987-04-01

    The records of 271 consecutive patients (373 eyes) who underwent neodymium-YAG laser iridotomy at our institution over a period of 12 months were reviewed. The majority of eyes (60.5%) were treated for chronic primary angle closure glaucoma, 23.3% had prophylactic iridotomy for occludable angles, 7.8% were treated for acute angle closure glaucoma, 3.2% required iridotomy for the relief of iris bombé secondary to anterior uveitis, and the rest (5.2%) were treated for miscellaneous causes of secondary angle closure. Laser iridotomy, with or without medical treatment, obviated further surgical treatment in most categories of eyes. Visual acuity remained unchanged or improved in the great majority (92%) of cases over the period of follow-up (range, two to 12 months; median, four months). Visual deterioration in 8% of eyes was attributed to the usual causes, such as normal cataract progression, but none was believed to be related to the laser treatment. This article discusses the advantages of the neodymium-YAG laser (over argon) for performing iridotomies. PMID:3566599

  12. Nanotechnology Applications for Glaucoma.

    PubMed

    Cetinel, Sibel; Montemagno, Carlo

    2016-01-01

    Glaucoma is the second leading cause of blindness worldwide, and the antiglaucoma treatments currently available suffer from various complications. Nanotechnology-based treatments show a great deal of promise in overcoming these complications and form the basis for next-generation glaucoma treatment strategies, with the help of applications such as controlled release, targeted delivery, increased bioavailability, diffusion limitations, and biocompatibility. Significant progress has been made in nanomedicine in the efficiency of antiglaucoma medications, nanofabrication systems such as microelectromechanical systems that remove the limitations of nanodevices, and tissue regeneration vesicles for developing glaucoma treatments not based on intraocular pressure. With the use of these advanced technologies, the prevention of glaucoma-induced blindness will be possible in the near future. Herein, we reviewed the recent advances in nanotechnology-based treatment strategies for glaucoma. PMID:26693592

  13. The management of complicated glaucoma

    PubMed Central

    Clement, C I; Goldberg, Ivan

    2011-01-01

    Complicated glaucomas present considerable diagnostic and management challenges. Response to treatment can be unpredictable or reduced compared with other glaucomas. However, target intraocular pressure and preservation of vision may be achieved with selected medical, laser and surgical treatment. The evidence for such treatment is expanding and consequently affords clinicians a better understanding of established and novel techniques. Herein we review the mechanisms involved in the development of complicated glaucoma and the current evidence supporting its management. PMID:21150026

  14. Laser-induced bioluminescence

    SciTech Connect

    Hickman, G.D.; Lynch, R.V. III

    1981-01-01

    A project has been initiated to determine the feasibility of developing a complete airborne remote sensing system for rapidly mapping high concentration patches of bioluminescent organisms in the world's oceans. Conceptually, this system would be composed of a laser illuminator to induce bioluminescence and a low light level image intensifier for detection of light. Initial laboratory measurements consisted of using a 2-J flash lamp pulsed optical dye laser to excite bioluminescence in the marine dinoflagellate Pyrocustis lunula at ambient temperature using Rhodamine 6G as the lasing dye (585 nm) and a laser pulse width of 1 microsec. After a latency period of 15-20 msec, the bioluminescence maximum occurred in the blue (480 nm is the wavelength maximum for most dinoflagellate bioluminescence) with the peaking occurring approximately 65 msec after the laser pulse. Planned experiments will investigate the effect of different excitation wavelengths and energies at various temperatures and salinities of the cultures.

  15. 193-nm excimer laser sclerostomy using a modified open mask delivery system in rhesus monkeys with experimental glaucoma.

    PubMed

    Allan, B D; van Saarloos, P P; Cooper, R L; Keogh, E J; Constable, I J

    1993-11-01

    Excimer laser sclerostomy is a new glaucoma filtration procedure in which the argon fluoride excimer laser at 193 nm is delivered ab externo through a modified open mask system incorporating an en-face air jet to dry the target area and preserve hemostasis during ablation and a conjunctival plication mechanism, which allows the conjunctival and scleral wounds created by through-and-through ablation to separate once the mask is removed. No preparatory dissection of the conjunctiva is required. Five 200-microns and five 500-microns sclerostomies were formed by ablation at a pulse repetition rate of 20 Hz and a fluence per pulse of 400 mJ/cm2 in fellow eyes of five rhesus monkeys with experimental glaucoma. Overall, seven of the ten eyes attained a functional result, with intraocular pressures remaining below 21 mmHg for 6 +/- 1 days and rising to the pre-operative level after 10 +/- 3 days without adjunctive antifibroblast medication. The duration of filtration for 200-microns and 500-microns sclerostomies was similar, and parallels that previously observed for posterior lip sclerectomy in the same animal model. The three eyes with no functional result all had incorrectly positioned sclerostomies. Choroidal detachment and significant shallowing of the anterior chamber did not occur. Excimer laser sclerostomy appears to be a viable technique for filtration, provided that mask placement is accurate. PMID:8258402

  16. Systematic review and meta-analysis on the efficacy of selective laser trabeculoplasty in open-angle glaucoma.

    PubMed

    Wong, Mandy Oi Man; Lee, Jacky Wai Yip; Choy, Bonnie Nga Kwan; Chan, Jonathan Cheuk Hung; Lai, Jimmy Shiu Ming

    2015-01-01

    Selective laser trabeculoplasty (SLT) is a relatively new type of laser used in treating open-angle glaucoma (OAG) and is reported to be equally efficacious to a first-line medication and argon laser trabeculoplasty (ALT). We summarize available evidence for considering SLT as an alternative treatment in OAG through systematic review and meta-analysis. Among OAG patients who range from newly diagnosed to those on maximally tolerated medical therapy, SLT results in a 6.9-35.9% intraocular pressure (IOP) reduction. Complications are rare and include an IOP spike requiring surgery, persistent macular edema, and corneal haze and thinning. Meta-analysis of randomized, controlled trials shows that SLT is non-inferior to ALT and medication in IOP reduction and also in achieving treatment success. Number of medications reduction is similar between SLT and ALT. More robust evidence is needed to determine its efficacy as a repeated procedure. PMID:25113610

  17. [Current trends in neovascular glaucoma treatment].

    PubMed

    Vancea, P P; Abu-Taleb, A

    2005-01-01

    Neovascular glaucoma is divided in three clinical stages: rubeosis iridis, secondary open-angle glaucoma, and synechia of the angle-closure glaucoma. 36% of neovascular glaucomas occurs after central retinal vein occlusion, 32% after diabetic proliferative retinopathy, and 13% occurs after carotid artery obstructive. The key of success in the treatment of neovascular glaucoma is the early and rightly diagnosis, the treatment is aimed mainly at relieving pain, as the prognosis for maintaining visual function is extremely poor. The most important surgical procedures are trabeculectomy, artificial drainage shunts and cyclo-distraction by trans-scleral diode laser. This essay presents a synthesis of modern principle data concerning neovascular glaucoma. PMID:16607783

  18. [Administration of premedication with fexofenadine for paclitaxel-induced hypersensitive reactions in breast cancer patients complicated with closed-angle glaucoma].

    PubMed

    Komatsubara, Kazuo; Miyoshi, Kyoko; Kogure, Yuuki; Matsuhisa, Tetsuaki; Eguchi, Hisae

    2010-01-01

    Paclitaxel (PTX) is one of the most important breast cancer treatment drugs. However, severe hypersensitivity reactions such as decreases in blood pressure and impaired breathing occur with high frequency. For the prevention of such hypersensitivity reactions, administration of a premedication composed of three components, diphenhydramine, ranitidine (or famotidine), and dexamethasone, has been advised in package insert information of medicine. Administration of diphenhydramine is difficult in breast cancer patients complicated with closed-angle glaucoma, because diphenhydramine has a weak anticholinergic adverse effect which can induce mydriasis and glaucoma attack. We studied the prevention of severe hypersensitivity reactions and of glaucoma attack in 2 breast cancer patients complicated with closed angle glaucoma at our hospital from April 2007 to March 2008. We switched from diphenhydramine to fexofenadine as the medicine to prevent hypersensitivity reactions. Hypersensitivity reactions were not observed throughout all courses in both patients, and no glaucoma attack was observed. PMID:20087041

  19. One Year of Glaucoma Research in Review: 2012 to 2013

    PubMed Central

    Kim, Charles; Demetriades, Anna M.; Radcliffe, Nathan M.

    2014-01-01

    Purpose The objective of this study was to provide the practicing clinical ophthalmologist with an update of pertinent glaucoma literature published from 2012 to 2013. Design Literature review. Methods The authors conducted a 1-year (July 1, 2012, to September 30, 2013) English-language glaucoma literature search on PubMed using the following terms: glaucoma, automated perimetry, optic nerve imaging, optical coherence tomography, glaucoma structure and function, intraocular pressure, central corneal thickness, glaucoma medical therapy, neuroprotection, glaucoma laser treatment, secondary glaucoma, glaucoma surgery, and miscellaneous topics in glaucoma. Results Of 2659 articles on glaucoma published during our time frame, this review selected original and review articles that reflect novel aspects and updates in the field of glaucoma, while excluding letters to the editor, unpublished works, and abstracts. Preference was given to human research. Conclusions This review focuses on literature that is applicable to ophthalmologists in practice and also highlights studies that may enhance the diagnosis and management of glaucoma. PMID:25177529

  20. Glaucoma (image)

    MedlinePlus

    Glaucoma is a condition of increased fluid pressure inside the eye. The increased pressure causes compression of ... nerve which can eventually lead to nerve damage. Glaucoma can cause partial vision loss, with blindness as ...

  1. [Angle-closure chronic glaucoma].

    PubMed

    Lachkar, Y

    2003-10-01

    The incidence of chronic angle closure glaucoma is considerably greater than the incidence of the acute type. This type of glaucoma may mimic primary open angle glaucoma with visual field deterioration, optic nerve alteration and intraocular pressure elevation with a quiet painless eye. Its diagnosis is based on indentation gonioscopy showing peripheral anterior synechiae. The mechanisms of angle closure are the pupillary block, the plateau iris configuration and the creeping form. The treatment of chronic angle closure glaucoma is based on laser peripheral iridotomy. PMID:14646832

  2. Noninvasive glaucoma procedures: current options and future innovations.

    PubMed

    Abdelrahman, Ahmed M

    2015-01-01

    Noninvasive glaucoma procedures (NIGPs) represent a new dawn in the management of glaucoma. They try to fill the gap between the shortcoming of invasive glaucoma surgeries and antiglaucoma medications. NIGPs were introduced as an adjunct or alternative treatments for glaucoma. Some of these procedures have shown good efficacy with few serious complications. Hence, they are now used as both primary and adjunctive therapy for glaucoma. The most common NIGPS involve laser and ultrasound technologies. Currently, the portfolio of NIGPs includes argon laser trabeculoplasty, selective laser trabeculoplasty, and micropulse diode laser trabeculoplasty. More recent innovations include therapeutic ultrasound for glaucoma, ultrasonic circular cyclocoagulation, and deep wave trabeculoplasty. PMID:25624667

  3. Noninvasive Glaucoma Procedures: Current Options and Future Innovations

    PubMed Central

    Abdelrahman, Ahmed M.

    2015-01-01

    Noninvasive glaucoma procedures (NIGPs) represent a new dawn in the management of glaucoma. They try to fill the gap between the shortcoming of invasive glaucoma surgeries and antiglaucoma medications. NIGPs were introduced as an adjunct or alternative treatments for glaucoma. Some of these procedures have shown good efficacy with few serious complications. Hence, they are now used as both primary and adjunctive therapy for glaucoma. The most common NIGPS involve laser and ultrasound technologies. Currently, the portfolio of NIGPs includes argon laser trabeculoplasty, selective laser trabeculoplasty, and micropulse diode laser trabeculoplasty. More recent innovations include therapeutic ultrasound for glaucoma, ultrasonic circular cyclocoagulation, and deep wave trabeculoplasty. PMID:25624667

  4. Laser induced ignition

    NASA Astrophysics Data System (ADS)

    Liedl, G.; Schuöcker, D.; Geringer, B.; Graf, J.; Klawatsch, D.; Lenz, H. P.; Piock, W. F.; Jetzinger, M.; Kapus, P.

    2007-05-01

    Nowadays, combustion engines and other combustion processes play an overwhelming and important role in everyday life. As a result, ignition of combustion processes is of great importance, too. Usually, ignition of a combustible material is defined in such a way that an ignition initiates a self-sustained reaction which propagates through the inflammable material even in the case that the ignition source has been removed. In most cases, a well defined ignition location and ignition time is of crucial importance. Spark plugs are well suited for such tasks but suffer from some disadvantages, like erosion of electrodes or restricted positioning possibilities. In some cases, ignition of combustible materials by means of high power laser pulses could be beneficial. High power lasers offer several different possibilities to ignite combustible materials, like thermal ignition, resonant ignition or optical breakdown ignition. Since thermal and resonant ignitions are not well suited on the requirements mentioned previously, only optical breakdown ignition will be discussed further. Optical breakdown of a gas within the focal spot of a high power laser allows a very distinct localization of the ignition spot in a combustible material. Since pulse duration is usually in the range of several nanoseconds, requirements on the ignition time are fulfilled easily, too. Laser peak intensities required for such an optical breakdown are in the range of 10 11 W/cm2. The hot plasma which forms during this breakdown initiates the following self-propagating combustion process. It has been shown previously that laser ignition of direct injection engines improves the fuel consumption as well as the exhaust emissions of such engines significantly. The work presented here gives a brief overview on the basics of laser induced ignition. Flame propagation which follows a successful ignition event can be distinguished into two diffrent regimes. Combustion processes within an engine are usually

  5. Management and Visual Outcome in Patients of Lens-induced Glaucomas at a Tertiary Eye Care Hospital in South India

    PubMed Central

    Vaibhav, K

    2016-01-01

    ABSTRACT Aims: To outline the different characteristics of glaucomas and to determine the risk factors and their consequences on postoperative visual acuity, intraocular pressure (IOP), and inflammation, including corneal changes and optic disk changes. Settings and designs: Longitudinal prospective study done over a period of 1.5 years in a medical college hospital. Materials and methods: Fifty patients of lens-induced glaucoma (LIG) were included. At presentation, visual acuity, IOP, and inflammation, including corneal changes, were recorded. After medical line of treatment, postoperatively patients were followed up regularly at 2 and 7 weeks interval and the same parameters were evaluated including optic disk changes. Statistical analysis used: Paired t-test, chi-square test wherever applicable with p-value < 0.05 as significant. Results: The mean age of presentation was 60.68 years with female to male ratio of 1.7:1. The best corrected visual acuity(BCVA) of 6/18 or more was found in 54% cases, whereas visual acuity of less than 6/60 was seen in 26% of cases. Visual acuity of 6/12 or better was achieved in 72% (p < 0.01) of cases with symptoms less than 2 weeks and in 59.10% of cases with IOP of less than 35 mm Hg at presentation. The mean IOP in cases with duration of symptoms of 2 to 4 weeks was 40.33 ± 9.36 mm Hg. Optic disk of the affected eye suffered damage in 42% of cases and in 80% of cases with symptoms for more than 2 weeks. Conclusion: Early diagnosis and treatment is beneficial in LIG cases. How to cite this article: Sharanabasamma M, Vaibhav K. Management and Visual Outcome in Patients of Lens-induced Glaucomas at a Tertiary Eye Care Hospital in South India. J Curr Glaucoma Pract 2016;10(2):68-75. PMID:27536050

  6. Therapeutic Effects of Sodium Hyaluronate on Ocular Surface Damage Induced by Benzalkonium Chloride Preserved Anti-glaucoma Medications

    PubMed Central

    Liu, Xing; Yu, Fen-Fen; Zhong, Yi-Min; Guo, Xin-Xing; Mao, Zhen

    2015-01-01

    Background: Long-term use of benzalkonium chloride (BAC)-preserved drugs is often associated with ocular surface toxicity. Ocular surface symptoms had a substantial impact on the glaucoma patients’ quality of life and compliance. This study aimed to investigate the effects of sodium hyaluronate (SH) on ocular surface toxicity induced by BAC-preserved anti-glaucoma medications treatment. Methods: Fifty-eight patients (101 eyes), who received topical BAC-preserved anti-glaucoma medications treatment and met the severe dry eye criteria, were included in the analysis. All patients were maintained the original topical anti-glaucoma treatment. In the SH-treated group (56 eyes), unpreserved 0.3% SH eye drops were administered with 3 times daily for 90 days. In the control group (55 eyes), phosphate-buffered saline were administered with 3 times daily for 90 days. Ocular Surface Disease Index (OSDI) questionnaire, break-up time (BUT) test, corneal fluorescein staining, corneal and conjunctival rose Bengal staining, Schirmer test, and conjunctiva impression cytology were performed sequentially on days 0 and 91. Results: Compared with the control group, SH-treated group showed decrease in OSDI scores (Kruskal-Wallis test: H = 38.668, P < 0.001), fluorescein and rose Bengal scores (Wilcoxon signed-ranks test: z = −3.843, P < 0.001, and z = −3.508, P < 0.001, respectively), increase in tear film BUT (t-test: t = −10.994, P < 0.001) and aqueous tear production (t-test: t = −10.328, P < 0.001) on day 91. The goblet cell density was increased (t-test: t = −9.981, P < 0.001), and the morphology of the conjunctival epithelium were also improved after SH treatment. Conclusions: SH significantly improved both symptoms and signs of ocular surface damage in patients with BAC-preserved anti-glaucoma medications treatment. SH could be proposed as a new attempt to reduce ocular surface toxicity, and alleviate symptoms of ocular surface damage in BAC-preserved anti-glaucoma

  7. Long-term Follow-up of a Case of Gold Shunt Surgery for Refractory Silicone Oil–induced Glaucoma

    PubMed Central

    Le, Ryan; Berger, Alan R.

    2016-01-01

    Purpose: To report the first case of gold shunt surgery for treatment of silicone oil–induced refractory glaucoma in a tertiary care academic center, with 5-year follow-up. Design: The study design is a case report. Participants: The participant was a patient who underwent gold shunt surgery. Methods: Institutional Research Ethics Board approval for the study was obtained. A diabetic patient was referred for refractory glaucoma with a history of proliferative diabetic retinal detachment, and surgery with silicone oil. She was uncontrolled on maximal medical therapy and following informed consent, gold shunt surgery was performed. Ocular outcomes and number of medications were reviewed over a 5-year period. Results: Following uncomplicated surgery, intraocular pressure was reduced from 41 to 14 mm Hg, and the number of medications was reduced from 4 to 1. Glaucomatous optic neuropathy remained stable. Conclusions: Gold shunt surgery in this challenging case of silicone oil refractory glaucoma provided long-term intraocular pressure control and reduced need for medication over a 5-year period. PMID:27253968

  8. [The refractory glaucomas].

    PubMed

    Valtot, F

    2003-10-01

    Refractory types of glaucoma continue to present a therapeutic challenge to ophthalmologists. Approaches toward the management of these difficult glaucomas are addressed in this paper. The first part devotes special attention to understand the cause(s) of the failure of previous filtering surgery(ies). The next part emphasizes filtration surgery with intraoperative application of antimetabolites: 5-fluorouracil or mitomycin C and the surgical and pharmacological management of failing filtration. In case of failure of multiple filtering surgery with application of antimetabolites, surgeons have to consider cyclodestructive procedures (transscleral diode laser or endoscopic cyclophotocoagulation) to reduce aqueous production, or fistulizing procedures with tube implants or other drainage devices (valves). PMID:14646834

  9. Molecular Genetics in Glaucoma

    PubMed Central

    Liu, Yutao

    2015-01-01

    Glaucoma is a family of diseases whose pathology is defined by the progressive loss of retinal ganglion cells. Clinically, glaucoma presents as a distinctive optic neuropathy with associated visual field loss. Primary open-angle glaucoma (POAG), chronic angle closure glaucoma (ACG), and exfoliation glaucoma (XFG) are the most prevalent forms of glaucoma globally and are the most common causes of glaucoma-related blindness worldwide. A host of genetic and environmental factors contribute to glaucoma phenotypes. This review examines the current status of genetic investigations of POAG, ACG, XFG, including the less common forms of glaucoma primary congenital glaucoma (PCG), the developmental glaucomas, and pigment dispersion glaucoma. PMID:21871452

  10. Anterior and Posterior Optic Nerve Head Blood Flow in Nonhuman Primate Experimental Glaucoma Model Measured by Laser Speckle Imaging Technique and Microsphere Method

    PubMed Central

    Wang, Lin; Cull, Grant A.; Piper, Chelsea; Burgoyne, Claude F.; Fortune, Brad

    2012-01-01

    Purpose. To characterize optic nerve head (ONH) blood flow (BF) changes in nonhuman primate experimental glaucoma (EG) using laser speckle flowgraphy (LSFG) and the microsphere method and to evaluate the correlation between the two methods. Methods. EG was induced in one eye each of 9 rhesus macaques by laser treatment to the trabecular meshwork. Prior to lasering and following onset of intraocular pressure (IOP) elevation, retinal never fiber layer thickness (RNFLT) and ONH BF were measured biweekly by spectral-domain optical coherence tomography and LSFG, respectively, until RNFLT loss was approximately 40% in the EG eye. Final BF was measured by LSFG and by the microsphere method in the anterior ONH (MS-BFANT), posterior ONH (MS-BFPOST), and peripapillary retina (MS-BFPP). Results. Baseline RNFLT and LSFG-BF showed no difference between the two eyes (P = 0.69 and P = 0.43, respectively, paired t-test). Mean (±SD) IOP was 30 ± 6 mm Hg in EG eyes and 13 ± 2 mm Hg in control eyes (P < 0.001). EG eye RNFLT and LSFG-BF were reduced by 42 ± 16% (P < 0.0001) and 22 ± 13% (P = 0.003), respectively, at the final time point. EG eye MS-BFANT, MS-BFPOST, and MS-BFPP were reduced by 41 ± 17% (P < 0.001), 22 ± 34% (P = 0.06), and 30 ± 12% (P = 0.001), respectively, compared with the control eyes. Interocular ONH LSFG-BF differences significantly correlated to that measured by the microsphere method (R2 = 0.87, P < 0.001). Conclusions. Chronic IOP elevation causes significant ONH BF decreases in the EG model. The high correlation between the BF reduction measured by LSFG and the microsphere method provides evidence that the LSFG is capable of assaying BF for a critical deep ONH region. PMID:23169886

  11. Managing advanced unilateral pseudoexfoliative glaucoma.

    PubMed

    Marques, André

    2014-01-01

    The only proven therapy for glaucoma is intraocular pressure (IOP) reduction, which can be accomplished by different means. Each should be properly discussed with patients in order to best preserve visual function and quality of life. We report a case of unilateral pseudoexfoliative glaucoma, treated for years with triple topical IOP-lowering drugs. The patient presented with advanced optic neuropathy and important ocular side effects secondary to the treatment. Having discussed his options and prognosis, laser trabeculoplasty was performed while maintaining the remaining therapy considering the advanced stage of glaucoma. His IOP was effectively reduced and no progression was noted after 1-year follow-up. Although medical therapy is the mainstream in glaucoma management, its side effects should not be ignored, especially in unilateral cases. Surgery might have been a better solution, but we chose to perform laser trabeculoplasty, an effective and safer alternative, considering the unlikely but serious risk of the "wipe-out phenomenon" in this case. PMID:24850557

  12. Intraocular Pressure-Lowering Potential of Subthreshold Selective Laser Trabeculoplasty in Patients with Primary Open-Angle Glaucoma

    PubMed Central

    Yang, Yang Fan; Xu, Jian Gang

    2016-01-01

    Purpose. To compare the efficacy of subthreshold and conventional selective laser trabeculoplasty (SLT) in lowering intraocular pressure (IOP) in the patients with primary open-angle glaucoma (POAG). Methods. Fifty-two eyes from fifty-two POAG patients were randomized into two groups, one group treated with subthreshold SLT using two-thirds of the conventional energy and the other one treated with the conventional energy. IOP was measured with the Goldmann tonometer and the anterior chamber inflammation was determined using laser flare meter. Results. The initial energy dosage used in subthreshold SLT group was significantly lower than the amount of the energy used in conventional SLT group (0.4 ± 0.1 mJ versus 0.6 ± 0.1 mJ, P = 0.030). The total energy dosage was also significantly lower in subthreshold SLT group compared to the other group (37.6 ± 3.3 mJ versus 51.8 ± 5.7 mJ, P = 0.036). However, the level of inflammation in aqueous humor, amount of reduction in IOP, and the success rate in controlling IOP was the same in both groups. Conclusion. The efficacy of subthreshold SLT group in reducing IOP in POAG patients is comparable to the efficacy of conventional SLT group. PMID:27529032

  13. Glaucoma medications.

    PubMed

    Chae, Bora; Cakiner-Egilmez, Tulay; Desai, Manishi

    2013-01-01

    Glaucoma is a common eye condition that affects millions of individuals worldwide, making it the second-leading cause of blindness. Because glaucoma is associated with increased IOP level, the primary goal in treatment of glaucoma includes lowering IOP to prevent further progression of the disease. While various surgical interventions exist, medical therapy is currently the first line of treatment. Medical treatment of glaucoma includes topical beta-blockers, alpha-2 agonists, prostaglandins, parasympathomimetics and CAIs. Anti-glaucoma agents help reduce IOP by affecting the production of aqueous humor or increasing the outflow of aqueous through the trabecular or uveoscleral pathway. Choosing an appropriate medical regimen can be challenging and various factors such as efficacy, safety, cost and patient compliance must be considered. First-line treatment is often topical beta-blockers or prostaglandin analogs. However, beta-blocking agents can be associated with systemic side effects and need to be used cautiously in patients with serious concomitant cardiopulmonary disease. Alpha-2 agonists and parasympathomimetics are often considered second- or third-line treatment options but good adjunctive agents. Oral CAIs are often indicated for patients with elevated IOP in an acute setting or for patients resistant to other glaucoma medications and patients who are not good surgical candidates. PMID:23505792

  14. Selective Laser Trabeculoplasty for Glaucoma Secondary to Emulsified Silicone Oil after Pars Plana Vitrectomy: A Pilot Study

    PubMed Central

    Alkin, Zeynep; Satana, Banu; Ozkaya, Abdullah; Basarir, Berna; Altan, Cigdem; Yazici, Ahmet Taylan; Demirok, Ahmet

    2014-01-01

    Background. To investigate the efficacy of selective laser trabeculoplasty (SLT) for lowering intraocular pressure (IOP) in patients with open angle glaucoma (OAG) secondary to emulsified silicone oil (SO). Methodology/Principal Findings. Prospective, interventional, consecutive case series of 11 eyes with sustained elevation of IOP after SO removal. The mean IOP at baseline, week 1, month 1, month 3, and month 6 was evaluated. The mean baseline IOP was significantly decreased from 25 ± 2.7 mmHg to 18.4 ± 5.5 mmHg at week 1 (P = 0.01), 17.9 ± 3.1 mmHg at month 1 (P = 0.008), 15.8 ± 3.9 mmHg at month 3 (P = 0.003), and 16.2 ± 4.7 mmHg at month 6 (P = 0.004). IOP < 21 mmHg was achieved in 91% of the eyes without a significant complication at month 6. Conclusion/Significance. SLT may be successful for lowering IOP in patients with OAG secondary to emulsified SO which was not controlled with maximum antiglaucomatous medical treatment. PMID:24822212

  15. Inducible scAAV2.GRE.MMP1 lowers IOP long-term in a large animal model for steroid-induced glaucoma gene therapy

    PubMed Central

    Borrás, Teresa; Buie, LaKisha K.; Spiga, Maria Grazia

    2016-01-01

    Current treatment of glaucoma relies on administration of daily drops or eye surgery. A gene therapy approach to treat steroid-induced glaucoma would bring a resolution to millions of people worldwide that depend on glucocorticoid therapy for a myriad of inflammatory disorders. Previously, we had characterized a short-term Adh.GRE.MMP1 gene vector for the production of steroid-induced MMP1 in the trabecular meshwork and tested reduction of elevated intraocular pressure (IOP) in a sheep model. Here we conducted a trial transferring the same transgene cassette to a clinically safe vector (scAAV2), and extended the therapeutic outcome to longer periods of times. No evidence of ocular and/or systemic toxicity was observed. Viral genome distributions showed potential re-inducible vector DNAs in the trabecular meshwork (0.4 vg/cell) and negligible copies in six major internal organs (0.00002-0.005 vg/cell). Histological sections confirmed successful transduction of scAAV2.GFP to the trabecular meshwork. Optimization of the sheep steroid–induced hypertensive model revealed that topical ophthalmic drug difluprednate 0.05% (durezol) induced the highest IOP elevation in the shortest time. This is the first efficacy/toxicity study of a feasible gene therapy treatment of steroid-induced hypertension using clinically accepted scAAV vectors in a large animal model. PMID:26855269

  16. Acute glaucoma following vitrectomy and silicone oil injection.

    PubMed Central

    Zborowski-Gutman, L; Treister, G; Naveh, N; Chen, V; Blumenthal, M

    1987-01-01

    Three cases are described of acute glaucoma following vitrectomy and silicone oil injection in proliferative vitreous retinopathy. The first case developed silicone-induced pupillary block in a phakic eye. Cases 2 and 3 developed elevated pressure in aphakic eyes with deep anterior chambers. Cases 1 and 3 were treated by laser iridectomy. Case 2 was treated by removal of silicone. The pathogenesis and treatment of these problems are discussed. PMID:3426996

  17. Inducible scAAV2.GRE.MMP1 lowers IOP long-term in a large animal model for steroid-induced glaucoma gene therapy.

    PubMed

    Borrás, T; Buie, L K; Spiga, M G

    2016-05-01

    Current treatment of glaucoma relies on administration of daily drops or eye surgery. A gene therapy approach to treat steroid-induced glaucoma would bring a resolution to millions of people worldwide who depend on glucocorticoid therapy for a myriad of inflammatory disorders. Previously, we had characterized a short-term Adh.GRE.MMP1 gene vector for the production of steroid-induced MMP1 in the trabecular meshwork and tested reduction of elevated intraocular pressure (IOP) in a sheep model. Here we conducted a trial transferring the same transgene cassette to a clinically safe vector (scAAV2), and extended the therapeutic outcome to longer periods of times. No evidence of ocular and/or systemic toxicity was observed. Viral genome distributions showed potential reinducible vector DNAs in the trabecular meshwork (0.4 v.g. per cell) and negligible copies in six major internal organs (0.00002-0.005 v.g. per cell). Histological sections confirmed successful transduction of scAAV2.GFP to the trabecular meshwork. Optimization of the sheep steroid-induced hypertensive model revealed that topical ophthalmic drug difluprednate 0.05% (durezol) induced the highest IOP elevation in the shortest time. This is the first efficacy/toxicity study of a feasible gene therapy treatment of steroid-induced hypertension using clinically accepted self-complementary adeno-associated vectors (scAAV) vectors in a large animal model. PMID:26855269

  18. Glaucoma, Open-Angle

    MedlinePlus

    ... Prevalent Cases of Glaucoma (in thousands) by Age, Gender, and Race/Ethnicity Because of their longer life ... Prevalent Cases of Glaucoma (in thousands) by Age, Gender, and Race/Ethnicity Projections for Glaucoma (2010-2030- ...

  19. Get Tested for Glaucoma!

    MedlinePlus

    ... of this page please turn Javascript on. Feature: Glaucoma Get Tested for Glaucoma! Past Issues / Fall 2009 Table of Contents Taylor ... aoa.org/ When were you finally diagnosed with glaucoma? Not until 1969, after a game of basketball. ...

  20. [Glaucoma medications, preservatives and the ocular surface.

    PubMed

    Aptel, F; Labbé, A; Baudouin, C; Bron, A; Lachkar, Y; Sellem, E; Renard, J-P; Nordmann, J-P; Rouland, J-F; Denis, P

    2014-10-14

    Several clinical and experimental studies have demonstrated that ocular surface disease is common in glaucoma patients receiving chronic glaucoma drops, and that the preservatives in these drops play a major role in the occurrence of ocular surface disease. These ocular surface changes may induce both symptoms reported by the patients and anterior segment clinical signs, and should be systematically assessed by history and exam in all glaucoma patients. In these patients with ocular surface disease, reducing the amount of preservatives administered to the eye should be strived for, rather than adding additional eye drops to alleviate or mask the side effects of the glaucoma drops. PMID:25440185

  1. Pressure-Induced Alterations in PEDF and PEDF-R Expression: Implications for Neuroprotective Signaling in Glaucoma

    PubMed Central

    Lee, Sean J; Duncan, D’Anne S; Echevarria, Franklin D; McLaughlin, William M; Hatcher, Jeremy B; Sappington, Rebecca M

    2015-01-01

    Introduction Alterations in neuron-glia signaling are implicated in glaucoma, a neurodegenerative disease characterized by retinal ganglion cell (RGC) death. Pigment epithelium derived factor (PEDF) is a secreted protein with potential neuroprotective qualities in retinal disease, including chronic ocular hypertension. Here we sought to determine whether moderate, short-term elevations in IOP alter PEDF signaling and whether pressure-induced PEDF signaling directly impacts RGC apoptosis. Methods In retina from naïve mice and mice with unilateral, microbead-induced glaucoma, we examined expression and cell type-specific localization of PEDF and its receptor (PEDF-R), using quantitative PCR and immunohistochemistry. Using primary cultures of purified RGCs and Müller cells, we examined cell type-specific expression of PEDF in response to 48 hours of elevated hydrostatic pressure, using multiplex ELISA and immunocytochemistry. We also measured pressure-induced apoptosis of RGCs in the presence or absence of atglistatin, a potent and selective inhibitor of PEDF-R, and recombinant PEDF, using TUNEL assays. Results PEDF and PEDF-R are constitutively expressed in naïve retina, primarily in the ganglion cell and nerve fiber layers. Elevated IOP increases PEDF and PEDF-R expression, particularly associated with RGCs and Müller cells. Elevated pressure in vitro increased PEDF secretion by 6-fold in RGCs and trended towards an increase in expression by Müller cells, as compared to ambient pressure. This was accompanied by changes in the subcellular localization of PEDF-R in both cell types. Inhibition of PEDF signaling with atglistatin increased pressure-induced apoptosis in RGCs and treatment with recombinant PEDF inhibited pressure-induced apoptosis, both in a dose-dependent manner. Conclusion Our findings suggest that moderate, short-term elevations in IOP promote PEDF signaling via up-regulation of both PEDF and PEDF-R. Based on in vivo and in vitro studies, this PEDF

  2. Acquired color vision loss and a possible mechanism of ganglion cell death in glaucoma.

    PubMed Central

    Nork, T M

    2000-01-01

    PURPOSE: First, to study the cellular mechanisms of acquired color vision loss in retinal detachment and diabetic retinopathy. Second, to learn why, in glaucoma, the type of color vision deficit that is observed is more characteristic of a retinal injury than it is of an optic neuropathy. Third, to test a hypothesis of photoreceptor-induced, ganglion cell death in glaucoma. METHODS: Various histologic techniques were employed to distinguish the L/M-cones (long/medium wavelength-sensitive cones, or red/green sensitive cones) from the S-cones (short wavelength-sensitive cones, or blue sensitive cones) in humans and monkeys with retinal detachment, humans with diabetic retinopathy, and both humans and monkeys with glaucoma. To test if the photoreceptors were contributing to ganglion cell death, laser photocoagulation was used in a experimental model of glaucoma to focally eliminate the photoreceptors. As a control, optic nerve transection was done following retinal laser photocoagulation in one animal. RESULTS: Selective and widespread loss of the S-cones was found in retinal detachment as well as diabetic retinopathy. By contrast, in human as well as experimental glaucoma, marked swelling of the L/M-cones was the predominant histopathologic feature. Retinal laser photocoagulation followed by experimental glaucoma resulted in selective protection of ganglion cells overlying the laser spots. This was not seen with retinal laser photocoagulation by optic nerve transection. CONCLUSIONS: In retinal detachment and diabetic retinopathy, acquired tritan-like color vision loss could be caused, or contributed to, by selective loss of the S-cones. Both L- and M-cones are affected in glaucoma, which is also consistent with a tritan-like deficit. Although not a therapeutic option, protection of ganglion cells by retinal laser in experimental glaucoma is consistent with an hypothesis of anterograde, photoreceptor-induced, ganglion cell death. Images FIGURE 1 FIGURE 2 FIGURE 3

  3. Twenty-Four-Hour Intraocular Pressure Related Changes Following Adjuvant Selective Laser Trabeculoplasty for Normal Tension Glaucoma

    PubMed Central

    Lee, Jacky W.Y.; Fu, Lin; Chan, Jonathan C.H.; Lai, Jimmy S.M.

    2014-01-01

    Abstract To investigate intraocular pressure (IOP) related patterns before and after selective laser trabeculoplasty (SLT) for normal tension glaucoma (NTG). In this prospective cohort study, 18 NTG patients underwent SLT. Success was defined as IOP reduction ≥20% by Goldmann applanation tonometry. 24-hour IOP-related pattern recording with a contact lens sensor (CLS) (SENSIMED Triggerfish®, Sensimed, Switzerland) was done before (baseline) and 1 month after SLT. A cosine function was fitted to the mean CLS patterns for each individual in the SLT success and non-success groups and the amplitude before and after SLT was calculated. Diurnal, nocturnal, and 24-hour CLS pattern local variability was determined for pre- and post-SLT sessions. Cosine amplitude and variability were compared before and after SLT by group using paired t-tests, with α = 0.05. Patients (11 women, 7 men) had a mean age of 65.1 ± 13.7 years. Mean IOP was 15.3 ± 2.2 mm Hg at baseline and was reduced by 17.0% to 12.7 ± 1.8 mm Hg 1 month after SLT (P = 0.001). SLT was successful in 8 patients (44%). The amplitude of the fitted cosine was reduced by 24.6% in the success group, but displayed an amplitude increase of 19.2% post-SLT in the non-success group. Higher diurnal local variability of the CLS pattern was observed after SLT in non-success subjects (P = 0.002), while nocturnal variability showed no significant change. The increase in diurnal variability in the non-success group led to an increase in 24-hour variability in this group (P = 0.001). No change in local variability (diurnal, nocturnal, and 24-hour) was seen in the success group. The IOP-related pattern cosinor amplitude was reduced in NTG patients with a successful SLT treatment whereas the non-success group exhibited an increase of cosine amplitude. Higher diurnal and 24-hour CLS pattern variability was observed in non-success patients 1 month post-SLT. PMID:25501089

  4. Transscleral diode laser cyclophotocoagulation for refractory glaucoma secondary to juvenile idiopathic arthritis: a short term follow-up.

    PubMed

    Dastiridou, Anna I; Androudi, Sofia; Praidou, Anna; Brazitikos, Periklis; Brozou, Catherine G; Tsironi, Evangelia E

    2013-08-01

    To evaluate the success rates of transscleral diode cyclophotocoagulation (TD-CPC) for refractory secondary glaucoma in a paediatric patient with juvenile idiopathic arthritis. Report of a case of a 6-year-old boy suffering from severe uveitis, and secondary open angle glaucoma. The patient had undergone bilateral cataract surgery, two prior trabeculectomies in the left and one in the right eye. He was under systemic immunomodulation with methotrexate and cyclosporine. He presented with medically uncontrolled glaucoma, with an intraocular pressure (IOP) of 36 and 34 mmHg in the right and left eye, respectively, under maximal medical antiglaucoma therapy. TD-CPC was performed under general anesthesia, including a total of 20 spots in the right and 34 in the left eye (2,000 mW, 2 s/spot) applied in one session. Visual acuity remained stable in the right eye and deteriorated in the left eye from 0.1 to no light perception. Postoperative hypotony was present 1 month post op and IOP was 14 mmHg in the left and 17 mmHg in the right eye, respectively, in the 6-month follow-up with a topical beta-blocker. The anterior chamber was quiet in both eyes. TD-CPC was effective in the short term as IOP lowering therapy in a pediatric patient with refractory uveitic glaucoma. PMID:23160822

  5. Molecular fragmentation induced by a femtosecond laser

    NASA Astrophysics Data System (ADS)

    Kosmidis, Constantine E.; Ledingham, Kenneth W. D.; Kilic, H. S.; McCanny, T.; Singhal, Raghunandan P.; Smith, D.; Langley, Andrew J.

    1998-07-01

    The 90 femtosecond laser induced fragmentation at 375 nm for a number of different nitro-molecules is compared to that induced by a nanosecond laser at the same wavelength by means of time-of-flight mass spectrometry. The potential of femtosecond laser mass spectrometry for analytical purposes is discussed.

  6. Recent advances in pharmacotherapy of glaucoma

    PubMed Central

    Gupta, S. K.; Niranjan D., Galpalli; Agrawal, S. S.; Srivastava, Sushma; Saxena, Rohit

    2008-01-01

    Glaucoma is a slow progressive degeneration of the retinal ganglion cells (RGCs) and the optic nerve axons, leading to irreversible blindness if left undiagnosed and untreated. Although increased intraocular pressure is a major risk factor of glaucoma, other factors include increased glutamate levels, alterations in nitric oxide (NO) metabolism, vascular alterations and oxidative damage caused by reactive oxygen species. Glaucoma is the second leading cause of blindness globally, accounting for 12.3% of the total blindness. Glaucoma has been broadly classified as primary or secondary open-angle or angle-closure glaucoma. The primary goal in management of glaucoma is to prevent the risk factor, especially elevated intraocular pressure (IOP), using medications, laser therapy or conventional surgery. The first-line treatment of glaucoma usually begins with the use of a topical selective or nonselective blocker or a prostaglandin analog. Second-line drugs of choice include alpha-agonists and topical carbonic anhydrase inhibitors. Cholinergic agonists are considered third-line treatment options. When a single therapy is not sufficient to lower the IOP, a combination therapy is indicated. To enhance the patient compliance, drug delivery systems like electronic devices, ocular inserts, tansdermal and mechanical drug delivery systems have been developed. Use of viscoelastic agents in ophthalmic formulations, emulsions and soluble ophthalmic drug inserts (SODI) enhance patience compliance and ocular drug delivery in patients in long-term glaucoma therapy. For patients who do not respond to antiglaucoma medications, laser trabeculoplasty and incisional surgery are recommended. Several nutrients and botanicals hold promise for the treatment of glaucoma, but most studies are preliminary, and larger, controlled studies are required. Future directions for the development of a novel therapy glaucoma may target glutamate inhibition, NMDA receptor blockade, exogenously applied

  7. Pseudophakic pupillary-block glaucoma.

    PubMed Central

    Werner, D.; Kaback, M.

    1977-01-01

    Four cases of iris-supported pseudophakic pupillary-block glaucoma were presented. Pupillary-block glaucoma is the first postoperative complication seen following the implantation of an intraocular lens, and in our series occurred at an incidence of 3-8%. A short review was made of pupillary-block glaucoma with all types of intraocular lenses, with emphasis on the iris-supported lens. The role of inflammation, haemorrhage, and vitreous and lens material in obstructing aqueous flow at the pupil and peripheral iridectomy site was emphasised. Pitfalls in the diagnosis and management of this condition were reviewed. Methods of prevention and treatment were reviewed with emphasis on early mydriasis, along with carbonic anhydrase inhibitors and hyperosmotic agents as a primary medical treatment. Iridectomy, laser iridotomy, or transfixation of the iris was mentioned as a surgical treatment. PMID:871462

  8. Activation of autophagy induces retinal ganglion cell death in a chronic hypertensive glaucoma model

    PubMed Central

    Park, H-Y Lopilly; Kim, J H; Park, C K

    2012-01-01

    Autophagy is reported to have important roles in relation to regulated cell death pathways and neurodegeneration. This study used chronic hypertensive glaucoma rat model to investigate whether the autophagy pathway has a role in the apoptosis of retinal ganglion cells (RGCs) after chronic intraocular pressure (IOP) elevation. Under electron microscopy, autophagosomes were markedly accumulated in the dendrites and cytoplasm of RGCs after IOP elevation. Western blot analysis showed that LC3-II/LC3-I and beclin-1 were upregulated throughout the 8-weeks period after IOP elevation. The pattern of LC3 immunostaining showed autophagy activation in the cytoplasm of RGCs to increase and peak at 4 weeks after IOP elevation. Most of these LC3B-positive RGCs underwent apoptosis by terminal deoxynucleotidyltransferase-mediated biotinylated UTP nick end labeling, and inhibition of autophagy with 3-methyladenine decreased RGC apoptosis. The activated pattern shows that autophagy is initially activated in the dendrites of the RGCs, but, thereafter autophagy is mainly activated in the cytoplasm of RGCs. This may show that autophagy is differently regulated in different compartments of the neuron. This present study showed that autophgy is activated in RGCs and has a role in autophagic cell death after chronic IOP elevation. PMID:22476098

  9. Repositioning of glaucoma tubes into the pars plana for refractory malignant glaucoma: a case report

    PubMed Central

    2013-01-01

    Introduction Malignant glaucoma occurs when the intraocular pressure elevates in the setting of a shallow anterior chamber and patent iridectomy. We describe a case in which malignant glaucoma that was refractory to conventional treatment and complete vitrectomy was successfully managed by rerouting the glaucoma tubes into the pars plana. Case presentation A 47-year-old Latino man had a history of neovascular glaucoma and subsequent peripheral anterior synechiae. He was status post-two glaucoma drainage devices. He developed pupillary block. Laser iridotomy was performed without complications. He subsequently developed malignant glaucoma that was refractory to yttrium aluminum garnet capsulohyaloidotomy of the anterior hyaloid. He underwent pars plana vitrectomy with successful control of his intraocular pressure. After 2 weeks, the malignant glaucoma recurred. He underwent repositioning of the tubes into the pars plana with successful control of his intraocular pressure. Conclusion In rare cases of malignant glaucoma refractive to yttrium aluminum garnet hyaloidotomy and vitrectomy, placement of glaucoma drainage devices is a reasonable alternative. PMID:23577950

  10. Management of exfoliative glaucoma: challenges and solutions

    PubMed Central

    Holló, Gábor; Katsanos, Andreas; Konstas, Anastasios GP

    2015-01-01

    Exfoliative glaucoma is the most common type of secondary open-angle glaucoma worldwide. It is characterized by high intraocular pressure (IOP) and worse 24-hour IOP characteristics. In order to minimize progression, treatment of exfoliative glaucoma has to provide a low long-term mean IOP and good 24-hour IOP control. To achieve these goals, fixed-dose combination eye drops, argon and selective laser trabeculoplasty, and various forms of surgery (trabeculectomy, deep sclerectomy, viscocanalostomy, ab interno trabeculotomy, trabecular aspiration, and cataract surgery) all need to be considered during the long-term management of the disease. Since exfoliative glaucoma is a disease of the elderly, and is frequently associated with systemic vascular disease, interdisciplinary consultations are of great clinical importance. These management aspects and the current medical, laser, and surgical results are covered in this review, with a special focus on the needs of the general ophthalmologist. PMID:26045655

  11. Management of exfoliative glaucoma: challenges and solutions.

    PubMed

    Holló, Gábor; Katsanos, Andreas; Konstas, Anastasios Gp

    2015-01-01

    Exfoliative glaucoma is the most common type of secondary open-angle glaucoma worldwide. It is characterized by high intraocular pressure (IOP) and worse 24-hour IOP characteristics. In order to minimize progression, treatment of exfoliative glaucoma has to provide a low long-term mean IOP and good 24-hour IOP control. To achieve these goals, fixed-dose combination eye drops, argon and selective laser trabeculoplasty, and various forms of surgery (trabeculectomy, deep sclerectomy, viscocanalostomy, ab interno trabeculotomy, trabecular aspiration, and cataract surgery) all need to be considered during the long-term management of the disease. Since exfoliative glaucoma is a disease of the elderly, and is frequently associated with systemic vascular disease, interdisciplinary consultations are of great clinical importance. These management aspects and the current medical, laser, and surgical results are covered in this review, with a special focus on the needs of the general ophthalmologist. PMID:26045655

  12. Laser Induced Surface Chemical Epitaxy

    NASA Astrophysics Data System (ADS)

    Stinespring, Charter D.; Freedman, Andrew

    1990-02-01

    Studies of the thermal and photon-induced surface chemistry of dimethyl cadmium (DMCd) and dimethyl tellurium (DMTe) on GaAs(100) substrates under ultrahigh vacuum conditions have been performed for substrate temperatures in the range of 123 K to 473 K. Results indicate that extremely efficient conversion of admixtures of DMTe and DMCd to CdTe can be obtained using low power (5 - 10 mJ cm-2) 193 nm laser pulses at substrate temperatures of 123 K. Subsequent annealing at 473 K produces an epitaxial film.

  13. Managing advanced unilateral pseudoexfoliative glaucoma

    PubMed Central

    Marques, André

    2014-01-01

    The only proven therapy for glaucoma is intraocular pressure (IOP) reduction, which can be accomplished by different means. Each should be properly discussed with patients in order to best preserve visual function and quality of life. We report a case of unilateral pseudoexfoliative glaucoma, treated for years with triple topical IOP-lowering drugs. The patient presented with advanced optic neuropathy and important ocular side effects secondary to the treatment. Having discussed his options and prognosis, laser trabeculoplasty was performed while maintaining the remaining therapy considering the advanced stage of glaucoma. His IOP was effectively reduced and no progression was noted after 1-year follow-up. Although medical therapy is the mainstream in glaucoma management, its side effects should not be ignored, especially in unilateral cases. Surgery might have been a better solution, but we chose to perform laser trabeculoplasty, an effective and safer alternative, considering the unlikely but serious risk of the “wipe-out phenomenon” in this case. PMID:24850557

  14. Secondary glaucoma in CAPN5-associated neovascular inflammatory vitreoretinopathy

    PubMed Central

    Cham, Abdourahman; Bansal, Mayank; Banda, Himanshu K; Kwon, Young; Tlucek, Paul S; Bassuk, Alexander G; Tsang, Stephen H; Sobol, Warren M; Folk, James C; Yeh, Steven; Mahajan, Vinit B

    2016-01-01

    Objective The objective of this study was to review the treatment outcomes of patients with secondary glaucoma in cases of autosomal dominant neovascular inflammatory vitreoretinopathy (ADNIV), a hereditary autoimmune uveitis due to mutations in CAPN5. Patients and methods A retrospective, observational case series was assembled from ADNIV patients with secondary glaucoma. The main outcome measures were intraocular pressure (IOP), visual acuity, use of antiglaucoma medications, ocular surgeries, and adverse outcomes. Perimetry and optic disk optical coherence tomography (OCT) were also analyzed. Results Nine eyes of five ADNIV patients with secondary glaucoma were reviewed. Each received a fluocinolone acetonide (FA) implant for the management of posterior uveitis. Following implantation, no eyes developed neovascular glaucoma. Five eyes (in patients 1, 2, and 5) required Ahmed glaucoma valve surgery for the management of steroid-responsive glaucoma. Patient 2 also developed angle closure with iris bombe and underwent laser peripheral iridotomy. Patient 4 had both hypotony and elevated IOP that required periodic antiglaucoma medication in the FA-implanted eye. Patient 3 did not develop steroid-response glaucoma in either eye. Optic disk examinations were obscured by fibrosis and better assessed with OCT. Conclusion ADNIV patients show combined mechanism secondary glaucoma best assessed by OCT of the optic disk. The FA implants have reduced uveitic and neovascular glaucoma. Nevertheless, IOP management remains complex due to steroid-response glaucoma, angle closure glaucoma, and hypotony. PMID:27390515

  15. Inducible and Endothelial Nitric Synthetase Expression and Nitrotyrosine Accumulation in Iris Vasculature of Patients with Primary Open-Angle Glaucoma: A Pilot Study

    PubMed Central

    Rokicki, Wojciech; Żaba, Małgorzata; Wyględowska-Promieńska, Dorota; Kabiesz, Adam; Reichman-Warmusz, Edyta; Brzozowa, Marlena; Majewski, Wojciech; Wojnicz, Romuald

    2015-01-01

    Background The “double-faced” effect of nitric oxide (NO) is thought to play an important role in triggering and progression of glaucoma. Material/Methods Iris samples were obtained during iridectomy in 35 patients (mean age of 65.4±5.3 years) with diagnosed primary open-angle glaucoma (POAG). The controls were collected postmortem from 10 donors with a mean age of 62.2±1.9 years. Visual field defects were evaluated by perimetry. The Hodapp-Parrish-Anderson classification was used to divide patients into 3 visual field defect groups. The intraocular pressure was measured 3 times before surgery using applanation tonometry. The phenotype activity of nitric oxide synthase (NOS) isoenzymes (endothelial – eNOS and inducible – iNOS) and expression of nitrotyrosine in iris vasculature was assessed. Results Significant differences were found between glaucoma patients and the controls in eNOS and iNOS activity (Mann-Whitney test, U=35.5, Z=−2.037, p=0.04 and U=21, Z=2.69, p=0.007, respectively). In addition, the results showed an upregulation of nitrotyrosine in the capillary endothelial cells in the study group, which was associated with the duration of diagnosed glaucoma (R-Spearman of 0.33, p=0.0047) and visual field mean defect MD (R-Spearman of 0.29, p=0.019). Moreover, the activity of nitrotyrosine was significantly correlated with iNOS immunoreactivity (R-Spearman of 0.5, p=0.0001). However, the iNOS activity significantly varied among Hodapp-Parrish-Anderson groups (p=0.03). Conclusions Our observations confirmed the association between glaucomatous disturbances and upregulation of iNOS, together with increased nitrotyrosine storage. PMID:25564962

  16. Laser induced biological heating analyzed

    NASA Astrophysics Data System (ADS)

    Liu, Phue

    1985-08-01

    A quantitative analysis of the vaporization of tumors by pulsed CO2 lasers, incision by CW CO2 lasers, tissue coagulation by argon lasers, thermal killing of cancerous cells by He-Ne lasers, and the application of heat by CO2 lasers is presented. Although the calculations are based on a simplified skin model, it may prove useful in clinical treatments.

  17. Secondary glaucoma as initial manifestation of uveal melanoma

    PubMed Central

    Othman, Ihab Saad; Assem, Maher; Zaki, Iman M.A.

    2013-01-01

    Purpose Secondary glaucoma can be induced by a variety of local ocular problems. Intraocular tumors may initially present as secondary glaucoma. Methods 8 consecutive patients with secondary glaucoma were found to have uveal melanoma. Thorough examination included detailed history, fundus examination with scleral depression, B scan ultrasonography, and CT/MRI scanning techniques. Results A single case presented with spontaneous hyphema, two patients presented with secondary glaucoma, extraocular melanoma and metastases, a single case was found to have angle block by an iridociliary ring melanoma and 4 cases presented with neovascular glaucoma. Enucleation was necessary in all 8 cases. Conclusions General ophthalmologists should be aware of these rare initial manifestations of intraocular tumors as secondary glaucoma. Enucleation would be recommended in most cases of intraocular malignancy manifesting as secondary glaucoma. One should be extremely cautious in doing a penetrating surgery in such cases. PMID:24227987

  18. [The place of SLT in managing glaucoma].

    PubMed

    Nordmann, J-P

    2008-07-01

    Selective laser trabeculoplasty (SLT) is effective in reducing intraocular pressure (IOP) in glaucomatous patients and patients with ocular hypertension. Equivalent to argon laser trabeculoplasty in terms of IOP reduction, SLT has the advantage of preserving surrounding structures. Easy and rapid to perform, SLT may be an interesting therapeutic approach in the management of glaucoma. PMID:18957918

  19. Glaucoma in Asian Populations

    MedlinePlus

    ... Us Donate In This Section Glaucoma In Asian Populations email Send this article to a friend by ... an even more serious problem as the world population and longevity increases. The other major glaucoma type ...

  20. Screening for Glaucoma

    MedlinePlus

    ... enough evidence to determine the potential benefits and harms of glaucoma screening for adults who do not ... Glaucoma is a group of diseases that can harm the eye’s optic nerve. The optic nerve carries ...

  1. Ultrasound for noninvasive control of laser-induced tissue heating and coagulation

    NASA Astrophysics Data System (ADS)

    Kleffner, Bernhard; Kriegerowski, Martin; Oltrup, Theo; Bende, Thomas; Jean, Benedikt J.

    1996-05-01

    The application of lasers to achieve localized thermal tissue damage is a common technique in minimally invasive surgery. Currently, there is no control during these treatments. In glaucoma therapy the laser energy applied and the beam direction are estimated prior to treatment, according to clinical experience and anatomic norm values. This lack of on-line control may limit success and lead to side effects. Precision and efficiency of treatment could be improved markedly by analysis of spatially resolved, temperature-dependent data obtained by Ultrasound Reflectometry. Thermally induced changes, as well as their localization were detected qualitatively in B-scan. Quantification was achieved by integration of high frequency RF-signals with the following resolution: spatial 50 micrometers , temporal 200 microsecond(s) , temperature 0.5 degree(s). The presented method is suitable for a non-invasive on-line therapy control.

  2. Laser-Induced Thermal Acoustics

    NASA Astrophysics Data System (ADS)

    Cummings, Eric Bryant

    1995-01-01

    Laser-induced thermal acoustics (LITA) is a new technique for remote nonintrusive measurement of thermophysical gas properties. LITA involves forming, via opto-acoustic effects, grating-shaped perturbations of gas properties by the use of intersecting beams from a short-pulse laser. A third beam scatters coherently into a signal beam off the perturbation grating via acousto-optical effects. The evolution of the gas perturbations modulates the scattered signal beam. Accurate values of the sound speed, transport properties, and composition of the gas can be extracted by analyzing the signal beam. An analytical expression for the spectrum, absolute magnitude, and time history of the LITA signal is derived. The optoacoustic effects of thermalization and electrostriction are treated. Finite beam-diameter, beam-duration, and thermalization-rate effects are included in the analysis. The expression accurately models experimental signals over a wide range of gas conditions. Experimental tests using LITA have been conducted on pure and NO_2-seeded air and helium at pressures ranging from {~ }0.1 kPa-14 MPa. Carbon dioxide has been explored near its liquid-vapor critical point. Accuracies of 0.1% in sound speed measurements have been achieved in these tests. Accuracies of {~}1% have been achieved in measurements of thermal diffusivity, although beam misalignment effects have typically degraded this accuracy by a factor of {~} 10-20. Using LITA, susceptibility spectra have been taken of approximately a femtogram of NO_2 . The effects of fluid motion and turbulence have been explored. LITA velocimetry has been demonstrated, in which the Doppler shift of light scattered from a flowing fluid is measured. LITA velocimetry requires no particle seeding, has a coherent signal beam, and can be applied to pulsed flows. LITA has also been applied to measure single-shot |chi^{(1) }|^2 or "Rayleigh scattering" spectra of a gas by the use of a technique of wavelength -division multiplexing

  3. Laser-induced thermal acoustics

    NASA Astrophysics Data System (ADS)

    Cummings, Eric B.

    Laser-induced thermal acoustics (LITA) is a new technique for remote nonintrusive measurement of thermophysical gas properties. LITA involves forming, via opto-acoustic effects, grating-shaped perturbations of gas properties using intersecting beams from a short-pulse laser. A third beam scatters coherently into a signal beam off the perturbation grating via acousto-optical effects. The evolution of the gas perturbations modulates the scattered signal beam. Accurate values of the sound speed, transport properties, and composition of the gas can be extracted by analyzing the signal beam.An analytical expression for the spectrum, absolute magnitude, and time history of the LITA signal is derived. The optoacoustic effects of thermalization and electrostriction are treated. Finite beam-diameter, beam-duration, and thermalization-rate effects are included in the analysis. The expression accurately models experimental signals over a wide range of gas conditions.Experimental tests using LITA have been conducted on pure and [...]-seeded air and helium at pressures ranging from ~0.1 kPa-14 MPa. Carbon dioxide has been explored near its liquid-vapor critical point. Accuracies of 0.1% in sound speed measurements have been achieved in these tests. Accuracies of ~1% have been achieved in measurements of thermal diffusivity, although beam misalignment effects have typically degraded this accuracy by a factor of ~10-20. Using LITA, susceptibility spectra have been taken of approximately a femtogram of [...]. The effects of fluid motion and turbulence have been explored. LITA velocimetry has been demonstrated, in which the Doppler shift of light scattered from a flowing fluid is measured. LITA velocimetry requires no particle seeding, has a coherent signal beam, and can be applied to pulsed flows. LITA has also been applied to measure single-shot [...] or "Rayleigh scattering" spectra of a gas using a technique of wavelength-division multiplexing, called multiplex LITA. The LITA

  4. Glaucoma eye drops adverse skin reactions.

    PubMed

    Cantisani, Carmen; Ambrifi, Marina; Frascani, Federica; Fazia, Gilda; Paolino, Giovanni; Lisi, Roberto; Calvieri, Stefano

    2014-01-01

    The term "Glaucoma" is used to describe a number of diseases of the eye characterized by a particular form of optic nerve damage that is often associated with high intraocular pressure (IOP). The open-angle glaucoma is the most common form that is also referred to as chronic glaucoma. This is described as an optic neuropathy with multifactorial nature in which there is a loss of characteristics of the optic nerve fibers. Therapeutic options for the treatment of this disease are different, you can take advantage of eye drops, laser therapy and conventional surgery or more combined treatments. Medicated eye drops are the most common way to treat glaucoma. Although eye drops are widely used, adverse reactions are not frequently observed and described. In particular, the adverse skin reactions are not frequently described in the literature, but often seen in dermatologic clinic, we reported their skin reactions and possible alternative treatments described in literature and their patent applications. PMID:25487259

  5. Glaucoma Research Foundation

    MedlinePlus

    ... second leading cause of blindness. How Glaucoma Affects Sight Facts and Statistics Request a Free Glaucoma Booklet Vision Loss Progression healthy advanced Tips for Glaucoma Care We've worked with patients, researchers, and eye care professionals to bring you the most helpful ...

  6. Glaucoma and optic nerve repair.

    PubMed

    Diekmann, Heike; Fischer, Dietmar

    2013-08-01

    Glaucoma is a leading cause of irreversible blindness worldwide and causes progressive visual impairment attributable to the dysfunction and death of retinal ganglion cells (RGCs). Progression of visual field damage is slow and typically painless. Thus, glaucoma is often diagnosed after a substantial percentage of RGCs has been damaged. To date, clinical interventions are mainly restricted to the reduction of intraocular pressure (IOP), one of the major risk factors for this disease. However, the lowering of IOP is often insufficient to halt or reverse the progress of visual loss, underlining the need for the development of alternative treatment strategies. Several lines of evidence suggest that axonal damage of RGCs occurs primary at the optic nerve head, where axons appear to be most vulnerable. Axonal injury leads to the functional loss of RGCs and subsequently induces the death of the neurons. However, the detailed molecular mechanism(s) underlying IOP-induced optic nerve injury remain poorly understood. Moreover, whether glaucoma pathophysiology is primarily axonal, glial, or vascular remains unclear. Therefore, protective strategies to prevent further axonal and subsequent soma degeneration are of great importance to limit the progression of sight loss. In addition, strategies that stimulate injured RGCs to regenerate and reconnect axons with their central targets are necessary for functional restoration. The present review provides an overview of the context of glaucoma pathogenesis and surveys recent findings regarding potential strategies for axonal regeneration of RGCs and optic nerve repair, focusing on the role of cytokines and their downstream signaling pathways. PMID:23512141

  7. Genetic bases for glaucoma.

    PubMed

    Fuse, Nobuo

    2010-05-01

    Glaucoma is the leading cause of visual impairment and blindness throughout the world. Primary open angle glaucoma (POAG; MIM 137760) is the main type of glaucoma in most populations, and more than 20 genetic loci for POAG have been reported. Only three causative genes have been identified in these loci, viz. myocilin (MYOC), optineurin (OPTN), and WD repeat domain 36 (WDR36). However, mutations in these genes account for only a small percentage of the patients with POAG. Some of these glaucoma cases have a Mendelian inheritance pattern, and a considerable fraction of the cases result from a large number of variants in several genes each contributing small effects. Glaucoma is considered to be a common disease such as diabetes mellitus, coronary disease, Crohn disease, and several( )common cancers. The main technological approaches used to identify the genes associated with glaucoma are the candidate gene approach, linkage analysis, case-control association study, and genome-wide association study. Association studies have found about 27 genes related to POAG, but the glaucoma-causing effects of these genes need to be investigated in more detail. The current trend is to use case-control association studies or genome-wide association studies to map the genes associated with glaucoma. Such studies are expected to greatly advance our understanding of the genetic basis of glaucoma, and to provide information on the effectiveness of glaucoma therapy. This review gives an overview on the genetic aspects of glaucoma. PMID:20431268

  8. Pediatric Glaucoma: Pharmacotherapeutic Options.

    PubMed

    Samant, Monica; Medsinge, Anagha; Nischal, Ken K

    2016-06-01

    Childhood glaucoma is a major therapeutic challenge for pediatric ophthalmologists and glaucoma specialists worldwide. Management depends on the etiology and age at presentation. A variety of drugs are available for the control of intraocular pressure in children; however, none of these drugs have been licensed by the regulatory agencies for use in children. Furthermore, evidence gained from randomized controlled trials in the pediatric population is sparse, and little is known regarding the use of newer anti-glaucoma preparations. This evidence-based review aims to discuss the available pharmacotherapeutic options for glaucoma in children. Topical adrenoceptor blockers, topical and systemic carbonic anhydrase inhibitors, prostaglandin (PG) analogs, adrenoceptor agonists, parasympathomimetics, and combined preparations are available for use in children, but usually as an off-label indication. Therefore, it is important to recognize that serious side effects have been reported, even with topical drops, and measures to reduce systemic absorption should be taken. Most drugs have been shown to have comparable ocular hypotensive effects, with the lowest occurrence of systemic side effects with PG analogs. Whereas a newly introduced prostaglandin analog, tafluprost, and some other preservative-free preparations have shown promising results in adult glaucoma patients, no pediatric reports are available as yet. Future studies may describe their role in treating pediatric glaucoma. This review also shares some suggested treatment pathways for primary congenital glaucoma (PCG), juvenile open angle glaucoma (JOAG), developmental glaucoma, aphakic/pseudophakic glaucoma, and uveitic glaucoma. PMID:27093864

  9. The Scarborough Glaucoma Survey

    PubMed Central

    Shenken, Ellis; Glas, S.

    1966-01-01

    A glaucoma screening survey was carried out in Scarborough, Ontario, to detect previously unsuspected cases of the disease. General practitioners were employed to perform Schiotz tonometry. Suspected cases were further tested with applanation tonometry and tonography with water drinking. Of the 17,968 persons examined, 999 had a family history of glaucoma. Forty-one of these had obvious clinical glaucoma. The use of Schiotz tonometry plus applanation tonometry in individuals with a positive family history uncovered 463 suspected of having glaucoma. Tonography with water drinking revealed 348 persons with abnormal findings. Of this number, 228 had clinical glaucoma and 120 preclinical glaucoma. Mass screening by tonometry was found to be valuable in detecting glaucoma in the early stages. In most instances, blindness from this disease can be prevented by early diagnosis. ImagesFig. 1Fig. 2Fig. 3 PMID:5912178

  10. Mice with an induced mutation in collagen 8A2 develop larger eyes and are resistant to retinal ganglion cell damage in an experimental glaucoma model

    PubMed Central

    Steinhart, Matthew R.; Cone, Frances E.; Nguyen, Cathy; Nguyen, Thao D.; Pease, Mary E.; Puk, Oliver; Graw, Jochen; Oglesby, Ericka N.

    2012-01-01

    Purpose To study susceptibility to glaucoma injury as it may be affected by mutations in ocular connective tissue components. Methods Mice homozygous for an N-ethyl-N-nitrosourea induced G257D exchange (Gly to Asp) missense mutation (Aca23) in their collagen 8A2 gene were studied to measure intraocular pressure (IOP), axial length and width, number of retinal ganglion cells (RGC), and inflation responses. Three month old homozygous Aca23 mutant and wild type (WT) mice had 6 weeks exposure to elevated IOP induced by polystyrene microbead injection. Additional Aca23 and matched controls were studied at ages of 10 and 18 months. Results Aca23 mice had no significant difference from WT in IOP level, and in both strains IOP rose with age. In multivariable models, axial length and width were significantly larger in Aca23 than WT, became larger with age, and were larger after exposure to glaucoma (n=227 mice). From inflation test data, the estimates of scleral stress resultants in Aca23 mice were similar to age-matched and younger WT C57BL/6 (B6) mice, while the strain estimates for Aca23 were significantly less than those for either WT group in the mid-sclera and in some of the more anterior scleral measures (p<0.001; n=29, 22, 20 eyes in Aca23, older WT, younger WT, respectively). With chronic IOP elevation, Aca23 eyes increased 9% in length and 7% in width, compared to untreated fellow eyes (p<0.05, <0.01). With similar elevated IOP exposure, WT eyes enlarged proportionately twice as much as Aca23, increasing in length by 18% and in nasal—temporal width by 13% (both p<0.001, Mann–Whitney test). In 4 month old control optic nerves, mean RGC axon number was not different in Aca23 and WT (46,905±7,592, 43,628±11,162, respectively; p=0.43, Mann–Whitney test, n=37 and 29). With chronic glaucoma, Aca23 mice had a mean axon loss of only 0.57±17%, while WT mice lost 21±31% (median loss: 1% versus 10%, n=37, 29, respectively; p=0.001; multivariable model adjusting for

  11. Interaction of Laser Induced Micro-shockwaves

    NASA Astrophysics Data System (ADS)

    Leela, Ch.; Bagchi, Suman; Tewari, Surya P.; Kiran, P. Prem

    Laser induced Shock Waves (LISWs) characterized by several optical methods provide Equation of State (EOS) for a variety of materials used in high-energy density physics experiments at Mbar pressures [1, 2]. Other applications include laser spark ignition for fuel-air mixtures, internal combustion engines, pulse detonation engines, laser shock peening [3], surface cleaning [4] and biological applications (SW lithotripsy) [5] to name a few.

  12. The Effect of Rebamipide on Ocular Surface Disorders Induced by Latanoprost and Timolol in Glaucoma Patients

    PubMed Central

    Tokuda, Naoto; Kitaoka, Yasushi; Matsuzawa, Akiko; Miyamoto, Junsuke; Sakae, Shinsuke; Munemasa, Yasunari; Takagi, Hitoshi

    2015-01-01

    Purpose. To examine the efficacy of ophthalmic rebamipide suspensions on ocular surface disorders induced by antiglaucoma eye drops. Patients and Methods. Forty eyes of 40 patients receiving latanoprost (0.005%) and timolol (0.5%) were included in this randomized prospective study. The patients were randomly divided into two groups (n = 20): the rebamipide-treated group and control group. Changes in intraocular pressure, tear film break-up time (TBUT), and corneal epithelial barrier function were evaluated at baseline, 4 weeks, and 8 weeks after rebamipide administration. Furthermore, superficial punctate keratopathy severity was evaluated by scoring the lesion area and density. Results. There was no significant difference in intraocular pressure before and after rebamipide treatment. However, corneal epithelial barrier function improved significantly 4 and 8 weeks after rebamipide treatment. TBUT was partially, but significantly, increased (P = 0.02) 8 weeks after rebamipide treatment, whereas no significant change was observed at 4 weeks. Additionally, a significant decrease in area and density of keratopathy was observed 8 weeks after rebamipide treatment but not at 4 weeks. The control group showed no significant difference compared to baseline. Conclusions. Our data suggests that rebamipide treatment may reduce the occurrence of drug-induced ocular surface disorder. PMID:26064674

  13. Study Of Laser-Induced Copolymerization

    NASA Technical Reports Server (NTRS)

    Miner, Gilda A.; Meador, Willard E.; Chang, C. Ken

    1993-01-01

    Report describes experiments on photopolymerization of styrene/maleic anhydride copolymer published as part of Laser Polymerization Program at NASA Langley Research Center. Presents basic study of copolymerization of styrene and maleic anhydride under laser-induced initiation and polymerization. Helps to clarify different theories on such initiation and represents significant advances in understanding of basic processes.

  14. Evaluation of functional integrity of the retinohypothalamic tract in advanced glaucoma using multifocal electroretinography and light-induced melatonin suppression.

    PubMed

    Pérez-Rico, Consuelo; de la Villa, Pedro; Arribas-Gómez, Ignacio; Blanco, Román

    2010-11-01

    The aim of the study was to investigate the survival of melanopsin-expressing retinal ganglion cells (mRGCs) and the functional integrity of the retinohypothalamic tract in patients with bilateral advanced glaucomatous optic neuropathy by measuring the neuroendocrine light response of the pineal gland. Nine patients with bilateral advanced primary open-angle glaucoma (glaucoma group) and nine normal control subjects (control group) were included in this pilot observational, prospective, case-control study. The best-corrected visual acuity logMAR, standard automated perimetry mean deviation, and the retinal nerve fiber layer thickness determined by optical coherence tomography and multifocal electroretinography were used to evaluate the changes. Melatonin was analyzed in the saliva by radioimmunoassay before and after exposure to bright light (600 lux) for 60 min at night. The advanced glaucoma group did not have any significant nocturnal melatonin suppression after exposure to bright light (14.28 ± 3.07 pg/ml pre-light melatonin concentration vs. 15.22 ± 3.56 pg/ml after light exposure; p = 0.798) unlike the marked melatonin suppression in the control group (22.43 ± 4.37 pg/ml pre-light melatonin concentration vs. 11.25 ± 1.89 pg/ml after light exposure; p < 0.002). Response density estimates by the scalar product amplitude measure for the interval 0-80 ms of the first-order kernel responses were similar in both groups, indicating that outer retinal function was significantly unchanged in the glaucoma group (5.95 ± 0.54 nV/dg^2) compared with the control group (6.20 ± 0.22 nV/dg^2) (p = 0.689). Our findings are consistent with the interpretation that the rhythmic secretion of melatonin was affected in advanced glaucoma, suggesting that attention should be paid to non-image-forming visual functions, such as control of circadian rhythm and the clinical impact in patients with glaucoma. PMID:20692255

  15. Laser Induced Chemical Liquid Phase Deposition (LCLD)

    SciTech Connect

    Nanai, Laszlo; Balint, Agneta M.

    2012-08-17

    Laser induced chemical deposition (LCLD) of metals onto different substrates attracts growing attention during the last decade. Deposition of metals onto the surface of dielectrics and semiconductors with help of laser beam allows the creation of conducting metal of very complex architecture even in 3D. In the processes examined the deposition occurs from solutions containing metal ions and reducing agents. The deposition happens in the region of surface irradiated by laser beam (micro reactors). Physics -chemical reactions driven by laser beam will be discussed for different metal-substrate systems. The electrical, optical, mechanical properties of created interfaces will be demonstrated also including some practical-industrial applications.

  16. Laser-induced caesium-137 decay

    SciTech Connect

    Barmina, E V; Simakin, A V; Shafeev, G A

    2014-08-31

    Experimental data are presented on the laser-induced beta decay of caesium-137. We demonstrate that the exposure of a gold target to a copper vapour laser beam (wavelengths of 510.6 and 578.2 nm, pulse duration of 15 ns) for 2 h in an aqueous solution of a caesium-137 salt reduces the caesium-137 activity by 70%, as assessed from the gamma activity of the daughter nucleus {sup 137m}Ba, and discuss potential applications of laser-induced caesium-137 decay in radioactive waste disposal. (letters)

  17. Does Marijuana Help Treat Glaucoma?

    MedlinePlus

    ... Ophthalmologist Patient Stories Español Eye Health / Tips & Prevention Marijuana Sections Does Marijuana Help Treat Glaucoma? Why Eye ... Don't Recommend Marijuana for Glaucoma Infographic Does Marijuana Help Treat Glaucoma? Written by: David Turbert , contributing ...

  18. Glaucoma Surgery in Pregnancy: A Case Series and Literature Review

    PubMed Central

    Razeghinejad, Mohammad Reza; Masoumpour, Masoumeh; Eghbal, Mohammad Hossein; Myers, Jonathan S.; Moster, Marlene R.

    2016-01-01

    Glaucoma management in pregnant patients is a real challenge, especially when the glaucoma is not controlled with medications. We report the results of 6 incisional glaucoma surgeries for the management of medically uncontrolled glaucoma patients during pregnancy. This retrospective, case series was conducted on the 6 eyes of 3pregnant patients with uncontrolled glaucoma using maximum tolerable medications. Details of the glaucoma surgical management of these patients as well as their postoperative care and pregnancy and clinical outcomes on longitudinal follow-up are discussed. All 3 patients had juvenile open-angle glaucoma and were on various anti-glaucoma medications, including oral acetazolamide. The first case described underwent trabeculectomy without antimetabolites in both eyes because of uncontrolled intraocular pressure with topical medications. The surgery was done with topical lidocaine jelly and subconjunctival lidocaine during the second and third trimesters. The second patient had an Ahmed valve implantation in both eyes during the second and third trimesters because of uncontrolled IOP with topical medications and no response to selective laser trabeculoplasty. Surgery was done with topical tetracaine and subconjunctival and sub-Tenon’s lidocaine. The third case had a Baerveldt valve implantation under general anesthesia in the second trimester. In selected pregnant glaucoma patients with medically uncontrolled intraocular pressure threatening vision, incisional surgery may lead to good outcomes for the patient with no risk for the fetus. PMID:27582594

  19. Glaucoma Surgery in Pregnancy: A Case Series and Literature Review.

    PubMed

    Razeghinejad, Mohammad Reza; Masoumpour, Masoumeh; Eghbal, Mohammad Hossein; Myers, Jonathan S; Moster, Marlene R

    2016-09-01

    Glaucoma management in pregnant patients is a real challenge, especially when the glaucoma is not controlled with medications. We report the results of 6 incisional glaucoma surgeries for the management of medically uncontrolled glaucoma patients during pregnancy. This retrospective, case series was conducted on the 6 eyes of 3pregnant patients with uncontrolled glaucoma using maximum tolerable medications. Details of the glaucoma surgical management of these patients as well as their postoperative care and pregnancy and clinical outcomes on longitudinal follow-up are discussed. All 3 patients had juvenile open-angle glaucoma and were on various anti-glaucoma medications, including oral acetazolamide. The first case described underwent trabeculectomy without antimetabolites in both eyes because of uncontrolled intraocular pressure with topical medications. The surgery was done with topical lidocaine jelly and subconjunctival lidocaine during the second and third trimesters. The second patient had an Ahmed valve implantation in both eyes during the second and third trimesters because of uncontrolled IOP with topical medications and no response to selective laser trabeculoplasty. Surgery was done with topical tetracaine and subconjunctival and sub-Tenon's lidocaine. The third case had a Baerveldt valve implantation under general anesthesia in the second trimester. In selected pregnant glaucoma patients with medically uncontrolled intraocular pressure threatening vision, incisional surgery may lead to good outcomes for the patient with no risk for the fetus. PMID:27582594

  20. Benzalkonium Chloride and Glaucoma

    PubMed Central

    Kaufman, Paul L.; Kiland, Julie A.

    2014-01-01

    Abstract Glaucoma patients routinely take multiple medications, with multiple daily doses, for years or even decades. Benzalkonium chloride (BAK) is the most common preservative in glaucoma medications. BAK has been detected in the trabecular meshwork (TM), corneal endothelium, lens, and retina after topical drop installation and may accumulate in those tissues. There is evidence that BAK causes corneal and conjunctival toxicity, including cell loss, disruption of tight junctions, apoptosis and preapoptosis, cytoskeleton changes, and immunoinflammatory reactions. These same effects have been reported in cultured human TM cells exposed to concentrations of BAK found in common glaucoma drugs and in the TM of primary open-angle glaucoma donor eyes. It is possible that a relationship exists between chronic exposure to BAK and glaucoma. The hypothesis that BAK causes/worsens glaucoma is being tested experimentally in an animal model that closely reflects human physiology. PMID:24205938

  1. [Late postcontusion secondary glaucoma].

    PubMed

    Chiseliţă, D; Vancea, P; Filiman, O; Brănişteanu, D; Bredetean, M; Poiata, I

    1995-01-01

    The investigation of 33 patients with late postcontusional glaucoma subjected to surgery and followed up for 25 +/- 8.24 months has revealed: the interval accident-surgery is shorter in the close-angle combined forms; the essential mechanisms responsible for glaucoma occurrence are: the alteration of trabecular meshwork (for open-angle glaucoma) and pupillary block (for close angle glaucoma); simple cases required antiglaucoma surgery (trabeculectomy, peripheral iridectomy) and the mixed ones required combined (trabeculectomy, lens extraction, lens implant) or sequential surgeries (antiglaucoma surgery, vitrectomy etc); the glaucomatous process was stopped in 83.4% of the open-angle glaucoma cases and progressed in 23.5% of the close-angle glaucoma cases; the functional improvements post antiglaucoma surgery combined with removal of opacities are lessened by the higher frequency of severe per- and post-operative complication. PMID:7654676

  2. 24-h Efficacy of Glaucoma Treatment Options.

    PubMed

    Konstas, Anastasios G P; Quaranta, Luciano; Bozkurt, Banu; Katsanos, Andreas; Garcia-Feijoo, Julian; Rossetti, Luca; Shaarawy, Tarek; Pfeiffer, Norbert; Miglior, Stefano

    2016-04-01

    Current management of glaucoma entails the medical, laser, or surgical reduction of intraocular pressure (IOP) to a predetermined level of target IOP, which is commensurate with either stability or delayed progression of visual loss. In the published literature, the hypothesis is often made that IOP control implies a single IOP measurement over time. Although the follow-up of glaucoma patients with single IOP measurements is quick and convenient, such measurements often do not adequately reflect the untreated IOP characteristics, or indeed the quality of treated IOP control during the 24-h cycle. Since glaucoma is a 24-h disease and the damaging effect of elevated IOP is continuous, it is logical that we should aim to understand the efficacy of all treatment options throughout the 24-h period. This article first reviews the concept and value of diurnal and 24-h IOP monitoring. It then critically evaluates selected available evidence on the 24-h efficacy of medical, laser and surgical therapy options. During the past decade several controlled trials have significantly enhanced our understanding on the 24-h efficacy of all glaucoma therapy options. Nevertheless, more long-term evidence is needed to better evaluate the 24-h efficacy of glaucoma therapy and the precise impact of IOP characteristics on glaucomatous progression and visual prognosis. PMID:26909513

  3. Traumatic Glaucoma in Children

    PubMed Central

    Kaur, Savleen; Singh Pandav, Surinder

    2014-01-01

    ABSTRACT Young patients are more prone to ocular trauma but most of the published studies describe complicated cataract as a result of trauma with its treatment modality. As a result, little is known about the different causes, common presenting signs and symptoms, visual outcomes, and most frequent management modalities of traumatic glaucoma in children. This review aims to study the demographical profile, presentation, management and outcome of traumatic glaucoma in children as well as the various factors associated with advanced glaucomatous changes. How to cite this article: Kaur S, Kaushik S, Pandav SS. Traumatic Glaucoma in Children. J Curr Glaucoma Pract 2014; 8(2):58-62. PMID:26997810

  4. Glaucoma: diagnosis and management.

    PubMed Central

    Infeld, D. A.; O'Shea, J. G.

    1998-01-01

    Glaucoma is the third most prevalent cause of global blindness, accounting for over 5 million blind. It is common in Western Countries; the estimated prevalence of primary open angle glaucoma rises from a total prevalence of 1.1% to approximately 3% of our population as it ages. Ethnicity affects both the risk of developing glaucoma and the outcome. It is an expensive disease both to detect and to treat. Recent scientific advances include elucidation of the genetic mechanism behind the disease and the study of haemodynamic and biochemical co-factors in the development of glaucomatous optic neuropathy, particularly in relation to the pathogenesis of normal tension glaucoma. Several new types of topical medication have recently been developed for use in glaucoma; both the impact of these therapies and their cost effectiveness remain to be evaluated. There are widely differing regimes which effectively treat glaucoma; some ophthalmologists prefer early surgical intervention whilst others reserve surgery for relatively advanced disease. All methods of current treatment rely on the reduction of intra-ocular pressure; as yet there is no medication which has been definitively proven to be either neuroprotective or to influence favourably optic nerve perfusion. Despite this, most sufferers of glaucoma are able to lead lives of quality. Increased community awareness of glaucoma, and earlier detection of the condition, will doubtless result in decreased morbidity due to glaucoma. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:10320884

  5. Metal surface nitriding by laser induced plasma

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  6. Laser-induced structural modifications in glass using a femtosecond laser and a CO2 laser

    NASA Astrophysics Data System (ADS)

    Tamaki, Takayuki; Nakazumi, Shinya; Nakamura, Keigo; Ono, Shunsuke

    2013-03-01

    In this paper, we present the investigation results on laser-induced structural modifications in a BK7 glass sample (OHARA, S-BSL7) by use of a femtosecond laser and a CO2 laser system. A femtosecond fiber laser system (wavelength: 1.06 μm, pulse duration: 250 fs) generates 1 MHz ultrashort laser pulses with a pulse energy up to 2 μJ, and a CO2 laser system generates CW (continuous wave) laser beam with a wavelength of 10.6 μm. Both laser beams were simultaneously irradiated on a BK7 glass substrate (30 mm × 5 mm × 0.7 mm thick). The structural modifications regions were created by translating the glass sample perpendicular to the laser axis with a distance of 1 mm and a scan speed of 0.1 mm/s. The dependence of structural modifications on the laser energy of femtosecond laser pulses and the power of CO2 laser beam were investigated. The results have demonstrated that the refractive index change region with the width of 3 μm was created with simultaneously irradiation of two laser beams although the structural modification regions, which were produced with only femtosecond laser pulses, were surface ablation. And the surface ablation regions were changed to the refractive index change regions as the energy of CO2 laser beam increase to more than 2W.

  7. Zeeman effect induced by intense laser light.

    PubMed

    Stambulchik, E; Maron, Y

    2014-08-22

    We analyze spectral line shapes of hydrogenlike species subjected to fields of electromagnetic waves. It is shown that the magnetic component of an electromagnetic wave may significantly influence the spectra. In particular, the Zeeman effect induced by a visible or infrared light can be experimentally observed using present-day powerful lasers. In addition, the effect may be used for diagnostics of focused beam intensities achieved at existing and newly built laser facilities. PMID:25192094

  8. Heat pump processes induced by laser radiation

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.

    1980-01-01

    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  9. Effect of CNTF on Retinal Ganglion Cell Survival in Experimental Glaucoma

    PubMed Central

    Pease, Mary Ellen; Zack, Donald J; Berlinicke, Cynthia; Bloom, Kristen; Cone, Frances; Wang, Yuxia; Klein, Ronald L.; Hauswirth, William W.; Quigley, Harry A.

    2009-01-01

    Purpose To assess the neuroprotective effect of virally-mediated over-expression of ciliary derived neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) in experimental rat glaucoma. Methods Laser-induced glaucoma was produced in one eye of 224 Wistar rats after injection of adeno-associated viral vectors (type 2) containing either CNTF, BDNF or both, using saline injected eyes and uninjected glaucoma eyes as controls. IOP was measured with the TonoLab and semi-automated optic nerve axon counts were performed by masked observers. IOP exposure over time was adjusted in multivariate regression analysis to calculate the effect of CNTF and BDNF. Results By multivariate regression, CNTF had a significant protective effect, with 15% less RGC axon death (p < 0.01). Both combined CNTF—BDNF and BDNF over-expression alone had no statistically significant improvement in RGC axon survival. By Western blot, there was a quantitative increase in CNTF and BDNF expression in retinas exposed to single viral vectors carrying each gene, but no increase with sequential injection of both vectors. Conclusion These data confirm that CNTF can exert a protective effect in experimental glaucoma. The reason for a lack of observed effect with the BDNF overexpression groups is unclear, but may be a function of the level of neurotrophin expression achieved. PMID:19060281

  10. Electromagnetically induced transparency with noisy lasers

    SciTech Connect

    Xiao Yanhong; Wang Tun; Baryakhtar, Maria; Jiang Liang; Lukin, Mikhail D.; Van Camp, Mackenzie; Crescimanno, Michael; Hohensee, Michael; Walsworth, Ronald L.; Phillips, David F.; Yelin, Susanne F.

    2009-10-15

    We demonstrate and characterize two coherent phenomena that can mitigate the effects of laser phase noise for electromagnetically induced transparency (EIT): a laser-power-broadening-resistant resonance in the transmitted intensity cross correlation between EIT optical fields, and a resonant suppression of the conversion of laser phase noise to intensity noise when one-photon noise dominates over two-photon-detuning noise. Our experimental observations are in good agreement with both an intuitive physical picture and numerical calculations. The results have wide-ranging applications to spectroscopy, atomic clocks, and magnetometers.

  11. Laser-induced electric breakdown in solids

    NASA Technical Reports Server (NTRS)

    Bloembergen, N.

    1974-01-01

    A review is given of recent experimental results on laser-induced electric breakdown in transparent optical solid materials. A fundamental breakdown threshold exists characteristic for each material. The threshold is determined by the same physical process as dc breakdown, namely, avalanche ionization. The dependence of the threshold on laser pulse duration and frequency is consistent with this process. The implication of this breakdown mechanism for laser bulk and surface damage to optical components is discussed. It also determines physical properties of self-focused filaments.

  12. Ultraviolet radiation induced discharge laser

    DOEpatents

    Gilson, Verle A.; Schriever, Richard L.; Shearer, James W.

    1978-01-01

    An ultraviolet radiation source associated with a suitable cathode-anode electrode structure, disposed in a gas-filled cavity of a high pressure pulsed laser, such as a transverse electric atmosphere (TEA) laser, to achieve free electron production in the gas by photoelectric interaction between ultraviolet radiation and the cathode prior to the gas-exciting cathode-to-anode electrical discharge, thereby providing volume ionization of the gas. The ultraviolet radiation is produced by a light source or by a spark discharge.

  13. Mestastable State Population in Laser Induced Plasmas

    NASA Technical Reports Server (NTRS)

    Kwong, V. H. S.; Kyriakides, C.; Ward, W. K.

    2006-01-01

    Laser induced plasma has been used as a source of neutrals and ions in the study of astrophysical plasmas. The purity of state of this source is essential in the determination of collision parameters such as the charge transfer rate coefficients between ions and neutrals. We will show that the temperature of the laser induced plasma is a rapidly decreasing function of time. The temperature is initially high but cools off rapidly through collisions with the expanding plasma electrons as the plasma recombines and streams into the vacuum. This rapid expansion of the plasma, similar to a supersonic jet, drastically lowers the internal energy of the neutrals and ions.

  14. Clinical Characteristics and Current Treatment of Glaucoma

    PubMed Central

    Cohen, Laura P.; Pasquale, Louis R.

    2014-01-01

    Glaucoma is a neurodegenerative disorder in which degenerating retinal ganglion cells (RGC) produce significant visual disability. Clinically, glaucoma refers to an array of conditions associated with variably elevated intraocular pressure (IOP) that contributes to RGC loss via mechanical stress, vascular abnormalities, and other mechanisms, such as immune phenomena. The clinical diagnosis of glaucoma requires assessment of the ocular anterior segment with slit lamp biomicroscopy, which allows the clinician to recognize signs of conditions that can produce elevated IOP. After measurement of IOP, a specialized prismatic lens called a gonioscope is used to determine whether the angle is physically open or closed. The structural manifestation of RGC loss is optic nerve head atrophy and excavation of the neuroretinal rim tissue. Treatment is guided by addressing secondary causes for elevated IOP (such as inflammation, infection, and ischemia) whenever possible. Subsequently, a variety of medical, laser, and surgical options are used to achieve a target IOP. PMID:24890835

  15. Corneal thickness in glaucoma.

    PubMed

    De Cevallos, E; Dohlman, C H; Reinhart, W J

    1976-02-01

    The central corneal stromal thickness of patients with open angle glaucoma, secondary glaucoma (the majority aphakic), or a history of unilateral acute angle closure glaucoma were measured and compared with the stromal thickness of a group of normal patients. In open angle glaucoma, there was a small but significant increase in the average stromal thickness. This thickness increase was, in all likelihood, due to an abnormal function of the endothelium in this disease since the level of the intraocular pressure did not seem to be a factor. There was no correlation between stromal thickness and duration of the glaucoma or type of anti-glaucomatous medication. Most cases of secondary glaucome, controlled medically or not, had markedly increased corneal thickness, again, most likely, due to endothelial damage rather than to level of intraocular pressure. After an angle closure attack, permanent damage to the cornea was found to be rare. PMID:1247273

  16. [Vascular factors in glaucoma].

    PubMed

    Mottet, B; Aptel, F; Geiser, M; Romanet, J P; Chiquet, C

    2015-12-01

    The exact pathophysiology of glaucoma is not fully understood. Understanding of the vascular pathophysiology of glaucoma requires: knowing the techniques for measuring ocular blood flow and characterizing the topography of vascular disease and the mechanisms involved in this neuropathy. A decreased mean ocular perfusion pressure and a loss of vascular autoregulation are implicated in glaucomatous disease. Early decrease in ocular blood flow has been identified in primary open-angle glaucoma and normal pressure glaucoma, contributing to the progression of optic neuropathy. The vascular damage associated with glaucoma is present in various vascular territories within the eye (from the ophthalmic artery to the retina) and is characterized by a decrease in basal blood flow associated with a dysfunction of vasoregulation. PMID:26597554

  17. Animal Models of Glaucoma

    PubMed Central

    A. Bouhenni, Rachida; Dunmire, Jeffrey; Sewell, Abby; Edward, Deepak P.

    2012-01-01

    Glaucoma is a heterogeneous group of disorders that progressively lead to blindness due to loss of retinal ganglion cells and damage to the optic nerve. It is a leading cause of blindness and visual impairment worldwide. Although research in the field of glaucoma is substantial, the pathophysiologic mechanisms causing the disease are not completely understood. A wide variety of animal models have been used to study glaucoma. These include monkeys, dogs, cats, rodents, and several other species. Although these models have provided valuable information about the disease, there is still no ideal model for studying glaucoma due to its complexity. In this paper we present a summary of most of the animal models that have been developed and used for the study of the different types of glaucoma, the strengths and limitations associated with each species use, and some potential criteria to develop a suitable model. PMID:22665989

  18. Application Of Laser Coagulation In Retinal Detachment And Open - Angle Glaucoma, On The Basis Of Own Experiments

    NASA Astrophysics Data System (ADS)

    Palacz, Olgierd; Karczewicz, Danuta; Owczarska, Wieslawa; Sylwestrzak, Zofia

    1987-10-01

    The first part of the paper presents the results of laser ¬Â¢hotocoaculation treatment involving: 141 patients with retinal detachment , 20 with holes in the macula, and 33 with holes at the eye fundus periphery. At estimating the results, the apposition of retina and the observation time have been taken into account. The second part contains the results of observation of 21 patients, in whom, in 26 eyes laser trabeculoplasty was performed. Normalization of intraocular pressure has been obtained in 76.9% of cases. The outflow coefficient after trabeculoplasty has increased in 57.6% of cases.

  19. Laser-induced gas vortices.

    PubMed

    Steinitz, Uri; Prior, Yehiam; Averbukh, Ilya Sh

    2012-07-20

    Recently, several femtosecond-laser techniques have demonstrated molecular excitation to high rotational states with a preferred sense of rotation. We consider collisional relaxation in a dense gas of such unidirectionally rotating molecules, and suggest that due to angular momentum conservation, collisions lead to the generation of macroscopic vortex gas flows. This argument is supported using the Direct Simulation Monte Carlo method, followed by a computational gas-dynamic analysis. PMID:22861845

  20. Spectroscopy During Laser Induced Shock Wave Lithotripsy

    NASA Astrophysics Data System (ADS)

    Engelhardt, R.; Meyer, W.; Hering, P.

    1988-06-01

    In the course of laser induced shock wave lithotripsy (LISL) by means of a flashlamp pumped dye laser a plasma is formed on the stone's surface. Spectral analysis of the plasma flash leads to chemical stone analysis during the procedure. A time resolved integral analysis of scattered and laser induced fluorescence light makes stone detection possible and avoids tissue damage. We used a 200 μm fiber to transmit a 2 μs, 50 mJ pulse to the stone's surface and a second 200 μ fiber for analysis. This transmission system is small and flexible enough for controlled endoscopic use in the treatment of human ureter or common bile duct stones. Under these conditions the stone selective effect of lasertripsy leads only to minor tissue injury.

  1. Seedless Laser Velocimetry Using Heterodyne Laser-Induced Thermal Acoustics

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Balla, R. Jeffrey; Herring, G. C.; Jenkins, Luther N.; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    A need exists for a seedless equivalent of laser Doppler velocimetry (LDV) for use in low-turbulence or supersonic flows or elsewhere where seeding is undesirable or impractical. A compact laser velocimeter using heterodyne non-resonant laser-induced thermal acoustics (LITA) to measure a single component of velocity is described. Neither molecular (e.g. NO2) nor particulate seed is added to the flow. In non-resonant LITA two beams split from a short-pulse pump laser are crossed; interference produces two counterpropagating sound waves by electrostriction. A CW probe laser incident on the sound waves at the proper angle is directed towards a detector. Measurement of the beating between the Doppler-shifted light and a highly attenuated portion of the probe beam allows determination of one component of flow velocity, speed of sound, and temperature. The sound waves essentially take the place of the particulate seed used in LDV. The velocimeter was used to study the flow behind a rearward-facing step in NASA Langley Research Center's Basic Aerodynamics Research Tunnel. Comparison is made with pitot-static probe data in the freestream over the range 0 m/s - 55 m/s. Comparison with LDV is made in the recirculation region behind the step and in a well-developed boundary layer in front of the step. Good agreement is found in all cases.

  2. Minimally invasive glaucoma surgery: current status and future prospects

    PubMed Central

    Richter, Grace M; Coleman, Anne L

    2016-01-01

    Minimally invasive glaucoma surgery aims to provide a medication-sparing, conjunctival-sparing, ab interno approach to intraocular pressure reduction for patients with mild-to-moderate glaucoma that is safer than traditional incisional glaucoma surgery. The current approaches include: increasing trabecular outflow (Trabectome, iStent, Hydrus stent, gonioscopy-assisted transluminal trabeculotomy, excimer laser trabeculotomy); suprachoroidal shunts (Cypass micro-stent); reducing aqueous production (endocyclophotocoagulation); and subconjunctival filtration (XEN gel stent). The data on each surgical procedure for each of these approaches are reviewed in this article, patient selection pearls learned to date are discussed, and expectations for the future are examined. PMID:26869753

  3. Aqueous shunts for glaucoma

    PubMed Central

    Minckler, Don; Vedula, Satyanarayana S; Li, Tianjing; Mathew, Milan; Ayyala, Ramesh; Francis, Brian

    2014-01-01

    Background Aqueous shunts are employed for intraocular pressure (IOP) control in primary and secondary glaucomas that fail medical, laser, and other surgical therapies. Objectives This review compares aqueous shunts for IOP control and safety. Search strategy We searched CENTRAL, MEDLINE, PubMed, EMBASE, NRR in January 2006, LILACS to February 2004 and reference lists of included trials. Selection criteria We included all randomized and quasi-randomized trials in which one arm of the study involved shunts. Data collection and analysis Two authors independently extracted data for included studies and a third adjudicated discrepancies. We contacted investigators for missing information. We used fixed-effect models and summarized continuous outcomes using mean differences. Main results We included fifteen trials with a total of 1153 participants with mixed diagnoses. Five studies reported details sufficient to verify the method of randomization but only two had adequate allocation concealment. Data collection and follow-up times were variable. Meta-analysis of two trials comparing Ahmed implant with trabeculectomy found trabeculectomy resulted in lower mean IOPs 11 to 13 months later (mean difference 3.81 mm Hg, 95% CI 1.94 to 5.69 mm Hg). Meta-analysis of two trials comparing double-plate Molteno implant with the Schocket shunt was not done due to substantial heterogeneity. One study comparing ridged with standard double-plate Molteno implants found no clinically significant differences in outcome. Two trials investigating the effectiveness of adjunctive mitomycin (MMC) with the Molteno and Ahmed implants found no evidence of benefit with MMC. Two trials that investigated surgical technique variations with the Ahmed found no benefit with partial tube ligation or excision of Tenon's capsule. One study concluded there were outcome advantages with a double versus a single-plate Molteno implant and one trial comparing the 350 mm2 and 500 mm2 Baerveldt shunts found no

  4. Glaucoma: Screening Can Save Your Sight!

    MedlinePlus

    ... of this page please turn Javascript on. Feature: Glaucoma Glaucoma: Screening Can Save Your Sight! Past Issues / Fall 2009 Table of Contents People with glaucoma see the world through a tunnel. Glaucoma is ...

  5. Confocal Laser Induced Fluorescence of Argon Plasmas

    NASA Astrophysics Data System (ADS)

    Scime, Earl; Soderholm, Mark

    2015-11-01

    Laser Induced Fluorescence (LIF) provides measurements of flow speed, temperature and when absolutely calibrated, density of ions or neutrals in a plasma. Traditionally, laser induced fluorescence requires two ports on a plasma device. One port is used for laser injection and the other is used for fluorescence emission collection. Traditional LIF is tedious and time consuming to align. These difficulties motivate the development of an optical configuration that requires a single port and remains fully aligned at all times; confocal LIF. Our confocal optical design employs a single two inch diameter lens to both inject the laser light and collect the stimulated emission from an argon plasma. A pair of axicon lenses create an annular beam path for the emission collection and the pump laser light is confined inside the annulus of the collection beam. The measurement location is scanned radially by manually adjusting the final focusing lens position. Here we present optical modeling of and initial results from the axicon based confocal optical system. The confocal measurements are compared to traditional, two-port, LIF measurements over the same radial range. This work is supported by US National Science Foundation grant number PHY-1360278.

  6. Laser-Induced Fluorescence in Gaseous [I[subscript]2] Excited with a Green Laser Pointer

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2007-01-01

    A green laser pointer could be used in a flashy demonstration of laser-induced fluorescence in the gas phase by directing the beam of the laser through a cell containing [I[subscript]2] at its room temperature vapor pressure. The experiment could be used to provide valuable insight into the requirements for laser-induced fluorescence (LIF) and the…

  7. Laser-induced lipolysis on adipose cells

    NASA Astrophysics Data System (ADS)

    Solarte, Efrain; Gutierrez, O.; Neira, Rodrigo; Arroyave, J.; Isaza, Carolina; Ramirez, Hugo; Rebolledo, Aldo F.; Criollo, Willian; Ortiz, C.

    2004-10-01

    Recently, a new liposuction technique, using a low-level laser (LLL) device and Ultrawet solution prior to the procedure, demonstrated the movement of fat from the inside to the outside of the adipocyte (Neira et al., 2002). To determine the mechanisms involved, we have performed Scanning and Transmission Electron Microscopy studies; Light transmittance measurements on adipocyte dilutions; and a study of laser light propagation in adipose tissue. This studies show: 1. Cellular membrane alterations. 2. LLL is capable to reach the deep adipose tissue layer, and 3. The tumescence solution enhances the light propagation by clearing the tissue. MRI studies demonstrated the appearance of fat on laser treated abdominal tissue. Besides, adipocytes were cultivated and irradiated to observe the effects on isolated cells. These last studies show: 1. 635 nm-laser alone is capable of mobilizing cholesterol from the cell membrane; this action is enhanced by the presence of adrenaline and lidocaine. 2. Intracellular fat is released from adipocytes by co joint action of adrenaline, aminophyline and 635 nm-laser. Results are consistent with a laser induced cellular process, which causes fat release from the adipocytes into the intercellular space, besides the modification of the cellular membranes.

  8. Kinetic Approach for Laser-Induced Plasmas

    SciTech Connect

    Omar, Banaz; Rethfeld, Baerbel

    2008-10-22

    Non-equilibrium distribution functions of electron gas and phonon gas excited with ultrashort intense laser pulses are calculated for laser-induced plasmas occurring in solids. The excitation during femtosecond irradiation and the subsequent thermalization of the free electrons, as well as the dynamics of phonons are described by kinetic equations. The microscopic collision processes, such as absorption by inverse bremsstrahlung, electron-electron collisions, and electron-phonon interactions are considered by complete Boltzmann collision integrals. We apply our kinetic approach for gold by taking s-band electron into account and compare it with the case of excitation of d-band electrons.

  9. Quantifying pulsed laser induced damage to graphene

    SciTech Connect

    Currie, Marc; Caldwell, Joshua D.; Bezares, Francisco J.; Robinson, Jeremy; Anderson, Travis; Chun, Hayden; Tadjer, Marko

    2011-11-21

    As an emerging optical material, graphene's ultrafast dynamics are often probed using pulsed lasers yet the region in which optical damage takes place is largely uncharted. Here, femtosecond laser pulses induced localized damage in single-layer graphene on sapphire. Raman spatial mapping, SEM, and AFM microscopy quantified the damage. The resulting size of the damaged area has a linear correlation with the optical fluence. These results demonstrate local modification of sp{sup 2}-carbon bonding structures with optical pulse fluences as low as 14 mJ/cm{sup 2}, an order-of-magnitude lower than measured and theoretical ablation thresholds.

  10. Modeling of Laser-Induced Metal Combustion

    SciTech Connect

    Boley, C D; Rubenchik, A M

    2008-02-20

    Experiments involving the interaction of a high-power laser beam with metal targets demonstrate that combustion plays an important role. This process depends on reactions within an oxide layer, together with oxygenation and removal of this layer by the wind. We present an analytical model of laser-induced combustion. The model predicts the threshold for initiation of combustion, the growth of the combustion layer with time, and the threshold for self-supported combustion. Solutions are compared with detailed numerical modeling as benchmarked by laboratory experiments.

  11. Facts about Glaucoma

    MedlinePlus

    ... remain blurred for several hours. Tonometry is the measurement of pressure inside the eye by using an ... the eye to detect glaucoma. Pachymetry is the measurement of the thickness of your cornea. Your eye ...

  12. Daily Life with Glaucoma

    MedlinePlus

    ... Close Send Thanks for emailing that article! Tweet Free Booklet You can also find the information in ... are not reflected on our website. Get Our Free Newsletter Subscribe Doctors Order booklets about glaucoma for ...

  13. African Americans and Glaucoma

    MedlinePlus

    ... Close Send Thanks for emailing that article! Tweet Free Booklet You can also find the information in ... are not reflected on our website. Get Our Free Newsletter Subscribe Doctors Order booklets about glaucoma for ...

  14. Five Common Glaucoma Tests

    MedlinePlus

    ... Close Send Thanks for emailing that article! Tweet Free Booklet You can also find the information in ... are not reflected on our website. Get Our Free Newsletter Subscribe Doctors Order booklets about glaucoma for ...

  15. Coping with Glaucoma

    MedlinePlus Videos and Cool Tools

    ... comprehensive eye examination performed by a qualified eye care professional such as an opthalmologistor optometrist. The exam ... at-risk individuals -- that's the recommendation of eye care professionals, and that's the way to stop glaucoma ...

  16. What Is Glaucoma?

    MedlinePlus

    ... Glaucoma is a disease that damages your eye's optic nerve. It usually happens when fluid builds up ... increases the pressure in your eye, damaging the optic nerve. It is estimated that three million Americans ...

  17. CW CO2 Laser Induced Chemical Reactions

    NASA Astrophysics Data System (ADS)

    Pola, Joseph

    1989-05-01

    CW CO2 laser driven reactions between sulfur hexafluoride and carbon oxide, carbon suboxide, carbonyl sulfide and carbon disulfide proceed at subatmospheric pressures and yield fluorinated carbon compounds and sulfur tetrafluoride. CW CO2 laser driven reactions of organic compounds in the presence of energy-conveying sulfur hexafluoride show reaction course different from that normally observed due to elimination of reactor hot surface effects. The examples concern the decomposition of polychlorohydrocarbons, 2-nitropropane, tert.-butylamine, allyl chloride, spirohexane, isobornyl acetate and the oxidation of haloolefins. CW CO2 laser induced fragmentation of 1-methyl-l-silacyclobutanes and 4-silaspiro(3.4)octane in the presence of sulfur hexafluoride is an effective way for preparation and deposition of stable organosilicon polymers.

  18. Laser-Induced Incandescence: Detection Issues

    NASA Technical Reports Server (NTRS)

    VanderWal, Randall L.

    1996-01-01

    Experimental LII (laser-induced incandescence) measurements were performed in a laminar gasjet flame to test the sensitivity of different LII signal collection strategies to particle size. To prevent introducing a particle size dependent bias in the LII signal, signal integration beginning with the excitation laser pulse is necessary . Signal integration times extending to 25 or 100 nsec after the laser pulse do not produce significant differences in radial profiles of the LII signal due to particle size effects with longer signal integration times revealing a decreased sensitivity to smaller primary particles. Long wavelength detection reduces the sensitivity of the LII signal to primary particle size. Excitation of LII using 1064 nm light is recommended to avoid creating photochemical interferences thus allowing LII signal collection to occur during the excitation pulse without spectral interferences.

  19. Laser-Induced Damage of Calcium Fluoride

    SciTech Connect

    Espana, Aubrey L.; Joly, Alan G.; Hess, Wayne P.; Dickinson, J T.

    2004-12-01

    Radiation damage of materials has long been of fundamental interest, especially since the growth of laser technology. One such source of damage comes from UV laser light. Laser systems continue to move into shorter wavelength ranges, but unfortunately are limited by the damage threshold of their optical components. For example, semiconductor lithography is making its way into the 157nm range and requires a material that can not only transmit this light (air cannot), but also withstand the highly energetic photons present at this shorter wavelength. CaF2, an alkaline earth halide, is the chosen material for vacuum UV 157 nm excimer radiation. It can transmit light down to 120 nm and is relatively inexpensive. Although it is readily available through natural and synthetic sources, it is often times difficult to find in high purity. Impurities in the crystal can result in occupied states in the band gap that induce photon absorption [2] and ultimately lead to the degradation of the material. In order to predict how well CaF2 will perform under irradiation of short wavelength laser light, one must understand the mechanisms for laser-induced damage. Laser damage is often a two-step process: initial photons create new defects in the lattice and subsequent photons excite these defects. When laser light is incident on a solid surface there is an initial production of electron-hole (e-h) pairs, a heating of free electrons and a generation of local heating around optically absorbing centers [3]. Once this initial excitation converts to the driving energy for nuclear motion, the result is an ejection of atoms, ions and molecules from the surface, known as desorption or ablation [3]. Secondary processes further driving desorption are photoabsorption, successive excitations of self-trapped excitons (STE's) and defects, and ionization of neutrals by incident laser light [3]. The combination of laser-induced desorption and the alterations to the electronic and geometrical

  20. Premium IOLs in Glaucoma

    PubMed Central

    Bhartiya, Shibal; Sharma, Anuj

    2013-01-01

    ABSTRACT Advanced technology or premium intraocular lenses have been developed to meet the patient expectations of perfect distance and near vision without the need for spectacles. Careful patient selection is critical when implanting these implants. This brief review focusses mainly on multifocal and toric IOLs and their application and limitations in patients with glaucoma. How to cite this article: Ichhpujani P, Bhartiya S, Sharma A. Premium IOLs in Glaucoma. J Current Glau Prac 2013;7(2): 54-57. PMID:26997783

  1. Glaucoma in developing countries

    PubMed Central

    Thomas, Ravi

    2012-01-01

    Objective: To describe the background and strategy required for the prevention of blindness from glaucoma in developing countries. Materials and Methods: Extrapolation of existing data and experience in eye care delivery and teaching models in an unequally developed country (India) are used to make recommendations. Results: Parameters like population attributable risk percentage indicate that glaucoma is a public health problem but lack of simple diagnostic techniques and therapeutic interventions are barriers to any effective plan. Case detection rather than population-based screening is the recommended strategy for detection. Population awareness of the disease is low and most patients attending eye clinics do not receive a routine comprehensive eye examination that is required to detect glaucoma (and other potentially blinding eye diseases). Such a routine is not taught or practiced by the majority of training institutions either. Angle closure can be detected clinically and relatively simple interventions (including well performed cataract surgery) can prevent blindness from this condition. The strategy for open angle glaucoma should focus on those with established functional loss. Outcomes of this proposed strategy are not yet available. Conclusions: Glaucoma cannot be managed in isolation. The objective should be to detect and manage all potential causes of blindness and prevention of blindness from glaucoma should be integrated into existing programs. The original pyramidal model of eye care delivery incorporates this principle and provides an initial starting point. The routine of comprehensive eye examination in every clinic and its teaching (and use) in residency programs is mandatory for the detection and management of potentially preventable blinding pathology from any cause, including glaucoma. Programs for detection of glaucoma should not be initiated unless adequate facilities for diagnosis and surgical intervention are in place and their monitoring

  2. Laser-Induced Damage of Calcium Fluoride

    SciTech Connect

    Espana, A.; Joly, A.G.; Hess, W.P.; Dickinson, J.T.

    2004-01-01

    As advances continue to be made in laser technology there is an increasing demand for materials that have high thresholds for laser-induced damage. Laser damage occurs when light is absorbed, creating defects in the crystal lattice. These defects can lead to the emission of atoms, ions and molecules from the sample. One specific field where laser damage is of serious concern is semiconductor lithography, which is beginning to use light at a wavelength of 157 nm. CaF2 is a candidate material for use in this new generation of lithography. In order to prevent unnecessary damage of optical components, it is necessary to understand the mechanisms for laser damage and the factors that serve to enhance it. In this research, we study various aspects of laser interactions with CaF2, including impurity absorbance and various forms of damage caused by incident laser light. Ultraviolet (UV) laser light at 266 nm with both femtosecond (fs) and nanosecond (ns) pulse widths is used to induce ion and neutral particle emission from cleaved samples of CaF2. The resulting mass spectra show significant differences suggesting that different mechanisms for desorption occur following excitation using the different pulse durations. Following irradiation by ns pulses at 266 nm, multiple single-photon absorption from defect states is likely responsible for ion emission whereas the fs case is driven by a multi-photon absorption process. This idea is further supported by the measurements made of the transmission and reflection of fs laser pulses at 266 nm, the results of which reveal a non-linear absorption process in effect at high incident intensities. In addition, the kinetic energy profiles of desorbed Ca and K contaminant atoms are different indicating that a different mechanism is responsible for their emission as well. Overall, these results show that purity plays a key role in the desorption of atoms from CaF2 when using ns pulses. On the other hand, once the irradiance reaches high

  3. Laser-induced electron capture mass spectrometry

    PubMed

    Wang; Giese

    2000-02-15

    Two techniques are reported for detection of electrophorederivatized compounds by laser-induced electron capture time-of-flight mass spectrometry (LI-EC-TOF-MS). In both cases, a nitrogen laser is used to induce the electron capture. The analyte is deposited in a matrix consisting of a compound with a low ionization potential such as benzo[ghi]perylene in the first technique, where the electron for electron capture apparently comes from this matrix. In the second technique, the analyte is deposited on a silver surface in the absence of matrix. It seems that "monoenergetic" ions instantly desorb from the target surface in the latter case, since the peak width in the continuous extraction mode essentially matches the pulse width of the laser (4 ns). Ten picomoles of 3-O-(pentafluorobenzyl)-alpha-estradiol were detected at a S/N > or = 50, where the spot size of the laser was approximately 0.25% of the sample spot. It is attractive that simple conditions can enable sensitive detection of electrophores on routine TOF-MS equipment. The technique can be anticipated to broaden the range of analytes in both polarity and size that can be detected by EC-MS relative to the range for GC/EC-MS. PMID:10701262

  4. Neuroprotection in Glaucoma

    PubMed Central

    Doozandeh, Azadeh; Yazdani, Shahin

    2016-01-01

    Glaucoma is a degenerative optic neuropathy characterized by retinal ganglion cell (RGC) loss and visual field defects. It is known that in some glaucoma patients, death of RGCs continues despite intraocular pressure (IOP) reduction. Neuroprotection in the field of glaucoma is defined as any treatment, independent of IOP reduction, which prevents RGC death. Glutamate antagonists, ginkgo biloba extract, neurotrophic factors, antioxidants, calcium channel blockers, brimonidine, glaucoma medications with blood regulatory effect and nitric oxide synthase inhibitors are among compounds with possible neuroprotective activity in preclinical studies. A few agents (such as brimonidine or memantine) with neuroprotective effects in experimental studies have advanced to clinical trials; however the results of clinical trials for these agents have not been conclusive. Nevertheless, lack of compelling clinical evidence has not prevented the off-label use of some of these compounds in glaucoma practice. Stem cell transplantation has been reported to halt experimental neurodegenerative disease processes in the absence of cell replacement. It has been hypothesized that transplantation of some types of stem cells activates multiple neuroprotective pathways via secretion of various factors. The advantage of this approach is a prolonged and targeted effect. Important concerns in this field include the secretion of unwanted harmful mediators, graft survival issues and tumorigenesis. Neuroprotection in glaucoma, pharmacologically or by stem cell transplantation, is an interesting subject waiting for broad and multidisciplinary collaborative studies to better clarify its role in clinical practice. PMID:27413504

  5. Neuroprotection in Glaucoma.

    PubMed

    Doozandeh, Azadeh; Yazdani, Shahin

    2016-01-01

    Glaucoma is a degenerative optic neuropathy characterized by retinal ganglion cell (RGC) loss and visual field defects. It is known that in some glaucoma patients, death of RGCs continues despite intraocular pressure (IOP) reduction. Neuroprotection in the field of glaucoma is defined as any treatment, independent of IOP reduction, which prevents RGC death. Glutamate antagonists, ginkgo biloba extract, neurotrophic factors, antioxidants, calcium channel blockers, brimonidine, glaucoma medications with blood regulatory effect and nitric oxide synthase inhibitors are among compounds with possible neuroprotective activity in preclinical studies. A few agents (such as brimonidine or memantine) with neuroprotective effects in experimental studies have advanced to clinical trials; however the results of clinical trials for these agents have not been conclusive. Nevertheless, lack of compelling clinical evidence has not prevented the off-label use of some of these compounds in glaucoma practice. Stem cell transplantation has been reported to halt experimental neurodegenerative disease processes in the absence of cell replacement. It has been hypothesized that transplantation of some types of stem cells activates multiple neuroprotective pathways via secretion of various factors. The advantage of this approach is a prolonged and targeted effect. Important concerns in this field include the secretion of unwanted harmful mediators, graft survival issues and tumorigenesis. Neuroprotection in glaucoma, pharmacologically or by stem cell transplantation, is an interesting subject waiting for broad and multidisciplinary collaborative studies to better clarify its role in clinical practice. PMID:27413504

  6. Glaucoma related Proteomic Alterations in Human Retina Samples

    PubMed Central

    Funke, Sebastian; Perumal, Natarajan; Beck, Sabine; Gabel-Scheurich, Silke; Schmelter, Carsten; Teister, Julia; Gerbig, Claudia; Gramlich, Oliver W.; Pfeiffer, Norbert; Grus, Franz H.

    2016-01-01

    Glaucoma related proteomic changes have been documented in cell and animal models. However, proteomic studies investigating on human retina samples are still rare. In the present work, retina samples of glaucoma and non-glaucoma control donors have been examined by a state-of-the-art mass spectrometry (MS) workflow to uncover glaucoma related proteomic changes. More than 600 proteins could be identified with high confidence (FDR < 1%) in human retina samples. Distinct proteomic changes have been observed in 10% of proteins encircling mitochondrial and nucleus species. Numerous proteins showed a significant glaucoma related level change (p < 0.05) or distinct tendency of alteration (p < 0.1). Candidates were documented to be involved in cellular development, stress and cell death. Increase of stress related proteins and decrease of new glaucoma related candidates, ADP/ATP translocase 3 (ANT3), PC4 and SRFS1-interacting protein 1 (DFS70) and methyl-CpG-binding protein 2 (MeCp2) could be documented by MS. Moreover, candidates could be validated by Accurate Inclusion Mass Screening (AIMS) and immunostaining and supported for the retinal ganglion cell layer (GCL) by laser capture microdissection (LCM) in porcine and human eye cryosections. The workflow allowed a detailed view into the human retina proteome highlighting new molecular players ANT3, DFS70 and MeCp2 associated to glaucoma. PMID:27425789

  7. New Tool to Predict Glaucoma

    MedlinePlus

    ... News About Us Donate In This Section A New Tool to Predict Glaucoma email Send this article ... determine if a patient has glaucoma. Recently, a new tool has become available to eye care specialists ...

  8. Improving Glaucoma Detection and Management

    ClinicalTrials.gov

    2015-12-09

    Glaucoma; Glaucoma Suspect; Diabetic Retinopathy; Ocular Hypertension; Cataract; Branch Retinal Vein Occlusion; Branch Retinal Arterial Occlusion; Central Retinal Vein Occlusion; Central Retinal Artery Occlusion; Epi-retinal Membrane; Macular Degeneration; Drusen; Loss of Vision

  9. Diabetes and Your Eyesight (Glaucoma)

    MedlinePlus

    ... without the eye disease. Neovascular glaucoma, a rare type of glaucoma, is always associated with other abnormalities, diabetes being the most common. In some cases of diabetic retinopathy, blood vessels on the retina are damaged. ...

  10. Caffeine administration prevents retinal neuroinflammation and loss of retinal ganglion cells in an animal model of glaucoma

    PubMed Central

    Madeira, Maria H.; Ortin-Martinez, Arturo; Nadal-Nícolas, Francisco; Ambrósio, António F.; Vidal-Sanz, Manuel; Agudo-Barriuso, Marta; Santiago, Ana Raquel

    2016-01-01

    Glaucoma is the second leading cause of blindness worldwide, being characterized by progressive optic nerve damage and loss of retinal ganglion cells (RGCs), accompanied by increased inflammatory response involving retinal microglial cells. The etiology of glaucoma is still unknown, and despite elevated intraocular pressure (IOP) being a major risk factor, the exact mechanisms responsible for RGC degeneration remain unknown. Caffeine, which is an antagonist of adenosine receptors, is the most widely consumed psychoactive drug in the world. Several evidences suggest that caffeine can attenuate the neuroinflammatory responses and afford protection upon central nervous system (CNS) injury. We took advantage of a well characterized animal model of glaucoma to investigate whether caffeine administration controls neuroinflammation and elicits neuroprotection. Caffeine or water were administered ad libitum and ocular hypertension (OHT) was induced by laser photocoagulation of the limbal veins in Sprague Dawley rats. Herein, we show that caffeine is able to partially decrease the IOP in ocular hypertensive animals. More importantly, we found that drinking caffeine prevented retinal microglia-mediated neuroinflammatory response and attenuated the loss of RGCs in animals with ocular hypertension (OHT). This study opens the possibility that caffeine or adenosine receptor antagonists might be a therapeutic option to manage RGC loss in glaucoma. PMID:27270337

  11. Caffeine administration prevents retinal neuroinflammation and loss of retinal ganglion cells in an animal model of glaucoma.

    PubMed

    Madeira, Maria H; Ortin-Martinez, Arturo; Nadal-Nícolas, Francisco; Ambrósio, António F; Vidal-Sanz, Manuel; Agudo-Barriuso, Marta; Santiago, Ana Raquel

    2016-01-01

    Glaucoma is the second leading cause of blindness worldwide, being characterized by progressive optic nerve damage and loss of retinal ganglion cells (RGCs), accompanied by increased inflammatory response involving retinal microglial cells. The etiology of glaucoma is still unknown, and despite elevated intraocular pressure (IOP) being a major risk factor, the exact mechanisms responsible for RGC degeneration remain unknown. Caffeine, which is an antagonist of adenosine receptors, is the most widely consumed psychoactive drug in the world. Several evidences suggest that caffeine can attenuate the neuroinflammatory responses and afford protection upon central nervous system (CNS) injury. We took advantage of a well characterized animal model of glaucoma to investigate whether caffeine administration controls neuroinflammation and elicits neuroprotection. Caffeine or water were administered ad libitum and ocular hypertension (OHT) was induced by laser photocoagulation of the limbal veins in Sprague Dawley rats. Herein, we show that caffeine is able to partially decrease the IOP in ocular hypertensive animals. More importantly, we found that drinking caffeine prevented retinal microglia-mediated neuroinflammatory response and attenuated the loss of RGCs in animals with ocular hypertension (OHT). This study opens the possibility that caffeine or adenosine receptor antagonists might be a therapeutic option to manage RGC loss in glaucoma. PMID:27270337

  12. Primary angle-closure glaucoma: an update.

    PubMed

    Wright, Carrie; Tawfik, Mohammed A; Waisbourd, Michael; Katz, Leslie J

    2016-05-01

    Primary angle-closure glaucoma is potentially a devastating disease, responsible for half of glaucoma-related blindness worldwide. Angle closure is characterized by appositional approximation or contact between the iris and trabecular meshwork. It tends to develop in eyes with shallow anterior chambers, anteriorly positioned or pushed lenses, and angle crowding. Risk of primary angle-closure glaucoma is high among women, the elderly and the hyperopic, and it is most prevalent in Asia. Investigation into genetic mechanisms of glaucoma inheritance is underway. Diagnosis relies on gonioscopy and may be aided by anterior segment optical coherence tomography and ultrasound biomicroscopy. Treatment is designed to control intraocular pressure while monitoring changes to the angle and optic nerve head. Treatment typically begins with medical management through pressure-reducing topical medications. Peripheral iridotomy is often performed to alleviate pupillary block, while laser iridoplasty has been found effective for mechanisms of closure other than pupillary block, such as plateau iris syndrome. Phacoemulsification, with or without goniosynechialysis, both in eyes with existing cataracts and in those with clear lenses, is thus far a viable treatment alternative. Long-term research currently underway will examine its efficacy in cases of angle closure in early stages of the disease. Endoscopic cyclophotocoagulation is another treatment option, which can be combined with cataract surgery. Trabeculectomy remains effective therapy for more advanced cases. PMID:26119516

  13. Laser-induced hydrocarbon contamination in vacuum

    NASA Astrophysics Data System (ADS)

    Riede, Wolfgang; Allenspacher, Paul; Schröder, Helmut; Wernham, Denny; Lien, Yngve

    2005-12-01

    We investigated laser-induced deposition processes on BK7 substrates under the influence of pulsed Q-switched Nd:YAG laser radiation, starting from small toluene partial pressures in a background vacuum environment. The composition and structure of the deposit was analyzed using microscopic methods like Nomarski DIC, dark-field and white-light interference microscopy, TEM, EDX and XPS. We found a distinct threshold for deposition built-up dependant on the partial pressure of toluene (0.2 J/cm2 at 0.1 mbar, 0.8 J/cm2 at 0.01 mbar toluene). The deposits strictly followed the spherical geometry of the laser spot. No deposit accumulated on MgF2 AR coated BK7 samples even at high toluene partial pressures. The onset of deposit was accompanied by periodic surface ripples formation. EDX and XPS analysis showed a carbon-like layer which strongly absorbed the 1 μm laser radiation. The typical number of shots applied was 50 000. In addition, long term lifetime tests of more than 5 Mio. shots per site were run.

  14. Snoring and Glaucoma

    PubMed Central

    Wang, Ya Xing; Xu, Liang; Li, Jian Jun; Yang, Hua; Zhang, Ya Qin; Jonas, Jost B.

    2014-01-01

    Purpose To examine a potential association between snoring and glaucoma in a population-based setting. Methods The population-based Beijing Eye Study 2011 included 3468 subjects with an age of 50+ years. The participants underwent a detailed ophthalmic examination. Glaucoma was determined according to the ophthalmoscopic appearance of the optic nerve head. Snoring assessed in an interview was graded into “severe snoring”, “moderate snoring”, and “no snoring”. Results Data on snoring and glaucoma were available for 3146 subjects. Snoring was reported for 1787 (66.8%) subjects, with moderate snoring reported for 1384 (44.0%) subjects and severe snoring for 403 (12.8%) subjects. In multivariate analysis, prevalence of severe snoring was significantly associated with male gender (P = 0.002; regression coefficient B: 0.36; Odds ratio (OR): 1.44 (95% confidence interval (CI): 1.14, 1.81)), higher body mass index (P<0.001; B: 0.12; OR: 1.13 (95%CI: 1.09, 1.16)), higher systolic blood pressure (P<0.001; B: 0.01; OR: 1.01 (95%CI: 1.005, 1.02)), younger age (P = 0.007; B: −0.018; OR: 0.98 (95%CI: 0.97, 0.995)), and higher cognitive function (P = 0.03; B: 0.04; OR: 1.04 (95%CI: 1.004, 1.08)), however it was not significantly associated with the prevalence of open-angle glaucoma (P = 0.10; B: −0.63; OR: 0.53 (95%CI: 0.25, 1.12)). Prevalence of severe snoring was neither significantly associated with the prevalence of angle-closure glaucoma (P = 0.65), retinal vein occlusions (P = 0.24), neuroretinal rim area (P = 0.19), retinal nerve fiber layer thickness (P = 0.16) nor vertical cup/disc ratio (P = 0.64). Conclusions Severe snoring was not significantly associated with the prevalence of open-angle glaucoma, angle-closure glaucoma or retinal vein occlusions after adjustment for age, gender, body mass index, systolic blood pressure and cognitive function score. Our population-based study did not reveal that snoring was a risk

  15. Fragmentation process induced by microsecond laser pulses during lithotripsy

    NASA Astrophysics Data System (ADS)

    Rink, K.; Delacrétaz, G.; Salathé, R. P.

    1992-07-01

    A fiber optic stress sensing technique is applied to evaluate the fragmentation mechanism for pulsed dye-laser lithotripsy. We demonstrate for the first time that the fragmentation process with microsecond laser pulses originates from the shock wave induced by the cavitation bubble collapse. This shock occurs some hundreds of microseconds after the laser pulse. The shock induced by the plasma expansion, which occurs during laser irradiation, has a minor effect.

  16. Nanodot formation induced by femtosecond laser irradiation

    SciTech Connect

    Abere, M. J.; Kang, M.; Goldman, R. S.; Yalisove, S. M.; Chen, C.; Rittman, D. R.; Phillips, J. D.; Torralva, B.

    2014-10-20

    The femtosecond laser generation of ZnSe nanoscale features on ZnSe surfaces was studied. Irradiation with multiple exposures produces 10–100 nm agglomerations of nanocrystalline ZnSe while retaining the original single crystal structure of the underlying material. The structure of these nanodots was verified using a combination of scanning transmission electron microscopy, scanning electron microscopy, and atomic force microscopy. The nanodots continue to grow hours after irradiation through a combination of bulk and surface diffusion. We suggest that in nanodot formation the result of ultrafast laser induced point defect formation is more than an order of magnitude below the ZnSe ultrafast melt threshold fluence. This unique mechanism of point defect injection will be discussed.

  17. Laser induced fluorescence of dental caries

    NASA Technical Reports Server (NTRS)

    Albin, S.; Byvik, C. E.; Buoncristiani, A. M.

    1988-01-01

    Significant differences between the optical spectra taken from sound regions of teeth and carious regions have been observed. These differences appear both in absorption and in laser induced fluorescence spectra. Excitation by the 488 nm line of an argon ion laser beam showed a peak in the emission intensity around 553 nm for the sound dental material while the emission peak from the carious region was red-shifted by approximately 40 nm. The relative absorption of carious region was significantly higher at 488 nm; however its fluorescence intensity peak was lower by an order of magnitude compared to the sound tooth. Implications of these results for a safe, reliable and early detection of dental caries are discussed.

  18. Laser-induced fluorescence imaging of bacteria

    NASA Astrophysics Data System (ADS)

    Hilton, Peter J.

    1998-12-01

    This paper outlines a method for optically detecting bacteria on various backgrounds, such as meat, by imaging their laser induced auto-fluorescence response. This method can potentially operate in real-time, which is many times faster than current bacterial detection methods, which require culturing of bacterial samples. This paper describes the imaging technique employed whereby a laser spot is scanned across an object while capturing, filtering, and digitizing the returned light. Preliminary results of the bacterial auto-fluorescence are reported and plans for future research are discussed. The results to date are encouraging with six of the eight bacterial strains investigated exhibiting auto-fluorescence when excited at 488 nm. Discrimination of these bacterial strains against red meat is shown and techniques for reducing background fluorescence discussed.

  19. Laser-induced autofluorescence of caries

    NASA Astrophysics Data System (ADS)

    Koenig, Karsten; Hibst, Raimund; Flemming, Gabriela; Schneckenburger, Herbert

    1993-07-01

    The laser induced autofluorescence from carious regions of human teeth was studied using a krypton ion laser at 407 nm as an excitation source, a fiberoptical detection system combined with a polychromator and an optical multichannel analyzer. In addition, time-resolved and time-gated fluorescence measurements in the nanosecond range were carried out. It was found that carious regions contain different fluorophores which emit in the red spectral range. The emission spectra with maxima around 590 nm, 625 nm and 635 nm are typical for metalloporphyrins, copro- and protoporphyrin. During excitation the fluorescence was bleached. Non-carious regions showed a broad fluorescence band with a maximum in the short-wavelength spectral region with shorter fluorescence decay times than the carious regions. Therefore, caries can be detected by spectral analysis of the autofluorescence as well as by determination of the fluorescence decay times or by time-gated imaging.

  20. Laser-induced gas-surface interactions

    NASA Astrophysics Data System (ADS)

    Chuang, T. J.

    Chemical reactions in homogeneous systems activated by laser radiation have been extensively investigated for more than a decade. The applications of lasers to promote gas-surface interactions have just been realized in recent years. The purpose of this paper is to examine the fundamental processes involved in laser-induced gas-surface chemical interactions. Specifically, the photon-enhanced adsorption, adsorbate-adsorbate and adsorbate-solid reactions, product formation and desorption processes are discussed in detail. The dynamic processes involved in photoexcitation of the electronic and vibrational states, the energy transfer and relaxation in competition with chemical interactions are considered. These include both single and multiple photon adsorption, and fundamental and overtone transitions in the excitation process, and inter- and intra-molecular energy transfer, and coupling with phonons, electron-hole pairs and surface plasmons in the energy relaxation process. Many current experimental and theoretical studies on the subject are reviewed and discussed with the goal of clarifying the relative importance of the surface interaction steps and relating the resulting concepts to the experimentally observed phenomena. Among the many gas-solid systems that have been investigated, there has been more extensive use of CO adsorbed on metals, and SF 6 and XeF 2 interactions with silicon as examples to illustrate the many facets of the electronically and vibrationally activated surface processes. Results on IR laser stimulated desorption of C 5H 5N and C 5D 5N molecules from various solid surfaces are also presented. It is clearly shown that rapid intermolecular energy exchange and molecule to surface energy transfer can have important effects on photodesorption cross sections and isotope selectivities. It is concluded that utilization of lasers in gas-surface studies not only can provide fundamental insight into the mechanism and dynamics involved in heterogeneous

  1. Exciting Directions in Glaucoma

    PubMed Central

    Rasmussen, Carol A; Kaufman, Paul L

    2014-01-01

    Glaucoma is a complex, life-long disease that requires an individualized, multifaceted approach to treatment. Most patients will be started on topical ocular hypotensive eyedrop therapy and over time, multiple classes of drugs will be needed to control their intraocular pressure (IOP). The search for drugs with novel mechanisms of action, to treat those who do not achieve adequate IOP control with, or become refractory to, current therapeutics, is ongoing, as is the search for more efficient, targeted drug delivery methods. Gene transfer and stem cell applications for glaucoma therapeutics are moving forward. Advances in imaging technologies improve our understanding of glaucoma pathophysiology and enable more refined patient evaluation and monitoring, improving patient outcomes. PMID:25433744

  2. Update on congenital glaucoma

    PubMed Central

    Mandal, Anil K; Chakrabarti, Debasis

    2011-01-01

    Congenital glaucoma is a global problem and poses a diagnostic and therapeutic challenge to the ophthalmologist. A detailed evaluation under general anesthesia is advisable to establish the diagnosis and plan for management. Medical therapy has a limited role and surgery remains the primary therapeutic modality. While goniotomy or trabeculotomy ab externo is valuable in the management of congenital glaucoma, primary combined trabeculotomy–trabeculectomy offers the best hope of success in advanced cases. Trabeculectomy with antifibrotic agent and glaucoma drainage devices has a role in the management of refractory cases, and cyclodestructive procedures should be reserved for patients where these procedures have failed. Early diagnosis, prompt therapeutic intervention and proper refractive correction are keys to success. Management of residual vision and visual rehabilitation should be an integral part of the management of children with low vision and lifelong follow-up is a must. PMID:21150027

  3. The Role of the IL-20 Subfamily in Glaucoma

    PubMed Central

    Wirtz, Mary K.; Keller, Kate E.

    2016-01-01

    Glaucoma is a common disease that leads to loss of peripheral vision and, if left untreated, ultimately to blindness. While the exact cause(s) of glaucoma is still unknown, two leading risk factors are age and elevated intraocular pressure. Several studies suggest a possible link between glaucoma and inflammation in humans and animal models. In particular, our lab recently identified a T104M mutation in IL-20 receptor-B (IL-20RB) in primary open angle glaucoma patients from a large pedigree. Several of the interleukin- (IL-) 20 family of cytokines and receptors are expressed in ocular tissues including the trabecular meshwork, optic nerve head, and retinal ganglion cells. The DBA/2J mouse develops high intraocular pressures with age and has characteristic optic nerve defects that make it a useful glaucoma model. IL-24 expression is significantly upregulated in the retina of these mice, while IL-20RA expression in the optic nerve is downregulated following pressure-induced damage. The identification of a mutation in the IL-20RB gene in a glaucoma pedigree and changes in expression levels of IL-20 family members in the DBA/2J mouse suggest that disruption of normal IL-20 signaling in the eye may contribute to degenerative processes associated with glaucoma. PMID:26903709

  4. Laser induced surface stress on water droplets.

    PubMed

    Wang, Neng; Lin, Zhifang; Ng, Jack

    2014-10-01

    Laser induced stress on spherical water droplets is studied. At mechanical equilibrium, the body stress vanishes therefore we consider only the surface stress. The surface stress on sub-wavelength droplets is slightly weaker along the light propagation direction. For larger droplets, due to their light focusing effect, the forward stress is significantly enhanced. For a particle roughly 3 micron in radius, when it is excited at whispering gallery mode with Q ∼ 10⁴ by a 1 Watt Gaussian beam, the stress can be enhanced by two orders of magnitude, and can be comparable with the Laplace pressure. PMID:25321955

  5. Comparision of laser-induced and classical ultasound

    NASA Astrophysics Data System (ADS)

    Niederhauser, Joel J.; Jaeger, Michael; Frenz, Martin

    2003-06-01

    A classical medical ultrasound system was combined with a pulsed laser source to allow laser-induced ultrasound imaging (optoacoustics). Classical ultrasound is based on reflection and scattering of an incident acoustic pulse at internal tissue structures. Laser-induced ultrasound is generated in situ by heating optical absorbing structures, such as blood vessels, with a 5 ns laser pulse (few degrees or fraction of degree), which generates pressure transients. Laser-induced ultrasound probes optical properties and therefore provides much higher contrast and complementary information compared to classical ultrasound. An ultrasound array transducer in combination with a commercial medical imaging system was used to record acoustic transients of both methods. Veins and arteries in a human forearm were identified in vivo using classical color doppler and oxygenation dependent optical absorption at 660 nm and 1064 nm laser wavelength. Safety limits of both methods were explored. Laser-induced ultrasound seems well suited to improve classical ultrasound imaging of subcutaneous regions.

  6. [Consensus on neovascular glaucoma].

    PubMed

    Hamard, P; Baudouin, C

    2000-03-01

    Neovascular glaucoma is a dreadful pathology with a rapid spontaneous evolution responsible for painful and blind eye. The main cause is an anterior neovascular proliferation following a broad retinal ischemia. Early diagnosis and treatment are required in order to maintain a good visual status and a satisfactory IOP control with medical, surgical or cylodestructive procedures. In any case, the treatment of the retinal ischemia has to be performed. One must keep in mind that the most efficient way to avoid the incidence of neovascular glaucoma is a strict control of clinical situations potentially responsible for retinal ischemia, namely VRO in elderly patients and diabetic retinopathy in younger patients. PMID:10740059

  7. [Contrast sensitivity in glaucoma].

    PubMed

    Bartos, D

    1989-05-01

    Author reports on results of the contrast sensitivity examinations using the Cambridge low-contrast lattice test supplied by Clement Clarke International LTD, in patients with open-angle glaucoma and ocular hypertension. In glaucoma patients there was observed statistically significant decrease of the contrast sensitivity. In patients with ocular hypertension decrease of the contrast sensitivity was in patients affected by corresponding changes of the visual field and of the optical disc. The main advantages of the Cambridge low-contrast lattice test were simplicity, rapidity and precision of its performance. PMID:2743444

  8. Laser Induced Fluorescence of the Iodine Ion

    NASA Astrophysics Data System (ADS)

    Hargus, William

    2014-10-01

    Iodine (I2) has been considered as a potential electrostatic spacecraft thruster propellant for approximately 2 decades, but has only recently been demonstrated. Energy conversion efficiency appears to be on par with xenon without thruster modification. Intriguingly, performance appears to exceed xenon at high acceleration potentials. As part of a continuing program for the development of non-intrusive plasma diagnostics for advanced plasma spacecraft propulsion, we have identified the I II 5d5D4 o state as metastable, and therefore containing a reservoir of excited state ions suitable for laser probing. The 5d5D4 o - 6p5P3 transition at 695.878 nm is convenient for diode laser excitation with the 5s5S2 o - 6p5P3 transition at 516.12 nm as an ideal candidate for non-resonant fluorescence collection. We have constructed a Penning type iodine microwave discharge lamp optimized for I II production for table-top measurements. This work demonstrates I II laser-induced fluorescence in a representative iodine discharge and will validate our previous theoretical work based on the limited available historical I II spectral data.

  9. Laser-Induced Magnetic Dipole Spectroscopy.

    PubMed

    Hintze, Christian; Bücker, Dennis; Domingo Köhler, Silvia; Jeschke, Gunnar; Drescher, Malte

    2016-06-16

    Pulse electron paramagnetic resonance measurements of nanometer scale distance distributions have proven highly effective in structural studies. They exploit the magnetic dipole-dipole coupling between spin labels site-specifically attached to macromolecules. The most commonly applied technique is double electron-electron resonance (DEER, also called pulsed electron double resonance (PELDOR)). Here we present the new technique of laser-induced magnetic dipole (LaserIMD) spectroscopy based on optical switching of the dipole-dipole coupling. In a proof of concept experiment on a model peptide, we find, already at a low quantum yield of triplet excitation, the same sensitivity for measuring the distance between a porphyrin and a nitroxide label as in a DEER measurement between two nitroxide labels. On the heme protein cytochrome C, we demonstrate that LaserIMD allows for distance measurements between a heme prosthetic group and a nitroxide label, although the heme triplet state is not directly observable by an electron spin echo. PMID:27163749

  10. Primary lens extraction for glaucoma management: A review article

    PubMed Central

    Eid, Tarek M.

    2011-01-01

    Recently, primary lens extraction alone gained more acceptance as an alternative surgical approach for glaucoma management. This view was supported by the advances in phacoemulsification and intraocular lenses with greater safety and visual recovery, in addition to a substantial reduction of intraocular pressure and deepening of the anterior chamber and filtration angle. The decrease in IOP after cataract surgery in primary open-angle glaucoma (POAG) is mild, less predictable, related to baseline levels, and may return to presurgical values after an initial period of reduction. Therefore, the IOP-lowering effect of primary cataract extraction in POAG may be insufficient to achieve adequate IOP control. The IOP reduction after lens extraction is consistently greater in eyes with primary angle closure glaucoma (PACG) than in eyes with POAG. Primary lens extraction in acute PACG eliminates, or at least, reduces the risk of recurrence of acute attacks and deepens the anterior chamber and widens the angle which reduces the risk of progression of peripheral anterior synechiae and development of chronic PACG. Primary lens extraction may be more preferable to glaucoma incisional surgery in mild to moderate PACG eyes with appositional angle closure. The decision to do lens extraction as a primary treatment for glaucoma should be individualized based upon several factors other than the effect on IOP. These factors include patients’ characteristics, surgeons’ skills and preferences, status of glaucoma control, type of cataract and intraocular lens implanted, and potential harm of laser treatment for late capsular opacification and fibrosis. PMID:23960947

  11. Eye Conditions in Older Adults: Open-Angle Glaucoma.

    PubMed

    Iroku-Malize, Tochi; Kirsch, Scott

    2016-06-01

    Glaucoma is the leading cause of irreversible vision loss in the United States, affecting 1.9% of individuals older than 40 years. The prevalence of the most common form, open-angle glaucoma, increases with age and is higher in non-Hispanic minorities. The progressive loss of peripheral vision in glaucoma often leads to difficulty with driving, particularly at night, and can increase the risk of falls and subsequent fractures. Although glaucoma usually is characterized by chronically elevated intraocular pressure, it is more accurately defined as an optic neuropathy. Typically, there are no warning signs or symptoms, and extensive and permanent optic nerve damage can occur before the patient is aware of visual field loss. A cup to disc ratio greater than 0.6 on ophthalmoscopy is suspicious for glaucoma, and visual field testing results show a characteristic peripheral loss. Medical and surgical treatments are aimed at decreasing intraocular pressure by decreasing production of aqueous humor and increasing its outflow. Drugs for glaucoma treatment include prostaglandin analogs, beta blockers, alpha2-adrenergic agonists, and carbonic anhydrase inhibitors. Surgical or laser treatment is indicated if medical management is unsuccessful. Alternative therapies are less effective and have more adverse effects than standard treatments. PMID:27348527

  12. OCT Imaging in Glaucoma

    NASA Astrophysics Data System (ADS)

    Nevins, Jessica E.; Wollstein, Gadi; Schuman, Joel S.

    The precise micron scale quantification of ocular structures provided by OCT turn this technology to be a valuable tool in clinical evaluation of glaucoma patients. This chapter describes the clinical utility of OCT from choosing the scan pattern and scan location to the interpretation of the test outcome.

  13. Pharmacotherapy of Glaucoma

    PubMed Central

    Schmidl, Doreen; Garhöfer, Gerhard; Popa-Cherecheanu, Alina

    2015-01-01

    Abstract Glaucoma is a group of diseases involving the optic nerve and associated structures, which is characterized by progressive visual field loss and typical changes of the optic nerve head (ONH). The only known treatment of the disease is reduction of intraocular pressure (IOP), which has been shown to reduce glaucoma progression in a variety of large-scale clinical trials. Nowadays, a relatively wide array of topical antiglaucoma drugs is available, including prostaglandin analogues, carbonic anhydrase inhibitors, beta-receptor antagonists, adrenergic agonists, and parasympathomimetics. In clinical routine, this allows for individualized treatment taking risk factors, efficacy, and safety into account. A major challenge is related to adherence to therapy. Sustained release devices may help minimize this problem but are not yet available for clinical routine use. Another hope arises from non-IOP-related treatment concepts. In recent years, much knowledge has been gained regarding the molecular mechanisms that underlie the disease process in glaucoma. This also strengthens the hope that glaucoma therapy beyond IOP lowering will become available. Implementing this concept with clinical trials remains, however, a challenge. PMID:25587905

  14. Ultraviolet femtosecond and nanosecond laser ablation of silicon: Ablation efficiency and laser-induced plasma expansion

    SciTech Connect

    Zeng, Xianzhong; Mao, Xianglei; Greif, Ralph; Russo, Richard E.

    2004-03-23

    Femtosecond laser ablation of silicon in air was studied and compared with nanosecond laser ablation at ultraviolet wavelength (266 nm). Laser ablation efficiency was studied by measuring crater depth as a function of pulse number. For the same number of laser pulses, the fs-ablated crater was about two times deeper than the ns-crater. The temperature and electron number density of the pulsed laser-induced plasma were determined from spectroscopic measurements. The electron number density and temperature of fs-pulse plasmas decreased faster than ns-pulse plasmas due to different energy deposition mechanisms. Images of the laser-induced plasma were obtained with femtosecond time-resolved laser shadowgraph imaging. Plasma expansion in both the perpendicular and the lateral directions to the laser beam were compared for femtosecond and nanosecond laser ablation.

  15. Femtosecond laser pulse induced birefringence in optically isotropic glass.

    SciTech Connect

    Vawter, Gregory Allen; Luk, Ting Shan; Guo, Junpeng; Yang, Pin; Burns, George Robert

    2003-07-01

    We used a regeneratively amplified Ti:sapphire femtosecond laser to create optical birefringence in an isotropic glass medium. Between two crossed polarizers, regions modified by the femtosecond laser show bright transmission with respect to the dark background of the isotropic glass. This observation immediately suggests that these regions possess optical birefringence. The angular dependence of transmission through the laser-modified region is consistent with that of an optically birefringent material. Laser-induced birefringence is demonstrated in different glasses, including fused silica and borosilicate glass. Experimental results indicate that the optical axes of laser-induced birefringence can be controlled by the polarization direction of the femtosecond laser. The amount of laser-induced birefringence depends on the pulse energy level and number of accumulated pulses.

  16. Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma

    PubMed Central

    Jia, Yali; Wei, Eric; Wang, Xiaogang; Zhang, Xinbo; Morrison, John C.; Parikh, Mansi; Lombardi, Lori H.; Gattey, Devin M.; Armour, Rebecca L.; Edmunds, Beth; Kraus, Martin F.; Fujimoto, James G.; Huang, David

    2014-01-01

    Purpose To compare optic disc perfusion between normal and glaucoma subjects using optical coherence tomography (OCT) angiography and detect optic disc perfusion changes in glaucoma. Design Observational, cross-sectional study. Participants Twenty-four normal subjects and 11 glaucoma patients were included. Methods One eye of each subject was scanned by a high-speed 1050 nm wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography algorithm (SSADA) was used to compute three-dimensional optic disc angiography. A disc flow index was computed from four registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc ratios. Wide field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness. Main Outcome Measurements Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations between disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression. Results In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in glaucoma subjects. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV respectively. The disc flow index was reduced by 25% in the glaucoma group (p = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation (R2 = 0.752, p = 0.001). These correlations were significant even after accounting for age, cup/disc area ratio, NFL, and rim area. Conclusions OCT angiography, generated by the new SSADA algorithm, repeatably measures optic disc perfusion. OCT

  17. Advanced Imaging for Glaucoma Study: Design, Baseline Characteristics, and Inter-Site Comparison

    PubMed Central

    Le, Phuc V.; Zhang, Xinbo; Francis, Brian A.; Varma, Rohit; Greenfield, David S.; Schuman, Joel S.; Loewen, Nils; Huang, David

    2014-01-01

    Purpose To report the baseline characteristics of the participants in the Advanced Imaging for Glaucoma Study. To compare the participating sites for variations among subjects and the performance of imaging instruments. Design Multi-center longitudinal observational cohort study Methods A total of 788 participants (1,329 eyes) were enrolled from three academic referral centers. There were 145 participants (289 eyes) in the normal group, 394 participants (663 eyes) in the glaucoma suspect/preperimetric glaucoma group, and 249 participants (377 eyes) in the perimetric glaucoma group. Participants underwent a full clinical exam, standard automated perimetry, and imaging with time-domain and Fourier-domain optical coherence tomography (OCT), scanning laser polarimetry, and confocal scanning laser ophthalmoscopy. Main Outcome Measures The baseline average, population standard deviation, and repeatability of imaging-derived anatomic variables were reported for each technology and center. Results Compared to the normal participants, glaucoma suspect/preperimetric glaucoma and perimetric glaucoma groups had significantly reduced anatomic measurements. Repeatability of nerve fiber layer thickness was best for Fourier-domain OCT (overall coefficient of variation < 2%), followed by time-domain OCT (coefficient of variation 2-2.9%), scanning laser polarimetry (coefficient of variation 2.6-4.5%), and confocal scanning laser ophthalmoscopy rim area (coefficient of variation 4.2-7.6%). A mixed-effects model showed that the differences between sites was less than 25 percent of the variation within groups and less than the differences between the normal and glaucoma suspect/preperimetric glaucoma group. Conclusions Site-to-site variation was smaller than both the variation within groups and the changes due to glaucoma. Therefore pooling of participants between sites is appropriate. PMID:25447111

  18. Mouse models of retinal ganglion cell death and glaucoma

    PubMed Central

    McKinnon, Stuart J.; Schlamp, Cassandra L.; Nickells, Robert W.

    2011-01-01

    Once considered too difficult to use for glaucoma studies, mice are now becoming a powerful tool in the research of the molecular and pathological events associated with this disease. Often adapting technologies first developed in rats, ganglion cell death in mice can be induced using acute models and chronic models of experimental glaucoma. Similarly, elevated IOP has been reported in transgenic animals carrying defects in targeted genes. Also, one group of mice, from the DBA/2 line of inbred animals, develops a spontaneous optic neuropathy with many features of human glaucoma that is associated with IOP elevation caused by an anterior chamber pigmentary disease. The advent of mice for glaucoma research is already having a significant impact on our understanding of this disease, principally because of the access to genetic manipulation technology and genetics already well established for these animals. PMID:19105954

  19. Angiogenesis in glaucoma filtration surgery and neovascular glaucoma: A review.

    PubMed

    Kim, Megan; Lee, Chelsea; Payne, Rachael; Yue, Beatrice Y J T; Chang, Jin-Hong; Ying, Hongyu

    2015-01-01

    Angiogenesis may pose a clinical challenge in glaucoma, for example, during the wound healing phase after glaucoma filtration surgery and in the severe secondary glaucoma called neovascular glaucoma (NVG). Upregulation of vascular endothelial growth factor (VEGF), a key mediator of angiogenesis, occurs in eyes that have undergone glaucoma filtration surgery, as well as those with NVG. This has led investigation of the ability of anti-vascular endothelial growth factor therapy to improve outcomes, and we examine the findings with respect to the safety and efficacy of anti-vascular endothelial growth factor agents, mainly bevacizumab and ranibizumab, in eyes that have undergone glaucoma filtration surgery or have NVG. Combining conventional therapies-such as antimetabolites after filtration surgery and panretinal photocoagulation in NVG-and anti-vascular endothelial growth factor drugs may produce a synergetic effect, although further studies are required to evaluate the long-term efficacy of combination treatments. PMID:25980779

  20. Glaucoma: Symptoms, Diagnosis, Treatment and Latest Research

    MedlinePlus

    ... Feature: Glaucoma Glaucoma: Symptoms, Diagnosis, Treatment and Latest Research Past Issues / Fall 2009 Table of Contents Symptoms ... patients may need to keep taking drugs. Latest Research Researchers are studying the causes of glaucoma, looking ...

  1. Genetics Home Reference: early-onset glaucoma

    MedlinePlus

    ... Glaucoma Genetic Testing Registry (2 links) Glaucoma, congenital Primary open angle glaucoma juvenile onset 1 ClinicalTrials.gov (1 link) ClinicalTrials.gov Scientific articles on PubMed (1 link) PubMed OMIM (2 links) ...

  2. Glaucoma: Symptoms, Diagnosis, Treatment and Latest Research

    MedlinePlus

    ... of this page please turn Javascript on. Feature: Glaucoma Glaucoma: Symptoms, Diagnosis, Treatment and Latest Research Past Issues / Fall 2009 Table of Contents Symptoms and Diagnosis Glaucoma can develop in one or both eyes. Often ...

  3. Electromagnetically Induced Guiding of Counter-propagating Lasers in Plasmas

    SciTech Connect

    First Author = G. Shvets; A. Pukhov

    1998-05-01

    The interaction of counter-propagating laser pulses in a plasma is considered. When the frequencies of the two lasers are close, nonlinear modification of the refraction index results in the mutual focusing of the two beams. A short (of order the plasma period) laser pulse can also be nonlinearly focused by a long counter-propagating beam which extends over the entire guiding length. This phenomenon of electromagnetically induced guiding can be utilized in laser-driven plasma accelerators.

  4. Lasing effects in a laser-induced plasma plume

    NASA Astrophysics Data System (ADS)

    Nagli, Lev; Gaft, Michael

    2015-11-01

    We have studied coherent emission from optically pumped preliminarily created laser induced plasma and demonstrate the possibility to create laser sources based on laser plasma as an active medium. The effect was studied in detail with Al plasma, and preliminary but promising results were also obtained with other atoms from the 13th and 14th groups of the periodic table. These lasers may be used as coherent light sources in a variety of optical applications.

  5. Ocular Blood Flow and Influencing Factors for Glaucoma.

    PubMed

    Nakazawa, Toru

    2016-01-01

    Open-angle glaucoma (OAG) is characterized by optic nerve fiber atrophy and deterioration of the visual field, corresponding to damage to the optic nerve head. Intraocular pressure (IOP) is currently the only evidence-based, treatable risk factor for OAG. However, normal-tension glaucoma, the most common type of OAG in Asia, is a type of glaucoma with an unclear pathogenesis. Glaucoma is suspected to be a multifactorial disease with IOP-dependent and IOP-independent risk factors, including decreased ocular blood flow (OBF), oxidative stress, decreased axoplasmic flow, and genetic background. A number of epidemiological studies have generated strong evidence that OBF may be an especially important risk factor for the progression of glaucoma. Recent innovations in laser speckle flowgraphy and optical coherence tomography-based angiography have allowed us to noninvasively monitor changes in the microcirculation of the optic nerve head with high reproducibility. Laser speckle flowgraphy-derived measurement parameters include mean blur rate and pulse wave form parameters, whereas the main optical coherence tomography angiography-derived parameter is the vessel index. Decreases in these parameters are associated with the severity of glaucomatous damage, and changes are detectible even in the earliest, preperimetric stage of glaucoma. In the future, OBF analysis may improve significantly because of continuing progress in the development of the relevant instruments. This review will summarize possible connections between systemic and OBF abnormalities and OAG, describe the scientific rationale for these connections, and discuss their potential implications. Thus, this review will summarize the role of OBF in glaucoma pathogenesis and discuss the wide range of IOP-independent risk factors. PMID:26886118

  6. Volume of a laser-induced microjet

    NASA Astrophysics Data System (ADS)

    Kawamoto, Sennosuke; Hayasaka, Keisuke; Noguchi, Yuto; Tagawa, Yoshiyuki

    2015-11-01

    Needle-free injection systems are of great importance for medical treatments. In spite of their great potential, these systems are not commonly used. One of the common problems is strong pain caused by diffusion shape of the jet. To solve this problem, the usage of a high-speed highly-focused microjet as needle-free injection system is expected. It is thus crucial to control important indicators such as ejected volume of the jet for its safe application. We conduct experiments to reveal which parameter influences mostly the ejected volume. In the experiments, we use a glass tube of an inner diameter of 500 micro-meter, which is filled with the liquid. One end is connected to a syringe and the other end is opened. Radiating the pulse laser instantaneously vapors the liquid, followed by the generation of a shockwave. We find that the maximum volume of a laser-induced bubble is approximately proportional to the ejected volume. It is also found that the occurrence of cavitation does not affect the ejected volume while it changes the jet velocity.

  7. Microcantilever Actuation by Laser Induced Photoacoustic Waves.

    PubMed

    Gao, Naikun; Zhao, Dongfang; Jia, Ran; Liu, Duo

    2016-01-01

    We present here a combined theoretical and experimental investigation on effective excitation of microcantilever by using photoacoustic waves. The photoacoustic waves arose from a vibrating Al foil induced by an intensity-modulated laser. We demonstrate that, superior to photothermal excitation, this new configuration avoids direct heating of the microcantilever, thus minimizing undesired thermal effects on the vibration of microcantilever, while still keeps the advantage of being a remote, non-contact excitation method. We also measured the vibration amplitude of the microcantilever as a function of distance between the microcantilever and the Al foil and found that the amplitudes decay gradually according to the inverse distance law. This method is universal and can be adopted in bio-microelectromechanical systems (BioMEMs) for the detection of small signals where detrimental thermal effects must be avoided. PMID:26814360

  8. Microcantilever Actuation by Laser Induced Photoacoustic Waves

    PubMed Central

    Gao, Naikun; Zhao, Dongfang; Jia, Ran; Liu, Duo

    2016-01-01

    We present here a combined theoretical and experimental investigation on effective excitation of microcantilever by using photoacoustic waves. The photoacoustic waves arose from a vibrating Al foil induced by an intensity-modulated laser. We demonstrate that, superior to photothermal excitation, this new configuration avoids direct heating of the microcantilever, thus minimizing undesired thermal effects on the vibration of microcantilever, while still keeps the advantage of being a remote, non-contact excitation method. We also measured the vibration amplitude of the microcantilever as a function of distance between the microcantilever and the Al foil and found that the amplitudes decay gradually according to the inverse distance law. This method is universal and can be adopted in bio-microelectromechanical systems (BioMEMs) for the detection of small signals where detrimental thermal effects must be avoided. PMID:26814360

  9. Laser-induced breakdown spectroscopy in China

    NASA Astrophysics Data System (ADS)

    Wang, Zhe; Yuan, Ting-Bi; Hou, Zong-Yu; Zhou, Wei-Dong; Lu, Ji-Dong; Ding, Hong-Bin; Zeng, Xiao-Yan

    2014-08-01

    Laser-induced breakdown spectroscopy (LIBS) has been regarded as a future superstar for chemical analysis for years due to its unique features such as little or no sample preparation, remote sensing, and fast and multi-element analysis. Chinese LIBS community is one of the most dynamically developing communities in the World. The aim of the work is to inspect what have been done in China for LIBS development and, based on the understanding of the overall status, to identify the challenges and opportunities for the future development. In this paper, the scientific contributions from Chinese LIBS community are reviewed for the following four aspects: fundamentals, instrumentation, data processing and modeling, and applications; and the driving force of LIBS development in China is analyzed, the critical issues for successful LIBS application are discussed, and in our opinion, the potential direction to improve the technology and to realize large scale commercialization in China is proposed.

  10. Microcantilever Actuation by Laser Induced Photoacoustic Waves

    NASA Astrophysics Data System (ADS)

    Gao, Naikun; Zhao, Dongfang; Jia, Ran; Liu, Duo

    2016-01-01

    We present here a combined theoretical and experimental investigation on effective excitation of microcantilever by using photoacoustic waves. The photoacoustic waves arose from a vibrating Al foil induced by an intensity-modulated laser. We demonstrate that, superior to photothermal excitation, this new configuration avoids direct heating of the microcantilever, thus minimizing undesired thermal effects on the vibration of microcantilever, while still keeps the advantage of being a remote, non-contact excitation method. We also measured the vibration amplitude of the microcantilever as a function of distance between the microcantilever and the Al foil and found that the amplitudes decay gradually according to the inverse distance law. This method is universal and can be adopted in bio-microelectromechanical systems (BioMEMs) for the detection of small signals where detrimental thermal effects must be avoided.

  11. Laser-Induced Spallation of Microsphere Monolayers.

    PubMed

    Hiraiwa, Morgan; Stossel, Melicent; Khanolkar, Amey; Wang, Junlan; Boechler, Nicholas

    2016-08-01

    The detachment of a semiordered monolayer of polystyrene microspheres adhered to an aluminum-coated glass substrate is studied using a laser-induced spallation technique. The microsphere-substrate adhesion force is estimated from substrate surface displacement measurements obtained using optical interferometry, and a rigid-body model that accounts for the inertia of the microspheres. The estimated adhesion force is compared with estimates obtained using an adhesive contact model together with interferometric measurements of the out-of-plane microsphere contact resonance, and with estimated work of adhesion values for the polystyrene-aluminum interface. Scanning electron microscope images of detached monolayer regions reveal a unique morphology, namely, partially detached monolayer flakes composed of single hexagonal close packed crystalline domains. This work contributes to the fields of microsphere adhesion and contact dynamics, and demonstrates a unique monolayer delamination morphology. PMID:27409715

  12. Laser-induced fluorescence-cued, laser-induced breakdown spectroscopy biological-agent detection

    SciTech Connect

    Hybl, John D.; Tysk, Shane M.; Berry, Shaun R.; Jordan, Michael P

    2006-12-01

    Methods for accurately characterizing aerosols are required for detecting biological warfare agents. Currently, fluorescence-based biological agent sensors provide adequate detection sensitivity but suffer from high false-alarm rates. Combining single-particle fluorescence analysis with laser-induced breakdown spectroscopy (LIBS) provides additional discrimination and potentially reduces false-alarm rates. A transportable UV laser-induced fluorescence-cued LIBS test bed has been developed and used to evaluate the utility of LIBS for biological-agent detection. Analysis of these data indicates that LIBS adds discrimination capability to fluorescence-based biological-agent detectors.However, the data also show that LIBS signatures of biological agent simulants are affected by washing. This may limit the specificity of LIBS and narrow the scope of its applicability in biological-agent detection.

  13. Laser-Induced-Fluorescence Photogrammetry and Videogrammetry

    NASA Technical Reports Server (NTRS)

    Danehy, Paul; Jones, Tom; Connell, John; Belvin, Keith; Watson, Kent

    2004-01-01

    surface of the target. The improved method is denoted laser-induced-fluorescence photogrammetry.

  14. Laser-induced periodic surface structuring of biopolymers

    NASA Astrophysics Data System (ADS)

    Pérez, Susana; Rebollar, Esther; Oujja, Mohamed; Martín, Margarita; Castillejo, Marta

    2013-03-01

    We report here on a systematic study about the formation of laser-induced periodic surface structures (LIPSS) on biopolymers. Self-standing films of the biopolymers chitosan, starch and the blend of chitosan with the synthetic polymer poly (vinyl pyrrolidone), PVP, were irradiated in air with linearly polarized laser beams at 193, 213 and 266 nm, with pulse durations in the range of 6-17 ns. The laser-induced periodic surface structures were topographically characterized by atomic force microscopy and the chemical modifications induced by laser irradiation were inspected via Raman spectroscopy. Formation of LIPSS parallel to the laser polarization direction, with periods similar to the laser wavelength, was observed at efficiently absorbed wavelengths in the case of the amorphous biopolymer chitosan and its blend with PVP, while formation of LIPSS is prevented in the crystalline starch biopolymer.

  15. Hypopyon following laser iridotomy.

    PubMed

    Cohen, J S; Bibler, L; Tucker, D

    1984-07-01

    Two patients who had laser iridotomy performed for pupillary block glaucoma developed hypopyon following surgery. One case had iris bombé with rubeosis iridis, and the other had chronic angle closure glaucoma. Factors contributing to inflammation and possible hypopyon following laser iridotomy are discussed. PMID:6472786

  16. Laser induced incandescence and laser induced breakdown spectroscopy based sensor development

    NASA Astrophysics Data System (ADS)

    Eseller, Kemal Efe

    In this doctoral dissertation, two laser-based sensors were evaluated for different applications. Laser Induced Incandescence (LII) is a technique which can provide non-intrusive quantitative measurement of soot and it provides a unique diagnostic tool to characterize engine performance. Since LII is linearly proportional to the soot volume fraction, it can provide in situ, real time measurement of soot volume fraction with high temporal and spatial resolution. LII has the capability to characterize soot formation during combustion. The soot volume fraction from both flames and a soot generator was investigated with LII. The effects of experimental parameters, such as laser fluence, gate delay, gate width and various laser beam focusing, on LII signal was studied. Laser Induced Breakdown Spectroscopy (LIBS), a diagnostic tool for in situ elemental analysis, has been evaluated for on-line, simultaneous, multi-species impurity monitoring in hydrogen. LIBS spectra with different impurity levels of nitrogen, argon, and oxygen were recorded and the intensity of the spectral lines of Ar, O, N, and H observed were used to form calibration plots for impurities in hydrogen measurements. An ungated detection method for LIBS has been developed and applied to equivalence ratio measurements of CH4/air and biofuel/air. LIBS has also been used to quantitatively analyze the composition of a slurry sample. The quenching effect of water in slurry samples causes low LIBS signal quality with poor sensitivity. Univariate and multivariate calibration was performed on LIBS spectra of dried slurry samples for elemental analysis of Mg, Si and Fe. Calibration results show that the dried slurry samples give good correlation between spectral intensity and elemental concentration.

  17. Laser Induced Birefringence in Pure Liquids

    NASA Astrophysics Data System (ADS)

    Harrison, Neil J.

    1991-01-01

    Available from UMI in association with The British Library. Laser induced birefringence or the Optical Kerr effect is a subject that has undergone much research over previous years and is an established technique for the study of many classes of materials. To date the measurements on various media have been characterized by the substantial time required to obtain results and the generally poor sensitivity of the apparatus used. This work describes the development of a new apparatus which is the first in the field to automate the signal capture and analysis utilizing a 1 Gigasample/second digitizing oscilloscope connected to a microcomputer to provide fast, accurate transient analysis. Careful design of the apparatus enabled operation at two inducing wavelengths of 532nm and 1064nm. The sensitivity and accuracy of the apparatus coupled with the rapid transient evaluation was tested on a number of well characterized samples including benzene, nitrobenzene, toluene and benzoyl chloride and was found to give excellent agreement with other workers. The apparatus was used to investigate the properties of the organic pure liquid series the n-alkanes before making the first measurements on the 1-alkenes, 1-alkynes, alcohols, carboxylic acids and three alkdienes. Results from these experiments were used to evaluate the contributions of sigma and pi bonds to the Optical Kerr effect in simple organic molecules. A review of all previously published Optical Kerr effect results for pure liquids was also carried out and the first comprehensive table of results complied.

  18. Glaucoma Management in Carotid Cavernous Fistula

    PubMed Central

    Calafiore, Silvia; Perdicchi, Andrea; Scuderi, Gianluca; Contestabile, Maria Teresa; Abdolrahimzadeh, Solmaz; Recupero, Santi Maria

    2016-01-01

    Carotid cavernous fistulas (CCF) are vascular communications between the carotid artery and the cavernous sinus. Ophthalmologists are called to diagnose and manage the condition in cases that present with ocular features. A 73-year-old female was referred to our glaucoma center clinic. Eight years before, she had started receiving medication for glaucoma and had undergone laser iridotomy, but a satisfactory management of intraocular pressure (IOP) had not been achieved. The patient was complaining of intermittent diplopia, bilateral proptosis, and conjunctival chemosis over the past 6 months. Best-corrected visual acuity in the right (OD) and left eye (OS) was 9/10 and 10/10, respectively. Visual field testing showed slight paracentral field defects mostly in OS. IOP was 20 mm Hg in OD and 34 mm Hg in OS. We referred the patient to neuroradiology, and MRI angiography revealed a CCF with angiographic classification of Cognard grade 2. Closure of the CCF by transarterial embolization was performed in the neuroradiology department. One week following the procedure, the clinical signs of diplopia, proptosis, and conjunctival chemosis had greatly improved, and IOP was reduced to 12 mm Hg OD and 19 mm Hg in OS. Glaucoma treatment was maintained with topical brimatoprost, brinzolamide, and timolol. Owing to the risk of vision loss associated with vascular stasis, retinal ischemia, and high IOP, ophthalmologists must be aware of the clinical features of CCF and should request appropriate imaging studies such as MRI angiography in order to confirm the diagnosis and plan multidisciplinary treatment. PMID:27462258

  19. Glaucoma Management in Carotid Cavernous Fistula.

    PubMed

    Calafiore, Silvia; Perdicchi, Andrea; Scuderi, Gianluca; Contestabile, Maria Teresa; Abdolrahimzadeh, Solmaz; Recupero, Santi Maria

    2016-01-01

    Carotid cavernous fistulas (CCF) are vascular communications between the carotid artery and the cavernous sinus. Ophthalmologists are called to diagnose and manage the condition in cases that present with ocular features. A 73-year-old female was referred to our glaucoma center clinic. Eight years before, she had started receiving medication for glaucoma and had undergone laser iridotomy, but a satisfactory management of intraocular pressure (IOP) had not been achieved. The patient was complaining of intermittent diplopia, bilateral proptosis, and conjunctival chemosis over the past 6 months. Best-corrected visual acuity in the right (OD) and left eye (OS) was 9/10 and 10/10, respectively. Visual field testing showed slight paracentral field defects mostly in OS. IOP was 20 mm Hg in OD and 34 mm Hg in OS. We referred the patient to neuroradiology, and MRI angiography revealed a CCF with angiographic classification of Cognard grade 2. Closure of the CCF by transarterial embolization was performed in the neuroradiology department. One week following the procedure, the clinical signs of diplopia, proptosis, and conjunctival chemosis had greatly improved, and IOP was reduced to 12 mm Hg OD and 19 mm Hg in OS. Glaucoma treatment was maintained with topical brimatoprost, brinzolamide, and timolol. Owing to the risk of vision loss associated with vascular stasis, retinal ischemia, and high IOP, ophthalmologists must be aware of the clinical features of CCF and should request appropriate imaging studies such as MRI angiography in order to confirm the diagnosis and plan multidisciplinary treatment. PMID:27462258

  20. Endothelin, Astrocytes and Glaucoma

    PubMed Central

    Prasanna, Ganesh; Krishnamoorthy, Raghu; Yorio, Thomas

    2010-01-01

    It has become increasingly clear that astrocytes may play an important role in the genesis of glaucoma. Astrogliosis occurs in response to ocular stress or the presence of noxious stimuli. Agents that appear to stimulate reactive gliosis are becoming increasingly clear. One class of agents that is emerging is the endothelins (ETs; specifically, ET-1). In this review we examine the interactions of ET-1 with astrocytes and provide examples where ET-1 appears to contribute to activation of astrocytes and play a role in the neurodegenerative effects that accompany such reactivation resulting in astrogliosis. These actions are presented in the context of glaucoma although information is also presented with respect to ET-1's role in the central nervous system and brain. While much has been learned with respect to ET-1/astrocyte interactions, there are still a number of questions concerning the potential therapeutic implications of these findings. Hopefully this review will stimulate others to examine this potential. PMID:20849847

  1. Neuroprotection in glaucoma

    PubMed Central

    Vasudevan, Sushil K; Gupta, Viney; Crowston, Jonathan G

    2011-01-01

    Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells and their axons. Recent evidence suggests that intraocular pressure (IOP) is only one of the many risk factors for this disease. Current treatment options for this disease have been limited to the reduction of IOP; however, it is clear now that the disease progression continues in many patients despite effective lowering of IOP. In the search for newer modalities in treating this disease, much data have emerged from experimental research the world over, suggesting various pathological processes involved in this disease and newer possible strategies to treat it. This review article looks into the current understanding of the pathophysiology of glaucoma, the importance of neuroprotection, the various possible pharmacological approaches for neuroprotection and evidence of current available medications. PMID:21150020

  2. Evolution of laser-induced plasma in solvent aerosols

    NASA Astrophysics Data System (ADS)

    Hening, Alexandru; Wroblewski, Ronald; George, Robert; McGirr, Scott

    2014-10-01

    This paper describes a novel technique for the detection of contaminants in air using the process of laser-induced filamentation. This work is focused primarily on the visible and infrared spectrum. Characterization of the temporal and spatial evolution of laser-generated plasma in solvent aerosols is necessary for the development of potential applications. Atmospheric aerosols impact capabilities of applications such as range from laser-induced ionized micro channels and filaments able to transfer high electric pulses over a few hundreds of meters, to the generation of plasma artifacts in air, far away from the laser source.

  3. Developments in laser trabeculoplasty.

    PubMed

    Tsang, Susanna; Cheng, Jason; Lee, Jacky W Y

    2016-01-01

    Laser trabeculoplasty has an increasing important role in the management of glaucoma as more emphasis is placed on minimally invasive therapies. In recent years, the following laser trabeculoplasty technologies have been introduced: micropulse laser trabeculoplasty, titanium-sapphire laser trabeculoplasty and pattern scanning trabeculoplasty. These lasers help to reduce the intraocular pressure (IOP) and the burden of glaucoma medical therapy. Literature findings regarding the safety and efficacy of these newer forms of laser trabeculoplasty in the treatment of open-angle glaucoma is summarised. These relatively newer procedures appear to have similar efficacy when compared with the former selective laser trabeculoplasty or argon laser trabeculoplasty. In addition, they potentially offer a more favourable safety profile with fewer complications, including postlaser inflammation and IOP spikes. Further large-scale studies are necessary to evaluate the long-term benefits of these newer forms of laser trabeculoplasty. Their initial promising results offer patients with glaucoma additional treatment alternatives. PMID:26377417

  4. Femtosecond laser-induced electronic plasma at metal surface

    SciTech Connect

    Chen Zhaoyang; Mao, Samuel S.

    2008-08-04

    We develop a theoretical analysis to model plasma initiation at the early stage of femtosecond laser irradiation of metal surfaces. The calculation reveals that there is a threshold intensity for the formation of a microscale electronic plasma at the laser-irradidated metal surface. As the full width at half maximum of a laser pulse increases from 15 to 200 fs, the plasma formation threshold decreases by merely about 20%. The dependence of the threshold intensity on laser pulse width can be attributed to laser-induced surface electron emission, in particular due to the effect of photoelectric effect.

  5. Studies of new media radiation induced laser

    NASA Technical Reports Server (NTRS)

    Han, K. S.; Shiu, Y. J.; Raju, S. R.; Hwang, I. H.; Tabibi, B.

    1984-01-01

    Various lasants were investigated especially, 2-iodohepafluoropropane (i-C3F7I) for the direct solar pumped lasers. Optical pumping of iodine laser was achieved using a small flashlamp. Using i-C3F7I as a laser gain medium, threshold inversion density, small signal gain, and laser performance at the elevated temperature were measured. The experimental results and analysis are presented. The iodine laser kinetics of the C3F7I and IBr system were numerically simulated. The concept of a direct solar-pumped laser amplifier using (i-C3F7I) as the laser material was evaluated and several kinetic coefficients for i-C3F7I laser system were reexamined. The results are discussed.

  6. Railgun system using a laser-induced plasma armature

    SciTech Connect

    Onozuka, M.; Oda, Y.; Azuma, K.

    1996-05-01

    Development of an electromagnetic railgun system that utilizes a laser-induced plasma armature formation has been conducted to investigate the application of the railgun system for high-speed pellet injection into fusion plasmas. Using the laser-induced plasma formation technique, the required breakdown voltage was reduced by one-tenth compared with that for the spark-discharged plasma. The railgun system successfully accelerated the laser-induced plasma armature by an electromagnetic force that accelerated the pellet. The highest velocity of the solid hydrogen pellets, obtained so far, was 2.6 km/sec using a 2m-long railgun. {copyright} {ital 1996 American Institute of Physics.}

  7. Laser-induced fluorescence of fused silica irradiated by ArF excimer laser

    SciTech Connect

    Zhang Haibo; Yuan Zhijun; Zhou Jun; Dong Jingxing; Wei Yunrong; Lou Qihong

    2011-07-01

    Laser-induced fluorescence (LIF) of high-purity fused silica irradiated by ArF excimer laser is studied experimentally. LIF bands of the fused silica centered at 281 nm, 478 nm, and 650 nm are observed simultaneously. Furthermore, the angular distribution of the three fluorescence peaks is examined. Microscopic image of the laser modified fused silica indicates that scattering of the generated fluorescence by laser-induced damage sites is the main reason for the angular distribution of LIF signals. Finally, the dependence of LIF signals intensities of the fused silica on laser power densities is presented. LIF signals show a squared power density dependence, which indicates that laser-induced defects are formed mainly via two-photon absorption processes.

  8. Microwave interferometry of laser induced air plasmas formed by short laser pulses

    SciTech Connect

    Jungwirth, P.W.

    1993-08-01

    Applications for the interaction of laser induced plasmas with electromagnetic probes requires time varying complex conductivity data for specific laser/electromagnetic probe geometries. Applications for this data include plasma switching (Q switching) and the study of ionization fronts. The plasmas were created in laboratory air by 100 ps laser pulses at a wavelength of 1 {mu}m. A long focal length lens focused the laser pulse into WR90 (X band) rectangular waveguide. Two different laser beam/electromagnetic probe geometries were investigated. For the longitudinal geometry, the laser pulse and the microwave counterpropagated inside the waveguide. For the transverse geometry, the laser created a plasma ``post`` inside the waveguide. The effects of the laser beam deliberately hitting the waveguide were also investigated. Each geometry exhibits its own characteristics. This research project focused on the longitudinal geometry. Since the laser beam intensity varies inside the waveguide, the charge distribution inside the waveguide also varies. A 10 GHz CW microwave probe traveled through the laser induced plasma. From the magnitude and phase of the microwave probe, a spatially integrated complex conductivity was calculated. No measurements of the temporal or spatial variation of the laser induced plasma were made. For the ``plasma post,`` the electron density is more uniform.

  9. Evaluation of pupillary response to light in patients with glaucoma: a study using computerized pupillometry.

    PubMed

    Martucci, Alessio; Cesareo, Massimo; Napoli, Domenico; Sorge, Roberto Pietro; Ricci, Federico; Mancino, Raffaele; Nucci, Carlo

    2014-12-01

    The aim of this study was to evaluate pupillary response to light stimulation in patients with different stages of glaucoma using computerized pupillometry. We conducted a retrospective study on a group of 44 glaucoma patients who had undergone complete ophthalmological examination, visual field test (Humphrey SITA Standard 24-2) and monocular dynamic pupillometry (MonCV3 Metrovision). Eyes were classified into stages of glaucoma according to visual field damage using the Glaucoma Staging System 2. A group of 18 healthy subjects, homogeneous for age and sex with glaucoma patients, was used as a control. The following parameters were considered-latency and duration of contraction and dilatation; initial, minimum, maximum, and mean pupil diameter; amplitude of contraction; contraction and dilatation speed; and percent pupil contraction (PPC). PPC and pupil contraction speed and minimum diameter showed covariate correlation with the stages of glaucoma. The control group significantly differed from the stage 3 group in terms of PPC and from the stage 4 group in terms of minimum diameter. There were significant differences between the stage 5 group and stage 1, 2, 3 and control groups. Ordinal logistic regression showed a correlation between pupil contraction speed, minimum diameter, PPC, initial diameter and the stage of glaucoma. The study showed that glaucoma damage is associated with altered values of pupillary response to light. This event may be the consequence of the progressive loss of retinal ganglion cells and their axons induced by glaucoma. PMID:24550056

  10. Optically Probed Laser-Induced Field-Free Molecular Alignment

    NASA Astrophysics Data System (ADS)

    Faucher, O.; Lavorel, B.; Hertz, E.; Chaussard, F.

    Molecular alignment induced by laser fields has been investigated in research laboratories for over two decades. It led to a better understanding of the fundamental processes at play in the interaction of strong laser fields with molecules, and also provided significant contributions to the fields of high harmonic generation, laser spectroscopy, and laser filamentation. In this chapter, we discuss molecular alignment produced under field-free conditions, as resulting from the interaction of a laser pulse of duration shorter than the rotational period of the molecule. The experimental results presented will be confined to the optically probed alignment of linear as well as asymmetric top molecules. Special care will be taken to describe and compare various optical methods that can be employed to characterize laser-induced molecular alignment. Promising applications of optically probed molecular alignment will be also demonstrated.

  11. Picosecond laser-induced water condensation in a cloud chamber.

    PubMed

    Sun, Haiyi; Liu, Yonghong; Ju, Jingjing; Tian, Ye; Bai, Yafeng; Liu, Yaoxiang; Du, Shengzhe; Wang, Cheng; Wang, Tiejun; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2016-09-01

    We investigated water condensation in a laboratory cloud chamber induced by picosecond (ps) laser pulses at ~350 ps (800 nm/1-1000 Hz) with a maximum peak power of ~25 MW. The peak power was much lower than the critical power for self-focusing in air (~3-10 GW depending on the pulse duration). Sparks, airflow and snow formation were observed under different laser energies or repetition rates. It was found that weaker ps laser pulses can also induce water condensation by exploding and breaking down ice crystals and/or water droplets into tiny particles although there was no formation of laser filament. These tiny particles would grow until precipitation in a super-saturation zone due to laser-induced airflow in a cold region with a large temperature gradient. PMID:27607654

  12. Research on radiation induced laser plasmas

    NASA Technical Reports Server (NTRS)

    Schneider, R. T.; Rowe, M. J.; Carter, B. D.; Walters, R. A.; Cox, J. D.; Liang, R.; Roxey, T.; Zapata, L.

    1979-01-01

    The development of high power nuclear pumped lasers is discussed. The excitation mechanism of continuous wave (CW) HeNe nuclear pumped lasers is studied and a CO2 nuclear pumped laser is used to demonstrate the CW output in the order of watts. The assumption that high power densities are only achievable by volume fission fragment sources is used to identify laser gases which are compatible with UF6 by excited states lifetime measurements. The examination of Xe2, XeF, and KrF under nuclear irradiation to determine if they are good candidates for nuclear-pumped lasers is described.

  13. Coherent microwave radiation from a laser induced plasma

    SciTech Connect

    Shneider, M. N.; Miles, R. B.

    2012-12-24

    We propose a method for generation of coherent monochromatic microwave/terahertz radiation from a laser-induced plasma. It is shown that small-scale plasma, located in the interaction region of two co-propagating plane-polarized laser beams, can be a source of the dipole radiation at a frequency equal to the difference between the frequencies of the lasers. This radiation is coherent and appears as a result of the so-called optical mixing in plasma.

  14. Improving sensitivity of laser-induced breakdown spectroscopy using laser plasmas interaction

    NASA Astrophysics Data System (ADS)

    Il'in, Alexey A.; Golik, Sergey S.; Nagorny, Ivan G.; Bulanov, Alexey V.

    2006-11-01

    Laser plasmas interaction and spectral characteristics of plasma were investigated at a laser breakdown in a normal atmosphere with the purpose of improving laser-induced breakdown spectroscopy sensitivity. Colliding plasmas interaction was investigated depending on mechanism of absorption wave of laser radiation and distance between foci. Laser supported detonation wave, breakdown wave and fast wave of ionization are absorption wave observed in experiment. It was shown that seed electrons for cascade breakdown in front of fast wave of ionization is occurred due to oxygen molecules photoionization. Molecular emission and collapse of intensity of plasma continuum during the initial moments of laser plasma expansion were registered. The line/continuum ratio was essentially increased in case of laser plasmas interaction. Thus laser plasmas interaction improves sensitivity of LIBS.

  15. Spontaneous malignant glaucoma in a patient with patent peripheral iridotomy

    PubMed Central

    2012-01-01

    Background To report a case of spontaneous malignant glaucoma in an Asian female. To propose the term “positive vitreous pressure glaucoma” to reflect the pathophysiology, treatment and prognosis of the condition. Case presentation A 56-year old Chinese female was diagnosed of primary angle closure glaucoma and had bilateral laser peripheral iridotomy one year ago. She presented with spontaneous onset of malignant glaucoma involving the left eye. The condition was treated successfully; the final best corrected visual acuity was 0.67 (decimal notation). Conclusion This case highlights that acute angle closure attack can occur in an eye with patent peripheral iridotomy. Early recognition and treatment is essential for good visual prognosis. PMID:23241197

  16. Neurodegeneration and Neuroprotection in Glaucoma.

    PubMed

    Gauthier, Angela C; Liu, Ji

    2016-03-01

    Glaucoma is the principal cause of irreversible blindness in the world. The disease leads to progressive optic nerve degeneration with a gradual loss of retinal ganglion cells. Neurodegeneration in glaucoma extends beyond the eye into the lateral geniculate nucleus and visual cortex, and the disease even shares some characteristics with other central nervous system degenerative disorders. Glaucoma destroys neurons through oxidative stress, impairment in axonal transport, neuroinflammation, and excitotoxicity. Autophagy may promote or inhibit disease progression. Currently, lowering intraocular pressure is the only way proven to delay glaucoma advancement. However, many new therapies are being developed, including antioxidants, adenosine receptor antagonists, Rho-pathway inhibitors, stem cell therapy, and neurotrophic factors. These therapies focus on neuroprotection, and they may eventually halt glaucoma progression or reverse the process of the disease itself. PMID:27505018

  17. Neurodegeneration and Neuroprotection in Glaucoma

    PubMed Central

    Gauthier, Angela C.; Liu, Ji

    2016-01-01

    Glaucoma is the principal cause of irreversible blindness in the world. The disease leads to progressive optic nerve degeneration with a gradual loss of retinal ganglion cells. Neurodegeneration in glaucoma extends beyond the eye into the lateral geniculate nucleus and visual cortex, and the disease even shares some characteristics with other central nervous system degenerative disorders. Glaucoma destroys neurons through oxidative stress, impairment in axonal transport, neuroinflammation, and excitotoxicity. Autophagy may promote or inhibit disease progression. Currently, lowering intraocular pressure is the only way proven to delay glaucoma advancement. However, many new therapies are being developed, including antioxidants, adenosine receptor antagonists, Rho-pathway inhibitors, stem cell therapy, and neurotrophic factors. These therapies focus on neuroprotection, and they may eventually halt glaucoma progression or reverse the process of the disease itself.

  18. Laser Induced Fluorescence on Molecular Discharges

    NASA Astrophysics Data System (ADS)

    Mulders, Hjalmar; Rijke, Arij; Girault, Vincent; Stoffels, Winfred

    2008-10-01

    In the last half century, mercury has been used widely as the radiating species in many low pressure fluorescent lamps. Mercury primarily radiates at 254 nm and 185 nm. These photons excite a phosphor that fluoresces back to the ground state producing visible photons. This process reduces the efficiency because much of the energy of the UV photons has to be discarded. Using a species that emits light closer to or even in the visible range reduces these losses. Ideally the species (or a mixture of several species) should build up the whole visible spectrum, much like in HID lamps. InBr seems to be a good candidate for such a lamp, because it is an efficient radiator that emits most of its light around 370 nm; much closer to the visible part of the spectrum. In order to get insight in the energy transfer processes going on in these molecules we have conducted a laser induced fluorescence (LIF) experiment on InBr vapour and on a plasma. We have measured the decay times of different rovibrational levels of the InBr-molecule as well as the spectral distribution of the fluorescence from these levels. From the former we calculated the rotational temperature of the plasma and from the latter we calculated the Franck-Condon factors for the A-state as well as the vibrational temperature.

  19. Tranexamic Acid Diminishes Laser-Induced Melanogenesis

    PubMed Central

    Kim, Myoung Shin; Bang, Seung Hyun; Kim, Jeong-Hwan; Shin, Hong-Ju; Choi, Jee-Ho

    2015-01-01

    Background The treatment of post-inflammatory hyperpigmentation (PIH) remains challenging. Tranexamic acid, a well-known anti-fibrinolytic drug, has recently demonstrated a curative effect towards melasma and ultraviolet-induced PIH in Asian countries. However, the precise mechanism of its inhibitory effect on melanogenesis is not fully understood. Objective In order to clarify the inhibitory effect of tranexamic acid on PIH, we investigated its effects on mouse melanocytes (i.e., melan-a cells) and human melanocytes. Methods Melan-a cells and human melanocytes were cultured with fractional CO2 laser-treated keratinocyte-conditioned media. Melanin content and tyrosinase activity were evaluated in cells treated with or without tranexamic acid. Protein levels of tyrosinase, tyrosinase-related protein (TRP)-1, and TRP-2 were evaluated in melan-a cells. Signaling pathway molecules involved in melanogenesis in melanoma cells were also investigated. Results Tranexamic acid-treated melanocytes exhibited reduced melanin content and tyrosinase activity. Tranexamic acid also decreased tyrosinase, TRP-1, and TRP-2 protein levels. This inhibitory effect on melanogenesis was considered to be involved in extracellular signal-regulated kinase signaling pathways and subsequently microphthalmia-associated transcription factor degradation. Conclusion Tranexamic acid may be an attractive candidate for the treatment of PIH. PMID:26082580

  20. Medical Applications of Laser Induced Breakdown Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pathak, A. K.; Rai, N. K.; Singh, Ankita; Rai, A. K.; Rai, Pradeep K.; Rai, Pramod K.

    2014-11-01

    Sedentary lifestyle of human beings has resulted in various diseases and in turn we require a potential tool that can be used to address various issues related to human health. Laser Induced Breakdown Spectroscopy (LIBS) is one such potential optical analytical tool that has become quite popular because of its distinctive features that include applicability to any type/phase of samples with almost no sample preparation. Several reports are available that discusses the capabilities of LIBS, suitable for various applications in different branches of science which cannot be addressed by traditional analytical methods but only few reports are available for the medical applications of LIBS. In the present work, LIBS has been implemented to understand the role of various elements in the formation of gallstones (formed under the empyema and mucocele state of gallbladder) samples along with patient history that were collected from Purvancal region of Uttar Pradesh, India. The occurrence statistics of gallstones under the present study reveal higher occurrence of gallstones in female patients. The gallstone occurrence was found more prevalent for those male patients who were having the habit of either tobacco chewing, smoking or drinking alcohols. This work further reports in-situ LIBS study of deciduous tooth and in-vivo LIBS study of human nail.

  1. IR laser-induced protein crystal transformation

    SciTech Connect

    Kiefersauer, Reiner Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-05-01

    A novel method and the associated instrumentation for improving crystalline order (higher resolution of X-ray diffraction and reduced mosaicity) of protein crystals by precisely controlled heating is demonstrated. Crystal transformation is optically controlled by a video system. A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress.

  2. IR laser-induced protein crystal transformation

    PubMed Central

    Kiefersauer, Reiner; Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-01-01

    A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress. PMID:24816092

  3. Anions in laser-induced plasmas

    NASA Astrophysics Data System (ADS)

    Shabanov, S. V.; Gornushkin, I. B.

    2016-07-01

    The equation of state for plasmas containing negative atomic and molecular ions (anions) is modeled. The model is based on the assumption that all ionization processes and chemical reactions are at local thermal equilibrium and the Coulomb interaction in the plasma is described by the Debye-Hückel theory. In particular, the equation of state is obtained for plasmas containing the elements Ca, Cl, C, Si, N, and Ar. The equilibrium reaction constants are calculated using the latest experimental and ab initio data of spectroscopic constants for the molecules CaCl_2, CaCl, Cl_2, N_2, C_2, Si_2, CN, SiN, SiC, and their positive and negative ions. The model is applied to laser-induced plasmas (LIPs) by including the equation of state into a fluid dynamic numerical model based on the Navier-Stokes equations describing an expansion of LIP plumes into an ambient gas as a reactive viscous flow with radiative losses. In particular, the formation of anions Cl-, C-, Si-, {{Cl}}2^{ - }, {{Si}}2^{ - }, {{C}}2^{ - }, CN-, SiC-, and SiN- in LIPs is investigated in detail.

  4. Laser-induced fluorescence in medical diagnostics

    NASA Astrophysics Data System (ADS)

    Andersson-Engels, Stefan; Johansson, Jonas; Svanberg, Katarina; Svanberg, Sune

    1990-07-01

    We have performed extensive investigations using laser-induced fluorescence in animal as well as human tissue in order to localize diseased tissue and thus discriminate such tissue from normal surrounding areas. In characterizing different tissue types the endogenous fluorescence (autofluorescence) as well as specific fluorescence from different photosensitising substances was utilized. We have investigated different experimental and human malignant tumors in vivo and in vitro as well as atherosclerotic lesions in vitro. A fiber-optic fluorosensor was constructed and used in the experiments and in the clinical examination of patients. Dimensionless spectroscopic functions were formed to ensure that the signals were independent of clinically uncontrollable variables such as distance variations, tissue topography, light source fluctuations and variations in detection efficiency. A multi-color two-dimensional imaging system was constructed for real-time imaging. The system was tested peroperatively and during standard examination patient procedures. Besides utilizing the time-integrated fluorescence signal we have also investigated the possibility of incorporating time-resolved fluorescence characterization.

  5. Q-Switched Alexandrite Laser-induced Chrysiasis

    PubMed Central

    Victor Ross, E.

    2015-01-01

    Background: Chyriasis is an uncommon side effect that occurs in patients who are receiving prolonged treatment with either intravenous or intramuscular gold as a distinctive blue-gray pigmentation of light-exposed skin. Laser-induced chrysiasis is a rarely described phenomenon in individuals who have received systemic gold and are subsequently treated with a Q-switched laser. Purpose: To describe the characteristics of patients with laser-induced chrysiasis. Methods: The authors describe a 60-year-old woman who developed chrysiasis at Q-switched alexandrite laser treatment sites. They also reviewed the medical literature using PubMed, searching the terms chrysiasis, gold, and laser-induced. Patient reports and previous reviews of these subjects were critically assessed and the salient features are presented. Results: Including the authors’ patient, laser-induced chrysiasis has been described in five Caucasian arthritis patients (4 women and 1 man); most of the patients had received more than 8g of systemic gold therapy during a period of 3 to 13 years. Gold therapy was still occurring or had been discontinued as long as 26 years prior to laser treatment. All of the patients immediately developed blue macules at the Q-switched laser treatment site. Resolution of the dyschromia occurred in a 70-year-old woman after two treatment sessions with a long-pulsed ruby laser and the authors’ patient after a sequential series of laser sessions using a long-pulsed alexandrite laser, followed by a nonablative fractional laser and an ablative carbon dioxide laser. Conclusion: Laser-induced chrysiasis has been observed following treatment with Q-switched lasers in patients who are receiving or have previously been treated with systemic gold. It can occur decades after treatment with gold has been discontinued. Therefore, inquiry regarding a prior history of treatment with gold—particularly in older patients with arthritis—should be considered prior to treatment with a Q

  6. Laser therapy for severe radiation-induced rectal bleeding

    SciTech Connect

    Ahlquist, D.A.; Gostout, C.J.; Viggiano, T.R.; Pemberton, J.H.

    1986-12-01

    Four patients with chronic hematochezia and transfusion-dependent anemia from postradiation rectal vascular lesions were successfully managed by endoscopic laser coagulation. In all four patients, symptomatic, hematologic, and endoscopic improvement was evident. Laser therapy for severe radiation-induced rectal bleeding seems to be safe and efficacious and should be considered before surgical intervention.

  7. Robust authentication through stochastic femtosecond laser filament induced scattering surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Haisu; Tzortzakis, Stelios

    2016-05-01

    We demonstrate a reliable authentication method by femtosecond laser filament induced scattering surfaces. The stochastic nonlinear laser fabrication nature results in unique authentication robust properties. This work provides a simple and viable solution for practical applications in product authentication, while also opens the way for incorporating such elements in transparent media and coupling those in integrated optical circuits.

  8. Current Surgical Options for the Management of Pediatric Glaucoma

    PubMed Central

    Morales, Jose; Al Shahwan, Sami; Al Odhayb, Sami; Al Jadaan, Ibrahim; Edward, Deepak P.

    2013-01-01

    Currently, there are numerous choices for the treatment of pediatric glaucoma depending on the type of glaucoma, the age of the patient, and other particularities of the condition discussed in this review. Traditionally, goniotomy and trabeculotomy ab externo have been the preferred choices of treatment for congenital glaucoma, and a variety of adult procedures adapted to children have been utilized for other types of pediatric glaucoma with variable results and complications. More recently, seton implantations of different types have become more popular to use in children, and newer techniques have become available including visualized cannulation and opening of Schlemm's canal, deep sclerectomy, trabectome, and milder more directed cyclodestructive procedures such as endolaser and transcleral diode laser cyclophotocoagulation. This paper reviews the different surgical techniques currently available, their indications, results, and most common complications to allow the surgeon treating these conditions to make a more informed choice in each particular case. Although the outcome of surgical treatment in pediatric glaucoma has improved significantly, its treatment remains challenging. PMID:23738051

  9. New directions in the treatment of normal tension glaucoma

    PubMed Central

    Song, Brian J; Caprioli, Joseph

    2014-01-01

    Glaucoma is a progressive optic neuropathy that causes characteristic changes of the optic nerve and visual field in relation to intraocular pressure (IOP). It is now known that glaucoma can occur at statistically normal IOPs and prevalence studies have shown that normal tension glaucoma (NTG) is more common than previously thought. While IOP is believed to be the predominant risk factor in primary open angle glaucoma (POAG), IOP-independent risk factors, such as vascular dysregulation, are believed to play an important part in the pathogenesis of NTG. Though certain distinguishing phenotypic features of NTG have been reported, such as an increased frequency of disc hemorrhages, acquired pits of the optic nerve and characteristic patterns of disc cupping and visual field loss, there is much overlap of the clinical findings in NTG with POAG, suggesting that NTG is likely part of a continuum of open angle glaucomas. However, IOP modification is still the mainstay of treatment in NTG. As in traditional POAG, reduction of IOP can be achieved with the use of medications, laser trabeculoplasty or surgery. Studies now show that the choice of medication may also be important in determining the outcomes of these patients. Though it is likely that future treatment of NTG will involve modification of both IOP and IOP-independent risk factors, current efforts to develop IOP-independent neuroprotective treatments have not yet proven to be effective in humans. PMID:24881596

  10. Improved Imaging With Laser-Induced Eddy Currents

    NASA Technical Reports Server (NTRS)

    Chern, Engmin J.

    1993-01-01

    System tests specimen of material nondestructively by laser-induced eddy-current imaging improved by changing method of processing of eddy-current signal. Changes in impedance of eddy-current coil measured in absolute instead of relative units.