Prevalence of refractive errors among schoolchildren in rural central Ethiopia.

PubMed

Mehari, Zelalem Addisu; Yimer, Abdirahman Wollie

2013-01-01

The aim of the present study was to assess the prevalence of refractive errors and visual impairment among schoolchildren in rural central Ethiopia. A cross-sectional study was conducted from November 2010 to January 2011 among 5,470 schoolchildren from 14 schools, of whom 4,238 (aged 7-18 years) were screened for refractive errors. In all participants, uncorrected vision and best corrected visual acuity were determined and those with a visual acuity of 6/12 or worse, underwent a complete ophthalmic examination to determine the cause of visual impairment. Myopia was defined as a spherical equivalent of -0.50 dioptre (D) or greater in one or both eyes and hyperopia as a spherical equivalent of +2.00 D or greater. A cylindrical power of -0.50 DC (D cylinder) or greater was considered as astigmatism. Chi-square was used to test differences in proportions. Differences were considered to be statistically significant at the five per cent level. Of the 4,238 children, 405 (9.5 per cent) were visually impaired and of these 267 children were diagnosed as having refractive errors, with an overall prevalence of 6.3 per cent, comprised of 6.1 per cent in boys and 6.6 per cent in girls. Myopia is the most prevalent refractive error; accounting for 6.0 per cent, followed by compound myopic astigmatism 1.2 per cent, then simple myopic astigmatism 0.5 per cent, mixed astigmatism 0.26 per cent and finally hyperopia 0.33 per cent. Reasons for visual acuity of 6/12 or worse in the better eye were found to be refractive error (65.9 per cent), corneal problems (12.8 per cent) and amblyopia (9.6 per cent). The prevalence of manifest strabismus in the study group was 1.1 per cent (n = 45). The study concluded that uncorrected refractive error is a common cause of visual impairment among schoolchildren in rural central Ethiopia. This indicates the need for regular school-screening programs that provide glasses at low cost or free of charge for those who have refractive errors. © 2012 The

Comparison of monochromatic aberrations in young adults with different visual acuity and refractive errors.

PubMed

Yazar, Seyhan; Hewitt, Alex W; Forward, Hannah; McKnight, Charlotte M; Tan, Alex; Mountain, Jenny A; Mackey, David A

2014-03-01

To compare the monochromatic aberrations in a large cohort of 20-year-old Australians with differing levels of visual acuity and explore the relationship between these aberrations and refractive error. Lions Eye Institute, Perth, Western Australia, Australia. Cross-sectional analysis of a population-based cohort. Monochromatic aberrations were measured using a Zywave II wavefront aberrometer with natural pupils in a dark room. The logMAR corrected distance visual acuity (CDVA) was measured monocularly under normal illumination. Cycloplegic autorefraction was also performed. The study enrolled 2039 eyes of 1040 participants. Data from 1007 right eyes were analyzed. The median CDVA and spherical equivalent were -0.06 logMAR (interquartile range [IQR], -0.10 to 0.00) and +0.25 diopters (D) (IQR, -0.38 to 0.63), respectively. The median 6.0 mm higher-order aberration (HOA) was 0.58 μm (IQR, 0.44 to 0.79). Coma-like aberrations and 3rd-, 4th-, and 5th-order HOAs were significantly different between subjects with a CDVA of -0.10 logMAR or better and those with a CDVA worse than -0.10 logMAR. Fourth-order aberrations Z(4,-4) (P=.024) and Z(4,-2) (P=.029) and 2nd-order aberration Z(2,0) (P<.001) differed significantly between myopic eyes, emmetropic eyes, and hyperopic eyes. Subjects with higher myopia had slightly higher total HOAs. The HOAs in this population were marginally higher than previously reported values. The findings confirm there is a difference in monochromatic aberrations between different vision and refractive groups. Results in this study will benefit decision-making processes in the clinical setting. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Piggyback intraocular lens implantation to correct pseudophakic refractive error after segmental multifocal intraocular lens implantation.

PubMed

Venter, Jan A; Oberholster, Andre; Schallhorn, Steven C; Pelouskova, Martina

2014-04-01

To evaluate refractive and visual outcomes of secondary piggyback intraocular lens implantation in patients diagnosed as having residual ametropia following segmental multifocal lens implantation. Data of 80 pseudophakic eyes with ametropia that underwent Sulcoflex aspheric 653L intraocular lens implantation (Rayner Intraocular Lenses Ltd., East Sussex, United Kingdom) to correct residual refractive error were analyzed. All eyes previously had in-the-bag zonal refractive multifocal intraocular lens implantation (Lentis Mplus MF30, models LS-312 and LS-313; Oculentis GmbH, Berlin, Germany) and required residual refractive error correction. Outcome measurements included uncorrected distance visual acuity, corrected distance visual acuity, uncorrected near visual acuity, distance-corrected near visual acuity, manifest refraction, and complications. One-year data are presented in this study. The mean spherical equivalent ranged from -1.75 to +3.25 diopters (D) preoperatively (mean: +0.58 ± 1.15 D) and reduced to -1.25 to +0.50 D (mean: -0.14 ± 0.28 D; P < .01). Postoperatively, 93.8% of eyes were within ±0.50 D and 98.8% were within ±1.00 D of emmetropia. The mean uncorrected distance visual acuity improved significantly from 0.28 ± 0.16 to 0.01 ± 0.10 logMAR and 78.8% of eyes achieved 6/6 (Snellen 20/20) or better postoperatively. The mean uncorrected near visual acuity changed from 0.43 ± 0.28 to 0.19 ± 0.15 logMAR. There was no significant change in corrected distance visual acuity or distance-corrected near visual acuity. No serious intraoperative or postoperative complications requiring secondary intraocular lens removal occurred. Sulcoflex lenses proved to be a predictable and safe option for correcting residual refractive error in patients diagnosed as having pseudophakia. Copyright 2014, SLACK Incorporated.

Paediatric Refractive Errors in an Eye Clinic in Osogbo, Nigeria.

PubMed

Michaeline, Isawumi; Sheriff, Agboola; Bimbo, Ayegoro

2016-03-01

Paediatric ophthalmology is an emerging subspecialty in Nigeria and as such there is paucity of data on refractive errors in the country. This study set out to determine the pattern of refractive errors in children attending an eye clinic in South West Nigeria. A descriptive study of 180 consecutive subjects seen over a 2-year period. Presenting complaints, presenting visual acuity (PVA), age and sex were recorded. Clinical examination of the anterior and posterior segments of the eyes, extraocular muscle assessment and refraction were done. The types of refractive errors and their grades were determined. Corrected VA was obtained. Data was analysed using descriptive statistics in proportions, chi square with p value <0.05. The age range of subjects was between 3 and 16 years with mean age = 11.7 and SD = 0.51; with males making up 33.9%.The commonest presenting complaint was blurring of distant vision (40%), presenting visual acuity 6/9 (33.9%), normal vision constituted >75.0%, visual impairment20% and low vision 23.3%. Low grade spherical and cylindrical errors occurred most frequently (35.6% and 59.9% respectively). Regular astigmatism was significantly more common, P <0.001. The commonest diagnosis was simple myopic astigmatism (41.1%). Four cases of strabismus were seen. Simple spherical and cylindrical errors were the commonest types of refractive errors seen. Visual impairment and low vision occurred and could be a cause of absenteeism from school. Low-cost spectacle production or dispensing unit and health education are advocated for the prevention of visual impairment in a hospital set-up.

Reduced vision and refractive errors, results from a school vision screening program in Kanchanpur District of far western Nepal.

PubMed

Awasthi, S; Pant, B P; Dhakal, H P

2010-01-01

At present there is no data available on reduced vision and refractive errors in school children of far western Nepal. So, school screening records were used to obtain data useful for planning of refractive services. Data are provided from school screening conducted by Geta Eye Hospital during February/March 2008. The cases with complete data sets on visual acuity, refractive error and age were included and analyzed using computer software. Of 1165 children (mean age 11.6 ± 2.5 years) examined, 98.8% (n = 1151) had uncorrected visual acuity of 6/9 and better in at least one eye whereas 1.2% (n = 14) had acuity 6/12 and worse in both eyes. Among them, either eye of 9 children improved to 6/9 and better with correction. However, visual acuity was 6/12 and worse in both eyes of 5 children even after correction. There were 24 children with refractive errors (myopia, 1.54%; n = 18 and hypermetropia, 0.51%; n = 6) in at least one eye. The spherical equivalent refraction was not significantly different with age and gender. The incidence of reduced vision and refractive errors among school children of this semi rural district were low.

Improvement of visual acuity by refraction in a low-vision population.

PubMed

Sunness, Janet S; El Annan, Jaafar

2010-07-01

Refraction often may be overlooked in low-vision patients, because the main cause of vision decrease is not refractive, but rather is the result of underlying ocular disease. This retrospective study was carried out to determine how frequently and to what extent visual acuity is improved by refraction in a low-vision population. Cross-sectional study. Seven hundred thirty-nine low-vision patients seen for the first time. A database with all new low-vision patients seen from November 2005 through June 2008 recorded presenting visual acuity using an Early Treatment Diabetic Retinopathy Study chart; it also recorded the best-corrected visual acuity (BCVA) if it was 2 lines or more better than the presenting visual acuity. Retinoscopy was carried out on all patients, followed by manifest refraction. Improvement in visual acuity. Median presenting acuity was 20/80(-2) (interquartile range, 20/50-20/200). There was an improvement of 2 lines or more of visual acuity in 81 patients (11% of all patients), with 22 patients (3% of all patients) improving by 4 lines or more. There was no significant difference in age or in presenting visual acuity between the group that did not improve by refraction and the group that did improve. When stratified by diagnosis, the only 2 diagnoses with a significantly higher rate of improvement than the age-related macular degeneration group were myopic degeneration and progressive myopia (odds ratio, 4.8; 95% confidence interval [CI], 3.0-6.7) and status post-retinal detachment (odds ratio, 7.1; 95% CI, 5.2-9.0). For 5 patients (6% of those with improvement), the eye that was 1 line or more worse than the fellow eye at presentation became the eye that was 1 line or more better than the fellow eye after refraction. A significant improvement in visual acuity was attained by refraction in 11% of the new low-vision patients. Improvement was seen across diagnoses and the range of presenting visual acuity. The worse-seeing eye at presentation may

Sources of medical error in refractive surgery.

PubMed

Moshirfar, Majid; Simpson, Rachel G; Dave, Sonal B; Christiansen, Steven M; Edmonds, Jason N; Culbertson, William W; Pascucci, Stephen E; Sher, Neal A; Cano, David B; Trattler, William B

2013-05-01

To evaluate the causes of laser programming errors in refractive surgery and outcomes in these cases. In this multicenter, retrospective chart review, 22 eyes of 18 patients who had incorrect data entered into the refractive laser computer system at the time of treatment were evaluated. Cases were analyzed to uncover the etiology of these errors, patient follow-up treatments, and final outcomes. The results were used to identify potential methods to avoid similar errors in the future. Every patient experienced compromised uncorrected visual acuity requiring additional intervention, and 7 of 22 eyes (32%) lost corrected distance visual acuity (CDVA) of at least one line. Sixteen patients were suitable candidates for additional surgical correction to address these residual visual symptoms and six were not. Thirteen of 22 eyes (59%) received surgical follow-up treatment; nine eyes were treated with contact lenses. After follow-up treatment, six patients (27%) still had a loss of one line or more of CDVA. Three significant sources of error were identified: errors of cylinder conversion, data entry, and patient identification error. Twenty-seven percent of eyes with laser programming errors ultimately lost one or more lines of CDVA. Patients who underwent surgical revision had better outcomes than those who did not. Many of the mistakes identified were likely avoidable had preventive measures been taken, such as strict adherence to patient verification protocol or rigorous rechecking of treatment parameters. Copyright 2013, SLACK Incorporated.

[Refractive errors as causes of visual impairment in children from public schools of the Botucatu region - SP].

PubMed

Oliveira, Claudia Akemi Shiratori de; Hisatomi, Kenia Scrocaro; Leite, Cristiano Pinheiro; Schellini, Silvana Artioli; Padovani, Carlos Roberto; Padovani, Carlos Roberto Pereira

2009-01-01

To evaluate the refractive errors as cause of visual impairment in school children from the Botucatu region. A sectional study was conducted evaluating preschool and elementary school students, according to gender, refractive error, visual acuity and treatment. Four thousand six hundred and twenty-three (4,623) children were submitted to visual acuity evaluation and 8.1% of them were submitted to complete ocular examination. There were 63.2% hyperopic astigmatism, 15.7% myopic astigmatism, 12.5% astigmatism, 4.9% hyperopia and 3.7% myopia. Corrective lenses were prescribed for 48.7% of the evaluated children. The most frequent refractive error was hyperopic astigmatism and 50% of the children received treatment. The frequency of refractive errors was 3.9% of the studied population.

Studies of intrastromal corneal ring segments for the correction of low to moderate myopic refractive errors.

PubMed Central

Schanzlin, D J

1999-01-01

PURPOSE: Intrastromal corneal ring segments (ICRS) were investigated for safety and reliability in the correction of low to moderate myopic refractive errors. METHODS: Initially, 74 patients with spherical equivalent refractive errors between -1.00 and -4.25 diopters (D) received the ICRS in 1 eye. After 6 months, 51 of these patients received the ICRS in the contralateral eye. The total number of eyes investigated was 125. The outcome measures were uncorrected and best-corrected visual acuity, predictability and stability of the refraction, refractive astigmatism, contrast sensitivity, and endothelial cell morphology. RESULTS: The 89 eyes with 12-month follow-up showed significant improvement with uncorrected visual acuities of 20/16 or better in 37%, 20/20 or better in 62%, and 20/40 or better in 97%. Cycloplegic refraction spherical equivalents showed that 68% of the eyes were within +/- 0.50 D and 90% within +/- 1.00 D of the intended correction. Refractive stability was present by 3 months after the surgery. Only 1 patients had a loss greater than 2 lines or 10 letters of best spectacle-corrected visual acuity, but the patient's acuity was 20/20. Refractive cylinder, contrast sensitivity, and endothelial cell morphology were not adversely affected. The ICRS was removed from the eyes of 6 patients. Three removals were prompted by glare and double images occurring at night; 3 were for nonmedical reasons. All patients returned to within +/- 1.00 D of their preoperative refractive spherical equivalent, and no patients lost more than 1 line of best corrected visual acuity by 3 months after ICRS removal. CONCLUSION: The ICRS safely and reliably corrects myopic refractive errors between -1.00 and -4.50 D. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 6 FIGURE 7 FIGURE 8 FIGURE 9 FIGURE 10 FIGURE 11 FIGURE 12 PMID:10703146

Screening for refractive error among primary school children in Bayelsa state, Nigeria

PubMed Central

Opubiri, Ibeinmo; Pedro-Egbe, Chinyere

2013-01-01

Introduction Vision screening study in primary school children has not been done in Bayelsa State. This study aims to screen for refractive error among primary school children in Bayelsa State and use the data to plan for school Eye Health Program. Methods A cross sectional study on screening for refractive error in school children was carried out in Yenagoa Local Government Area of Bayelsa State in June 2009. A multistage sampling technique was used to select the study population (pupils aged between 5-15 years). Visual acuity (VA) for each eye, was assessed outside the classroom at a distance of 6 meters. Those with VA ≤6/9 were presented with a pinhole and the test repeated. Funduscopy was done inside a poorly lit classroom. An improvement of the VA with pinhole was considered refractive error. Data was analyzed with EPI INFO version 6. Results A total of 1,242 school children consisting of 658 females and 584 males were examined.About 97.7% of pupils had normal VA (VA of 6/6) while 56 eyes had VAs ≤ 6/9. Of these 56 eyes, the visual acuity in 49 eyes (87.5%) improved with pinhole. Twenty seven pupils had refractive error, giving a prevalence of 2.2%. Refractive error involved both eyes in 22 pupils (81.5%) and the 8-10 years age range had the highest proportion (40.7%) of cases of refractive error followed by the 9-13 year-old age range (37%). Conclusion The prevalence of refractive error was 2.2% and most eyes (97.7%) had normal vision. PMID:23646210

Prevalence of amblyopia and refractive errors in an unscreened population of children.

PubMed

Polling, Jan-Roelof; Loudon, Sjoukje E; Klaver, Caroline C W

2012-11-01

To describe the frequency of refractive errors and amblyopia in unscreened children aged 2 months to 12 years from a rural town in Poland. Five hundred ninety-one children were identified by medical records and examined in a standardized manner.Visual acuity was measured using LogMAR charts; refractive error was determined using retinoscopy or autorefraction after cycloplegia. Myopia was defined as spherical equivalent (SE) ≤ -0.50 D, emmetropia as SE between -0.5 D and+0.5 D, mild hyperopia as SE between +0.5 D and +2.0 D, and high hyperopia as SE Q+2.0 D. Amblyopia was classified as best-corrected visual acuity ≥0.3 (≤ 20/40) LogMAR, in combination with a 2 LogMAR line difference between the two eyes and the presence of an amblyogenic factor. Refractive errors ranged from 84.2% in children aged up to 2 years to 75.5% in those aged 10 to 12 years.Refractive error showed a myopic shift with age; myopia prevalence increased from 2.2% in those aged 6 to 7 years to 6.3% in those aged 10 to 12 years. Of the examined children, 77 (16.3%) had refractive errors, with visual loss; of these,60 (78%) did not use corrections. The prevalence of amblyopia was 3.1%, and refractive error attributed to the amblyopiain 9 of 13 (69%) children. Refractive errors are common in Caucasian children and often remain undiagnosed. The prevalence of amblyopia was three times higher in this unscreened population compared with screened populations. Greater awarenessof these common treatable visual conditions in children is warranted.

Assessment of Grating Acuity in Infants and Toddlers Using an Electronic Acuity Card: The Dobson Card.

PubMed

Mohan, Kathleen M; Miller, Joseph M; Harvey, Erin M; Gerhart, Kimberly D; Apple, Howard P; Apple, Deborah; Smith, Jordana M; Davis, Amy L; Leonard-Green, Tina; Campus, Irene; Dennis, Leslie K

2016-01-01

To determine if testing binocular visual acuity in infants and toddlers using the Acuity Card Procedure (ACP) with electronic grating stimuli yields clinically useful data. Participants were infants and toddlers ages 5 to 36.7 months referred by pediatricians due to failed automated vision screening. The ACP was used to test binocular grating acuity. Stimuli were presented on the Dobson Card. The Dobson Card consists of a handheld matte-black plexiglass frame with two flush-mounted tablet computers and is similar in size and form to commercially available printed grating acuity testing stimuli (Teller Acuity Cards II [TACII]; Stereo Optical, Inc., Chicago, IL). On each trial, one tablet displayed a square-wave grating and the other displayed a luminance-matched uniform gray patch. Stimuli were roughly equivalent to the stimuli available in the printed TACII stimuli. After acuity testing, each child received a cycloplegic eye examination. Based on cycloplegic retinoscopy, patients were categorized as having high or low refractive error per American Association for Pediatric Ophthalmology and Strabismus vision screening referral criteria. Mean acuities for high and low refractive error groups were compared using analysis of covariance, controlling for age. Mean visual acuity was significantly poorer in children with high refractive error than in those with low refractive error (P = .015). Electronic stimuli presented using the ACP can yield clinically useful measurements of grating acuity in infants and toddlers. Further research is needed to determine the optimal conditions and procedures for obtaining accurate and clinically useful automated measurements of visual acuity in infants and toddlers. Copyright 2016, SLACK Incorporated.

The Montrachet Study: study design, methodology and analysis of visual acuity and refractive errors in an elderly population.

PubMed

Creuzot-Garcher, Catherine; Binquet, Christine; Daniel, Sandrine; Bretillon, Lionel; Acar, Nyiazi; de Lazzer, Aurélie; Arnould, Laurent; Tzourio, Christophe; Bron, Alain M; Delcourt, Cécile

2016-03-01

To describe the design of the Montrachet Study (Maculopathy Optic Nerve nuTRition neurovAsCular and HEarT diseases) and to report visual acuity and refractive errors in this elderly population. Participants were recruited in Dijon (France), from the ongoing population-based 3C Study. In 2009-2011, 1153 participants from the 3 Cities Study, aged 75 years or more, had an initial eye examination and were scheduled for eye examinations. The eye examination comprised visual acuity, refraction, visual field, ocular surface assessment, photographs and OCT of the macula and the optic disc, measurement of intra-ocular pressure, central corneal thickness and macular pigment assessment. Information on cardiovascular and neurologic diseases and a large comprehensive database (blood samples, genetic testing, cognitive tests, MRI) were available from the 3C Study. Presenting visual acuity <20/60 in the better eye was found in 2.3% (95% CI 1.5-3.2) of the participants with no gender differences. Visual impairment increased with age from 1.5% (95% CI 0.3-2.7) for those aged 75-79 years to 5.6% (95% CI 2.9-8.4) for patients 85 years and older (p = 0.0003). Spherical equivalent did not differ between men and women (p = 0.8) and decreased with age whatever the lens status. Despite the high prevalence of self-reported eye diseases in this elderly population, visual impairment was low and increased with age. The Montrachet Study may help to better estimate the prevalence of eye diseases in people over 75 years of age and to seek associations with cardiovascular and neurologic diseases and their potential risk factors. © 2015 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.

Refractive errors in Mercyland Specialist Hospital, Osogbo, Western Nigeria.

PubMed

Adeoti, C O; Egbewale, B E

2008-06-01

The study was conducted to determine the magnitude and pattern of refractive errors in order to provide facilities for its management. A prospective study of 3601 eyes of 1824 consective patients was conducted. Information obtained included age, sex, occupation, visual acuity, type and degree of refractive error. The data was analysed using Statistical Package for Social Sciences 11.0 version) Computer Software. Refractive error was found in 1824(53.71%) patients. There were 832(45.61%) males and 992(54.39%) females with a mean age of 35.55. Myopia was the commonest (1412(39.21% eyes). Others include hypermetropia (840(23.33% eyes), astigmatism (785(21.80%) and 820 patients (1640 eyes) had presbyopia. Anisometropia was present in 791(44.51%) of 1777 patients that had bilateral refractive errors. Two thousand two hundred and fifty two eyes has spherical errors. Out of 2252 eyes with spherical errors, 1308 eyes (58.08%) had errors -0.50 to +0.50 dioptres, 567 eyes (25.18%) had errors less than -0.50 dioptres of whom 63 eyes (2.80%) had errors less than -5.00 dioptres while 377 eyes (16.74%) had errors greater than +0.50 dioptres of whom 81 eyes (3.60%) had errors greater than +2.00 dioptres. The highest error was 20.00 dioptres for myopia and 18.00 dioptres for hypermetropia. Refractive error is common in this environment. Adequate provision should be made for its correction bearing in mind the common types and degrees.

The Refractive Error of Professional Baseball Players.

PubMed

Laby, Daniel M; Kirschen, David G

2017-05-01

High levels of visual acuity are required to hit a baseball effectively. Research has shown that any decrease in vision is likely caused by low-order optical aberrations. This study is designed to validate the SVOne autorefractor, and describe the amount and type, of low-order optical aberrations present in a large cohort of professional baseball players. A retrospective chart review on the 608 Major League Baseball players evaluated during the 2016 Spring Training Season was performed. Results for a subset of players who had both manifest refraction as well as autorefraction were calculated. Subsequently, after determining the accuracy of the autorefraction system in this population, refractive results for the entire population were determined. There was a borderline statistically significant difference in mean spherical refractive error (M) between the manifest refraction and the SVOne auto refraction (-0.273D in the manifest refraction method vs. -0.503D in the SVOne method, P = .06) in the subset of athletes who underwent both tests. Additionally, there was no difference in the J0 or J45 cylindrical component vectors for each method. For the entire eligible population, the SVOne autorefraction system found a mean spherical refractive error (M) of -0.228D, a J0 value of -0.013D, and a J45 value of -0.040D. These data suggest that the SVOne autorefraction system is generally able to measure the refractive error in the baseball population. The system was slightly biased, often reporting more myopia in myopic subjects. Thus, careful evaluation of the refractive status of these athletes coupled with careful subjective refractive correction for those with less than average vision for baseball is strongly suggested.

Refractive errors in children and adolescents in Bucaramanga (Colombia).

PubMed

Galvis, Virgilio; Tello, Alejandro; Otero, Johanna; Serrano, Andrés A; Gómez, Luz María; Castellanos, Yuly

2017-01-01

The aim of this study was to establish the frequency of refractive errors in children and adolescents aged between 8 and 17 years old, living in the metropolitan area of Bucaramanga (Colombia). This study was a secondary analysis of two descriptive cross-sectional studies that applied sociodemographic surveys and assessed visual acuity and refraction. Ametropias were classified as myopic errors, hyperopic errors, and mixed astigmatism. Eyes were considered emmetropic if none of these classifications were made. The data were collated using free software and analyzed with STATA/IC 11.2. One thousand two hundred twenty-eight individuals were included in this study. Girls showed a higher rate of ametropia than boys. Hyperopic refractive errors were present in 23.1% of the subjects, and myopic errors in 11.2%. Only 0.2% of the eyes had high myopia (≤-6.00 D). Mixed astigmatism and anisometropia were uncommon, and myopia frequency increased with age. There were statistically significant steeper keratometric readings in myopic compared to hyperopic eyes. The frequency of refractive errors that we found of 36.7% is moderate compared to the global data. The rates and parameters statistically differed by sex and age groups. Our findings are useful for establishing refractive error rate benchmarks in low-middle-income countries and as a baseline for following their variation by sociodemographic factors.

Seven-year incidence of uncorrected refractive error among an elderly Chinese population in Shihpai, Taiwan: The Shihpai Eye Study

PubMed Central

Kuang, T-M; Tsai, S-Y; Liu, C J-L; Ko, Y-C; Lee, S-M; Chou, P

2016-01-01

Purpose To report the 7-year incidence of uncorrected refractive error in a metropolitan Chinese elderly population. Methods The Shihpai Eye Study 2006 included 460/824 (55.8%) subjects (age range 72–94 years old) of 1361 participants in the 1999 baseline survey for a follow-up eye examination. Visual acuity was assessed using a Snellen chart, uncorrected refractive error was defined as presenting visual acuity (naked eye if without spectacles and with distance spectacles if worn) in the better eye of <6/12 that improved to no impairment (≥6/12) after refractive correction. Results The 7-year incidence of uncorrected refractive error was 10.5% (95% confidence interval (CI): 7.6–13.4%). 92.7% of participants with uncorrection and 77.8% with undercorrection were able to improve at least two lines of visual acuity by refractive correction. In multivariate analysis controlling for covariates, uncorrected refractive error was significantly related to myopia (relative risk (RR): 3.15; 95% CI: 1.31–7.58) and living alone (RR: 2.94; 95% CI 1.14–7.53), whereas distance spectacles worn during examination was protective (RR: 0.35; 95% CI: 0.14–0.88). Conclusion Our study indicated that the incidence of uncorrected refractive error was high (10.5%) in this elderly Chinese population. Living alone and myopia are predisposing factors, whereas wearing distance spectacles at examination is protective. PMID:26795416

Refractive errors, visual impairment, and the use of low-vision devices in albinism in Malawi.

PubMed

Schulze Schwering, M; Kumar, N; Bohrmann, D; Msukwa, G; Kalua, K; Kayange, P; Spitzer, M S

2015-04-01

This study focuses on the refractive implications of albinism in Malawi, which is mostly associated with the burden of visual impairment. The main goal was to describe the refractive errors and to analyze whether patients with albinism in Malawi, Sub-Saharan Africa, benefit from refraction. Age, sex, refractive data, uncorrected and best-corrected visual acuity (UCVA, BCVA), colour vision, contrast sensitivity, and the prescription of sunglasses and low vision devices were collected for a group of 120 albino individuals with oculocutaneous albinism (OCA). Refractive errors were evaluated objectively and subjectively by retinoscopy, and followed by cycloplegic refraction to reconfirm the results. Best-corrected visual acuity (BCVA) was also assessed binocularly. One hundred and twenty albino subjects were examined, ranging in age from 4 to 25 years (median 12 years), 71 (59 %) boys and 49 (41 %) girls. All exhibited horizontal pendular nystagmus. Mean visual acuity improved from 0.98 (0.33) logMAR to 0.77 (0.15) logMAR after refraction (p < 0.001). The best improvement of VA was achieved in patients with mild to moderate myopia. Patients with albinism who were hyperopic more than +1.5 D hardly improved from refraction. With the rule (WTR) astigmatism was more present (37.5 %) than against the rule (ATR) astigmatism (3.8 %). Patients with astigmatism less than 1.5 D improved in 15/32 of cases (47 %) by 2 lines or more. Patients with astigmatism equal to or more than 1.5 D in any axis improved in 26/54 of cases (48 %) by 2 lines or more. Refraction improves visual acuity of children with oculocutaneous albinism in a Sub-Saharan African population in Malawi. The mean improvement was 2 logMAR units.

Self correction of refractive error among young people in rural China: results of cross sectional investigation

PubMed Central

Zhang, Mingzhi; Zhang, Riping; He, Mingguang; Liang, Wanling; Li, Xiaofeng; She, Lingbing; Yang, Yunli; MacKenzie, Graeme; Silver, Joshua D; Ellwein, Leon; Moore, Bruce

2011-01-01

Objective To compare outcomes between adjustable spectacles and conventional methods for refraction in young people. Design Cross sectional study. Setting Rural southern China. Participants 648 young people aged 12-18 (mean 14.9 (SD 0.98)), with uncorrected visual acuity ≤6/12 in either eye. Interventions All participants underwent self refraction without cycloplegia (paralysis of near focusing ability with topical eye drops), automated refraction without cycloplegia, and subjective refraction by an ophthalmologist with cycloplegia. Main outcome measures Uncorrected and corrected vision, improvement of vision (lines on a chart), and refractive error. Results Among the participants, 59% (384) were girls, 44% (288) wore spectacles, and 61% (393/648) had 2.00 dioptres or more of myopia in the right eye. All completed self refraction. The proportion with visual acuity ≥6/7.5 in the better eye was 5.2% (95% confidence interval 3.6% to 6.9%) for uncorrected vision, 30.2% (25.7% to 34.8%) for currently worn spectacles, 96.9% (95.5% to 98.3%) for self refraction, 98.4% (97.4% to 99.5%) for automated refraction, and 99.1% (98.3% to 99.9%) for subjective refraction (P=0.033 for self refraction v automated refraction, P=0.001 for self refraction v subjective refraction). Improvements over uncorrected vision in the better eye with self refraction and subjective refraction were within one line on the eye chart in 98% of participants. In logistic regression models, failure to achieve maximum recorded visual acuity of 6/7.5 in right eyes with self refraction was associated with greater absolute value of myopia/hyperopia (P<0.001), greater astigmatism (P=0.001), and not having previously worn spectacles (P=0.002), but not age or sex. Significant inaccuracies in power (≥1.00 dioptre) were less common in right eyes with self refraction than with automated refraction (5% v 11%, P<0.001). Conclusions Though visual acuity was slightly worse with self refraction than automated or

Visual acuity, refractive error, and endothelial cell density six months after Descemet stripping and automated endothelial keratoplasty (DSAEK).

PubMed

Koenig, Steven B; Covert, Douglas J; Dupps, William J; Meisler, David M

2007-07-01

To evaluate visual acuity, refractive outcomes, and endothelial cell density 6 months after Descemet stripping and automated endothelial keratoplasty (DSAEK). We performed an institutional review board-approved prospective study of a surgical case series of 34 patients at 2 institutions undergoing DSAEK for Fuchs endothelial dystrophy, pseudophakic bullous keratopathy, or aphakic bullous keratopathy with or without simultaneous phacoemulsification and intraocular lens implantation. Clinical outcomes, including best spectacle-corrected visual acuity (BSCVA), spherical equivalent refraction, and refractive astigmatism and topographic or keratometric astigmatism, were assessed at the 6-month postoperative examination and compared with preoperative values with paired Student t tests. The change in endothelial cell density from the eye bank examination to 6 months after transplantation was similarly evaluated. BSCVA averaged 20/99 preoperatively and 20/42 postoperatively (P < 0.0001). After DSAEK, 30 (88.2%) of 34 patients showed improved BSCVA, and 21 (61.8%) of the 34 patients achieved a BSCVA of 20/40 or better. For patients not undergoing simultaneous phacoemulsification and intraocular lens implantation, a hyperopic shift in refraction of 1.19 +/- 1.32 D was noted. Refractive astigmatism, topographic astigmatism, and keratometry showed no statistically significant change. Endothelial cell density of donor corneas averaged 2826 +/- 370 cells/mm, whereas the mean postoperative density was 1396 +/- 440 cells/mm. This finding corresponded to an average loss of 1426 cells/mm (50% loss; P = 0.0001). The first half of cases experienced an average cell loss of 1674 cells/mm (59% loss) compared with 1181 (41% loss) in the second half of cases (P = 0.005). Three (9%) of 34 grafts experienced iatrogenic graft failure and required reoperation with new donor tissue. Also, 9 (27%) of 34 grafts experienced dislocation in the early postoperative period and required repositioning

[Epidemiology of refractive errors].

PubMed

Wolfram, C

2017-07-01

Refractive errors are very common and can lead to severe pathological changes in the eye. This article analyzes the epidemiology of refractive errors in the general population in Germany and worldwide and describes common definitions for refractive errors and clinical characteristics for pathologicaal changes. Refractive errors differ between age groups due to refractive changes during the life time and also due to generation-specific factors. Current research about the etiology of refractive errors has strengthened the influence of environmental factors, which led to new strategies for the prevention of refractive pathologies.

Does Assessing Eye Alignment along with Refractive Error or Visual Acuity Increase Sensitivity for Detection of Strabismus in Preschool Vision Screening?

PubMed Central

2007-01-01

Purpose Preschool vision screenings often include refractive error or visual acuity (VA) testing to detect amblyopia, as well as alignment testing to detect strabismus. The purpose of this study was to determine the effect of combining screening for eye alignment with screening for refractive error or reduced VA on sensitivity for detection of strabismus, with specificity set at 90% and 94%. Methods Over 3 years, 4040 preschool children were screened in the Vision in Preschoolers (VIP) Study, with different screening tests administered each year. Examinations were performed to identify children with strabismus. The best screening tests for detecting children with any targeted condition were noncycloplegic retinoscopy (NCR), Retinomax autorefractor (Right Manufacturing, Virginia Beach, VA), SureSight Vision Screener (Welch-Allyn, Inc., Skaneateles, NY), and Lea Symbols (Precision Vision, LaSalle, IL and Good-Lite Co., Elgin, IL) and HOTV optotypes VA tests. Analyses were conducted with these tests of refractive error or VA paired with the best tests for detecting strabismus (unilateral cover testing, Random Dot “E” [RDE] and Stereo Smile Test II [Stereo Optical, Inc., Chicago, IL]; and MTI PhotoScreener [PhotoScreener, Inc., Palm Beach, FL]). The change in sensitivity that resulted from combining a test of eye alignment with a test of refractive error or VA was determined with specificity set at 90% and 94%. Results Among the 4040 children, 157 were identified as having strabismus. For screening tests conducted by eye care professionals, the addition of a unilateral cover test to a test of refraction generally resulted in a statistically significant increase (range, 15%–25%) in detection of strabismus. For screening tests administered by trained lay screeners, the addition of Stereo Smile II to SureSight resulted in a statistically significant increase (21%) in sensitivity for detection of strabismus. Conclusions The most efficient and low-cost ways to achieve

Refractive Errors

MedlinePlus

... and lens of your eye helps you focus. Refractive errors are vision problems that happen when the shape ... cornea, or aging of the lens. Four common refractive errors are Myopia, or nearsightedness - clear vision close up ...

[A study of refractive errors in a primary school in Cotonou, Benin].

PubMed

Sounouvou, I; Tchabi, S; Doutetien, C; Sonon, F; Yehouessi, L; Bassabi, S K

2008-10-01

Determine the epidemiologic aspects and the degree of severity of different refractive errors in primary schoolchildren. A prospective and descriptive study was conducted from 1 December 2005 to 31 March 2006 on schoolchildren ranging from 4 to 16 years of age in a public primary school in Cotonou, Benin. The refraction was evaluated for any visual acuity lower than or equal to 0.7. The study included 1057 schoolchildren. The average age of the study population was 8.5+/-2.6 years with a slight predominance of females (51.8%). The prevalence of refractive error was 10.6% and astigmatism accounted for the most frequent refractive anomaly (91.9%). Myopia and the hyperopia were associated with astigmatism in 29.4% and 16.1% of the cases, respectively. The age bracket from 6 to 11 years accounted for the majority of refractive errors (75.9%), without age and sex being risk factors (p=0.811 and p=0.321, respectively). The average vision of the ametropic eye was 0.61, with a clear predominance of slight refractive errors (89.3%) and particularly of low-level simple astigmatism (45.5%). The relatively low prevalence of refractive error observed does not obviate the need for implementing actions to improve the ocular health of schoolchildren.

Prevalence of refractive errors in children in Equatorial Guinea.

PubMed

Soler, Margarita; Anera, Rosario G; Castro, José J; Jiménez, Raimundo; Jiménez, José R

2015-01-01

The aim of this work is to evaluate the epidemiological aspects of the refractive errors in school-aged children in Malabo (Island of Bioko), Equatorial Guinea (western-central Africa). A total of 425 schoolchildren (209 male subjects and 216 female subjects, aged between 6 and 16 years) were examined to evaluate their refraction errors in Malabo, Equatorial Guinea (western-central Africa). The examination included autorefraction with cycloplegia, measurement of visual acuity (VA) for far vision, and the curvature radii of the main meridians of the anterior surface of the cornea. A low prevalence of myopia was found (≤-0.50 diopters [D] spherical equivalent), with unilateral and bilateral myopia being 10.4 and 5.2%, respectively. The prevalence of unilateral and bilateral hypermetropia (≥2.0 D spherical equivalent) was 3.1 and 1.6%, respectively. Astigmatism (≤-0.75 D) was found in unilateral form in 32.5% of these children, whereas bilateral astigmatism was found in 11.8%. After excluding children having any ocular pathology, the low prevalence of high refractive errors signified good VA in these children. Significant differences were found in the distribution of the refractive errors by age and type of schooling (public or private) but not by sex. In general, the radii of the anterior of the cornea did not vary significantly with age. The mean refractive errors found were low and therefore VA was high in these children. There was a low prevalence of myopia, with significantly higher values in those who attended private schools (educationally and socioeconomically more demanding). Astigmatism was the most frequent refractive error.

Uncorrected refractive errors.

PubMed

Naidoo, Kovin S; Jaggernath, Jyoti

2012-01-01

Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC), were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR) Development, Service Development and Social Entrepreneurship.

Uncorrected refractive errors

PubMed Central

Naidoo, Kovin S; Jaggernath, Jyoti

2012-01-01

Global estimates indicate that more than 2.3 billion people in the world suffer from poor vision due to refractive error; of which 670 million people are considered visually impaired because they do not have access to corrective treatment. Refractive errors, if uncorrected, results in an impaired quality of life for millions of people worldwide, irrespective of their age, sex and ethnicity. Over the past decade, a series of studies using a survey methodology, referred to as Refractive Error Study in Children (RESC), were performed in populations with different ethnic origins and cultural settings. These studies confirmed that the prevalence of uncorrected refractive errors is considerably high for children in low-and-middle-income countries. Furthermore, uncorrected refractive error has been noted to have extensive social and economic impacts, such as limiting educational and employment opportunities of economically active persons, healthy individuals and communities. The key public health challenges presented by uncorrected refractive errors, the leading cause of vision impairment across the world, require urgent attention. To address these issues, it is critical to focus on the development of human resources and sustainable methods of service delivery. This paper discusses three core pillars to addressing the challenges posed by uncorrected refractive errors: Human Resource (HR) Development, Service Development and Social Entrepreneurship. PMID:22944755

Refractive Error Study in Children: results from Mechi Zone, Nepal.

PubMed

Pokharel, G P; Negrel, A D; Munoz, S R; Ellwein, L B

2000-04-01

To assess the prevalence of refractive error and vision impairment in school age children in the terai area of the Mechi zone in Eastern Nepal. Random selection of village-based clusters was used to identify a sample of children 5 to 15 years of age. Children in the 25 selected clusters were enumerated through a door-to-door household survey and invited to village sites for examination. Visual acuity measurements, cycloplegic retinoscopy, cycloplegic autorefraction, ocular motility evaluation, and anterior segment, media, and fundus examinations were done from May 1998 through July 1998. Independent replicate examinations for quality assurance monitoring took place in all children with reduced vision and in a sample of those with normal vision in seven villages. A total of 5,526 children from 3,724 households were enumerated, and 5,067 children (91.7%) were examined. The prevalence of uncorrected, presenting, and best visual acuity 0.5 (20/40) or worse in at least one eye was 2.9%, 2.8%, and 1.4%, respectively; 0.4% had best visual acuity 0.5 or worse in both eyes. Refractive error was the cause in 56% of the 200 eyes with reduced uncorrected vision, amblyopia in 9%, other causes in 19%, with unexplained causes in the remaining 16%. Myopia -0.5 diopter or less in either eye or hyperopia 2 diopters or greater was observed in less than 3% of children. Hyperopia risk was associated with female gender and myopia risk with older age. The prevalence of reduced vision is very low in school-age children in Nepal, most of it because of correctable refractive error. Further studies are needed to determine whether the prevalence of myopia will be higher for more recent birth cohorts.

Prevalence of Amblyopia and Refractive Errors Among Primary School Children

PubMed Central

Rajavi, Zhale; Sabbaghi, Hamideh; Baghini, Ahmad Shojaei; Yaseri, Mehdi; Moein, Hamidreza; Akbarian, Shadi; Behradfar, Narges; Hosseini, Simin; Rabei, Hossein Mohammad; Sheibani, Kourosh

2015-01-01

Purpose: To determine the prevalence of amblyopia and refractive errors among 7 to 12-year-old primary school children in Tehran, Iran. Methods: This population-based cross-sectional study included 2,410 randomly selected students. Visual acuity was tested using an E-chart on Yang vision tester. Refractive errors were measured by photorefractometry and cycloautorefraction. Strabismus was checked using cover test. Direct ophthalmoscopy was used to assess the anterior segment, lens opacities, red reflex and fundus. Functional amblyopia was defined as best corrected visual acuity ≤20/40 in one or both eyes with no anatomical problems. Results: Amblyopia was present in 2.3% (95% CI: 1.8% to 2.9%) of participants with no difference between the genders. Amblyopic subjects were significantly younger than non-amblyopic children (P=0.004). Overall, 15.9% of hyperopic and 5.9% of myopic cases had amblyopia. The prevalence of hyperopia ≥+2.00D, myopia ≤-0.50D, astigmatism ≥0.75D, and anisometropia (≥1.00D) was 3.5%, 4.9%, 22.6%, and 3.9%, respectively. With increasing age, the prevalence of myopia increased (P<0.001), that of hyperopia decreased (P=0.007), but astigmatism showed no change. Strabismus was found in 2.3% of cases. Strabismus (OR=17.9) and refractive errors, especially anisometropia (OR=12.87) and hyperopia (OR=11.87), were important amblyogenic risk factors. Conclusion: The high prevalence of amblyopia in our subjects in comparison to developed countries reveals the necessity of timely and sensitive screening methods. Due to the high prevalence of amblyopia among children with refractive errors, particularly high hyperopia and anisometropia, provision of glasses should be specifically attended by parents and supported by the Ministry of Health and insurance organizations. PMID:27051485

PREVALENCE OF UNCORRECTED REFRACTIVE ERRORS IN ADULTS AGED 30 YEARS AND ABOVE IN A RURAL POPULATION IN PAKISTAN.

PubMed

Abdullah, Ayesha S; Jadoon, Milhammad Zahid; Akram, Mohammad; Awan, Zahid Hussain; Azam, Mohammad; Safdar, Mohammad; Nigar, Mohammad

2015-01-01

Uncorrected refractive errors are a leading cause of visual disability globally. This population-based study was done to estimate the prevalence of uncorrected refractive errors in adults aged 30 years and above of village Pawakah, Khyber Pakhtunkhwa (KPK), Pakistan. It was a cross-sectional survey in which 1000 individuals were included randomly. All the individuals were screened for uncorrected refractive errors and those whose visual acuity (VA) was found to be less than 6/6 were refracted. In whom refraction was found to be unsatisfactory (i.e., a best corrected visual acuity of <6/6) further examination was done to establish the cause for the subnormal vision. A total of 917 subjects participated in the survey (response rate 92%). The prevalence of uncorrected refractive errors was found to be 23.97% among males and 20% among females. The prevalence of visually disabling refractive errors was 6.89% in males and 5.71% in females. The prevalence was seen to increase with age, with maximum prevalence in 51-60 years age group. Hypermetropia (10.14%) was found to be the commonest refractive error followed by Myopia (6.00%) and Astigmatism (5.6%). The prevalence of Presbyopia was 57.5% (60.45% in males and 55.23% in females). Poor affordability was the commonest barrier to the use of spectacles, followed by unawareness. Cataract was the commonest reason for impaired vision after refractive correction. The prevalence of blindness was 1.96% (1.53% in males and 2.28% in females) in this community with cataract as the commonest cause. Despite being the most easily avoidable cause of subnormal vision uncorrected refractive errors still account for a major proportion of the burden of decreased vision in this area. Effective measures for the screening and affordable correction of uncorrected refractive errors need to be incorpora'ted into the health care delivery system.

Investigating the relationship between foveal morphology and refractive error in a population with infantile nystagmus syndrome.

PubMed

Healey, Natasha; McLoone, Eibhlin; Mahon, Gerald; Jackson, A Jonathan; Saunders, Kathryn J; McClelland, Julie F

2013-04-26

We explored associations between refractive error and foveal hypoplasia in infantile nystagmus syndrome (INS). We recruited 50 participants with INS (albinism n = 33, nonalbinism infantile nystagmus [NAIN] n = 17) aged 4 to 48 years. Cycloplegic refractive error and logMAR acuity were obtained. Spherical equivalent (SER), most ametropic meridian (MAM) refractive error, and better eye acuity (VA) were used for analyses. High resolution spectral-domain optical coherence tomography (SD-OCT) was used to obtain foveal scans, which were graded using the Foveal Hypoplasia Grading Scale. Associations between grades of severity of foveal hypoplasia, and refractive error and VA were explored. Participants with more severe foveal hypoplasia had significantly higher MAMs and SERs (Kruskal-Wallis H test P = 0.005 and P = 0.008, respectively). There were no statistically significant associations between foveal hypoplasia and cylindrical refractive error (Kruskal-Wallis H test P = 0.144). Analyses demonstrated significant differences between participants with albinism or NAIN in terms of SER and MAM (Mann-Whitney U test P = 0.001). There were no statistically significant differences between astigmatic errors between participants with albinism and NAIN. Controlling for the effects of albinism, results demonstrated no significant associations between SER, and MAM and foveal hypoplasia (partial correlation P > 0.05). Poorer visual acuity was associated statistically significantly with more severe foveal hypoplasia (Kruskal-Wallis H test P = 0.001) and with a diagnosis of albinism (Mann-Whitney U test P = 0.001). Increasing severity of foveal hypoplasia is associated with poorer VA, reflecting reduced cone density in INS. Individuals with INS also demonstrate a significant association between more severe foveal hypoplasia and increasing hyperopia. However, in the absence of albinism, there is no significant relation between refractive outcome and degree of foveal hypoplasia

Prevalence of refractive errors in Möbius sequence.

PubMed

Cronemberger, Monica Fialho; Polati, Mariza; Debert, Iara; Mendonça, Tomás Scalamandré; Souza-Dias, Carlos; Miller, Marilyn; Ventura, Liana Oliveira; Nakanami, Célia Regina; Goldchmit, Mauro

2013-01-01

To assess the prevalence of refractive errors in Möbius sequence. This study was carried out during the Annual Meeting of the Brazilian Möbius Society in November 2008. Forty-four patients diagnosed with the Möbius sequence were submitted to a comprehensive assessment, on the following specialties: ophthalmology, neurology, genetics, psychiatry, psychology and dentistry. Forty-three patients were cooperative and able to undertake the ophthalmological examination. Twenty-two (51.2 %) were male and 21 (48.8%) were female. The average age was 8.3 years (from 2 to 17 years). The visual acuity was evaluated using a retro-illuminated logMAR chart in cooperative patients. All children were submitted to exams on ocular motility, cyclopegic refraction, and fundus examination. From the total of 85 eyes, using the spherical equivalent, the major of the eyes (57.6%) were emmetropics (>-0.50 D and <+2.00 D). The prevalence of astigmatism greater than or equal to 0.75 D was 40%. The prevalence of refractive errors, by the spherical equivalent, was 42.4% in this studied group.

Refractive Error, Visual Acuity and Causes of Vision Loss in Children in Shandong, China. The Shandong Children Eye Study

PubMed Central

Wu, Jian Feng; Bi, Hong Sheng; Wang, Shu Mei; Hu, Yuan Yuan; Wu, Hui; Sun, Wei; Lu, Tai Liang; Wang, Xing Rong; Jonas, Jost B.

2013-01-01

Purpose To examine the prevalence of refractive errors and prevalence and causes of vision loss among preschool and school children in East China. Methods Using a random cluster sampling in a cross-sectional school-based study design, children with an age of 4–18 years were selected from kindergartens, primary schools, and junior and senior high schools in the rural Guanxian County and the city of Weihai. All children underwent a complete ocular examination including measurement of uncorrected (UCVA) and best corrected visual acuity (BCVA) and auto-refractometry under cycloplegia. Myopia was defined as refractive error of ≤−0.5 diopters (D), high myopia as ≤−6.0D, and amblyopia as BCVA ≤20/32 without any obvious reason for vision reduction and with strabismus or refractive errors as potential reasons. Results Out of 6364 eligible children, 6026 (94.7%) children participated. Prevalence of myopia (overall: 36.9±0.6%;95% confidence interval (CI):36.0,38.0) increased (P<0.001) from 1.7±1.2% (95%CI:0.0,4.0) in the 4-years olds to 84.6±3.2% (95%CI:78.0,91.0) in 17-years olds. Myopia was associated with older age (OR:1.56;95%CI:1.52,1.60;P<0.001), female gender (OR:1.22;95%CI:1.08,1.39;P = 0.002) and urban region (OR:2.88;95%CI:2.53,3.29;P<0.001). Prevalence of high myopia (2.0±0.2%) increased from 0.7±0.3% (95%CI:0.1,1.3) in 10-years olds to 13.9±3.0 (95%CI:7.8,19.9) in 17-years olds. It was associated with older age (OR:1.50;95%CI:1.41,1.60;P<0.001) and urban region (OR:3.11;95%CI:2.08,4.66);P<0.001). Astigmatism (≥0.75D) (36.3±0.6%;95%CI:35.0,38.0) was associated with older age (P<0.001;OR:1.06;95%CI:1.04,1.09), more myopic refractive error (P<0.001;OR:0.94;95%CI:0.91,0.97) and urban region (P<0.001;OR:1.47;95%CI:1.31,1.64). BCVA was ≤20/40 in the better eye in 19 (0.32%) children. UCVA ≤20/40 in at least one eye was found in 2046 (34.05%) children, with undercorrected refractive error as cause in 1975 (32.9%) children. Amblyopia (BCVA �

Delayed visual attention caused by high myopic refractive error.

PubMed

Winges, Kimberly M; Zarpellon, Ursula; Hou, Chuan; Good, William V

2005-06-01

Delayed visual maturation (DVM) is usually a retrospective diagnosis given to infants who are born with no or poor visually-directed behavior, despite normal acuity on objective testing, but who recover months later. This condition can be organized into several types based on associated neurodevelopmental or ocular findings, but the etiology of DVM is probably complex and involves multiple possible origins. Here we report two infants who presented with delayed visual maturation (attention). They were visually unresponsive at birth but were later found to have high myopic errors. Patient 1 had -4 D right eye, -5 D left eye. Patient 2 had -9 D o.u. Upon spectacle correction at 5 and 4 months, respectively, both infants immediately displayed visually-directed behavior, suggesting that a high refractive error was the cause of inattention in these patients. These findings could add to knowledge surrounding DVM and the diagnosis of apparently blind infants. Findings presented here also indicate the importance of prompt refractive error measurement in such cases.

Refractive errors and schizophrenia.

PubMed

Caspi, Asaf; Vishne, Tali; Reichenberg, Abraham; Weiser, Mark; Dishon, Ayelet; Lubin, Gadi; Shmushkevitz, Motti; Mandel, Yossi; Noy, Shlomo; Davidson, Michael

2009-02-01

Refractive errors (myopia, hyperopia and amblyopia), like schizophrenia, have a strong genetic cause, and dopamine has been proposed as a potential mediator in their pathophysiology. The present study explored the association between refractive errors in adolescence and schizophrenia, and the potential familiality of this association. The Israeli Draft Board carries a mandatory standardized visual accuracy assessment. 678,674 males consecutively assessed by the Draft Board and found to be psychiatrically healthy at age 17 were followed for psychiatric hospitalization with schizophrenia using the Israeli National Psychiatric Hospitalization Case Registry. Sib-ships were also identified within the cohort. There was a negative association between refractive errors and later hospitalization for schizophrenia. Future male schizophrenia patients were two times less likely to have refractive errors compared with never-hospitalized individuals, controlling for intelligence, years of education and socioeconomic status [adjusted Hazard Ratio=.55; 95% confidence interval .35-.85]. The non-schizophrenic male siblings of schizophrenia patients also had lower prevalence of refractive errors compared to never-hospitalized individuals. Presence of refractive errors in adolescence is related to lower risk for schizophrenia. The familiality of this association suggests that refractive errors may be associated with the genetic liability to schizophrenia.

Global magnitude of visual impairment caused by uncorrected refractive errors in 2004

PubMed Central

Pascolini, Donatella; Mariotti, Silvio P; Pokharel, Gopal P

2008-01-01

Abstract Estimates of the prevalence of visual impairment caused by uncorrected refractive errors in 2004 have been determined at regional and global levels for people aged 5 years and over from recent published and unpublished surveys. The estimates were based on the prevalence of visual acuity of less than 6/18 in the better eye with the currently available refractive correction that could be improved to equal to or better than 6/18 by refraction or pinhole. A total of 153 million people (range of uncertainty: 123 million to 184 million) are estimated to be visually impaired from uncorrected refractive errors, of whom eight million are blind. This cause of visual impairment has been overlooked in previous estimates that were based on best-corrected vision. Combined with the 161 million people visually impaired estimated in 2002 according to best-corrected vision, 314 million people are visually impaired from all causes: uncorrected refractive errors become the main cause of low vision and the second cause of blindness. Uncorrected refractive errors can hamper performance at school, reduce employability and productivity, and generally impair quality of life. Yet the correction of refractive errors with appropriate spectacles is among the most cost-effective interventions in eye health care. The results presented in this paper help to unearth a formerly hidden problem of public health dimensions and promote policy development and implementation, programmatic decision-making and corrective interventions, as well as stimulate research. PMID:18235892

Refractive errors in children with autism in a developing country.

PubMed

Ezegwui, I R; Lawrence, L; Aghaji, A E; Okoye, O I; Okoye, O; Onwasigwe, E N; Ebigbo, P O

2014-01-01

In a resource-limited country visual problems of mentally challenged individuals are often neglected. The present study aims to study refractive errors in children diagnosed with autism in a developing country. Ophthalmic examination was carried out on children diagnosed with autism attending a school for the mentally challenged in Enugu, Nigeria between December 2009 and May 2010. Visual acuity was assessed using Lea symbols. Anterior and posterior segments were examined. Cycloplegic refraction was performed. Data was entered on the protocol prepared for the study and analyzed using Statistical Package for the Social Sciences version 17 (Chicago IL, USA). A total of 21 children with autism were enrolled in the school; 18 of whom were examined giving coverage of 85.7%. The age range was 5-15 years, with a mean of 10.28 years (standard deviation ± 3.20). There were 13 boys and 5 girls. One child had bilateral temporal pallor of the disc and one had bilateral maculopathy with diffuse chorioretinal atrophy. Refraction revealed 4 children (22.2%) had astigmatism and 2 children (11.1%) had hypermetropia. Significant refractive error mainly astigmatism was noted in the children with autism. Identifying refractive errors in these children early and providing appropriate corrective lenses may help optimize their visual functioning and impact their activities of daily life in a positive way.

Uncorrected refractive error and presbyopia among junior high school teachers in Jakarta, Indonesia.

PubMed

Ehrlich, Joshua R; Laoh, Alex; Kourgialis, Nick; Prasetyanti, Widya; Zakiyah, Rima; Faillace, Silvana; Friedman, David S

2013-12-01

To report on the frequency of observed refractive and accommodative errors among junior high school teachers in Jakarta, Indonesia, who participated in a Helen Keller International screening, refraction and spectacle distribution program. A total of 965 teachers from 19 schools were eligible for screening; those with uncorrected distance visual acuity (VA) ≤ 6/12-3 and teachers ≥ 35 years old with uncorrected end-point print size >Jaeger (J) 6 were referred. Autorefraction and subjective refraction were performed for teachers with confirmed decreased VA. Refractive error was considered present if sphere ≤-0.75 diopters (D), sphere ≥+0.25D or cylinder ≤-0.50 D resulted in ≥ 2 lines of improvement in VA. Presbyopia was considered present if an end-point print size >J6 improved by ≥ 1 optotype with the use of a lens ≥+1.00 D. Overall, 866 teachers were screened (89.7% of those eligible) with complete screening data available for 858 (99.0%), among whom 762 failed screening. Distance refraction data were available for 666 of 762 (87.4%) and near refraction data for 520 of 686 (75.8%) teachers who failed screening. Of those screened, 76.2 ± 9.0% of teachers had refractive and/or accommodative error and 57.1 ± 7.6% had uncorrected refractive and/or accommodative error. Overall and uncorrected distance refractive error affected 44.2 ± 3.7% and 36.0 ± 3.6%, respectively; overall and uncorrected presbyopia affected 66.4 ± 8.1% and 41.0 ± 6.6%, respectively. As defined in this program, refractive and accommodative errors were common among teachers in Jakarta.

Uncorrected refractive error and associated factors among primary school children in Debre Markos District, Northwest Ethiopia

PubMed Central

2014-01-01

Background Uncorrected Refractive Error is one of the leading cause amblyopia that exposes children to poor school performance. It refrain them from productive working lives resulting in severe economic and social loses in their latter adulthood lives. The objective of the study was to assess the prevalence of uncorrected refractive error and its associated factors among school children in Debre Markos District. Method A cross section study design was employed. Four hundred thirty two students were randomly selected using a multistage stratified sampling technique. The data were collected by trained ophthalmic nurses through interview, structured questionnaires and physical examinations. Snellens visual acuity measurement chart was used to identify the visual acuity of students. Students with visual acuity less than 6/12 had undergone further examination using auto refractor and cross-checked using spherical and cylindrical lenses. The data were entered into epi data statistical software version 3.1 and analyzed by SPSS version 20. The statistical significance was set at α ≤ 0.05. Descriptive, bivariate and multivariate analyses were done using odds ratios with 95% confidence interval. Result Out of 432 students selected for the study, 420 (97.2%) were in the age group 7–15 years. The mean age was 12 ± 2.1SD. Overall prevalence of refractive error was 43 (10.2%). Myopia was found among the most dominant 5.47% followed by astigmatism 1.9% and hyperopia 1.4% in both sexes. Female sex (AOR: 3.96, 95% CI: 1.55-10.09), higher grade level (AOR: 4.82, 95% CI: 1.98-11.47) and using computers regularly (AOR: 4.53, 95% CI: 1.58-12.96) were significantly associated with refractive error. Conclusion The burden of uncorrected refractive errors is high among primary schools children. Myopia was common in both sexes. The potential risk factors were sex, regular use of computers and higher grade level of students. Hence, school health programs should work on health

Prevalence of Refractive Errors Among School Children in Gondar Town, Northwest Ethiopia

PubMed Central

Yared, Assefa Wolde; Belaynew, Wasie Taye; Destaye, Shiferaw; Ayanaw, Tsegaw; Zelalem, Eshete

2012-01-01

Purpose: Many children with poor vision due to refractive error remain undiagnosed and perform poorly in school. The situation is worse in the Sub-Saharan Africa, including Ethiopia, and current information is lacking. The objective of this study is to determine the prevalence of refractive error among children enrolled in elementary schools in Gondar town, Ethiopia. Materials and Methods: This was a cross-sectional study of 1852 students in 8 elementary schools. Subjects were selected by multistage random sampling. The study parameters were visual acuity (VA) evaluation and ocular examination. VA was measured by staff optometrists with the Snellen E-chart while students with subnormal vision were examined using pinhole, retinoscopy evaluation and subjective refraction by ophthalmologists. Results: The study cohort was comprised of 45.8% males and 54.2% females from 8 randomly selected elementary schools with a response rate of 93%. Refractive errors in either eye were present in 174 (9.4%) children. Of these, myopia was diagnosed in 55 (31.6%) children in the right and left eyes followed by hyperopia in 46 (26.4%) and 39 (22.4%) in the right and left eyes respectively. Low myopia was the most common refractive error in 61 (49.2%) and 68 (50%) children for the right and left eyes respectively. Conclusions: Refractive error among children is a common problem in Gondar town and needs to be assessed at every health evaluation of school children for timely treatment. PMID:23248538

Prevalence of refractive errors among school children in gondar town, northwest ethiopia.

PubMed

Yared, Assefa Wolde; Belaynew, Wasie Taye; Destaye, Shiferaw; Ayanaw, Tsegaw; Zelalem, Eshete

2012-10-01

Many children with poor vision due to refractive error remain undiagnosed and perform poorly in school. The situation is worse in the Sub-Saharan Africa, including Ethiopia, and current information is lacking. The objective of this study is to determine the prevalence of refractive error among children enrolled in elementary schools in Gondar town, Ethiopia. This was a cross-sectional study of 1852 students in 8 elementary schools. Subjects were selected by multistage random sampling. The study parameters were visual acuity (VA) evaluation and ocular examination. VA was measured by staff optometrists with the Snellen E-chart while students with subnormal vision were examined using pinhole, retinoscopy evaluation and subjective refraction by ophthalmologists. The study cohort was comprised of 45.8% males and 54.2% females from 8 randomly selected elementary schools with a response rate of 93%. Refractive errors in either eye were present in 174 (9.4%) children. Of these, myopia was diagnosed in 55 (31.6%) children in the right and left eyes followed by hyperopia in 46 (26.4%) and 39 (22.4%) in the right and left eyes respectively. Low myopia was the most common refractive error in 61 (49.2%) and 68 (50%) children for the right and left eyes respectively. Refractive error among children is a common problem in Gondar town and needs to be assessed at every health evaluation of school children for timely treatment.

Prevalence and associated risk factors of undercorrected refractive errors among people with diabetes in Shanghai.

PubMed

Zhu, Mengjun; Tong, Xiaowei; Zhao, Rong; He, Xiangui; Zhao, Huijuan; Zhu, Jianfeng

2017-11-28

To investigate the prevalence and risk factors of undercorrected refractive error (URE) among people with diabetes in the Baoshan District of Shanghai, where data for undercorrected refractive error are limited. The study was a population-based survey of 649 persons (aged 60 years or older) with diabetes in Baoshan, Shanghai in 2009. One copy of the questionnaire was completed for each subject. Examinations included a standardized refraction and measurement of presenting and best-corrected visual acuity (BCVA), tonometry, slit lamp biomicroscopy, and fundus photography. The calculated age-standardized prevalence rate of URE was 16.63% (95% confidence interval [CI] 13.76-19.49). For visual impairment subjects (presenting vision worse than 20/40 in the better eye), the prevalence of URE was up to 61.11%, and 75.93% of subjects could achieve visual acuity improvement by at least one line using appropriate spectacles. Under multiple logistic regression analysis, older age, female gender, non-farmer, increasing degree of myopia, lens opacities status, diabetic retinopathy (DR), body mass index (BMI) index lower than normal, and poor glycaemic control were associated with higher URE levels. Wearing distance eyeglasses was a protective factor for URE. The undercorrected refractive error in diabetic adults was high in Shanghai. Health education and regular refractive assessment are needed for diabetic adults. Persons with diabetes should be more aware that poor vision is often correctable, especially for those with risk factors.

Study on the refractive errors of school going children of Pokhara city in Nepal.

PubMed

Niroula, D R; Saha, C G

Refractive errors are the one of the most common visual disorders found worldwide in school going children and also it is one of the causes of blindness. It can easily be prevented, if timely proper measures are taken. In Kathmandu valley and Mechi Zone of Nepal, the distribution of refractive errors was found to be very high. No records are available from the Western part of Nepal. Considering the importance of the refractive errors the present study had been undertaken in Pokhara city. 964 subjects (474 boys, 490 girls) were selected between age groups 10 to 19 years from 6 schools representing different region of Pokhara. After Preliminary examination: on acuity of vision with Snellen's and Jaeger's charts, the subjects were referred to the Manipal Teaching Hospital, Pokhara for confirmation of the refractive errors. Sixty two schools children (6.43%), out of 964 had refractive errors. The myopia was found to be most common (4.05%). The refractive errors were found more in Private school children (9.29%) than Government school children (4.23%), which is statistically significant (P < 0.05). More boys (7.59%) were found to have suffered from refractive errors than girls (5.31%). Further, children with vegetarian diet (10.52%) had greater number of refractive errors than non-vegetarian diet children (6.17%). In the present study, percentage distribution of myopia was found to be higher (4.05%) than the hyperopia (1.24%) and astigmatism (1.14%). Interestingly, in the present study the refractive errors were found significantly higher in Private schools children than Government schools because the children who read in Private schools have higher socioeconomic status; spend more time in home work, watching Television and Computer as compared to government schools children. These near activities of the eyes causes stress on eyes of the children and might be one of the causes of developing myopia.

Evaluating refraction and visual acuity with the Nidek autorefractometer AR-360A in a randomized population-based screening study.

PubMed

Stoor, Katri; Karvonen, Elina; Liinamaa, Johanna; Saarela, Ville

2017-11-30

The evaluation of visual acuity (VA) and refraction in the Northern Finland Birth Cohort Eye study was performed using the Nidek AR-360A autorefractometer. The accuracy of the method for this population-based screening study was assessed. Measurements of the refractive error were obtained from the right eyes of 1238 subjects (mean age 47), first objectively with the AR-360A and then subjectively by an optometrist. Agreement with the subjective refraction was calculated for sphere, cylinder, mean spherical equivalent (MSE), cylindrical vectors J 45 and J 0 and presbyopic correction (add). Visual acuity (VA) was measured using an ETDRS chart and the autorefractometer. The refractive error measured with the AR-360A was higher than the subjective refraction performed by the optometrist for sphere (0.007 D ± 0.24 D p = 0.30) and also for cylinder (-0.16 D ± 0.20 D p < 0.0005). The bias between the measurements of MSE, J 45 and J 0 was low: -0.07 D ± 0.22 D (p = 0.002), 0.01 D ± 0.43 D (p = 0.25) and -0.01 D ± 0.42 D (p = 0.43), respectively. The amount of add measured by the autorefractometer was higher than the subjective 0.35 D ± 0.29 D (p < 0.0005). There was a statistically significant correlation between VA (p < 0.0005) and the difference between the subjective and objective refraction. In 99.2% of the measurements, visual values were within one decimal line of each other. The Nidek AR-360A autorefractometer is an accurate tool for determining the refraction and VA in a clinical screening trial. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Prevalence of refractive error in malay primary school children in suburban area of Kota Bharu, Kelantan, Malaysia.

PubMed

Hashim, Syaratul-Emma; Tan, Hui-Ken; Wan-Hazabbah, W H; Ibrahim, Mohtar

2008-11-01

Refractive error remains one of the primary causes of visual impairment in children worldwide, and the prevalence of refractive error varies widely. The objective of this study was to determine the prevalence of refractive error and study the possible associated factors inducing refractive error among primary school children of Malay ethnicity in the suburban area of Kota Bharu, Kelantan, Malaysia. A school-based cross-sectional study was performed from January to July 2006 by random selection on Standard 1 to Standard 6 students of 10 primary schools in the Kota Bharu district. Visual acuity assessment was measured using logMAR ETDRS chart. Positive predictive value of uncorrected visual acuity equal or worse than 20/40, was used as a cut-off point for further evaluation by automated refraction and retinoscopic refraction. A total of 840 students were enumerated but only 705 were examined. The prevalence of uncorrected visual impairment was seen in 54 (7.7%) children. The main cause of the uncorrected visual impairment was refractive error which contributed to 90.7% of the total, and with 7.0% prevalence for the studied population. Myopia is the most common type of refractive error among children aged 6 to 12 years with prevalence of 5.4%, followed by hyperopia at 1.0% and astigmatism at 0.6%. A significant positive correlation was noted between myopia development with increasing age (P <0.005), more hours spent on reading books (P <0.005) and background history of siblings with glasses (P <0.005) and whose parents are of higher educational level (P <0.005). Malays in suburban Kelantan (5.4%) have the lowest prevalence of myopia compared with Malays in the metropolitan cities of Kuala Lumpur (9.2%) and Singapore (22.1%). The ethnicity-specific prevalence rate of myopia was the lowest among Malays in Kota Bharu, followed by Kuala Lumpur, and is the highest among Singaporean Malays. Better socio-economic factors could have contributed to higher myopia rates in the

Prevalence of uncorrected refractive errors among school-age children in the School District of Philadelphia.

PubMed

Mayro, Eileen L; Hark, Lisa A; Shiuey, Eric; Pond, Michael; Siam, Linda; Hill-Bennett, Tamara; Tran, Judie; Khanna, Nitasha; Silverstein, Marlee; Donaghy, James; Zhan, Tingting; Murchison, Ann P; Levin, Alex V

2018-06-01

To determine the prevalence and severity of uncorrected refractive errors in school-age children attending Philadelphia public schools. The Wills Eye Vision Screening Program for Children is a community-based pediatric vision screening program designed to detect and correct refractive errors and refer those with nonrefractive eye diseases for examination by a pediatric ophthalmologist. Between January 2014 and June 2016 the program screened 18,974 children in grades K-5 in Philadelphia public schools. Children who failed the vision screening were further examined by an on-site ophthalmologist or optometrist; children whose decreased visual acuity was not amenable to spectacle correction were referred to a pediatric ophthalmologist. Of the 18,974 children screened, 2,492 (13.1%) exhibited uncorrected refractive errors: 1,776 (9.4%) children had myopia, 459 (2.4%) had hyperopia, 1,484 (7.8%) had astigmatism, and 846 (4.5%) had anisometropia. Of the 2,492 with uncorrected refractive error, 368 children (14.8%) had more than one refractive error diagnosis. In stratifying refractive error diagnoses by severity, mild myopia (spherical equivalent of -0.50 D to < -3.00 D) was the most common diagnosis, present in 1,573 (8.3%) children. In this urban population 13.1% of school-age children exhibited uncorrected refractive errors. Blurred vision may create challenges for students in the classroom; school-based vision screening programs can provide an avenue to identify and correct refractive errors. Copyright © 2018 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Prevalence and pattern of refractive errors among primary school children in Al Hassa , Saudi Arabia.

PubMed

Al Wadaani, Fahd Abdullah; Amin, Tarek Tawfik; Ali, Ayub; Khan, Atuar Rahman

2012-11-11

Some 12.8 million in the age group 5-15 years are visually impaired from uncorrected or inadequately corrected refractive errors. In Saudi Arabia, the size of this public health problem is not well defined especially among primary schoolchildren. The purpose of this cross-sectional study was to assess the prevalence and pattern of refractive errors among primary school children in Al Hassa, Saudi Arabia.  A total of 2246 Saudi primary school children aged 6 to 14 years of both genders were selected using multistage sampling method form 30 primary schools located in the three different areas of Al Hassa. School children were interviewed to collect demographics and vision data using a special data collection form followed by screening for refractive errors by trained optometrists within the school premises using a standardized protocol. Assessment of visual acuity and ocular motility evaluation were carried out and cover-uncover test was performed. Children detected with defective vision were referred for further examination employing subjective refraction with auto refractometer and objective refraction using streak retinoscopy after 1% cyclopentolate. Of the screened school children (N=2002), the overall prevalence of refractive errors was 13.7% (n=274), higher among females (Odds ratio, OR=1.39, P=0.012) and significantly more among students of rural residence (OR=2.40, P=0.001). The prevalence of refractive errors was disproportionately more among those aged 12-14 years (OR=9.02, P=0.001). Only 9.4% of students with poor vision were wore spectacles for correction. Myopia was the most commonly encountered refractive error among both genders (65.7% of the total errors encountered). Uncorrected refractive errors affected a sizable portion of primary school children in Al Hassa, Saudi Arabia. Primary schoolchildren especially females, rural and older children represents high risk group for refractive errors for which the included children were unaware.

Prevalence and Pattern of Refractive Errors among Primary School Children in Al Hassa, Saudi Arabia

PubMed Central

Wadaani, Fahd Abdullah Al; Amin, Tarek Tawfik; Ali, Ayub; Khan, Ataur Rahman

2013-01-01

Some 12.8 million in the age group 5–15 years are visually impaired from uncorrected or inadequately corrected refractive errors. In Saudi Arabia, the size of this public health problem is not well defined especially among primary schoolchildren. The purpose of this cross-sectional study was to assess the prevalence and pattern of refractive errors among primary school children in Al Hassa, Saudi Arabia. A total of 2246 Saudi primary school children aged 6 to 14 years of both genders were selected using multistage sampling method form 30 primary schools located in the three different areas of Al Hassa. School children were interviewed to collect demographics and vision data using a special data collection form followed by screening for refractive errors by trained optometrists within the school premises using a standardized protocol. Assessment of visual acuity and ocular motility evaluation were carried out and cover-uncover test was performed. Children detected with defective vision were referred for further examination employing subjective refraction with auto refractometer and objective refraction using streak retinoscopy after 1% cyclopentolate. Of the screened school children (N=2002), the overall prevalence of refractive errors was 13.7% (n=274), higher among females (Odds ratio, OR=1.39, P=0.012) and significantly more among students of rural residence (OR=2.40, P=0.001). The prevalence of refractive errors was disproportionately more among those aged 12-14 years (OR=9.02, P=0.001). Only 9.4% of students with poor vision were wore spectacles for correction. Myopia was the most commonly encountered refractive error among both genders (65.7% of the total errors encountered). Uncorrected refractive errors affected a sizable portion of primary school children in Al Hassa, Saudi Arabia. Primary schoolchildren especially females, rural and older children represents high risk group for refractive errors for which the included children were unaware. PMID:23283044

Refractive error and visual impairment in private school children in Ghana.

PubMed

Kumah, Ben D; Ebri, Anne; Abdul-Kabir, Mohammed; Ahmed, Abdul-Sadik; Koomson, Nana Ya; Aikins, Samual; Aikins, Amos; Amedo, Angela; Lartey, Seth; Naidoo, Kovin

2013-12-01

To assess the prevalence of refractive error and visual impairment in private school children in Ghana. A random selection of geographically defined classes in clusters was used to identify a sample of school children aged 12 to 15 years in the Ashanti Region. Children in 60 clusters were enumerated and examined in classrooms. The examination included visual acuity, retinoscopy, autorefraction under cycloplegia, and examination of anterior segment, media, and fundus. For quality assurance, a random sample of children with reduced and normal vision were selected and re-examined independently. A total of 2454 children attending 53 private schools were enumerated, and of these, 2435 (99.2%) were examined. Prevalence of uncorrected, presenting, and best visual acuity of 20/40 or worse in the better eye was 3.7, 3.5, and 0.4%, respectively. Refractive error was the cause of reduced vision in 71.7% of 152 eyes, amblyopia in 9.9%, retinal disorders in 5.9%, and corneal opacity in 4.6%. Exterior and anterior segment abnormalities occurred in 43 (1.8%) children. Myopia (at least -0.50 D) in one or both eyes was present in 3.2% of children when measured with retinoscopy and in 3.4% measured with autorefraction. Myopia was not significantly associated with gender (P = 0.82). Hyperopia (+2.00 D or more) in at least one eye was present in 0.3% of children with retinoscopy and autorefraction. The prevalence of reduced vision in Ghanaian private school children due to uncorrected refractive error was low. However, the prevalence of amblyopia, retinal disorders, and corneal opacities indicate the need for early interventions.

Prevalence of vision impairment and refractive error in school children in Ba Ria - Vung Tau province, Vietnam.

PubMed

Paudel, Prakash; Ramson, Prasidh; Naduvilath, Thomas; Wilson, David; Phuong, Ha Thanh; Ho, Suit M; Giap, Nguyen V

2014-04-01

To assess the prevalence of vision impairment and refractive error in school children 12-15 years of age in Ba Ria - Vung Tau province, Vietnam. Prospective, cross-sectional study. 2238 secondary school children. Subjects were selected based on stratified multistage cluster sampling of 13 secondary schools from urban, rural and semi-urban areas. The examination included visual acuity measurements, ocular motility evaluation, cycloplegic autorefraction, and examination of the external eye, anterior segment, media and fundus. Visual acuity and principal cause of vision impairment. The prevalence of uncorrected and presenting visual acuity ≤6/12 in the better eye were 19.4% (95% confidence interval, 12.5-26.3) and 12.2% (95% confidence interval, 8.8-15.6), respectively. Refractive error was the cause of vision impairment in 92.7%, amblyopia in 2.2%, cataract in 0.7%, retinal disorders in 0.4%, other causes in 1.5% and unexplained causes in the remaining 2.6%. The prevalence of vision impairment due to myopia in either eye (-0.50 diopter or greater) was 20.4% (95% confidence interval, 12.8-28.0), hyperopia (≥2.00 D) was 0.4% (95% confidence interval, 0.0-0.7) and emmetropia with astigmatism (≥0.75 D) was 0.7% (95% confidence interval, 0.2-1.2). Vision impairment due to myopia was associated with higher school grade and increased time spent reading and working on a computer. Uncorrected refractive error, particularly myopia, among secondary school children in Vietnam is a major public health problem. School-based eye health initiative such as refractive error screening is warranted to reduce vision impairment. © 2013 The Authors. Clinical & Experimental Ophthalmology published by Wiley Publishing Asia Pty Ltd on behalf of Royal Australian and New Zealand College of Ophthalmologists.

Visual Acuity and Over-refraction in Myopic Children Fitted with Soft Multifocal Contact Lenses.

PubMed

Schulle, Krystal L; Berntsen, David A; Sinnott, Loraine T; Bickle, Katherine M; Gostovic, Anita T; Pierce, Gilbert E; Jones-Jordan, Lisa A; Mutti, Donald O; Walline, Jeffrey J

2018-04-01

Practitioners fitting contact lenses for myopia control frequently question whether a myopic child can achieve good vision with a high-add multifocal. We demonstrate that visual acuity is not different than spectacles with a commercially available, center-distance soft multifocal contact lens (MFCL) (Biofinity Multifocal "D"; +2.50 D add). To determine the spherical over-refraction (SOR) necessary to obtain best-corrected visual acuity (BCVA) when fitting myopic children with a center-distance soft MFCL. Children (n = 294) aged 7 to 11 years with myopia (spherical component) of -0.75 to -5.00 diopters (D) (inclusive) and 1.00 D cylinder or less (corneal plane) were fitted bilaterally with +2.50 D add Biofinity "D" MFCLs. The initial MFCL power was the spherical equivalent of a standardized subjective refraction, rounded to the nearest 0.25 D step (corneal plane). An SOR was performed monocularly (each eye) to achieve BCVA. Binocular, high-contrast logMAR acuity was measured with manifest spectacle correction and MFCLs with over-refraction. Photopic pupil size was measured with a pupilometer. The mean (±SD) age was 10.3 ± 1.2 years, and the mean (±SD) SOR needed to achieve BCVA was OD: -0.61 ± 0.24 D/OS: -0.58 ± 0.27 D. There was no difference in binocular high-contrast visual acuity (logMAR) between spectacles (-0.01 ± 0.06) and best-corrected MFCLs (-0.01 ± 0.07) (P = .59). The mean (±SD) photopic pupil size (5.4 ± 0.7 mm) was not correlated with best MFCL correction or the over-refraction magnitude (both P ≥ .09). Children achieved BCVA with +2.50 D add MFCLs that was not different than with spectacles. Children typically required an over-refraction of -0.50 to -0.75 D to achieve BCVA. With a careful over-refraction, these +2.50 D add MFCLs provide good distance acuity, making them viable candidates for myopia control.

[Prevalence of refractive errors in 7 and 8 year-old children in the province of Western Pomerania].

PubMed

Muszyńska-Lachota, Izabela; Czepita, Damian; uczyńska, Violetta; Wysiecki, Przemysław

2005-01-01

To determine the prevalence of refractive errors in 7 and 8 year-old schoolchildren in the province of Western Pomerania. 140 pupils of elementary schools were examined. Measurements of visual acuity and retinoscopy after cycloplegia were carried out. Prevalence of hyperopia, myopia, and astigmatism was 76.1%, 3.3% and 5.1%, respectively. No statistically significant differences between 7 and 8 year-old children were found. 1. There is a relatively high prevalence of refractive errors, with hyperopia prevailing, among 7 and 8 year-old schoolchildren. 2. Myopia in young children is a cause for concern an further studies. 3. High prevalence of refractive errors in children calls for systematic examination and focused interviewing by medical professionals of the school health care system.

A survey of the prevalence of refractive errors among children in lower primary schools in Kampala district.

PubMed

Kawuma, Medi; Mayeku, Robert

2002-08-01

Refractive errors are a known cause of visual impairment and may cause blindness worldwide. In children, refractive errors may prevent those afflicted from progressing with their studies. In Uganda, like in many developing countries, there is no established vision-screening programme for children on commencement of school, such that those with early onset of such errors will have many years of poor vision. Over all, there is limited information on refractive errors among children in Africa. To determine the prevalence of refractive errors among school children attending lower primary in Kampala district; the frequency of the various types of refractive errors, and their relationship to sexuality and ethnicity. A cross-sectional descriptive study. Kampala district, Uganda A total of 623 children aged between 6 and 9 years had a visual acuity testing done at school using the same protocol; of these 301 (48.3%) were boys and 322 (51.7%) girls. Seventy-three children had a significant refractive error of +/-0.50 or worse in one or both eyes, giving a prevalence of 11.6% and the commonest single refractive error was astigmatism, which accounted for 52% of all errors. This was followed by hypermetropia, and myopia was the least common. Significant refractive errors occur among primary school children aged 6 to 9 years at a prevalence of approximately 12%. Therefore, there is a need to have regular and simple vision testing in primary school children at least at the commencement of school so as to defect those who may suffer from these disabilities.

Prevalence of vision impairment and refractive error in school children in Ba Ria – Vung Tau province, Vietnam

PubMed Central

Paudel, Prakash; Ramson, Prasidh; Naduvilath, Thomas; Wilson, David; Phuong, Ha Thanh; Ho, Suit M; Giap, Nguyen V

2014-01-01

Background To assess the prevalence of vision impairment and refractive error in school children 12–15 years of age in Ba Ria – Vung Tau province, Vietnam. Design Prospective, cross-sectional study. Participants 2238 secondary school children. Methods Subjects were selected based on stratified multistage cluster sampling of 13 secondary schools from urban, rural and semi-urban areas. The examination included visual acuity measurements, ocular motility evaluation, cycloplegic autorefraction, and examination of the external eye, anterior segment, media and fundus. Main Outcome Measures Visual acuity and principal cause of vision impairment. Results The prevalence of uncorrected and presenting visual acuity ≤6/12 in the better eye were 19.4% (95% confidence interval, 12.5–26.3) and 12.2% (95% confidence interval, 8.8–15.6), respectively. Refractive error was the cause of vision impairment in 92.7%, amblyopia in 2.2%, cataract in 0.7%, retinal disorders in 0.4%, other causes in 1.5% and unexplained causes in the remaining 2.6%. The prevalence of vision impairment due to myopia in either eye (–0.50 diopter or greater) was 20.4% (95% confidence interval, 12.8–28.0), hyperopia (≥2.00 D) was 0.4% (95% confidence interval, 0.0–0.7) and emmetropia with astigmatism (≥0.75 D) was 0.7% (95% confidence interval, 0.2–1.2). Vision impairment due to myopia was associated with higher school grade and increased time spent reading and working on a computer. Conclusions Uncorrected refractive error, particularly myopia, among secondary school children in Vietnam is a major public health problem. School-based eye health initiative such as refractive error screening is warranted to reduce vision impairment. PMID:24299145

Phakic intraocular lenses for the treatment of refractive errors: an evidence-based analysis.

PubMed

2009-01-01

The objective of this analysis is to review the effectiveness, safety, and cost-effectiveness of phakic intraocular lenses (pIOLs) for the treatment of myopia, hyperopia, and astigmatism. CONDITION AND TARGET POPULATION REFRACTIVE ERRORS: Refractive errors occur when the eye cannot focus light properly. In myopia (near- or short-sightedness), distant objects appear blurry because the axis of the eye is too long or the cornea is too steep, so light becomes focused in front of the retina. Hyperopia (far sightedness) occurs when light is focused behind the retina causing nearby objects to appear blurry. In astigmatism, blurred or distorted vision occurs when light is focused at two points rather than one due to an irregularly shaped cornea or lens. Refractive errors are common worldwide, but high refractive errors are less common. In the United States, the prevalence of high myopia (≤ -5 D) in people aged 20 to 39, 40 to 59, and 60 years and older is 7.4% (95% confidence interval [CI], 6.5% - 8.3%), 7.8% (95% CI, 6.4% - 8.6%), and 3.1% (95% CI, 2.2% - 3.9%), respectively. The prevalence of high hyperopia (≥ 3 D) is 1.0% (95% CI, .6% - 1.4%), 2.4% (95% CI, 1.7% - 3.0%), and 10.0% (95% CI, 9.1% - 10.9%) for the same age groupings. Finally, the prevalence of astigmatism (≥ 1 D cylinder) is 23.1% (95% CI, 21.6% - 24.5%), 27.6% (95% CI, 25.8% - 29.3%) and 50.1% (48.2% - 52.0%). LOW VISION: According to the Ontario Schedule of Benefits, low visual acuity is defined by a best spectacle corrected visual acuity (BSCVA) of 20/50 (6/15) or less in the better eye and not amenable to further medical and/or surgical treatment. Similarly, the Ontario Assistive Devices Program defines low vision as BSCVA in the better eye in the range of 20/70 or less that cannot be corrected medically, surgically, or with ordinary eyeglasses or contact lenses. Estimates of the prevalence of low vision vary. Using the criteria of BSCVA ranging from 20/70 to 20/160, one study estimated that 35

Refractive errors and binocular dysfunctions in a population of university students.

PubMed

Risovic, D J; Misailovic, K R; Eric-Marinkovic, J M; Kosanovic-Jakovic, N G; Milenkovic, S M; Petrovic, L Z

2008-01-01

This clinical study was performed to determine the presence of refractive errors and binocular dysfunctions in a population of university students. Refraction and binocular function were evaluated in a young patient population (230 students and 234 nonstudent subjects, aged 18-27 years). Distance visual acuity (DVA) and near visual acuity (NVA), refraction, cover test (CT), ocular motility, near-point of convergence, horizontal phoria measurement by Maddox wing, negative and positive vergence amplitude in prism diopters, fusion amplitude in synoptophore, as well as stereoacuity (Titmus test) were tested. Emmetropia was the most frequent refractive status in our student and nonstudent groups (78.7%). Myopia was the most frequent refractive disorder in the whole population (13.1%). Myopia and hypermetropia were significantly more frequent in the students than in nonstudents (chi-square emp 47.55). Exophoria is significantly more frequent in myopic subjects. Vergence amplitude (t test 0.000) and fusion amplitude (t test 0.005) show significantly lower values in student population. Results of Titmus test in the student group is significantly worse than in the nonstudent group (t test 0.000). Maddox wing resulted in significantly higher degree of heterophoria in the student population (t test 0.000). Myopic subjects, in the student group (t test 0.002) as well as in the nonstudent group (t test 0.001), show significantly better results in Titmus test. High near visual demand could be the most important factor for higher incidence of myopia, worse convergence and fusion amplitude, higher degree of exophoria, and worse results in Titmus test in the student population.

[Incidence of refractive errors with corrective aids subsequent selection].

PubMed

Benes, P; Synek, S; Petrová, S; Sokolová, Sidlová J; Forýtková, L; Holoubková, Z

2012-02-01

This study follows the occurrence of refractive errors in population and the possible selection of the appropriate type of corrective aids. Objective measurement and subsequent determination of the subjective refraction of the eye is on essential act in opotmetric practice. The file represented by 615 patients (1230 eyes) is divided according to the refractive error of myopia, hyperopia and as a control group are listed emetropic clients. The results of objective and subjective values of refraction are compared and statistically processed. The study included 615 respondents. To determine the objective refraction the autorefraktokeratometer with Placido disc was used and the values of spherical and astigmatic correction components, including the axis were recorded. These measurements were subsequently verified and tested subjectively using the trial lenses and the projection optotype to the normal investigative distance of 5 meters. After this the appropriate corrective aids were then recommended. Group I consists of 123 men and 195 women with myopia (n = 635) of clients with an average age 39 +/- 18,9 years. Objective refraction - sphere: -2,57 +/- 2,46 D, cylinder: -1,1 +/- 1,01 D, axis of: 100 degrees +/- 53,16 degrees. Subjective results are as follows--the value of sphere: -2,28 +/- 2,33 D, cylinder -0,63 +/- 0,80 D, axis of: 99,8 degrees +/- 56,64 degrees. Group II is represented hyperopic clients and consists of 67 men and 107 women (n = 348). The average age is 58,84 +/- 16,73 years. Objective refraction has values - sphere: +2,81 +/- 2,21 D, cylinder: -1,0 +/- 0,94 D; axis 95 degree +/- 45,4 degrees. Subsequent determination of subjective refraction has the following results - sphere: +2,28 +/- 2,06 D; cylinder: -0,49 +/- 0,85 D, axis of: 95,9 degrees +/- 46,4 degrees. Group III consists from emetropes whose final minimum viasual acuity was Vmin = 1,0 (5/5) or better. Overall, this control group is represented 52 males and 71 females (n = 247). The average

Refractive error in school children in an urban and rural setting in Cambodia.

PubMed

Gao, Zoe; Meng, Ngy; Muecke, James; Chan, Weng Onn; Piseth, Horm; Kong, Aimee; Jnguyenphamhh, Theresa; Dehghan, Yalda; Selva, Dinesh; Casson, Robert; Ang, Kim

2012-02-01

To assess the prevalence of refractive error in schoolchildren aged 12-14 years in urban and rural settings in Cambodia's Phnom Penh and Kandal provinces. Ten schools from Phnom Penh Province and 26 schools from Kandal Province were randomly selected and surveyed in October 2010. Children were examined by teams of Australian and Cambodian optometrists, ophthalmic nurses and ophthalmologists who performed visual acuity (VA) testing and cycloplegic refraction. A total of 5527 children were included in the study. The prevalence of uncorrected, presenting and best-corrected VA ≤ 6/12 in the better eye were 2.48% (95% confidence interval [CI] 2.02-2.83%), 1.90% (95% CI 1.52-2.24%) and 0.36% (95% CI 0.20-0.52%), respectively; 43 children presented with glasses whilst a total of 315 glasses were dispensed. The total prevalence of refractive error was 6.57% (95% CI 5.91-7.22%), but there was a significant difference between urban (13.7%, 95% CI 12.2-15.2%) and rural (2.5%, 95% CI 2.03-3.07%) schools (P < 0.0001). Refractive error accounted for 91.2% of visually impaired eyes, cataract for 1.7%, and other causes for 7.1%. Myopia (spherical equivalent ≤ -0.50 diopters [D] in either eye) was associated with increased age, female gender and urban schooling. The prevalence of refractive error was significantly higher in urban Phnom Penh schools than rural schools in Kandal Province. The prevalence of refractive error, particularly myopia was relatively low compared to previous reports in Asia. The majority of children did not have appropriate correction with spectacles, highlighting the need for more effective screening and optical intervention.

Survey of Radar Refraction Error Corrections

DTIC Science & Technology

2016-11-01

ELECTRONIC TRAJECTORY MEASUREMENTS GROUP RCC 266-16 SURVEY OF RADAR REFRACTION ERROR CORRECTIONS DISTRIBUTION A: Approved for...DOCUMENT 266-16 SURVEY OF RADAR REFRACTION ERROR CORRECTIONS November 2016 Prepared by Electronic...This page intentionally left blank. Survey of Radar Refraction Error Corrections, RCC 266-16 iii Table of Contents Preface

Crystalline lens power and refractive error.

PubMed

Iribarren, Rafael; Morgan, Ian G; Nangia, Vinay; Jonas, Jost B

2012-02-01

To study the relationships between the refractive power of the crystalline lens, overall refractive error of the eye, and degree of nuclear cataract. All phakic participants of the population-based Central India Eye and Medical Study with an age of 50+ years were included. Calculation of the refractive lens power was based on distance noncycloplegic refractive error, corneal refractive power, anterior chamber depth, lens thickness, and axial length according to Bennett's formula. The study included 1885 subjects. Mean refractive lens power was 25.5 ± 3.0 D (range, 13.9-36.6). After adjustment for age and sex, the standardized correlation coefficients (β) of the association with the ocular refractive error were highest for crystalline lens power (β = -0.41; P < 0.001) and nuclear lens opacity grade (β = -0.42; P < 0.001), followed by axial length (β = -0.35; P < 0.001). They were lowest for corneal refractive power (β = -0.08; P = 0.001) and anterior chamber depth (β = -0.05; P = 0.04). In multivariate analysis, refractive error was significantly (P < 0.001) associated with shorter axial length (β = -1.26), lower refractive lens power (β = -0.95), lower corneal refractive power (β = -0.76), higher lens thickness (β = 0.30), deeper anterior chamber (β = 0.28), and less marked nuclear lens opacity (β = -0.05). Lens thickness was significantly lower in eyes with greater nuclear opacity. Variations in refractive error in adults aged 50+ years were mostly influenced by variations in axial length and in crystalline lens refractive power, followed by variations in corneal refractive power, and, to a minor degree, by variations in lens thickness and anterior chamber depth.

Wavefront coherence area for predicting visual acuity of post-PRK and post-PARK refractive surgery patients

NASA Astrophysics Data System (ADS)

Garcia, Daniel D.; van de Pol, Corina; Barsky, Brian A.; Klein, Stanley A.

1999-06-01

Many current corneal topography instruments (called videokeratographs) provide an `acuity index' based on corneal smoothness to analyze expected visual acuity. However, post-refractive surgery patients often exhibit better acuity than is predicted by such indices. One reason for this is that visual acuity may not necessarily be determined by overall corneal smoothness but rather by having some part of the cornea able to focus light coherently onto the fovea. We present a new method of representing visual acuity by measuring the wavefront aberration, using principles from both ray and wave optics. For each point P on the cornea, we measure the size of the associated coherence area whose optical path length (OPL), from a reference plane to P's focus, is within a certain tolerance of the OPL for P. We measured the topographies and vision of 62 eyes of patients who had undergone the corneal refractive surgery procedures of photorefractive keratectomy (PRK) and photorefractive astigmatic keratectomy (PARK). In addition to high contrast visual acuity, our vision tests included low contrast and low luminance to test the contribution of the PRK transition zone. We found our metric for visual acuity to be better than all other metrics at predicting the acuity of low contrast and low luminance. However, high contrast visual acuity was poorly predicted by all of the indices we studied, including our own. The indices provided by current videokeratographs sometimes fail for corneas whose shape differs from simple ellipsoidal models. This is the case with post-PRK and post-PARK refractive surgery patients. Our alternative representation that displays the coherence area of the wavefront has considerable advantages, and promises to be a better predictor of low contrast and low luminance visual acuity than current shape measures.

Comparison of self-refraction using a simple device, USee, with manifest refraction in adults.

PubMed

Annadanam, Anvesh; Varadaraj, Varshini; Mudie, Lucy I; Liu, Alice; Plum, William G; White, J Kevin; Collins, Megan E; Friedman, David S

2018-01-01

The USee device is a new self-refraction tool that allows users to determine their own refractive error. We evaluated the ease of use of USee in adults, and compared the refractive error correction achieved with USee to clinical manifest refraction. Sixty adults with uncorrected visual acuity <20/30 and spherical equivalent between -6.00 and +6.00 diopters completed manifest refraction and self-refraction. Subjects had a mean (±SD) age of 53.1 (±18.6) years, and 27 (45.0%) were male. Mean (±SD) spherical equivalent measured by manifest refraction and self-refraction were -0.90 D (±2.53) and -1.22 diopters (±2.42), respectively (p = 0.001). The proportion of subjects correctable to ≥20/30 in the better eye was higher for manifest refraction (96.7%) than self-refraction (83.3%, p = 0.005). Failure to achieve visual acuity ≥20/30 with self-refraction in right eyes was associated with increasing age (per year, OR: 1.05; 95% CI: 1.00-1.10) and higher cylindrical power (per diopter, OR: 7.26; 95% CI: 1.88-28.1). Subjectively, 95% of participants thought USee was easy to use, 85% thought self-refraction correction was better than being uncorrected, 57% thought vision with self-refraction correction was similar to their current corrective lenses, and 53% rated their vision as "very good" or "excellent" with self-refraction. Self-refraction provides acceptable refractive error correction in the majority of adults. Programs targeting resource-poor settings could potentially use USee to provide easy on-site refractive error correction.

Comparison of self-refraction using a simple device, USee, with manifest refraction in adults

PubMed Central

Annadanam, Anvesh; Mudie, Lucy I.; Liu, Alice; Plum, William G.; White, J. Kevin; Collins, Megan E.; Friedman, David S.

2018-01-01

Background The USee device is a new self-refraction tool that allows users to determine their own refractive error. We evaluated the ease of use of USee in adults, and compared the refractive error correction achieved with USee to clinical manifest refraction. Methods Sixty adults with uncorrected visual acuity <20/30 and spherical equivalent between –6.00 and +6.00 diopters completed manifest refraction and self-refraction. Results Subjects had a mean (±SD) age of 53.1 (±18.6) years, and 27 (45.0%) were male. Mean (±SD) spherical equivalent measured by manifest refraction and self-refraction were –0.90 D (±2.53) and –1.22 diopters (±2.42), respectively (p = 0.001). The proportion of subjects correctable to ≥20/30 in the better eye was higher for manifest refraction (96.7%) than self-refraction (83.3%, p = 0.005). Failure to achieve visual acuity ≥20/30 with self-refraction in right eyes was associated with increasing age (per year, OR: 1.05; 95% CI: 1.00–1.10) and higher cylindrical power (per diopter, OR: 7.26; 95% CI: 1.88–28.1). Subjectively, 95% of participants thought USee was easy to use, 85% thought self-refraction correction was better than being uncorrected, 57% thought vision with self-refraction correction was similar to their current corrective lenses, and 53% rated their vision as “very good” or “excellent” with self-refraction. Conclusion Self-refraction provides acceptable refractive error correction in the majority of adults. Programs targeting resource-poor settings could potentially use USee to provide easy on-site refractive error correction. PMID:29390026

Headache and refractive errors in children.

PubMed

Roth, Zachary; Pandolfo, Katie R; Simon, John; Zobal-Ratner, Jitka

2014-01-01

To investigate the association between uncorrected or miscorrected refractive errors in children and headache, and to determine whether correction of refractive errors contributes to headache resolution. Results of ophthalmic examination, including refractive error, were recorded at initial visit for headache. If resolution of headache on subsequent visits was not documented, a telephone call was placed to their caregivers to inquire whether headache had resolved. Of the 158 patients, 75.3% had normal or unchanged eye examinations, including refractions.Follow-up data were available for 110 patients. Among those, 32 received new or changed spectacle correction and 78 did not require a change in refraction.Headaches improved in 76.4% of all patients, whether with (71.9%) or without (78.2%) a change in refractive correction. The difference between these two groups was not statistically significant (P = .38). Headaches in children usually do not appear to be caused by ophthalmic disease, including refractive error. The prognosis for improvement is favorable, regardless of whether refractive correction is required. Copyright 2014, SLACK Incorporated.

Headaches associated with refractive errors: myth or reality?

PubMed

Gil-Gouveia, R; Martins, I P

2002-04-01

Headache and refractive errors are very common conditions in the general population, and those with headache often attribute their pain to a visual problem. The International Headache Society (IHS) criteria for the classification of headache includes an entity of headache associated with refractive errors (HARE), but indicates that its importance is widely overestimated. To compare overall headache frequency and HARE frequency in healthy subjects with uncorrected or miscorrected refractive errors and a control group. We interviewed 105 individuals with uncorrected refractive errors and a control group of 71 subjects (with properly corrected or without refractive errors) regarding their headache history. We compared the occurrence of headache and its diagnosis in both groups and assessed its relation to their habits of visual effort and type of refractive errors. Headache frequency was similar in both subjects and controls. Headache associated with refractive errors was the only headache type significantly more common in subjects with refractive errors than in controls (6.7% versus 0%). It was associated with hyperopia and was unrelated to visual effort or to the severity of visual error. With adequate correction, 72.5% of the subjects with headache and refractive error reported improvement in their headaches, and 38% had complete remission of headache. Regardless of the type of headache present, headache frequency was significantly reduced in these subjects (t = 2.34, P =.02). Headache associated with refractive errors was rarely identified in individuals with refractive errors. In those with chronic headache, proper correction of refractive errors significantly improved headache complaints and did so primarily by decreasing the frequency of headache episodes.

Visual impairment, uncorrected refractive error, and accelerometer-defined physical activity in the United States.

PubMed

Willis, Jeffrey R; Jefferys, Joan L; Vitale, Susan; Ramulu, Pradeep Y

2012-03-01

To examine how accelerometer-measured physical activity is affected by visual impairment (VI) and uncorrected refractive error (URE). Cross-sectional study using data from the 2003-2004/2005-2006 National Health and Nutritional Examination Survey. Visual impairment was defined as better-eye postrefraction visual acuity worse than 20/40. Uncorrected refractive error was defined as better-eye presenting visual acuity of 20/50 or worse, improving to 20/40 or better with refraction. Adults older than 20 years with normal sight, URE, and VI were analyzed. The main outcome measures were steps per day and daily minutes of moderate or vigorous physical activity (MVPA). Five thousand seven hundred twenty-two participants (57.1%) had complete visual acuity and accelerometer data. Individuals with normal sight took an average of 9964 steps per day and engaged in an average of 23.5 minutes per day of MVPA, as compared with 9742 steps per day and 23.1 minutes per day of MVPA in individuals with URE (P > .50 for both) and 5992 steps per day and 9.3 minutes/d of MVPA in individuals with VI (P < .01 for both). In multivariable models, individuals with VI took 26% fewer steps per day (P < .01; 95% CI, 18%-34%) and spent 48% less time in MVPA (P < .01; 95% CI, 37%-57%) than individuals with normal sight. The decrement in steps and MVPA associated with VI equaled or exceeded that associated with self-reported chronic obstructive pulmonary disease, diabetes mellitus, arthritis, stroke, or congestive heart failure. Visual impairment, but not URE, impacts physical activity equal to or greater than other serious medical conditions. The substantial decrement in physical activity observed in nonrefractive vision loss highlights a need for better strategies to safely improve mobility and increase physical activity in this group.

Intertester agreement in refractive error measurements.

PubMed

Huang, Jiayan; Maguire, Maureen G; Ciner, Elise; Kulp, Marjean T; Quinn, Graham E; Orel-Bixler, Deborah; Cyert, Lynn A; Moore, Bruce; Ying, Gui-Shuang

2013-10-01

To determine the intertester agreement of refractive error measurements between lay and nurse screeners using the Retinomax Autorefractor and the SureSight Vision Screener. Trained lay and nurse screeners measured refractive error in 1452 preschoolers (3 to 5 years old) using the Retinomax and the SureSight in a random order for screeners and instruments. Intertester agreement between lay and nurse screeners was assessed for sphere, cylinder, and spherical equivalent (SE) using the mean difference and the 95% limits of agreement. The mean intertester difference (lay minus nurse) was compared between groups defined based on the child's age, cycloplegic refractive error, and the reading's confidence number using analysis of variance. The limits of agreement were compared between groups using the Brown-Forsythe test. Intereye correlation was accounted for in all analyses. The mean intertester differences (95% limits of agreement) were -0.04 (-1.63, 1.54) diopter (D) sphere, 0.00 (-0.52, 0.51) D cylinder, and -0.04 (1.65, 1.56) D SE for the Retinomax and 0.05 (-1.48, 1.58) D sphere, 0.01 (-0.58, 0.60) D cylinder, and 0.06 (-1.45, 1.57) D SE for the SureSight. For either instrument, the mean intertester differences in sphere and SE did not differ by the child's age, cycloplegic refractive error, or the reading's confidence number. However, for both instruments, the limits of agreement were wider when eyes had significant refractive error or the reading's confidence number was below the manufacturer's recommended value. Among Head Start preschool children, trained lay and nurse screeners agree well in measuring refractive error using the Retinomax or the SureSight. Both instruments had similar intertester agreement in refractive error measurements independent of the child's age. Significant refractive error and a reading with low confidence number were associated with worse intertester agreement.

Prevalence and predictors of refractive error and spectacle coverage in Nakuru, Kenya: a cross-sectional, population-based study.

PubMed

Bastawrous, Andrew; Mathenge, Wanjiku; Foster, Allen; Kuper, Hannah

2013-10-01

A cross-sectional study was undertaken in Nakuru, Kenya to assess the prevalence of refractive error and the spectacle coverage in a population aged ≥50 years. Of the 5,010 subjects who were eligible, 4,414 underwent examination (response rate 88.1 %). LogMAR visual acuity was assessed in all participants and refractive error was measured in both eyes using a Topcon auto refractor RM8800. Detailed interviews were undertaken and ownership of spectacles was assessed. Refractive error was responsible for 51.7 % of overall visual impairment (VI), 85.3 % (n = 191) of subjects with mild VI, 42.7 % (n = 152) of subjects with moderate VI, 16.7 % (n = 3) of subjects with severe VI and no cases of blindness. Myopia was more common than hyperopia affecting 59.5 % of those with refractive error compared to 27.4 % for hyperopia. High myopia (<-5.0 DS) was also more common than extreme hyperopia (>+5.0 DS). Of those who needed distance spectacles (spectacle coverage), 25.5 % owned spectacles. In conclusion, the oldest, most poor and least educated are most likely to have no spectacles and they should be specifically targeted when refractive services are put in place.

Refractive errors in a rural Korean adult population: the Namil Study.

PubMed

Yoo, Y C; Kim, J M; Park, K H; Kim, C Y; Kim, T-W

2013-12-01

To assess the prevalence of refractive errors, including myopia, high myopia, hyperopia, astigmatism, and anisometropia, in rural adult Koreans. We identified 2027 residents aged 40 years or older in Namil-myeon, a rural town in central South Korea. Of 1928 eligible residents, 1532 subjects (79.5%) participated. Each subject underwent screening examinations including autorefractometry, corneal curvature measurement, and best-corrected visual acuity. Data from 1215 phakic right eyes were analyzed. The prevalence of myopia (spherical equivalent (SE) <-0.5 diopters (D)) was 20.5% (95% confidence interval (CI): 18.2-22.8%), of high myopia (SE <-6.0 D) was 1.0% (95% CI: 0.4-1.5%), of hyperopia (SE>+0.5 D) was 41.8% (95% CI: 38.9-44.4%), of astigmatism (cylinder <-0.5 D) was 63.7% (95% CI: 61.0-66.4%), and of anisometropia (difference in SE between eyes >1.0 D) was 13.8% (95% CI: 11.9-15.8%). Myopia prevalence decreased with age and tended to transition into hyperopia with age up to 60-69 years. In subjects older than this, the trend in SE refractive errors reversed with age. The prevalence of astigmatism and anisometropia increased consistently with age. The refractive status was not significantly different between males and females. The prevalence of myopia and hyperopia in rural adult Koreans was similar to that of rural Chinese. The prevalence of high myopia was lower in this Korean sample than in other East Asian populations, and astigmatism was the most frequently occurring refractive error.

Refractive error and visual impairment in school children in Northern Ireland.

PubMed

O'Donoghue, L; McClelland, J F; Logan, N S; Rudnicka, A R; Owen, C G; Saunders, K J

2010-09-01

To describe the prevalence of refractive error (myopia and hyperopia) and visual impairment in a representative sample of white school children. The Northern Ireland Childhood Errors of Refraction study, a population-based cross-sectional study, examined 661 white 12-13-year-old and 392 white 6-7-year-old children between 2006 and 2008. Procedures included assessment of monocular logarithm of the minimum angle of resolution (logMAR), visual acuity (unaided and presenting) and binocular open-field cycloplegic (1% cyclopentolate) autorefraction. Myopia was defined as -0.50DS or more myopic spherical equivalent refraction (SER) in either eye, hyperopia as > or =+2.00DS SER in either eye if not previously classified as myopic. Visual impairment was defined as >0.30 logMAR units (equivalent to 6/12). Levels of myopia were 2.8% (95% CI 1.3% to 4.3%) in younger and 17.7% (95% CI 13.2% to 22.2%) in older children: corresponding levels of hyperopia were 26% (95% CI 20% to 33%) and 14.7% (95% CI 9.9% to 19.4%). The prevalence of presenting visual impairment in the better eye was 3.6% in 12-13-year-old children compared with 1.5% in 6-7-year-old children. Almost one in four children fails to bring their spectacles to school. This study is the first to provide robust population-based data on the prevalence of refractive error and visual impairment in Northern Irish school children. Strategies to improve compliance with spectacle wear are required.

Refractive Status and Prevalence of Refractive Errors in Suburban School-age Children

PubMed Central

Pi, Lian-Hong; Chen, Lin; Liu, Qin; Ke, Ning; Fang, Jing; Zhang, Shu; Xiao, Jun; Ye, Wei-Jiang; Xiong, Yan; Shi, Hui; Yin, Zheng-Qin

2010-01-01

Objective: This study investigated the distribution pattern of refractive status and prevalence of refractive errors in school-age children in Western China to determine the possible environmental factors. Methods: A random sampling strategy in geographically defined clusters was used to identify children aged 6-15 years in Yongchuan, a socio-economically representative area in Western China. We carried out a door-to-door survey and actual eye examinations, including visual acuity measurements, stereopsis examination, anterior segment and eyeball movements, fundus examinations, and cycloplegic retinoscopy with 1% cyclopentolate. Results: A total of 3469 children living in 2552 households were selected, and 3070 were examined. The distributions of refractive status were positively-skewed for 6-8-year-olds, and negatively-skewed for 9-12 and 13-15-year-olds. The prevalence of hyperopia (≥+2.00 D spherical equivalent [SE]), myopia (≤-0.50 D SE), and astigmatism (≥1.00 diopter of cylinder [DC]) were 3.26%, 13.75%, and 3.75%, respectively. As children's ages increased, the prevalence rate of hyperopia decreased (P<0.001) and that of myopia increased significantly (P<0.001). Children in academically challenging schools had a higher risk of myopia (P<0.001) and astigmatism (≥1.00DC, P =0.04) than those in regular schools. Conclusion: The distribution of refractive status changes gradually from positively-skewed to negatively-skewed distributions as age increases, with 9-year-old being the critical age for the changes. Environmental factors and study intensity influence the occurrence and development of myopia. PMID:20975844

Age-Specific Prevalence of Visual Impairment and Refractive Error in Children Aged 3-10 Years in Shanghai, China.

PubMed

Ma, Yingyan; Qu, Xiaomei; Zhu, Xiaofeng; Xu, Xun; Zhu, Jianfeng; Sankaridurg, Padmaja; Lin, Senlin; Lu, Lina; Zhao, Rong; Wang, Ling; Shi, Huijing; Tan, Hui; You, Xiaofang; Yuan, Hong; Sun, Sifei; Wang, Mingjin; He, Xiangui; Zou, Haidong; Congdon, Nathan

2016-11-01

We assessed changes in age-specific prevalence of refractive error at the time of starting school, by comparing preschool and school age cohorts in Shanghai, China. A cross-sectional study was done in Jiading District, Shanghai during November and December 2013. We randomly selected 7 kindergartens and 7 primary schools, with probability proportionate to size. Chinese children (n = 8398) aged 3 to 10 years were enumerated, and 8267 (98.4%) were included. Children underwent distance visual acuity assessment and refraction measurement by cycloplegic autorefraction and subjective refraction. The prevalence of uncorrected visual acuity (UCVA), presenting visual acuity, and best-corrected visual acuity in the better eye of ≤20/40 was 19.8%, 15.5%, and 1.7%, respectively. Among those with UCVA ≤ 20/40, 93.2% could achieve visual acuity of ≥20/32 with refraction. Only 28.7% (n = 465) of children with UCVA in the better eye of ≤20/40 wore glasses. Prevalence of myopia (spherical equivalent ≤-0.5 diopters [D] in at least one eye) increased from 1.78% in 3-year-olds to 52.2% in 10-year-olds, while prevalence of hyperopia (spherical equivalent ≥+2.0 D) decreased from 17.8% among 3-year-olds to 2.6% by 10 years of age. After adjusting for age, attending elite "high-level" school was statistically associated with greater myopia prevalence. The prevalence of myopia was lower or comparable to that reported in other populations from age 3 to 5 years, but increased dramatically after 6 years, consistent with a strong environmental role of schooling on myopia development.

Prevalence of amblyopia and patterns of refractive error in the amblyopic children of a tertiary eye care center of Nepal.

PubMed

Sapkota, K; Pirouzian, A; Matta, N S

2013-01-01

Refractive error is a common cause of amblyopia. To determine prevalence of amblyopia and the pattern and the types of refractive error in children with amblyopia in a tertiary eye hospital of Nepal. A retrospective chart review of children diagnosed with amblyopia in the Nepal Eye Hospital (NEH) from July 2006 to June 2011 was conducted. Children of age 13+ or who had any ocular pathology were excluded. Cycloplegic refraction and an ophthalmological examination was performed for all children. The pattern of refractive error and the association between types of refractive error and types of amblyopia were determined. Amblyopia was found in 0.7 % (440) of 62,633 children examined in NEH during this period. All the amblyopic eyes of the subjects had refractive error. Fifty-six percent (248) of the patients were male and the mean age was 7.74 ± 2.97 years. Anisometropia was the most common cause of amblyopia (p less than 0.001). One third (29 %) of the subjects had bilateral amblyopia due to high ametropia. Forty percent of eyes had severe amblyopia with visual acuity of 20/120 or worse. About twothirds (59.2 %) of the eyes had astigmatism. The prevalence of amblyopia in the Nepal Eye Hospital is 0.7%. Anisometropia is the most common cause of amblyopia. Astigmatism is the most common types of refractive error in amblyopic eyes. © NEPjOPH.

Population-based survey of refractive error among school-aged children in rural northern China: the Heilongjiang eye study.

PubMed

Li, Zhijian; Xu, Keke; Wu, Shubin; Lv, Jia; Jin, Di; Song, Zhen; Wang, Zhongliang; Liu, Ping

2014-01-01

The prevalence of refractive error in the north of China is unknown. The study aimed to estimate the prevalence and associated factors of refractive error in school-aged children in a rural area of northern China. Cross-sectional study. The cluster random sampling method was used to select the sample. A total of 1700 subjects of 5 to 18 years of age were examined. All participants underwent ophthalmic evaluation. Refraction was performed under cycloplegia. Association of refractive errors with age, sex, and education was analysed. The main outcome measure was prevalence rates of refractive error among school-aged children. Of the 1700 responders, 1675 were eligible. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye was 6.3%, 3.0% and 1.2%, respectively. The prevalence of myopia was 5.0% (84/1675, 95% CI, 4.8%-5.4%) and of hyperopia was 1.6% (27/1675, 95% CI, 1.0%-2.2%). Astigmatism was evident in 2.0% of the subjects. Myopia increased with increasing age, whereas hyperopia and astigmatism were associated with younger age. Myopia, hyperopia and astigmatism were more common in females. We also found that prevalence of refractive error were associated with education. Myopia and astigmatism were more common in those with higher degrees of education. This report has provided details of the refractive status in a rural school-aged population. Although the prevalence of refractive errors is lower in the population, the unmet need for spectacle correction remains a significant challenge for refractive eye-care services. © 2013 Royal Australian and New Zealand College of Ophthalmologists.

The prevalence of refractive errors in 6- to 15-year-old schoolchildren in Dezful, Iran.

PubMed

Norouzirad, Reza; Hashemi, Hassan; Yekta, Abbasali; Nirouzad, Fereidon; Ostadimoghaddam, Hadi; Yazdani, Negareh; Dadbin, Nooshin; Javaherforoushzadeh, Ali; Khabazkhoob, Mehdi

2015-01-01

To determine the prevalence of refractive errors, among 6- to 15-year-old schoolchildren in the city of Dezful in western Iran. In this cross-sectional study, 1375 Dezful schoolchildren were selected through multistage cluster sampling. After obtaining written consent, participants had uncorrected and corrected visual acuity tests and cycloplegic refraction at the school site. Refractive errors were defined as myopia [spherical equivalent (SE) -0.5 diopter (D)], hyperopia (SE ≥ 2.0D), and astigmatism (cylinder error > 0.5D). 1151 (83.7%) schoolchildren participated in the study. Of these, 1130 completed their examinations. 21 individuals were excluded because of poor cooperation and contraindication for cycloplegic refraction. Prevalence of myopia, hyperopia, and astigmatism were 14.9% (95% confidence interval (CI): 10.1-19.6), 12.9% (95% CI: 7.2-18.6), and 45.3% (95% CI: 40.3-50.3), respectively. Multiple logistic regression analysis showed an age-related increase in myopia prevalence (p < 0.001) and a decrease in hyperopia prevalence (p < 0.001). There was a higher prevalence of myopia in boys (p<0.001) and hyperopia in girls (p = 0.007). This study showed a considerably high prevalence of refractive errors among the Iranian population of schoolchildren in Dezful in the west of Iran. The prevalence of myopia is considerably high compared to previous studies in Iran and increases with age.

Prevalence of Refractive Errors among High School Students in Western Iran

PubMed Central

Hashemi, Hassan; Rezvan, Farhad; Beiranvand, Asghar; Papi, Omid-Ali; Hoseini Yazdi, Hosein; Ostadimoghaddam, Hadi; Yekta, Abbas Ali; Norouzirad, Reza; Khabazkhoob, Mehdi

2014-01-01

Purpose To determine the prevalence of refractive errors among high school students. Methods In a cross-sectional study, we applied stratified cluster sampling on high school students of Aligoudarz, Western Iran. Examinations included visual acuity, non-cycloplegic refraction by autorefraction and fine tuning with retinoscopy. Myopia and hyperopia were defined as spherical equivalent of -0.5/+0.5 diopter (D) or worse, respectively; astigmatism was defined as cylindrical error >0.5 D and anisometropia as an interocular difference in spherical equivalent exceeding 1 D. Results Of 451 selected students, 438 participated in the study (response rate, 97.0%). Data from 434 subjects with mean age of 16±1.3 (range, 14 to 21) years including 212 (48.8%) male subjects was analyzed. The prevalence of myopia, hyperopia and astigmatism was 29.3% [95% confidence interval (CI), 25-33.6%], 21.7% (95%CI, 17.8-25.5%), and 20.7% (95%CI, 16.9-24.6%), respectively. The prevalence of myopia increased significantly with age [odds ratio (OR)=1.30, P=0.003] and was higher among boys (OR=3.10, P<0.001). The prevalence of hyperopia was significantly higher in girls (OR=0.49, P=0.003). The prevalence of astigmatism was 25.9% in boys and 15.8% in girls (OR=2.13, P=0.002). The overall prevalence of high myopia and high hyperopia were 0.5% and 1.2%, respectively. The prevalence of with-the-rule, against-the-rule, and oblique astigmatism was 14.5%, 4.8% and 1.4%, respectively. Overall, 4.6% (95%CI, 2.6-6.6%) of subjects were anisometropic. Conclusion More than half of high school students in Aligoudarz had at least one type of refractive error. Compared to similar studies, the prevalence of refractive errors was high in this age group. PMID:25279126

[Refractive errors in patients with cerebral palsy].

PubMed

Mrugacz, Małgorzata; Bandzul, Krzysztof; Kułak, Wojciech; Poppe, Ewa; Jurowski, Piotr

2013-04-01

Ocular changes are common in patients with cerebral palsy (CP) and they exist in about 50% of cases. The most common are refractive errors and strabismus disease. The aim of the paper was to estimate the relativeness between refractive errors and neurological pathologies in patients with selected types of CP. MATERIAL AND METHODS. The subject of the analysis was showing refractive errors in patients within two groups of CP: diplegia spastica and tetraparesis, with nervous system pathologies taken into account. Results. This study was proven some correlations between refractive errors and type of CP and severity of the CP classified in GMFCS scale. Refractive errors were more common in patients with tetraparesis than with diplegia spastica. In the group with diplegia spastica more common were myopia and astigmatism, however in tetraparesis - hyperopia.

The U.S. Air Force Photorefractive Keratectomy (PRK) Study: Evaluation of Residual Refractive Error and High- and Low-Contrast Visual Acuity

DTIC Science & Technology

2006-07-01

values for statistical analyses in terms of Snellen equivalent VA (Ref 44) and lines gained vs . lost after PRK . The Snellen VA values shown in the...AFRL-SA-BR-TR-2010-0011 THE U.S. AIR FORCE PHOTOREFRACTIVE KERATECTOMY ( PRK ) STUDY: Evaluation of Residual Refractive Error and High...July 2006 4. TITLE AND SUBTITLE THE U.S. AIR FORCE PHOTOREFRACTIVE KERATECTOMY ( PRK ) STUDY: Evaluation of Residual Refractive Error and High- and

Refractive errors in a rural Korean adult population: the Namil Study

PubMed Central

Yoo, Y C; Kim, J M; Park, K H; Kim, C Y; Kim, T-W

2013-01-01

Purpose To assess the prevalence of refractive errors, including myopia, high myopia, hyperopia, astigmatism, and anisometropia, in rural adult Koreans. Methods We identified 2027 residents aged 40 years or older in Namil-myeon, a rural town in central South Korea. Of 1928 eligible residents, 1532 subjects (79.5%) participated. Each subject underwent screening examinations including autorefractometry, corneal curvature measurement, and best-corrected visual acuity. Results Data from 1215 phakic right eyes were analyzed. The prevalence of myopia (spherical equivalent (SE) <−0.5 diopters (D)) was 20.5% (95% confidence interval (CI): 18.2−22.8%), of high myopia (SE <−6.0 D) was 1.0% (95% CI: 0.4−1.5%), of hyperopia (SE>+0.5 D) was 41.8% (95% CI: 38.9−44.4%), of astigmatism (cylinder <−0.5 D) was 63.7% (95% CI: 61.0−66.4%), and of anisometropia (difference in SE between eyes >1.0 D) was 13.8% (95% CI: 11.9−15.8%). Myopia prevalence decreased with age and tended to transition into hyperopia with age up to 60−69 years. In subjects older than this, the trend in SE refractive errors reversed with age. The prevalence of astigmatism and anisometropia increased consistently with age. The refractive status was not significantly different between males and females. Conclusions The prevalence of myopia and hyperopia in rural adult Koreans was similar to that of rural Chinese. The prevalence of high myopia was lower in this Korean sample than in other East Asian populations, and astigmatism was the most frequently occurring refractive error. PMID:24037232

Global Vision Impairment and Blindness Due to Uncorrected Refractive Error, 1990-2010.

PubMed

Naidoo, Kovin S; Leasher, Janet; Bourne, Rupert R; Flaxman, Seth R; Jonas, Jost B; Keeffe, Jill; Limburg, Hans; Pesudovs, Konrad; Price, Holly; White, Richard A; Wong, Tien Y; Taylor, Hugh R; Resnikoff, Serge

2016-03-01

The purpose of this systematic review was to estimate worldwide the number of people with moderate and severe visual impairment (MSVI; presenting visual acuity <6/18, ≥3/60) or blindness (presenting visual acuity <3/60) due to uncorrected refractive error (URE), to estimate trends in prevalence from 1990 to 2010, and to analyze regional differences. The review focuses on uncorrected refractive error which is now the most common cause of avoidable visual impairment globally. : The systematic review of 14,908 relevant manuscripts from 1990 to 2010 using Medline, Embase, and WHOLIS yielded 243 high-quality, population-based cross-sectional studies which informed a meta-analysis of trends by region. The results showed that in 2010, 6.8 million (95% confidence interval [CI]: 4.7-8.8 million) people were blind (7.9% increase from 1990) and 101.2 million (95% CI: 87.88-125.5 million) vision impaired due to URE (15% increase since 1990), while the global population increased by 30% (1990-2010). The all-age age-standardized prevalence of URE blindness decreased 33% from 0.2% (95% CI: 0.1-0.2%) in 1990 to 0.1% (95% CI: 0.1-0.1%) in 2010, whereas the prevalence of URE MSVI decreased 25% from 2.1% (95% CI: 1.6-2.4%) in 1990 to 1.5% (95% CI: 1.3-1.9%) in 2010. In 2010, URE contributed 20.9% (95% CI: 15.2-25.9%) of all blindness and 52.9% (95% CI: 47.2-57.3%) of all MSVI worldwide. The contribution of URE to all MSVI ranged from 44.2 to 48.1% in all regions except in South Asia which was at 65.4% (95% CI: 62-72%). : We conclude that in 2010, uncorrected refractive error continues as the leading cause of vision impairment and the second leading cause of blindness worldwide, affecting a total of 108 million people or 1 in 90 persons.

Refractive errors among patients attending the ophthalmology department of a medical college in North-East India

PubMed Central

Natung, Tanie; Taye, Trishna; Lyngdoh, Laura Amanda; Dkhar, Begonia; Hajong, Ranendra

2017-01-01

Purpose: To determine the magnitude and pattern of refractive errors among patients attending the ophthalmology department of a new medical college in North-East India. Materials and Methods: A prospective study of the new patients (age ≥5 years), who were phakic and whose unaided visual acuities were worse than 20/20 but improved with pinhole, was done. Complete ophthalmic examination and refraction with appropriate cycloplegia for age were done for the 4582 eligible patients. Spherical equivalents (SE) of refractive errors of the right eyes were used for analysis. Results: Of the 4582 eligible patients, 2546 patients had refractive errors (55.56%). The proportion of emmetropia (SE − 0.50–+0.50 diopter sphere [DS]), myopia (SE <−0.50 DS), high myopia (SE >−5.0 DS), and hypermetropia (>+0.50 DS for adults and >+2.0 DS for children) were 53.1%, 27.4%, 2.6%, and 16.9%, respectively. The proportion of hyperopia increased till 59 years and then decreased with age (P = 0.000). The proportion of myopia and high myopia decreased significantly with age after 39 years (P = 0.000 and P = 0.004, respectively). Of the 1510 patients with astigmatism, 17% had with-the-rule (WTR), 23.4% had against-the-rule (ATR), and 19% had oblique astigmatisms. The proportion of WTR and ATR astigmatisms significantly decreased (P = 0.000) and increased (P = 0.000) with age, respectively. Conclusions: This study has provided the magnitude and pattern of refractive errors in the study population. It will serve as the initial step for conducting community-based studies on the prevalence of refractive errors in this part of the country since such data are lacking from this region. Moreover, this study will help the primary care physicians to have an overview of the magnitude and pattern of refractive errors presenting to a health-care center as refractive error is an established and significant public health problem worldwide. PMID:29417005

Refractive errors among patients attending the ophthalmology department of a medical college in North-East India.

PubMed

Natung, Tanie; Taye, Trishna; Lyngdoh, Laura Amanda; Dkhar, Begonia; Hajong, Ranendra

2017-01-01

To determine the magnitude and pattern of refractive errors among patients attending the ophthalmology department of a new medical college in North-East India. A prospective study of the new patients (age ≥5 years), who were phakic and whose unaided visual acuities were worse than 20/20 but improved with pinhole, was done. Complete ophthalmic examination and refraction with appropriate cycloplegia for age were done for the 4582 eligible patients. Spherical equivalents (SE) of refractive errors of the right eyes were used for analysis. Of the 4582 eligible patients, 2546 patients had refractive errors (55.56%). The proportion of emmetropia (SE - 0.50-+0.50 diopter sphere [DS]), myopia (SE <-0.50 DS), high myopia (SE >-5.0 DS), and hypermetropia (>+0.50 DS for adults and >+2.0 DS for children) were 53.1%, 27.4%, 2.6%, and 16.9%, respectively. The proportion of hyperopia increased till 59 years and then decreased with age ( P = 0.000). The proportion of myopia and high myopia decreased significantly with age after 39 years ( P = 0.000 and P = 0.004, respectively). Of the 1510 patients with astigmatism, 17% had with-the-rule (WTR), 23.4% had against-the-rule (ATR), and 19% had oblique astigmatisms. The proportion of WTR and ATR astigmatisms significantly decreased ( P = 0.000) and increased ( P = 0.000) with age, respectively. This study has provided the magnitude and pattern of refractive errors in the study population. It will serve as the initial step for conducting community-based studies on the prevalence of refractive errors in this part of the country since such data are lacking from this region. Moreover, this study will help the primary care physicians to have an overview of the magnitude and pattern of refractive errors presenting to a health-care center as refractive error is an established and significant public health problem worldwide.

Visual disability, visual function, and myopia among rural chinese secondary school children: the Xichang Pediatric Refractive Error Study (X-PRES)--report 1.

PubMed

Congdon, Nathan; Wang, Yunfei; Song, Yue; Choi, Kai; Zhang, Mingzhi; Zhou, Zhongxia; Xie, Zhenling; Li, Liping; Liu, Xueyu; Sharma, Abhishek; Wu, Bin; Lam, Dennis S C

2008-07-01

To evaluate visual acuity, visual function, and prevalence of refractive error among Chinese secondary-school children in a cross-sectional school-based study. Uncorrected, presenting, and best corrected visual acuity, cycloplegic autorefraction with refinement, and self-reported visual function were assessed in a random, cluster sample of rural secondary school students in Xichang, China. Among the 1892 subjects (97.3% of the consenting children, 84.7% of the total sample), mean age was 14.7 +/- 0.8 years, 51.2% were female, and 26.4% were wearing glasses. The proportion of children with uncorrected, presenting, and corrected visual disability (< or = 6/12 in the better eye) was 41.2%, 19.3%, and 0.5%, respectively. Myopia < -0.5, < -2.0, and < -6.0 D in both eyes was present in 62.3%, 31.1%, and 1.9% of the subjects, respectively. Among the children with visual disability when tested without correction, 98.7% was due to refractive error, while only 53.8% (414/770) of these children had appropriate correction. The girls had significantly (P < 0.001) more presenting visual disability and myopia < -2.0 D than did the boys. More myopic refractive error was associated with worse self-reported visual function (ANOVA trend test, P < 0.001). Visual disability in this population was common, highly correctable, and frequently uncorrected. The impact of refractive error on self-reported visual function was significant. Strategies and studies to understand and remove barriers to spectacle wear are needed.

Prevalence of refractive errors in a rural South Indian population.

PubMed

Raju, Prema; Ramesh, S Ve; Arvind, Hemamalini; George, Ronnie; Baskaran, Mani; Paul, Pradeep G; Kumaramanickavel, Govindasamy; McCarty, Catherine; Vijaya, Lingam

2004-12-01

To report the prevalence of refractive errors in a rural south Indian population. Four thousand eight hundred subjects (age, >39 years) from rural south India were enumerated for a population-based study. All participants underwent complete ophthalmic evaluation. Subjects who were phakic in the right eye with best corrected visual acuity of 20/40 or better were included for analysis. Association of refractive errors with age, sex, cataract, and diabetes mellitus were analyzed. Of the 3924 responders, 2508 were eligible. The unadjusted prevalence of emmetropia (spherical equivalent [SE], -0.50 to +0.50 diopter sphere [DS]), myopia (SE < -0.50 DS), high myopia (SE < -5.00 DS), and hyperopia (SE > 0.50 DS) were 50.60%, 26.99%, 3.71%, and 18.70% and age and gender adjusted for the rural Tamil Nadu population were 46.77%, 30.97%, 4.32%, and 17.94%, respectively. The prevalence of emmetropia decreased significantly with age (P < 0.0001), and the prevalence of myopia and high myopia increased significantly with age (P < 0.001) and were significantly associated with nuclear sclerosis (P < 0.001). The prevalence of hyperopia increased until 60 years of age and then decreased. Hyperopia was more common among women than men (P < 0.001) and was negatively associated with nuclear sclerosis (P < 0.001) and positively with diabetes mellitus (P = 0.008). Of the participants with astigmatism (cylindrical error greater than 0.50 DC), 9.80% had with-the-rule (WTR) and 77.44% against-the-rule (ATR) astigmatism. The prevalence of WTR and ATR astigmatism significantly decreased (P < 0.001) and increased (P = 0.006) with age, respectively. The pattern of refractive errors in this rural south Indian population is similar to those reported in other tropical regions of the world.

A comparative clinical survey of the prevalence of refractive errors and eye diseases in urban and rural school children.

PubMed

Uzma, Nazia; Kumar, B Santhosh; Khaja Mohinuddin Salar, B M; Zafar, Mohammed Atheshm; Reddy, V Devender

2009-06-01

To assess the prevalence of refractive error and common ocular diseases in school-aged children in urban and rural populations in and around Hyderabad, India. Population-based, cross-sectional study. A total of 3314 school children, 1789 from urban areas and 1525 from rural areas. The examination included visual acuity measurements, retinoscopy and autorefraction under cycloplegia, examination of the anterior segment and external eye, and ocular motility evaluation. In the urban group the prevalence of uncorrected presenting and best-corrected visual impairment (< or = 20/40 in the better eye) was 9.8%, which dropped to 7.1% with presenting vision and was further reduced to 1.1% with best-corrected visual acuity. Uncorrected visual acuity in the rural group was 6.6%, which dropped to 3.3% with presenting vision and was further reduced to 2.5% with best-corrected visual acuity. The prevalence of refractive error was greater (25.2%) in the urban than the rural group (8%). Myopia measured with autorefraction was observed in 51.4% of urban children and 16.7% in rural children. Increased literacy rate, duration of study hours, and older age of the child were found to have contributed more to the prevalence of myopia in the urban group. Hyperopia with autorefraction was found to be 3.3% in the urban and 3.1% in the rural group. Hyperopia was associated with younger age in the study group. Trachoma was the leading cause of ocular morbidity in the rural group (3.5%) compared with the urban group (0.16%). Night blindness was reported in 3.2% of children in the rural group and 0.33% in the urban group. Vitamin A deficiency, low socio-economic status, and poor personal and environmental hygienic practice were found to have a positive correlation with ocular morbidity among rural group children. Provision of health education, periodic visual screening programs, and primary eye care by trained health care personnel in the elementary schools will prevent the prevalence of

Refractive errors in Aminu Kano Teaching Hospital, Kano Nigeria.

PubMed

Lawan, Abdu; Eme, Okpo

2011-12-01

The aim of the study is to retrospectively determine the pattern of refractive errors seen in the eye clinic of Aminu Kano Teaching Hospital, Kano-Nigeria from January to December, 2008. The clinic refraction register was used to retrieve the case folders of all patients refracted during the review period. Information extracted includes patient's age, sex, and types of refractive error. All patients had basic eye examination (to rule out other causes of subnormal vision) including intra ocular pressure measurement and streak retinoscopy at two third meter working distance. The final subjective refraction correction given to the patients was used to categorise the type of refractive error. Refractive errors was observed in 1584 patients and accounted for 26.9% of clinic attendance. There were more females than males (M: F=1.0: 1.2). The common types of refractive errors are presbyopia in 644 patients (40%), various types of astigmatism in 527 patients (33%), myopia in 216 patients (14%), hypermetropia in 171 patients (11%) and aphakia in 26 patients (2%). Refractive errors are common causes of presentation in the eye clinic. Identification and correction of refractive errors should be an integral part of eye care delivery.

Refraction and visual acuity in a national Danish cohort of 4-year-old children of extremely preterm delivery.

PubMed

Fledelius, Hans C; Bangsgaard, Regitze; Slidsborg, Carina; laCour, Morten

2015-06-01

A recent threefold increase in laser treatment for advanced retinopathy of prematurity (ROP) triggered a nationwide preschool ophthalmic and developmental status among extremely preterm survivors. Here, we discuss refraction and visual acuity. Survivors (n = 178) from a national birth cohort (February 2004 to March 2006) of gestational age <28 weeks (PT) and 56 full-term (FT) controls attended for evaluation at age 4 years. Cycloplegic refraction and keratometry were achieved by Retinomax autokeratorefractor and visual acuities by symbol recognition (HOTV, logMAR). The refractive distribution presented a myopic tail (4.5%) and a hyperopic tail (11.9% ≥+2.5 D) as special preterm features, and corneas were more curved. Astigmatism and anisometropia were only marginally increased, and visual acuities were generally good. Best-corrected binocular median logMAR visual acuity was 0.1 in FT and 0.2 in PT, in Snellen equivalents 0.8 and 0.63. Snellen acuity ≤0.5 occurred across the ROP subgroups, but mainly in those with at least ROP stage 3. Two children had low vision. The overall fair outcome for refraction and function is in accordance with other recent northern Europe experience. The results differ in particular from the poorer ophthalmic outcomes reported in the pioneer US treatment studies (cryotherapy for ROP and ETROP). The diode laser ablations (n = 32) appeared effective in our series; except one child, all treated subjects had good or fair social vision at the age of 4 years. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Associations between hyperopia and other vision and refractive error characteristics.

PubMed

Kulp, Marjean Taylor; Ying, Gui-Shuang; Huang, Jiayan; Maguire, Maureen; Quinn, Graham; Ciner, Elise B; Cyert, Lynn A; Orel-Bixler, Deborah A; Moore, Bruce D

2014-04-01

To investigate the association of hyperopia greater than +3.25 diopters (D) with amblyopia, strabismus, anisometropia, astigmatism, and reduced stereoacuity in preschoolers. Three- to five-year-old Head Start preschoolers (N = 4040) underwent vision examination including monocular visual acuity (VA), cover testing, and cycloplegic refraction during the Vision in Preschoolers Study. Visual acuity was tested with habitual correction and was retested with full cycloplegic correction when VA was reduced below age norms in the presence of significant refractive error. Stereoacuity testing (Stereo Smile II) was performed on 2898 children during study years 2 and 3. Hyperopia was classified into three levels of severity (based on the most positive meridian on cycloplegic refraction): group 1: greater than or equal to +5.00 D, group 2: greater than +3.25 D to less than +5.00 D with interocular difference in spherical equivalent greater than or equal to 0.50 D, and group 3: greater than +3.25 D to less than +5.00 D with interocular difference in spherical equivalent less than 0.50 D. "Without" hyperopia was defined as refractive error of +3.25 D or less in the most positive meridian in both eyes. Standard definitions were applied for amblyopia, strabismus, anisometropia, and astigmatism. Relative to children without hyperopia, children with hyperopia greater than +3.25 D (n = 472, groups 1, 2, and 3) had a higher proportion of amblyopia (34.5 vs. 2.8%, p < 0.0001) and strabismus (17.0 vs. 2.2%, p < 0.0001). More severe levels of hyperopia were associated with higher proportions of amblyopia (51.5% in group 1 vs. 13.2% in group 3) and strabismus (32.9% in group 1 vs. 8.4% in group 3; trend p < 0.0001 for both). The presence of hyperopia greater than +3.25 D was also associated with a higher proportion of anisometropia (26.9 vs. 5.1%, p < 0.0001) and astigmatism (29.4 vs. 10.3%, p < 0.0001). Median stereoacuity of nonstrabismic, nonamblyopic children with hyperopia (n = 206

Refractive Error in a Sample of Black High School Children in South Africa.

PubMed

Wajuihian, Samuel Otabor; Hansraj, Rekha

2017-12-01

This study focused on a cohort that has not been studied and who currently have limited access to eye care services. The findings, while improving the understanding of the distribution of refractive errors, also enabled identification of children requiring intervention and provided a guide for future resource allocation. The aim of conducting the study was to determine the prevalence and distribution of refractive error and its association with gender, age, and school grade level. Using a multistage random cluster sampling, 1586 children, 632 males (40%) and 954 females (60%), were selected. Their ages ranged between 13 and 18 years with a mean of 15.81 ± 1.56 years. The visual functions evaluated included visual acuity using the logarithm of minimum angle of resolution chart and refractive error measured using the autorefractor and then refined subjectively. Axis astigmatism was presented in the vector method where positive values of J0 indicated with-the-rule astigmatism, negative values indicated against-the-rule astigmatism, whereas J45 represented oblique astigmatism. Overall, patients were myopic with a mean spherical power for right eye of -0.02 ± 0.47; mean astigmatic cylinder power was -0.09 ± 0.27 with mainly with-the-rule astigmatism (J0 = 0.01 ± 0.11). The prevalence estimates were as follows: myopia (at least -0.50) 7% (95% confidence interval [CI], 6 to 9%), hyperopia (at least 0.5) 5% (95% CI, 4 to 6%), astigmatism (at least -0.75 cylinder) 3% (95% CI, 2 to 4%), and anisometropia 3% (95% CI, 2 to 4%). There was no significant association between refractive error and any of the categories (gender, age, and grade levels). The prevalence of refractive error in the sample of high school children was relatively low. Myopia was the most prevalent, and findings on its association with age suggest that the prevalence of myopia may be stabilizing at late teenage years.

Refractive error and presbyopia among adults in Fiji.

PubMed

Brian, Garry; Pearce, Matthew G; Ramke, Jacqueline

2011-04-01

To characterize refractive error, presbyopia and their correction among adults aged ≥ 40 years in Fiji, and contribute to a regional overview of these conditions. A population-based cross-sectional survey using multistage cluster random sampling. Presenting distance and near vision were measured and dilated slitlamp examination performed. The survey achieved 73.0% participation (n=1381). Presenting binocular distance vision ≥ 6/18 was achieved by 1223 participants. Another 79 had vision impaired by refractive error. Three of these were blind. At threshold 6/18, 204 participants had refractive error. Among these, 125 had spectacle-corrected presenting vision ≥ 6/18 ("met refractive error need"); 79 presented wearing no (n=74) or under-correcting (n=5) distance spectacles ("unmet refractive error need"). Presenting binocular near vision ≥ N8 was achieved by 833 participants. At threshold N8, 811 participants had presbyopia. Among these, 336 attained N8 with presenting near spectacles ("met presbyopia need"); 475 presented with no (n=402) or under-correcting (n=73) near spectacles ("unmet presbyopia need"). Rural residence was predictive of unmet refractive error (p=0.040) and presbyopia (p=0.016) need. Gender and household income source were not. Ethnicity-gender-age-domicile-adjusted to the Fiji population aged ≥ 40 years, "met refractive error need" was 10.3% (95% confidence interval [CI] 8.7-11.9%), "unmet refractive error need" was 4.8% (95%CI 3.6-5.9%), "refractive error correction coverage" was 68.3% (95%CI 54.4-82.2%),"met presbyopia need" was 24.6% (95%CI 22.4-26.9%), "unmet presbyopia need" was 33.8% (95%CI 31.3-36.3%), and "presbyopia correction coverage" was 42.2% (95%CI 37.6-46.8%). Fiji refraction and dispensing services should encourage uptake by rural dwellers and promote presbyopia correction. Lack of comparable data from neighbouring countries prevents a regional overview.

Refractive errors in low-income preschoolers.

PubMed

Brody, Barbara L; Roch-Levecq, Anne-Catherine; Klonoff-Cohen, Hillary S; Brown, Stuart I

2007-01-01

To estimate the overall prevalence of refractive errors in a study population of low-income preschoolers in San Diego County. The study sample included 507 preschool children selected from a study population of all 3-5 year-old children in Head Start and San Diego Unified School District preschools (74% Latino). The sample was examined by optometrists in the mobile clinic of the University of California, San Diego, Department of Ophthalmology with retinoscopy under cycloplegia to assess the presence of refractive errors defined as myopia >or=2D in 3-4 year-olds and >or=1D in > 4 year-olds; hyperopia >or=4D in 3-4 year-olds and >or=3D in > 4 year-olds; and astigmatism >or=1.75D in 3-4 year-olds and >or=1.5D in > 4 year-olds. Anisometropia was defined as >or=1.25D difference between the eyes. Emmetropia was defined as refractive errors below these levels. A total of 16% (n = 81 children) (95% confidence interval: 15.4-16.5) met study definitions of refractive errors in at least one eye. Myopia was found in 3%, (OD Mean Sphere = 2.4D); hyperopia in 7.5% (OD Mean Sphere = 3.8D); astigmatism in 5.5% (OD Mean Cylinder = 2.3D); and 84% were emmetropic (OD Mean Sphere = 1.3D). Hyperopia and astigmatism were the most frequent refractive errors in this sample of low-income preschoolers, most of whom were Latino.

The Relationship between Crystalline Lens Power and Refractive Error in Older Chinese Adults: The Shanghai Eye Study.

PubMed

He, Jiangnan; Lu, Lina; He, Xiangui; Xu, Xian; Du, Xuan; Zhang, Bo; Zhao, Huijuan; Sha, Jida; Zhu, Jianfeng; Zou, Haidong; Xu, Xun

2017-01-01

To report calculated crystalline lens power and describe the distribution of ocular biometry and its association with refractive error in older Chinese adults. Random clustering sampling was used to identify adults aged 50 years and above in Xuhui and Baoshan districts of Shanghai. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by IOL Master. The crystalline lens power of right eyes was calculated using modified Bennett-Rabbetts formula. We analyzed 6099 normal phakic right eyes. The mean crystalline lens power was 20.34 ± 2.24D (range: 13.40-36.08). Lens power, spherical equivalent, and anterior chamber depth changed linearly with age; however, axial length, corneal power and AL/CR ratio did not vary with age. The overall prevalence of hyperopia, myopia, and high myopia was 48.48% (95% CI: 47.23%-49.74%), 22.82% (95% CI: 21.77%-23.88%), and 4.57% (95% CI: 4.05-5.10), respectively. The prevalence of hyperopia increased linearly with age while lens power decreased with age. In multivariate models, refractive error was strongly correlated with axial length, lens power, corneal power, and anterior chamber depth; refractive error was slightly correlated with best corrected visual acuity, age and sex. Lens power, hyperopia, and spherical equivalent changed linearly with age; Moreover, the continuous loss of lens power produced hyperopic shifts in refraction in subjects aged more than 50 years.

Unbiased Estimation of Refractive State of Aberrated Eyes

PubMed Central

Martin, Jesson; Vasudevan, Balamurali; Himebaugh, Nikole; Bradley, Arthur; Thibos, Larry

2011-01-01

To identify unbiased methods for estimating the target vergence required to maximize visual acuity based on wavefront aberration measurements. Experiments were designed to minimize the impact of confounding factors that have hampered previous research. Objective wavefront refractions and subjective acuity refractions were obtained for the same monochromatic wavelength. Accommodation and pupil fluctuations were eliminated by cycloplegia. Unbiased subjective refractions that maximize visual acuity for high contrast letters were performed with a computer controlled forced choice staircase procedure, using 0.125 diopter steps of defocus. All experiments were performed for two pupil diameters (3mm and 6mm). As reported in the literature, subjective refractive error does not change appreciably when the pupil dilates. For 3 mm pupils most metrics yielded objective refractions that were about 0.1D more hyperopic than subjective acuity refractions. When pupil diameter increased to 6 mm, this bias changed in the myopic direction and the variability between metrics also increased. These inaccuracies were small compared to the precision of the measurements, which implies that most metrics provided unbiased estimates of refractive state for medium and large pupils. A variety of image quality metrics may be used to determine ocular refractive state for monochromatic (635nm) light, thereby achieving accurate results without the need for empirical correction factors. PMID:21777601

Amblyopia and refractive errors among school-aged children with low socioeconomic status in southeastern Turkey.

PubMed

Caca, Ihsan; Cingu, Abdullah Kursat; Sahin, Alparslan; Ari, Seyhmus; Dursun, Mehmet Emin; Dag, Umut; Balsak, Selahattin; Alakus, Fuat; Yavuz, Abdullah; Palanci, Yilmaz

2013-01-01

To investigate the prevalence of refractive errors and other eye diseases, incidence and types of amblyopia in school-aged children, and their relation to gender, age, parental education, and socioeconomic factors. A total of 21,062 children 6 to 14 years old were screened. The examination included visual acuity measurements and ocular motility evaluation. Autorefraction under cycloplegia and examination of the external eye, anterior segment, media, and fundus were performed. There were 11,118 females and 9,944 males. The average age was 10.56 ± 3.59 years. When all of the children were evaluated, 3.2% had myopia and 5.9% had hyperopia. Astigmatism 0.50 D or greater was present in 14.3% of children. Myopia was associated with older age, female gender, and higher parental education. Hyperopia was inversely proportional with older age. Spectacles were needed in 4,476 (22.7%) children with refractive errors, and 10.6% of children were unaware of their spectacle needs. Amblyopia was detected in 2.6% of all children. The most common causes of amblyopia were anisometropia (1.2%) and strabismus (0.9%). Visual impairment is a common disorder in school-aged children. Eye health screening programs are beneficial in early detection and proper treatment of refractive errors. Copyright 2013, SLACK Incorporated.

Development of a refractive error quality of life scale for Thai adults (the REQ-Thai).

PubMed

Sukhawarn, Roongthip; Wiratchai, Nonglak; Tatsanavivat, Pyatat; Pitiyanuwat, Somwung; Kanato, Manop; Srivannaboon, Sabong; Guyatt, Gordon H

2011-08-01

To develop a scale for measuring refractive error quality of life (QOL) for Thai adults. The full survey comprised 424 respondents from 5 medical centers in Bangkok and from 3 medical centers in Chiangmai, Songkla and KhonKaen provinces. Participants were emmetropes and persons with refractive correction with visual acuity of 20/30 or better An item reduction process was employed by combining 3 methods-expert opinion, impact method and item-total correlation methods. The classical reliability testing and the validity testing including convergent, discriminative and construct validity was performed. The developed questionnaire comprised 87 items in 6 dimensions: 1) quality of vision, 2) visual function, 3) social function, 4) psychological function, 5) symptoms and 6) refractive correction problems. It is the 5-level Likert scale type. The Cronbach's Alpha coefficients of its dimensions ranged from 0.756 to 0. 979. All validity testing were shown to be valid. The construct validity was validated by the confirmatory factor analysis. A short version questionnaire comprised 48 items with good reliability and validity was also developed. This is the first validated instrument for measuring refractive error quality of life for Thai adults that was developed with strong research methodology and large sample size.

Refractive errors affect the vividness of visual mental images.

PubMed

Palermo, Liana; Nori, Raffaella; Piccardi, Laura; Zeri, Fabrizio; Babino, Antonio; Giusberti, Fiorella; Guariglia, Cecilia

2013-01-01

The hypothesis that visual perception and mental imagery are equivalent has never been explored in individuals with vision defects not preventing the visual perception of the world, such as refractive errors. Refractive error (i.e., myopia, hyperopia or astigmatism) is a condition where the refracting system of the eye fails to focus objects sharply on the retina. As a consequence refractive errors cause blurred vision. We subdivided 84 individuals according to their spherical equivalent refraction into Emmetropes (control individuals without refractive errors) and Ametropes (individuals with refractive errors). Participants performed a vividness task and completed a questionnaire that explored their cognitive style of thinking before their vision was checked by an ophthalmologist. Although results showed that Ametropes had less vivid mental images than Emmetropes this did not affect the development of their cognitive style of thinking; in fact, Ametropes were able to use both verbal and visual strategies to acquire and retrieve information. Present data are consistent with the hypothesis of equivalence between imagery and perception.

The effects of partial and full correction of refractive errors on sensorial and motor outcomes in children with refractive accommodative esotropia.

PubMed

Sefi-Yurdakul, Nazife; Kaykısız, Hüseyin; Koç, Feray

2018-03-17

To investigate the effects of partial and full correction of refractive errors on sensorial and motor outcomes in children with refractive accommodative esotropia (RAE). The records of pediatric cases with full RAE were reviewed; their first and last sensorial and motor findings were evaluated in two groups, classified as partial (Group 1) and full correction (Group 2) of refractive errors. The mean age at first admission was 5.84 ± 3.62 years in Group 1 (n = 35) and 6.35 ± 3.26 years in Group 2 (n = 46) (p = 0.335). Mean change in best corrected visual acuity (BCVA) was 0.24 ± 0.17 logarithm of the minimum angle of resolution (logMAR) in Group 1 and 0.13 ± 0.16 logMAR in Group 2 (p = 0.001). Duration of deviation, baseline refraction and amount of reduced refraction showed significant effects on change in BCVA (p < 0.05). Significant correlation was determined between binocular vision (BOV), duration of deviation and uncorrected baseline amount of deviation (p < 0.05). The baseline BOV rates were significantly high in fully corrected Group 2, and also were found to have increased in Group 1 (p < 0.05). Change in refraction was - 0.09 ± 1.08 and + 0.35 ± 0.76 diopters in Groups 1 and 2, respectively (p = 0.005). Duration of deviation, baseline refraction and the amount of reduced refraction had significant effects on change in refraction (p < 0.05). Change in deviation without refractive correction was - 0.74 ± 7.22 prism diopters in Group 1 and - 3.24 ± 10.41 prism diopters in Group 2 (p = 0.472). Duration of follow-up and uncorrected baseline deviation showed significant effects on change in deviation (p < 0.05). Although the BOV rates and BCVA were initially high in fully corrected patients, they finally improved significantly in both the fully and partially corrected patients. Full hypermetropic correction may also cause an increase in the refractive error with a

Effect of refractive error on temperament and character properties.

PubMed

Kalkan Akcay, Emine; Canan, Fatih; Simavli, Huseyin; Dal, Derya; Yalniz, Hacer; Ugurlu, Nagihan; Gecici, Omer; Cagil, Nurullah

2015-01-01

To determine the effect of refractive error on temperament and character properties using Cloninger's psychobiological model of personality. Using the Temperament and Character Inventory (TCI), the temperament and character profiles of 41 participants with refractive errors (17 with myopia, 12 with hyperopia, and 12 with myopic astigmatism) were compared to those of 30 healthy control participants. Here, temperament comprised the traits of novelty seeking, harm-avoidance, and reward dependence, while character comprised traits of self-directedness, cooperativeness, and self-transcendence. Participants with refractive error showed significantly lower scores on purposefulness, cooperativeness, empathy, helpfulness, and compassion (P<0.05, P<0.01, P<0.05, P<0.05, and P<0.01, respectively). Refractive error might have a negative influence on some character traits, and different types of refractive error might have different temperament and character properties. These personality traits may be implicated in the onset and/or perpetuation of refractive errors and may be a productive focus for psychotherapy.

Refractive errors in students from Middle Eastern backgrounds living and undertaking schooling in Australia.

PubMed

Azizoglu, Serap; Junghans, Barbara M; Barutchu, Ayla; Crewther, Sheila G

2011-01-01

  Environmental factors associated with schooling systems in various countries have been implicated in the rising prevalence of myopia, making the comparison of prevalence of refractive errors in migrant populations of interest. This study aims to determine the prevalence of refractive errors in children of Middle Eastern descent, raised and living in urban Australia but actively maintaining strong ties to their ethnic culture, and to compare them with those in the Middle East where myopia prevalence is generally low.   A total of 354 out of a possible 384 late primary/early secondary schoolchildren attending a private school attracting children of Middle Eastern background in Melbourne were assessed for refractive error and visual acuity. A Shin Nippon open-field NVision-K5001 autorefractor was used to carry out non-cycloplegic autorefraction while viewing a distant target. For statistical analyses students were divided into three age groups: 10-11 years (n = 93); 12-13 years (n = 158); and 14-15 years (n = 102).   All children were bilingual and classified as of Middle Eastern (96.3 per cent) or Egyptian (3.7 per cent) origin. Ages ranged from 10 to 15 years, with a mean of 13.17 ± 0.8 (SEM) years. Mean spherical equivalent refraction (SER) for the right eye was +0.09 ± 0.07 D (SEM) with a range from -7.77 D to +5.85 D. The prevalence of myopia, defined as a spherical equivalent refraction 0.50 D or more of myopia, was 14.7 per cent. The prevalence of hyperopia, defined as a spherical equivalent refraction of +0.75 D or greater, was 16.4 per cent, while hyperopia of +1.50 D or greater was 5.4 per cent. A significant difference in SER was seen as a function of age; however, no significant gender difference was seen.   This is the first study to report the prevalence of refractive errors for second-generation Australian schoolchildren coming from a predominantly Lebanese Middle Eastern Arabic background, who endeavour to maintain their ethnic ties. The

The child self-refraction study results from urban Chinese children in Guangzhou.

PubMed

He, Mingguang; Congdon, Nathan; MacKenzie, Graeme; Zeng, Yangfa; Silver, Joshua D; Ellwein, Leon

2011-06-01

To compare visual and refractive outcomes between self-refracting spectacles (Adaptive Eyecare, Ltd, Oxford, UK), noncycloplegic autorefraction, and cycloplegic subjective refraction. Cross-sectional study. Chinese school-children aged 12 to 17 years. Children with uncorrected visual acuity ≤ 6/12 in either eye underwent measurement of the logarithm of the minimum angle of resolution visual acuity, habitual correction, self-refraction without cycloplegia, autorefraction with and without cycloplegia, and subjective refraction with cycloplegia. Proportion of children achieving corrected visual acuity ≥ 6/7.5 with each modality; difference in spherical equivalent refractive error between each of the modalities and cycloplegic subjective refractive error. Among 556 eligible children of consenting parents, 554 (99.6%) completed self-refraction (mean age, 13.8 years; 59.7% girls; 54.0% currently wearing glasses). The proportion of children with visual acuity ≥ 6/7.5 in the better eye with habitual correction, self-refraction, noncycloplegic autorefraction, and cycloplegic subjective refraction were 34.8%, 92.4%, 99.5% and 99.8%, respectively (self-refraction versus cycloplegic subjective refraction, P<0.001). The mean difference between cycloplegic subjective refraction and noncycloplegic autorefraction (which was more myopic) was significant (-0.328 diopter [D]; Wilcoxon signed-rank test P<0.001), whereas cycloplegic subjective refraction and self-refraction did not differ significantly (-0.009 D; Wilcoxon signed-rank test P = 0.33). Spherical equivalent differed by ≥ 1.0 D in either direction from cycloplegic subjective refraction more frequently among right eyes for self-refraction (11.2%) than noncycloplegic autorefraction (6.0%; P = 0.002). Self-refraction power that differed by ≥ 1.0 D from cycloplegic subjective refractive error (11.2%) was significantly associated with presenting without spectacles (P = 0.011) and with greater absolute power of both

Emmetropisation and the aetiology of refractive errors

PubMed Central

Flitcroft, D I

2014-01-01

The distribution of human refractive errors displays features that are not commonly seen in other biological variables. Compared with the more typical Gaussian distribution, adult refraction within a population typically has a negative skew and increased kurtosis (ie is leptokurtotic). This distribution arises from two apparently conflicting tendencies, first, the existence of a mechanism to control eye growth during infancy so as to bring refraction towards emmetropia/low hyperopia (ie emmetropisation) and second, the tendency of many human populations to develop myopia during later childhood and into adulthood. The distribution of refraction therefore changes significantly with age. Analysis of the processes involved in shaping refractive development allows for the creation of a life course model of refractive development. Monte Carlo simulations based on such a model can recreate the variation of refractive distributions seen from birth to adulthood and the impact of increasing myopia prevalence on refractive error distributions in Asia. PMID:24406411

Peripheral refraction profiles in subjects with low foveal refractive errors.

PubMed

Tabernero, Juan; Ohlendorf, Arne; Fischer, M Dominik; Bruckmann, Anna R; Schiefer, Ulrich; Schaeffel, Frank

2011-03-01

To study the variability of peripheral refraction in a population of 43 subjects with low foveal refractive errors. A scan of the refractive error in the vertical pupil meridian of the right eye of 43 subjects (age range, 18 to 80 years, foveal spherical equivalent, < ± 2.5 diopter) over the central ± 45° of the visual field was performed using a recently developed angular scanning photorefractor. Refraction profiles across the visual field were fitted with four different models: (1) "flat model" (refractions about constant across the visual field), (2) "parabolic model" (refractions follow about a parabolic function), (3) "bi-linear model" (linear change of refractions with eccentricity from the fovea to the periphery), and (4) "box model" ("flat" central area with a linear change in refraction from a certain peripheral angle). Based on the minimal residuals of each fit, the subjects were classified into one of the four models. The "box model" accurately described the peripheral refractions in about 50% of the subjects. Peripheral refractions in six subjects were better characterized by a "linear model," in eight subjects by a "flat model," and in eight by the "parabolic model." Even after assignment to one of the models, the variability remained strikingly large, ranging from -0.75 to 6 diopter in the temporal retina at 45° eccentricity. The most common peripheral refraction profile (observed in nearly 50% of our population) was best described by the "box model." The high variability among subjects may limit attempts to reduce myopia progression with a uniform lens design and may rather call for a customized approach.

Refractive errors and cataract as causes of visual impairment in Brazil.

PubMed

Eduardo Leite Arieta, Carlos; Nicolini Delgado, Alzira Maria; José, Newton Kara; Temporini, Edméia Rita; Alves, Milton Ruiz; de Carvalho Moreira Filho, Djalma

2003-02-01

To identify the main causes of visual impairment (VA acuity test. Using Snellen charts, visual acuity testing was done by trained auxiliaries and medical students. The positive cases were then examined by ophthalmologists Criteria were established for the classification of the diagnoses and statistical analysis was performed. After the self-test of visual acuity, 60,404 patients came to have their visual acuity tested; 11,462 (18.97%) cases were considered positive and were submitted to complete eye examination; 5447 (42.7%) received spectacles for vision improvement, and 2704 (23.59%) had cataract surgery done. Other important causes of visual impairment were senile macular degeneration (5.4%) and glaucoma (4.02%). The main causes of visual impairment were non-corrected refractive errors and senile cataract. Ophthalmic community-based campaigns to serve the older population are recommended in order to detect and treat the identified cases and to indicate possible changes in the health care system.

Refractive Errors Affect the Vividness of Visual Mental Images

PubMed Central

Palermo, Liana; Nori, Raffaella; Piccardi, Laura; Zeri, Fabrizio; Babino, Antonio; Giusberti, Fiorella; Guariglia, Cecilia

2013-01-01

The hypothesis that visual perception and mental imagery are equivalent has never been explored in individuals with vision defects not preventing the visual perception of the world, such as refractive errors. Refractive error (i.e., myopia, hyperopia or astigmatism) is a condition where the refracting system of the eye fails to focus objects sharply on the retina. As a consequence refractive errors cause blurred vision. We subdivided 84 individuals according to their spherical equivalent refraction into Emmetropes (control individuals without refractive errors) and Ametropes (individuals with refractive errors). Participants performed a vividness task and completed a questionnaire that explored their cognitive style of thinking before their vision was checked by an ophthalmologist. Although results showed that Ametropes had less vivid mental images than Emmetropes this did not affect the development of their cognitive style of thinking; in fact, Ametropes were able to use both verbal and visual strategies to acquire and retrieve information. Present data are consistent with the hypothesis of equivalence between imagery and perception. PMID:23755186

PREVALENCE OF REFRACTIVE ERRORS IN MADRASSA STUDENTS OF HARIPUR DISTRICT.

PubMed

Atta, Zoia; Arif, Abdus Salam; Ahmed, Iftikhar; Farooq, Umer

2015-01-01

Visual impairment due to refractive errors is one of the most common problems among school-age children and is the second leading cause of treatable blindness. The Right to Sight, a global initiative launched by a coalition of non-government organizations and the World Health Organization (WHO), aims to eliminate avoidable visual impairment and blindness at a global level. In order to achieve this goal it is important to know the prevalence of different refractive errors in a community. Children and teenagers are the most susceptible groups to be affected by refractive errors. So, this population needs to be screened for different types of refractive errors. The study was done with the objective to find the frequency of different types of refractive errors in students of madrassas between the ages of 5-20 years in Haripur. This cross sectional study was done with 300 students between ages of 5-20 years in Madrassas of Haripur. The students were screened for refractive errors and the types of the errors were noted. After screening for refractive errors-the glasses were prescribed to the students. Myopia being 52.6% was the most frequent refractive error in students, followed by hyperopia 28.4% and astigmatism 19%. This study showed that myopia is an important problem in madrassa population. Females and males are almost equally affected. Spectacle correction of refractive errors is the cheapest and easy solution of this problem.

The Relationship between Crystalline Lens Power and Refractive Error in Older Chinese Adults: The Shanghai Eye Study

PubMed Central

He, Jiangnan; Lu, Lina; He, Xiangui; Xu, Xian; Du, Xuan; Zhang, Bo; Zhao, Huijuan; Sha, Jida; Zhu, Jianfeng; Zou, Haidong; Xu, Xun

2017-01-01

Purpose To report calculated crystalline lens power and describe the distribution of ocular biometry and its association with refractive error in older Chinese adults. Methods Random clustering sampling was used to identify adults aged 50 years and above in Xuhui and Baoshan districts of Shanghai. Refraction was determined by subjective refraction that achieved the best corrected vision based on monocular measurement. Ocular biometry was measured by IOL Master. The crystalline lens power of right eyes was calculated using modified Bennett-Rabbetts formula. Results We analyzed 6099 normal phakic right eyes. The mean crystalline lens power was 20.34 ± 2.24D (range: 13.40–36.08). Lens power, spherical equivalent, and anterior chamber depth changed linearly with age; however, axial length, corneal power and AL/CR ratio did not vary with age. The overall prevalence of hyperopia, myopia, and high myopia was 48.48% (95% CI: 47.23%–49.74%), 22.82% (95% CI: 21.77%–23.88%), and 4.57% (95% CI: 4.05–5.10), respectively. The prevalence of hyperopia increased linearly with age while lens power decreased with age. In multivariate models, refractive error was strongly correlated with axial length, lens power, corneal power, and anterior chamber depth; refractive error was slightly correlated with best corrected visual acuity, age and sex. Conclusion Lens power, hyperopia, and spherical equivalent changed linearly with age; Moreover, the continuous loss of lens power produced hyperopic shifts in refraction in subjects aged more than 50 years. PMID:28114313

Screening for Impaired Visual Acuity in Older Adults: US Preventive Services Task Force Recommendation Statement.

PubMed

Siu, Albert L; Bibbins-Domingo, Kirsten; Grossman, David C; Baumann, Linda Ciofu; Davidson, Karina W; Ebell, Mark; García, Francisco A R; Gillman, Matthew; Herzstein, Jessica; Kemper, Alex R; Krist, Alex H; Kurth, Ann E; Owens, Douglas K; Phillips, William R; Phipps, Maureen G; Pignone, Michael P

2016-03-01

Update of the US Preventive Services Task Force (USPSTF) recommendation on screening for impaired visual acuity in older adults. The USPSTF reviewed the evidence on screening for visual acuity impairment associated with uncorrected refractive error, cataracts, and age-related macular degeneration among adults 65 years or older in the primary care setting; the benefits and harms of screening; the accuracy of screening; and the benefits and harms of treatment of early vision impairment due to uncorrected refractive error, cataracts, and age-related macular degeneration. This recommendation applies to asymptomatic adults 65 years or older who do not present to their primary care clinician with vision problems. The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in older adults. (I statement).

Prevalence of refractive error, presbyopia, and unmet need of spectacle coverage in a northern district of Bangladesh: Rapid Assessment of Refractive Error study.

PubMed

Muhit, Mohammad; Minto, Hasan; Parvin, Afroza; Jadoon, Mohammad Z; Islam, Johurul; Yasmin, Sumrana; Khandaker, Gulam

2018-04-01

To determine the prevalence of refractive error (RE), presbyopia, spectacle coverage, and barriers to uptake optical services in Bangladesh. Rapid assessment of refractive error (RARE) study following the RARE protocol was conducted in a northern district (i.e., Sirajganj) of Bangladesh (January 2010-December 2012). People aged 15-49 years were selected, and eligible participants had habitual distance and near visual acuity (VA) measured and ocular examinations were performed in those with VA<6/18. Those with phakic eyes with VA <6/18, but improving to ≥6/18 with pinhole or optical correction, were considered as RE and people aged ≥35 years with binocular unaided near vision of refraction services is required to correct REs and presbyopia in Bangladesh.

Population density and refractive error among Chinese children.

PubMed

Zhang, Mingzhi; Li, Liping; Chen, Lizhen; Lee, Jack; Wu, Jiasi; Yang, Amy; Chen, Connie; Xu, Daocheng; Lam, Dennis S C; Sharma, Abhishek; Griffiths, Sian; Gao, Yang; Congdon, Nathan

2010-10-01

China is urbanizing rapidly, and the prevalence of myopia is high. This study was conducted to identify the reasons for observed differences in the prevalence of myopia among urban versus rural Chinese children. All children with uncorrected acuity of 6/12 or worse and a 50% random sample of children with vision better than 6/12 at all secondary schools in mixed rural-urban Liangying Township, Guangdong, underwent cycloplegic refraction, and provided data on age, gender, parental education, weekly near work and time outdoors, and urban development level of respondents' neighborhoods (12-item questionnaire). Population density of 32 villages and urban zones in Liangying was calculated from census figures (mean population density, 217 persons/km(2); range, 94-957; mean for Guangdong, 486). Among 5844 eligible children, 4612 (78.9%) had parental consent and completed examinations; 2957 were refracted per protocol, and 2480 (83.9%) of these had questionnaire data. Those with completed examinations were more likely to be girls (P < 0.001), and questionnaire respondents were more myopic (P = 0.02), but otherwise did not differ significantly from nonrespondents. In multivariate models, older age (P < 0.001), more near work (P = 0.02), and higher population density (P = 0.003), but not development index, parental education, or time outdoors were significantly associated with more myopic refractive error. Higher population density appears to be associated with myopia risk, independent of academic activity, time spent outdoors, familial educational level, or economic development, factors that have been thought to explain higher myopia prevalence among urban children. Mechanisms for this apparent association should be sought.

The albino chick as a model for studying ocular developmental anomalies, including refractive errors, associated with albinism.

PubMed

Rymer, Jodi; Choh, Vivian; Bharadwaj, Shrikant; Padmanabhan, Varuna; Modilevsky, Laura; Jovanovich, Elizabeth; Yeh, Brenda; Zhang, Zhan; Guan, Huanxian; Payne, W; Wildsoet, Christine F

2007-10-01

Albinism is associated with a variety of ocular anomalies including refractive errors. The purpose of this study was to investigate the ocular development of an albino chick line. The ocular development of both albino and normally pigmented chicks was monitored using retinoscopy to measure refractive errors and high frequency A-scan ultrasonography to measure axial ocular dimensions. Functional tests included an optokinetic nystagmus paradigm to assess visual acuity, and flash ERGs to assess retinal function. The underlying genetic abnormality was characterized using a gene microarray, PCR and a tyrosinase assay. The ultrastructure of the retinal pigment epithelium (RPE) was examined using transmission electron microscopy. PCR confirmed that the genetic abnormality in this line is a deletion in exon 1 of the tyrosinase gene. Tyrosinase gene expression in isolated RPE cells was minimally detectable, and there was minimal enzyme activity in albino feather bulbs. The albino chicks had pink eyes and their eyes transilluminated, reflecting the lack of melanin in all ocular tissues. All three main components, anterior chamber, crystalline lens and vitreous chamber, showed axial expansion over time in both normal and albino animals, but the anterior chambers of albino chicks were consistently shallower than those of normal chicks, while in contrast, their vitreous chambers were longer. Albino chicks remained relatively myopic, with higher astigmatism than the normally pigmented chicks, even though both groups underwent developmental emmetropization. Albino chicks had reduced visual acuity yet the ERG a- and b-wave components had larger amplitudes and shorter than normal implicit times. Developmental emmetropization occurs in the albino chick but is impaired, likely because of functional abnormalities in the RPE and/or retina as well as optical factors. In very young chicks the underlying genetic mutation may also contribute to refractive error and eye shape abnormalities.

[Determining factors for deciding whether or not to treat refractive errors and cataract in people with a learning disability].

PubMed

van Isterdael, C E D; Stilma, J S; Bezemer, P D; Tijmes, N T

2008-05-03

A study into the treatment of refractive errors and cataract in a selected population with learning disabilities. Design. Retrospective. In the years 1993-2003, 5205 people (mean age: 39 years) were referred to the visual advisory centre of Bartiméus (one of three institutes for the visually impaired in the Netherlands) by learning disability physicians and were assessed ophthalmologically. This assessment consisted of a measurement of visual acuity and refractive error, slitlamp examination and retinoscopy, and was performed at the client's accommodation. Advised treatment for spectacle prescriptions and referral for cataract surgery were registered. Refractive errors were found in 35% (1845/5205) of the patients with learning disabilities; 49% (905/1845) already wore spectacles; another 14% (265/1845) were prescribed spectacles for the first time. Of those with presbyopia, 12% (232/1865) had reading glasses and 10% (181/1865) were given a first prescription for spectacles. The most important determinant for not prescribing spectacles was: presence of severe learning disability (odds ratio (OR): 3.7). Cataract was present in 10% (497/5205) of the population; 399 patients were advised to be referred for surgery, 55% (219/399) were referred ofwhom 26% (57/219) had surgery. Moderately severe bilateral cataract was the only determinant of cataract surgery (OR: 7.8). Refractive errors and cataract were not always treated in this group. One of the reasons for non-treatment of refractive errors was a severe learning disability. The reason for treatment or non-treatment in patients with cataract was less clear.

Self‐assessment of refractive errors using a simple optical approach

PubMed Central

Kraft, Caroline; Ohlendorf, Arne; Wahl, Siegfried

2018-01-01

Background This explorative study investigated procedures for the self‐assessment of spherocylindrical refractive errors. Methods Eighteen participants with a mean age of 34.0 ± 8.8 years were enrolled. Adjustable Alvarez lenses were mounted in a rotatable ring holder and two procedures were tested for the self‐adjustment: (1) rotation of the lens in three meridians: 0°, 60° and 120° and (2) rotation of the optotypes in the same meridians. Starting from maximum positive power, the participants were required to decrease the power of the Alvarez lens until the optotypes (0.0 logMAR) appeared to be clear the first time. Best‐corrected visual acuity (BVA) was measured using a psychophysical staircase procedure. Bland–Altmann analysis was carried out in order to calculate the limits of agreement between the self‐refraction method and the standard subjective refraction. Results Using procedure 1, 77 per cent of the subjects achieved a VA ≥ 0.1 logMAR (6/7.5) and the same was true for 88 per cent of the subjects using procedure 2. Using procedure 1, a significantly worse BVA was found, when compared to subjective refraction (ΔVA = −0.15 logMAR, F3,140 = 7.11, p = 0.046, median test). Analysis of variance (ANOVA) analysis showed a significant influence of the refraction method on the oblique astigmatism component J45 but not for the spherical equivalent M and the straight astigmatism component J0 (M: F3,140 = 0.532, p = 0.661; J0: F3,140 = 0.056, p = 0.983; J45: F3,140 = 13.97, p < 0.001; ANOVA). The limits of agreement for the spherical equivalent error M were ± 1.10 D and ± 1.20 D and for the astigmatic components J0 ± 0.78 D and ± 0.59 D and for J45 ± 0.62 D and ± 0.54 D, for procedure 1 and procedure 2, respectively. Conclusions Fixed adjustable Alvarez lenses and rotatable stimuli can provide a fast and precise self‐assessment method to measure the spherocylindrical

Visual impairment attributable to uncorrected refractive error and other causes in the Ghanaian youth: The University of Cape Coast Survey

PubMed Central

Abokyi, Samuel; Ilechie, Alex; Nsiah, Peter; Darko-Takyi, Charles; Abu, Emmanuel Kwasi; Osei-Akoto, Yaw Jnr; Youfegan-Baanam, Mathurin

2015-01-01

Purpose To determine the prevalence of visual impairment attributable to refractive error and other causes in a youthful Ghanaian population. Methods A prospective survey of all consecutive visits by first-year tertiary students to the Optometry clinic between August, 2013 and April, 2014. Of the 4378 first-year students aged 16–39 years enumerated, 3437 (78.5%) underwent the eye examination. The examination protocol included presenting visual acuity (PVA), ocular motility, and slit-lamp examination of the external eye, anterior segment and media, and non-dilated fundus examination. Pinhole acuity and fundus examination were performed when the PVA ≤ 6/12 in one or both eyes to determine the principal cause of the vision loss. Results The mean age of participants was 21.86 years (95% CI: 21.72–21.99). The prevalence of bilateral visual impairment (BVI; PVA in the better eye ≤6/12) and unilateral visual impairment UVI; PVA in the worse eye ≤6/12) were 3.08% (95% CI: 2.56–3.72) and 0.79% (95% CI: 0.54–1.14), respectively. Among 106 participants with BVI, refractive error (96.2%) and corneal opacity (3.8%) were the causes. Of the 27 participants with UVI, refractive error (44.4%), maculopathy (18.5%) and retinal disease (14.8%) were the major causes. There was unequal distribution of BVI in the different age groups, with those above 20 years having a lesser burden. Conclusion Eye screening and provision of affordable spectacle correction to the youth could be timely to eliminate visual impairment. PMID:26025809

[New possibilities screening of refractive errors among children].

PubMed

Ondrejková, M; Kyselová, P

2013-06-01

To establish early detection of refractive errors among children in Slovakia. Different screening methods have been evaluated and compared in this work. we have been working on a prospective study. Pre-school children in kindergardens in Central Slovakia were checked up between years 2009-2011. Effectiveness of various screening methods was compared within 2 groups, using test-type and Plusoptix Vision Screener. Parentęs of children positive to refractive errors were recommended to consult a paediatrician ophthalmologist. 3982 children were examined. As a result, 13-14.1% of children who have not been examinated by the specialist, were positive. 53.3% of them went to see the doctor afterwards. establishment of early refractive errors screening is an important method how to prevent strabismus and amblyopia. It is very important to improve parentęs knowledge about the risk of refractive errors and also to improve screening methods with collaboration with kindergarten teachers.

The distribution of refractive errors among children attending Lumbini Eye Institute, Nepal.

PubMed

Rai, S; Thapa, H B; Sharma, M K; Dhakhwa, K; Karki, R

2012-01-01

Uncorrected refractive error is an important cause of childhood blindness and visual impairment. To describe the patterns of refractive errors among children attending the outpatient clinic at the Department of Pediatric Ophthalmology, Lumbini Eye Institute, Bhairahawa, Nepal. Records of 133 children with refractive errors aged 5 - 15 years from both the urban and rural areas of Nepal and the adjacent territory of India attending the hospital between September and November 2010 were examined for patterns of refractive errors. The SPSS statistical software was used to perform data analysis. The commonest type of refractive error among the children was astigmatism (47 %) followed by myopia (34 %) and hyperopia (15 %). The refractive error was more prevalent among children of both the genders of age group 11-15 years as compared to their younger counterparts (RR = 1.22, 95 % CI = 0.66 - 2.25). The refractive error was more common (70 %) in the rural than the urban children (26 %). The rural females had a higher (38 %) prevalence of myopia than urban females (18 %). Among the children with refractive errors, only 57 % were using spectacles at the initial presentation. Astigmatism is the commonest type of refractive error among the children of age 5 - 15 years followed by hypermetropia and myopia. Refractive error remains uncorrected in a significant number of children. © NEPjOPH.

Visual impairment attributable to uncorrected refractive error and other causes in the Ghanaian youth: The University of Cape Coast Survey.

PubMed

Abokyi, Samuel; Ilechie, Alex; Nsiah, Peter; Darko-Takyi, Charles; Abu, Emmanuel Kwasi; Osei-Akoto, Yaw Jnr; Youfegan-Baanam, Mathurin

2016-01-01

To determine the prevalence of visual impairment attributable to refractive error and other causes in a youthful Ghanaian population. A prospective survey of all consecutive visits by first-year tertiary students to the Optometry clinic between August, 2013 and April, 2014. Of the 4378 first-year students aged 16-39 years enumerated, 3437 (78.5%) underwent the eye examination. The examination protocol included presenting visual acuity (PVA), ocular motility, and slit-lamp examination of the external eye, anterior segment and media, and non-dilated fundus examination. Pinhole acuity and fundus examination were performed when the PVA≤6/12 in one or both eyes to determine the principal cause of the vision loss. The mean age of participants was 21.86 years (95% CI: 21.72-21.99). The prevalence of bilateral visual impairment (BVI; PVA in the better eye ≤6/12) and unilateral visual impairment UVI; PVA in the worse eye ≤6/12) were 3.08% (95% CI: 2.56-3.72) and 0.79% (95% CI: 0.54-1.14), respectively. Among 106 participants with BVI, refractive error (96.2%) and corneal opacity (3.8%) were the causes. Of the 27 participants with UVI, refractive error (44.4%), maculopathy (18.5%) and retinal disease (14.8%) were the major causes. There was unequal distribution of BVI in the different age groups, with those above 20 years having a lesser burden. Eye screening and provision of affordable spectacle correction to the youth could be timely to eliminate visual impairment. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Pattern of refractive errors among the Nepalese population: a retrospective study.

PubMed

Shrestha, S P; Bhat, K S; Binu, V S; Barthakur, R; Natarajan, M; Subba, S H

2010-01-01

Refractive errors are a major cause of visual impairment in the population. To find the pattern of refractive errors among patients evaluated in a tertiary care hospital in the western region of Nepal. The present hospital-based retrospective study was conducted in the Department of Ophthalmology of the Manipal Teaching Hospital, situated in Pokhara, Nepal. Patients who had refractive error of at least 0.5 D (dioptre) were included for the study. During the study period, 15,410 patients attended the outpatient department and 10.8% of the patients were identified as having refractive error. The age of the patients in the present study ranged between 5 - 90 years. Myopia was the commonest refractive error followed by hypermetropia. There was no difference in the frequency of the type of refractive errors when they were defined using right the eye, the left eye or both the eyes. Males predominated among myopics and females predominated among hypermetropics. The majority of spherical errors was less than or equal to 2 D. Astigmatic power above 1D was rarely seen with hypermetropic astigmatism and was seen in around 13 % with myopic astigmatism. "Astigmatism against the rule" was more common than "astigmatism with the rule", irrespective of age. Refractive errors progressively shift along myopia up to the third decade and change to hypermetropia till the seventh decade. Hyperopic shift in the refractive error in young adults should be well noted while planning any refractive surgery in younger patients with myopia. © Nepal Ophthalmic Society.

Evaluation of visual acuity measurements after autorefraction vs manual refraction in eyes with and without diabetic macular edema.

PubMed

Sun, Jennifer K; Qin, Haijing; Aiello, Lloyd Paul; Melia, Michele; Beck, Roy W; Andreoli, Christopher M; Edwards, Paul A; Glassman, Adam R; Pavlica, Michael R

2012-04-01

To compare visual acuity (VA) scores after autorefraction vs manual refraction in eyes of patients with diabetes mellitus and a wide range of VAs. The letter score from the Electronic Visual Acuity (EVA) test from the electronic Early Treatment Diabetic Retinopathy Study was measured after autorefraction (AR-EVA score) and after manual refraction (MR-EVA score), which is the research protocol of the Diabetic Retinopathy Clinical Research Network. Testing order was randomized, study participants and VA examiners were masked to refraction source, and a second EVA test using an identical supplemental manual refraction (MR-EVAsuppl score) was performed to determine test-retest variability. In 878 eyes of 456 study participants, the median MR-EVA score was 74 (Snellen equivalent, approximately 20/32). The spherical equivalent was often similar for manual refraction and autorefraction (median difference, 0.00; 5th-95th percentile range, -1.75 to 1.13 diopters). However, on average, the MR-EVA scores were slightly better than the AR-EVA scores, across the entire VA range. Furthermore, the variability between the AR-EVA scores and the MR-EVA scores was substantially greater than the test-retest variability of the MR-EVA scores (P < .001). The variability of differences was highly dependent on the autorefractor model. Across a wide range of VAs at multiple sites using a variety of autorefractors, VA measurements tend to be worse with autorefraction than manual refraction. Differences between individual autorefractor models were identified. However, even among autorefractor models that compare most favorably with manual refraction, VA variability between autorefraction and manual refraction is higher than the test-retest variability of manual refraction. The results suggest that, with current instruments, autorefraction is not an acceptable substitute for manual refraction for most clinical trials with primary outcomes dependent on best-corrected VA.

Non-topography-guided PRK combined with CXL for the correction of refractive errors in patients with early stage keratoconus.

PubMed

Fadlallah, Ali; Dirani, Ali; Chelala, Elias; Antonios, Rafic; Cherfan, George; Jarade, Elias

2014-10-01

To evaluate the safety and clinical outcome of combined non-topography-guided photorefractive keratectomy (PRK) and corneal collagen cross-linking (CXL) for the treatment of mild refractive errors in patients with early stage keratoconus. A retrospective, nonrandomized study of patients with early stage keratoconus (stage 1 or 2) who underwent simultaneous non-topography-guided PRK and CXL. All patients had at least 2 years of follow-up. Data were collected preoperatively and postoperatively at the 6-month, 1-year, and 2-year follow-up visit after combined non-topography-guided PRK and CXL. Seventy-nine patients (140 eyes) were included in the study. Combined non-topography-guided PRK and CXL induced a significant improvement in both visual acuity and refraction. Uncorrected distance visual acuity significantly improved from 0.39 ± 0.22 logMAR before combined non-topography-guided PRK and CXL to 0.12 ± 0.14 logMAR at the last follow-up visit (P <.001) and corrected distance visual acuity remained stable (0.035 ± 0.062 logMAR preoperatively vs 0.036 ± 0.058 logMAR postoperatively, P =.79). The mean spherical equivalent decreased from -1.78 ± 1.43 to -0.42 ± 0.60 diopters (D) (P <.001), and the mean cylinder decreased from 1.47 ± 1.10 to 0.83 ± 0.55 D (P <.001). At the last follow-up visit mean keratometry flat was 43.30 ± 1.75 vs 45.62 ± 1.72 D preoperatively (P = .03) and mean keratometry steep was 44.39 ± 3.14 vs 46.53 ± 2.13 D preoperatively (P = .02). Mean central corneal thickness decreased from 501.74 ± 13.11 to 475.93 ± 12.25 µm following combined non-topography-guided PRK and CXL (P < .001). No intraoperative complications occurred. Four eyes developed mild haze that responded well to a short course of topical steroids. No eye developed infectious keratitis. Combined non-topography-guided PRK and CXL is an effective and safe option for correcting mild refractive error and improving visual acuity in patients with early stable keratoconus

Prevalence of refractive errors and associated risk factors in subjects with type 2 diabetes mellitus SN-DREAMS, report 18.

PubMed

Rani, Padmaja Kumari; Raman, Rajiv; Rachapalli, Sudhir R; Kulothungan, Vaitheeswaran; Kumaramanickavel, Govindasamy; Sharma, Tarun

2010-06-01

To report the prevalence of refractive errors and the associated risk factors in subjects with type 2 diabetes mellitus from an urban Indian population. Population-based, cross-sectional study. One thousand eighty participants selected from a pool of 1414 subjects with diabetes. A population-based sample of 1414 persons (age >40 years) with diabetes (identified as per the World Health Organization criteria) underwent a comprehensive eye examination, including objective and subjective refractions. One thousand eighty subjects who were phakic in the right eye with best corrected visual acuity of > or =20/40 were included in the analysis for prevalence of refractive errors. Univariate and multivariate analyses were done to find out the independent risk factors associated with the refractive errors. The mean refraction was +0.20+/-1.72, and the Median, +0.25 diopters. The prevalence of emmetropia (spherical equivalent [SE], -0.50 to +0.50 diopter sphere [DS]) was 39.26%. The prevalence of myopia (SE <-0.50 DS), high myopia (SE <-5.00 DS), hyperopia (SE >+0.50 DS), and astigmatism (SE <-0.50 cyl) was 19.4%, 1.6%, 39.7%, and 47.4%, respectively. The advancing age was an important risk factor for the three refractive errors: for myopia, odds ratio (OR; 95% confidence interval [CI] 4.06 [1.74-9.50]; for hyperopia, OR [95% CI] 5.85 [2.56-13.39]; and for astigmatism, OR [95% CI] 2.51 [1.34-4.71]). Poor glycemic control was associated with myopia (OR [95% CI] 4.15 [1.44-11.92]) and astigmatism (OR [95% CI] 2.01 [1.04-3.88]). Female gender was associated with hyperopia alone) OR [95% CI] 2.00 [1.42-2.82]. The present population-based study from urban India noted a high prevalence of refractive errors (60%) among diabetic subjects >40 years old; the prevalence of astigmatism (47%) was higher than hyperopia (40%) or myopia (20%). Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Postoperative Refractive Errors Following Pediatric Cataract Extraction with Intraocular Lens Implantation.

PubMed

Indaram, Maanasa; VanderVeen, Deborah K

2018-01-01

Advances in surgical techniques allow implantation of intraocular lenses (IOL) with cataract extraction, even in young children. However, there are several challenges unique to the pediatric population that result in greater degrees of postoperative refractive error compared to adults. Literature review of the techniques and outcomes of pediatric cataract surgery with IOL implantation. Pediatric cataract surgery is associated with several sources of postoperative refractive error. These include planned refractive error based on age or fellow eye status, loss of accommodation, and unexpected refractive errors due to inaccuracies in biometry technique, use of IOL power formulas based on adult normative values, and late refractive changes due to unpredictable eye growth. Several factors can preclude the achievement of optimal refractive status following pediatric cataract extraction with IOL implantation. There is a need for new technology to reduce postoperative refractive surprises and address refractive adjustment in a growing eye.

Atmospheric refraction effects on baseline error in satellite laser ranging systems

NASA Technical Reports Server (NTRS)

Im, K. E.; Gardner, C. S.

1982-01-01

Because of the mathematical complexities involved in exact analyses of baseline errors, it is not easy to isolate atmospheric refraction effects; however, by making certain simplifying assumptions about the ranging system geometry, relatively simple expressions can be derived which relate the baseline errors directly to the refraction errors. The results indicate that even in the absence of other errors, the baseline error for intercontinental baselines can be more than an order of magnitude larger than the refraction error.

Refractive errors in medical students in Singapore.

PubMed

Woo, W W; Lim, K A; Yang, H; Lim, X Y; Liew, F; Lee, Y S; Saw, S M

2004-10-01

Refractive errors are becoming more of a problem in many societies, with prevalence rates of myopia in many Asian urban countries reaching epidemic proportions. This study aims to determine the prevalence rates of various refractive errors in Singapore medical students. 157 second year medical students (aged 19-23 years) in Singapore were examined. Refractive error measurements were determined using a stand-alone autorefractor. Additional demographical data was obtained via questionnaires filled in by the students. The prevalence rate of myopia in Singapore medical students was 89.8 percent (Spherical equivalence (SE) at least -0.50 D). Hyperopia was present in 1.3 percent (SE more than +0.50 D) of the participants and the overall astigmatism prevalence rate was 82.2 percent (Cylinder at least 0.50 D). Prevalence rates of myopia and astigmatism in second year Singapore medical students are one of the highest in the world.

[Refractive errors among schoolchildren in the central region of Togo].

PubMed

Nonon Saa, K B; Atobian, K; Banla, M; Rédah, T; Maneh, N; Walser, A

2013-11-01

Untreated refractive errors represent the main visual impairment in the world but also the easiest to avoid. The goal of this survey is to use clinical and epidemiological data to efficiently plan distribution of corrective glasses in a project supported by the Swiss Red Cross in the central region of Togo. To achieve this goal, 66 primary schools were identified randomly in the catchment area of the project. The teachers at these schools were previously trained to test visual acuity (VA). The schoolchildren referred by these teachers were examined by eye care professionals. The schoolchildren with ametropia (VA≤7/10 in at least one eye) underwent cycloplegic autorefraction. Of a total of 19,252 registered schoolchildren, 13,039 underwent VA testing by the teachers (participation rate=68%). Among them, 366 cases of ametropia were identified (prevalence about 3%). The average age of the schoolchildren examined was 10.7±2.3years, with a sex ratio of 1.06. Autorefraction, which was performed for 37% of the schoolchildren with ametropia allowed them to be classified into three groups: hyperopia (4%), myopia (5%) and astigmatism of all types (91%). Regardless of the type of ametropia, the degree of severity was mild in 88%. The results of this survey have highlighted the importance of the teachers' contribution to eye care education in the struggle against refractive errors within the school environment, as well as helping to efficiently plan actions against ametropia. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Prevalence of refractive errors in Tibetan adolescents.

PubMed

Qian, Xuehan; Liu, Beihong; Wang, Jing; Wei, Nan; Qi, Xiaoli; Li, Xue; Li, Jing; Zhang, Ying; Hua, Ning; Ning, Yuxian; Ding, Gang; Ma, Xu; Wang, Binbin

2018-05-11

The prevalence of adolescent eye disease in remote areas of the Qinghai-Tibet Plateau has rarely been reported. To understand the prevalence of common eye diseases in Tibet, we performed ocular-disease screening on students from primary and secondary schools in Tibet, and compared the prevalence to that in the Central China Plain (referred to here as the "plains area"). The refractive status of students was evaluated with a Spot™ vision screener. The test was conducted three or fewer times for both eyes of each student and results with best correction were recorded. A total of 3246 students from primary and secondary schools in the Tibet Naidong district were screened, yielding a refractive error rate of 28.51%, which was significantly lower than that of the plains group (28.51% vs. 56.92%, p < 0.001). In both groups, the prevalence of refractive errors among females was higher than that among males. We found that Tibetan adolescents had a lower prevalence of refractive errors than did adolescents in the plains area, which may be related to less intensive schooling and greater exposure to sunlight.

Linkage analysis of quantitative refraction and refractive errors in the Beaver Dam Eye Study.

PubMed

Klein, Alison P; Duggal, Priya; Lee, Kristine E; Cheng, Ching-Yu; Klein, Ronald; Bailey-Wilson, Joan E; Klein, Barbara E K

2011-07-13

Refraction, as measured by spherical equivalent, is the need for an external lens to focus images on the retina. While genetic factors play an important role in the development of refractive errors, few susceptibility genes have been identified. However, several regions of linkage have been reported for myopia (2q, 4q, 7q, 12q, 17q, 18p, 22q, and Xq) and for quantitative refraction (1p, 3q, 4q, 7p, 8p, and 11p). To replicate previously identified linkage peaks and to identify novel loci that influence quantitative refraction and refractive errors, linkage analysis of spherical equivalent, myopia, and hyperopia in the Beaver Dam Eye Study was performed. Nonparametric, sibling-pair, genome-wide linkage analyses of refraction (spherical equivalent adjusted for age, education, and nuclear sclerosis), myopia and hyperopia in 834 sibling pairs within 486 extended pedigrees were performed. Suggestive evidence of linkage was found for hyperopia on chromosome 3, region q26 (empiric P = 5.34 × 10(-4)), a region that had shown significant genome-wide evidence of linkage to refraction and some evidence of linkage to hyperopia. In addition, the analysis replicated previously reported genome-wide significant linkages to 22q11 of adjusted refraction and myopia (empiric P = 4.43 × 10(-3) and 1.48 × 10(-3), respectively) and to 7p15 of refraction (empiric P = 9.43 × 10(-4)). Evidence was also found of linkage to refraction on 7q36 (empiric P = 2.32 × 10(-3)), a region previously linked to high myopia. The findings provide further evidence that genes controlling refractive errors are located on 3q26, 7p15, 7p36, and 22q11.

Linkage Analysis of Quantitative Refraction and Refractive Errors in the Beaver Dam Eye Study

PubMed Central

Duggal, Priya; Lee, Kristine E.; Cheng, Ching-Yu; Klein, Ronald; Bailey-Wilson, Joan E.; Klein, Barbara E. K.

2011-01-01

Purpose. Refraction, as measured by spherical equivalent, is the need for an external lens to focus images on the retina. While genetic factors play an important role in the development of refractive errors, few susceptibility genes have been identified. However, several regions of linkage have been reported for myopia (2q, 4q, 7q, 12q, 17q, 18p, 22q, and Xq) and for quantitative refraction (1p, 3q, 4q, 7p, 8p, and 11p). To replicate previously identified linkage peaks and to identify novel loci that influence quantitative refraction and refractive errors, linkage analysis of spherical equivalent, myopia, and hyperopia in the Beaver Dam Eye Study was performed. Methods. Nonparametric, sibling-pair, genome-wide linkage analyses of refraction (spherical equivalent adjusted for age, education, and nuclear sclerosis), myopia and hyperopia in 834 sibling pairs within 486 extended pedigrees were performed. Results. Suggestive evidence of linkage was found for hyperopia on chromosome 3, region q26 (empiric P = 5.34 × 10−4), a region that had shown significant genome-wide evidence of linkage to refraction and some evidence of linkage to hyperopia. In addition, the analysis replicated previously reported genome-wide significant linkages to 22q11 of adjusted refraction and myopia (empiric P = 4.43 × 10−3 and 1.48 × 10−3, respectively) and to 7p15 of refraction (empiric P = 9.43 × 10−4). Evidence was also found of linkage to refraction on 7q36 (empiric P = 2.32 × 10−3), a region previously linked to high myopia. Conclusions. The findings provide further evidence that genes controlling refractive errors are located on 3q26, 7p15, 7p36, and 22q11. PMID:21571680

Intermediate visual acuity of presbyopic individuals with and without distance and bifocal lens corrections.

DOT National Transportation Integrated Search

1977-03-01

Visual acuity was determined at the intermediate range for older individuals with various combinations of ocular refractive error (nine subcategories) and accommodative power (three subcategories). Subjects (N=249) read numerals ranging in size to me...

Profile of refractive errors in cerebral palsy: impact of severity of motor impairment (GMFCS) and CP subtype on refractive outcome.

PubMed

Saunders, Kathryn J; Little, Julie-Anne; McClelland, Julie F; Jackson, A Jonathan

2010-06-01

To describe refractive status in children and young adults with cerebral palsy (CP) and relate refractive error to standardized measures of type and severity of CP impairment and to ocular dimensions. A population-based sample of 118 participants aged 4 to 23 years with CP (mean 11.64 +/- 4.06) and an age-appropriate control group (n = 128; age, 4-16 years; mean, 9.33 +/- 3.52) were recruited. Motor impairment was described with the Gross Motor Function Classification Scale (GMFCS), and subtype was allocated with the Surveillance of Cerebral Palsy in Europe (SCPE). Measures of refractive error were obtained from all participants and ocular biometry from a subgroup with CP. A significantly higher prevalence and magnitude of refractive error was found in the CP group compared to the control group. Axial length and spherical refractive error were strongly related. This relation did not improve with inclusion of corneal data. There was no relation between the presence or magnitude of spherical refractive errors in CP and the level of motor impairment, intellectual impairment, or the presence of communication difficulties. Higher spherical refractive errors were significantly associated with the nonspastic CP subtype. The presence and magnitude of astigmatism were greater when intellectual impairment was more severe, and astigmatic errors were explained by corneal dimensions. Conclusions. High refractive errors are common in CP, pointing to impairment of the emmetropization process. Biometric data support this In contrast to other functional vision measures, spherical refractive error is unrelated to CP severity, but those with nonspastic CP tend to demonstrate the most extreme errors in refraction.

Uncorrected refractive errors and spectacle utilisation rate in Tehran: the unmet need

PubMed Central

Fotouhi, A; Hashemi, H; Raissi, B; Mohammad, K

2006-01-01

Aim To determine the prevalence of the met and unmet need for spectacles and their associated factors in the population of Tehran. Methods 6497 Tehran citizens were enrolled through random cluster sampling and were invited to a clinic for an interview and ophthalmic examination. 4354 (70.3%) participated in the survey, and refraction measurement results of 4353 people aged 5 years and over are presented. The unmet need for spectacles was defined as the proportion of people who did not use spectacles despite a correctable visual acuity of worse than 20/40 in the better eye. Results The need for spectacles in the studied population, standardised for age and sex, was 14.1% (95% confidence interval (CI), 12.8% to 15.4%). This need was met with appropriate spectacles in 416 people (9.3% of the total sample), while it was unmet in 230 people, representing 4.8% of the total sample population (95% CI, 4.1% to 5.4%). The spectacle coverage rate (met need/(met need + unmet need)) was 66.0%. Multivariate logistic regression showed that variables of age, education, and type of refractive error were associated with lack of spectacle correction. There was an increase in the unmet need with older age, lesser education, and myopia. Conclusion This survey determined the met and unmet need for spectacles in a Tehran population. It also identified high risk groups with uncorrected refractive errors to guide intervention programmes for the society. While the study showed the unmet need for spectacles and its determinants, more extensive studies towards the causes of unmet need are recommended. PMID:16488929

The use of a supplemental sulcus fixated IOL (HumanOptics Add-On IOL) to correct pseudophakic refractive errors.

PubMed

Basarir, Berna; Kaya, Vedat; Altan, Cigdem; Karakus, Sezen; Pinarci, Eylem Y; Demirok, Ahmet

2012-01-01

To evaluate the safety and efficacy of piggybacking with the HumanOptics Add-On intraocular lens (IOL) to correct pseudophakic refractive errors. Ten eyes of 10 patients with pseudophakic refractive errors were included in this study. All patients were targeted for a range of refraction -0.50 to +0.50 D. Uncorrected and corrected distance visual acuities (UDVA and CDVA, respectively), endothelial cell count (ECC), anterior chamber depth (ACD), the distance between intraocular lenses, and contrast sensitivity measurements under mesopic, scotopic, and scotopic with glare conditions were evaluated preoperatively and postoperatively. The mean age of the patients was 54±27 years (range 4-78). Mean follow-up time was 10.5±1.36 months (range 6-15 months). Mean diopters of implanted Add-On IOLs were -1.4±6.9 (range -12 to +9 D). Mean preoperative and postoperative UDVA was 0.133±0.12 and 0.73±0.27, respectively (p=0.0001); mean preoperative and postoperative CDVA were 0.77±0.26 and 0.79±0.27, respectively (p=0.066). Mean preoperative and postoperative ACD were 3.87±0.91 mm vs 3.58±1.05 mm, respectively (p=0.343); mean inter-IOL distance was 0.53±0.08 mm. Mean preoperative and postoperative ECC were 2455±302 and 2426±294, respectively (p=0.55). All patients were within the targeted refractive range of -0.50 D to +0.50 D. No complications were observed during the operations or postoperative follow-up period. Piggybacking with the Add-On IOL is a safe, efficient, and reliable technique to correct pseudophakic refractive errors.

Relationship between refractive error and ocular biometrics in twin children: the Guangzhou Twin Eye Study.

PubMed

Wang, Decai; Liu, Bin; Huang, Shengsong; Huang, Wenyong; He, Mingguang

2014-09-01

A cross-sectional study was conducted to explore the relationship between refractive error and ocular biometrics in children from the Guangzhou twin eye study. Twin participants aged 7-15 years were selected from Guangzhou Twin Eye Study. Ocular examinations included visual acuity measurement, ocular motility evaluation, autorefraction under cycloplegia, and anterior segment, media, and fundus examination. Axial length (AL), anterior chamber depth (ACD), and corneal curvature radius were measured using partial coherence laser interferometry. A multivariate linear regression model was used for statistical analysis. Twin children from Guangzhou city showed a decreased spherical equivalent with age, whereas both AL and ACD were increased and corneal curvature radius remained unchanged. When adjusted by age and gender, the data from 77% of twins presenting with spherical equivalent changes indicated that these were caused by predictable variables (R2 = 0.77, P < 0.001). Primary factors affecting children's refraction included axial length (β = -0.97,P < 0.001), ACD (β = 0.33, P < 0.001), and curvature radius (β = 2.10, P < 0.001). Girls had a higher tendency for myopic status than did boys (β = -0.26, P < 0.001). Age exerted no effect upon the changes in refraction (β = -0.01, P = 0.25). Refraction is correlated with ocular biometrics. Refractive status is largely determined by axial length as the major factor.

Refractive Lenticule Transplantation for Correction of Iatrogenic Hyperopia and High Astigmatism After LASIK.

PubMed

Lazaridis, Apostolos; Reinstein, Dan Z; Archer, Timothy J; Schulze, Stephan; Sekundo, Walter

2016-11-01

To design a technique for intrastromal transplantation of stromal lenticules with specific refractive power for correction of post-LASIK induced hyperopia and astigmatism. A 28-year-old patient was referred for consultation after complicated LASIK for moderate myopia and astigmatism. The refractive error of the right eye was severely overcorrected due to data entry error. Post-LASIK refraction showed high astigmatism (right eye: +6.50 -9.00 @ 84°) and corrected distance visual acuity (CDVA) of 20/32. The corneal thickness was 282 µm. A refractive lenticule transplantation was performed due to contact lens intolerance, poor visual acuity, and severe anisometropia. A toric and myopic lenticule, obtained from a donor using the femtosecond lenticule extraction technique, was implanted under the flap to reduce the refractive error, bring the refraction of the eye to the level correctable by phakic intraocular lens, and restore corneal volume. Six weeks postoperatively, the donor lenticule was spread smoothly in the interface with a minor temporal decentration in relation to pupil center. The refraction showed a reduction of astigmatism but a stronger myopization compared to preoperative calculations (right eye: -6.50 -4.00 @ 70°). At 3 months, the CDVA returned to the preoperative value of 20/32. One year postoperatively, corneal tomography showed no signs of ectasia and biomicroscopy revealed no signs of rejection. After implanting a toric myopic implantable collamer lens, the patient regained uncorrected distance visual acuity of 20/40 and full stereopsis. The refractive lenticule transplantation technique offers a solution for rare cases of post-LASIK hyperopia and high astigmatism while restoring the volume of thin corneas. Moreover, it is a reversible procedure with low probability of rejection. [J Refract Surg. 2016;32(11):780-786.]. Copyright 2016, SLACK Incorporated.

Refractive eye surgery in treating functional amblyopia in children.

PubMed

Levenger, Samuel; Nemet, Pinhas; Hirsh, Ami; Kremer, Israel; Nemet, Arie

2006-01-01

While excimer laser refractive surgery is recommended and highly successful for correcting refractive errors in adults, its use in children has not been extensively exercised or studied. We report our experience treating children with amblyopia due to high anisometropia, high astigmatism, high myopia and with associated developmental delay. Review of patient records of our refractive clinic. A retrospective review was made of all 11 children with stable refractive errors who were unsuccessfully treated non-surgically and then underwent corneal refractive surgery and in one case, lenticular surgery. Seven had high myopic anisometropia, 2 had high astigmatism, and two had high myopia--one with Down's Syndrome and one with agenesis of the corpus callosum. The surgical refractive treatment eliminated or reduced the anisometropia, reduced the astigmatic error, improved vision and improved the daily function of the children with developmental delay. There were no complications or untoward results. Refractive surgery is safe and effective in treating children with high myopic anisometropia, high astigmatism, high myopia and developmental delay due to the resulting poor vision. Surgery can improve visual acuity in amblyopia not responding to routine treatment by correcting the refractive error and refractive aberrations.

Uncorrected and corrected refractive error experiences of Nepalese adults: a qualitative study.

PubMed

Kandel, Himal; Khadka, Jyoti; Shrestha, Mohan Krishna; Sharma, Sadhana; Neupane Kandel, Sandhya; Dhungana, Purushottam; Pradhan, Kishore; Nepal, Bhagavat P; Thapa, Suman; Pesudovs, Konrad

2018-04-01

The aim of this study was to explore the impact of corrected and uncorrected refractive error (URE) on Nepalese people's quality of life (QoL), and to compare the QoL status between refractive error subgroups. Participants were recruited from Tilganga Institute of Ophthalmology and Dhulikhel Hospital, Nepal. Semi-structured in-depth interviews were conducted with 101 people with refractive error. Thematic analysis was used with matrices produced to compare the occurrence of themes and categories across participants. Themes were identified using an inductive approach. Seven major themes emerged that determined refractive error-specific QoL: activity limitation, inconvenience, health concerns, psycho-social impact, economic impact, general and ocular comfort symptoms, and visual symptoms. Activity limitation, economic impact, and symptoms were the most important themes for the participants with URE, whereas inconvenience associated with wearing glasses was the most important issue in glasses wearers. Similarly, possibilities of having side effects or complications were the major concerns for participants wearing contact lens. In general, refractive surgery addressed socio-emotional impact of wearing glasses or contact lens. However, the surgery participants had concerns such as possibility of having to wear glasses again due to relapse of refractive error. Impact of refractive error on people's QoL is multifaceted. Significance of the identified themes varies by refractive error subgroups. Refractive correction may not always address QoL impact of URE but often add unique QoL issues. This study findings also provide content for developing an item-bank for quantitatively measuring refractive error-specific QoL in developing country setting.

Automatic diagnostic system for measuring ocular refractive errors

NASA Astrophysics Data System (ADS)

Ventura, Liliane; Chiaradia, Caio; de Sousa, Sidney J. F.; de Castro, Jarbas C.

1996-05-01

Ocular refractive errors (myopia, hyperopia and astigmatism) are automatic and objectively determined by projecting a light target onto the retina using an infra-red (850 nm) diode laser. The light vergence which emerges from the eye (light scattered from the retina) is evaluated in order to determine the corresponding ametropia. The system basically consists of projecting a target (ring) onto the retina and analyzing the scattered light with a CCD camera. The light scattered by the eye is divided into six portions (3 meridians) by using a mask and a set of six prisms. The distance between the two images provided by each of the meridians, leads to the refractive error of the referred meridian. Hence, it is possible to determine the refractive error at three different meridians, which gives the exact solution for the eye's refractive error (spherical and cylindrical components and the axis of the astigmatism). The computational basis used for the image analysis is a heuristic search, which provides satisfactory calculation times for our purposes. The peculiar shape of the target, a ring, provides a wider range of measurement and also saves parts of the retina from unnecessary laser irradiation. Measurements were done in artificial and in vivo eyes (using cicloplegics) and the results were in good agreement with the retinoscopic measurements.

Refractive errors among children, adolescents and adults attending eye clinics in Mexico.

PubMed

Gomez-Salazar, Francisco; Campos-Romero, Abraham; Gomez-Campaña, Humberto; Cruz-Zamudio, Cinthia; Chaidez-Felix, Mariano; Leon-Sicairos, Nidia; Velazquez-Roman, Jorge; Flores-Villaseñor, Hector; Muro-Amador, Secundino; Guadron-Llanos, Alma Marlene; Martinez-Garcia, Javier J; Murillo-Llanes, Joel; Sanchez-Cuen, Jaime; Llausas-Vargas, Alejando; Alapizco-Castro, Gerardo; Irineo-Cabrales, Ana; Graue-Hernandez, Enrique; Ramirez-Luquin, Tito; Canizalez-Roman, Adrian

2017-01-01

To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. Refractive data from 676 856 patients aged 6 to 90y were collected from optometry clinics in fourteen states of Mexico between 2014 and 2015. The refractive errors were classified by the spherical equivalent (SE), as follows: sphere+½ cylinder. Myopia (SE>-0.50 D), hyperopia (SE>+0.50 D), emmetropia (-0.50≤SE≤+0.50), and astigmatism alone (cylinder≥-0.25 D). A negative cylinder was selected as a notation. The proportion (95% confidence interval) among all of the subjects was hyperopia 21.0% (20.9-21.0), emmetropia 40.7% (40.5-40.8), myopia 24.8% (24.7-24.9) and astigmatism alone 13.5% (13.4-13.5). Myopia was the most common refractive error and frequency seemed to increase among the young population (10 to 29 years old), however, hyperopia increased among the aging population (40 to 79 years old), and astigmatism alone showed a decreasing trend with age (6 to 90y; from 19.7% to 10.8%). There was a relationship between age and all refractive errors (approximately 60%, aged 50 and older). The proportion of any clinically important refractive error was higher in males (61.2%) than in females (58.3%; P <0.0001). From fourteen states that collected information, the proportion of refractive error showed variability in different geographical areas of Mexico. Myopia is the most common refractive error in the population studied. This study provides the first data on refractive error in Mexico. Further programs and studies must be developed to address the refractive errors needs of the Mexican population.

Refractive errors among children, adolescents and adults attending eye clinics in Mexico

PubMed Central

Gomez-Salazar, Francisco; Campos-Romero, Abraham; Gomez-Campaña, Humberto; Cruz-Zamudio, Cinthia; Chaidez-Felix, Mariano; Leon-Sicairos, Nidia; Velazquez-Roman, Jorge; Flores-Villaseñor, Hector; Muro-Amador, Secundino; Guadron-Llanos, Alma Marlene; Martinez-Garcia, Javier J.; Murillo-Llanes, Joel; Sanchez-Cuen, Jaime; Llausas-Vargas, Alejando; Alapizco-Castro, Gerardo; Irineo-Cabrales, Ana; Graue-Hernandez, Enrique; Ramirez-Luquin, Tito; Canizalez-Roman, Adrian

2017-01-01

AIM To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. METHODS Refractive data from 676 856 patients aged 6 to 90y were collected from optometry clinics in fourteen states of Mexico between 2014 and 2015. The refractive errors were classified by the spherical equivalent (SE), as follows: sphere+½ cylinder. Myopia (SE>-0.50 D), hyperopia (SE>+0.50 D), emmetropia (-0.50≤SE≤+0.50), and astigmatism alone (cylinder≥-0.25 D). A negative cylinder was selected as a notation. RESULTS The proportion (95% confidence interval) among all of the subjects was hyperopia 21.0% (20.9-21.0), emmetropia 40.7% (40.5-40.8), myopia 24.8% (24.7-24.9) and astigmatism alone 13.5% (13.4-13.5). Myopia was the most common refractive error and frequency seemed to increase among the young population (10 to 29 years old), however, hyperopia increased among the aging population (40 to 79 years old), and astigmatism alone showed a decreasing trend with age (6 to 90y; from 19.7% to 10.8%). There was a relationship between age and all refractive errors (approximately 60%, aged 50 and older). The proportion of any clinically important refractive error was higher in males (61.2%) than in females (58.3%; P<0.0001). From fourteen states that collected information, the proportion of refractive error showed variability in different geographical areas of Mexico. CONCLUSION Myopia is the most common refractive error in the population studied. This study provides the first data on refractive error in Mexico. Further programs and studies must be developed to address the refractive errors needs of the Mexican population. PMID:28546940

Retrospective analysis of refractive errors in children with vision impairment.

PubMed

Du, Jojo W; Schmid, Katrina L; Bevan, Jennifer D; Frater, Karen M; Ollett, Rhondelle; Hein, Bronwyn

2005-09-01

Emmetropization is the reduction in neonatal refractive errors that occurs after birth. Ocular disease may affect this process. We aimed to determine the relative frequency of ocular conditions causing vision impairment in the pediatric population and characterize the refractive anomalies present. We also compared the causes of vision impairment in children today to those between 1974 and 1981. Causes of vision impairment and refractive data of 872 children attending a pediatric low-vision clinic from 1985 to 2002 were retrospectively collated. As a result of associated impairments, refractive data were not available for 59 children. An analysis was made of the causes of vision impairment, the distribution of refractive errors in children with vision impairment, and the average type of refractive error for the most commonly seen conditions. We found that cortical or cerebral vision impairment (CVI) was the most common condition causing vision impairment, accounting for 27.6% of cases. This was followed by albinism (10.6%), retinopathy of prematurity (ROP; 7.0%), optic atrophy (6.2%), and optic nerve hypoplasia (5.3%). Vision impairment was associated with ametropia; fewer than 25% of the children had refractive errors < or = +/-1 D. The refractive error frequency plots (for 0 to 2-, 6 to 8-, and 12 to 14-year age bands) had a Gaussian distribution indicating that the emmetropization process was abnormal. The mean spherical equivalent refractive error of the children (n = 813) was +0.78 +/- 6.00 D with 0.94 +/- 1.24 D of astigmatism and 0.92 +/- 2.15 D of anisometropia. Most conditions causing vision impairment such as albinism were associated with low amounts of hyperopia. Moderate myopia was observed in children with ROP. The relative frequency of ocular conditions causing vision impairment in children has changed since the 1970s. Children with vision impairment often have an associated ametropia suggesting that the emmetropization system is also impaired.

Child Development and Refractive Errors in Preschool Children

PubMed Central

Ibironke, Josephine O.; Friedman, David S.; Repka, Michael X.; Katz, Joanne; Giordano, Lydia; Hawse, Patricia; Tielsch, James M.

2011-01-01

Purpose Many parents are concerned about their child's development. The purpose of this study is to determine if parental concerns about overall development are associated with significant refractive errors among urban preschool children. Methods A cross-sectional population-based study was conducted to evaluate the prevalence of ocular disorders in white and African American children 6 through 71 months of age in Baltimore, Maryland, United States. A comprehensive eye examination with cycloplegic refraction was performed. Parental concerns about development were measured with the Parents' Evaluation of Developmental Status screening tool. 2381 of 2546 eligible children (93.5%) completed the refraction and the parental interview. Results Parental concerns about development were present in 510 of the 2381 children evaluated (21.4%; 95% CI: 9.8% – 23.1%). The adjusted odds ratios [OR] of parental concerns with hyperopia (≥ 3.00D) was 1.26 (95% CI: 0.90 – 1.74), with myopia (≥ 1.00D) was 1.29 (95% CI: 0.83 – 2.03), with astigmatism (≥ 1.50D) was 1.44 (95% CI: 1.08 – 1.93) irrespective of the type of astigmatism, and with anisometropia ≥ 2.00D was 2.61 (95% CI: 1.07 – 6.34). The odds of parental concerns about development significantly increased in children older than 36 months with hyperopia ≥ 3.00D, astigmatism ≥ 1.50D, or anisometropia ≥ 2.00D. Conclusions Parental concerns about general developmental problems were associated with some types of refractive error, astigmatism ≥ 1.50D and anisometropia ≥ 2.00D in children ages 6 to 71 months. Parental concerns were also more likely in children older than 36 months of age with hypermetropia, astigmatism or anisometropia. Parental concerns were not associated with myopia. Due to the potential consequences of uncorrected refractive errors, children whose parents have expressed concerns regarding development should be referred for an eye examination with cycloplegic refraction to rule out

New advances in amblyopia therapy II: refractive therapies.

PubMed

Kraus, Courtney L; Culican, Susan M

2018-06-05

The treatment of anisometropic or ametropic amblyopia has traditionally enjoyed a high treatment success rate. Early initiation and consistent use of spectacle correction can completely resolve amblyopia in a majority of patients. For those with anisometropic amblyopia that fail to improve with glasses wear alone, patching or atropine penalisation can lead to equalisation of visual acuity. However, successful treatment requires full-time compliance with refractive correction and this can be a challenge for a patient population that often has one eye with good acuity without correction. Other barriers for a select population with high anisometropic or ametropic amblyopia include rejection of glasses for various reasons including discomfort, behavioural or sensory problems, postural issues and visually significant aniseikonia. When consistent wear of optical correction proves difficult and patching/atropine remains a major obstacle, surgical correction of refractive error has proven success in achieving vision improvement. Acting as a means to achieve spectacle independence or reducing the overall needed refractive correction, refractive surgery can offer a unique treatment option for this patient population. Laser surgery, phakic intraocular lenses and clear lens exchange are three approaches to altering the refractive state of the eye. Each has documented success in improving vision, particularly in populations where glasses wear has not been possible. Surgical correction of refractive error has a risk profile greater than that of more traditional therapies. However, its use in a specific population offers the opportunity for improving visual acuity in children who otherwise have poor outcomes with glasses and patching/atropine alone. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Refractive errors among students occupying rooms lighted with incandescent or fluorescent lamps.

PubMed

Czepita, Damian; Gosławski, Wojciech; Mojsa, Artur

2004-01-01

The purpose of the study was to determine whether the development of refractive errors could be associated with exposure to light emitted by incandescent or fluorescent lamps. 3636 students were examined (1638 boys and 1998 girls, aged 6-18 years, mean age 12.1, SD 3.4). The examination included retinoscopy with cycloplegia. Myopia was defined as refractive error < or = -0.5 D, hyperopia as refractive error > or = +1.5 D, astigmatism as refractive error > 0.5 DC. Anisometropia was diagnosed when the difference in the refraction of both eyes was > 1.0 D. The children and their parents completed a questionnaire on exposure to light at home. Data were analyzed statistically with the chi2 test. P values of less than 0.05 were considered statistically significant. It was found that the use of fluorescent lamps was associated with an increase in the occurrence of hyperopia (P < 0.01). There was no association between sleeping with the light turned on and prevalence of refractive errors.

Refractive errors and refractive development in premature infants.

PubMed

Ozdemir, O; Tunay, Z Ozen; Acar, D Erginturk; Acar, U

2015-12-01

To examine refractive errors and refractive development in premature infants. Premature infants in the retinopathy of prematurity (ROP) screening program were recruited and examined longitudinally between 28 and 58 weeks postmenstrual age. For performing cycloplegic retinoscopy, 1% tropicamide was administered, two drops with a 10-minute interval, in order to paralyze accommodation and to achieve cycloplegia. Birth weight, gestational age, gender and acute ROP disease were recorded. The relationship between spherical equivalent, astigmatism and postmenstrual age was evaluated. A total of 798 readings were obtained from 258 infants (131 females, 127 males) between 28 and 58 weeks postmenstrual age. The median number of examinations was 3 (minimum 1, maximum 7). In the comparisons of birth weight, gestational age, spherical equivalent and astigmatism between genders, there were no statistically significant differences (P>0.05). Gestational age (regression analysis, r(2)=0.30, P<0.01) and birth weight (regression analysis, r(2)=0.22, P<0.01) had a significant effect on refractive error development. Preterm babies with lower birth weight and those born more prematurely had lower spherical equivalent. The spherical equivalent of the eyes correlated significantly with the postmenstrual age of the infants (r=0.512, P<0.01). Infants with low gestational age and low birth weight also had low spherical equivalent. Moreover, spherical equivalent correlated with increasing postmenstrual age. However, astigmatism did not correlate with postmenstrual age and did not associate with gestational age or birth weight. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

[Nature or nurture: effects of parental ametropia on children's refractive errors].

PubMed

Landmann, A; Bechrakis, E

2013-12-01

The aim of this study was to quantify the degree of association between juvenile refraction errors and parental refraction status. Using a simple questionnaire we conducted a cross-sectional study to determine the prevalence and magnitudes of refractive errors and of parental refraction status in a sample (n=728) of 10- to 18-year-old Austrian grammar school students. Students with myopia or hyperopia were more likely to have ametropic parents and refraction was more myopic in juveniles with one or two parents being ametropic. The prevalence of myopia in children with 2 ametropic parents was 54%, decreasing to 35% in pupils with 1 and to 13% in children with no ametropic parents. The odds ratio for 1 and 2 compared with no ametropic parents was 8.3 and 3.7 for myopia and 1.3 and 1.6 for hyperopia, respectively. Furthermore, the data indicate a stronger influence of the maternal ametropia on children's refractive errors than paternal ametropia. Genetic factors play a significant role in refractive error and may be of dominant influence for school myopia under conditions of low environmental variation.

Refractive error at birth and its relation to gestational age.

PubMed

Varughese, Sara; Varghese, Raji Mathew; Gupta, Nidhi; Ojha, Rishikant; Sreenivas, V; Puliyel, Jacob M

2005-06-01

The refractive status of premature infants is not well studied. This study was done to find the norms of refractive error in newborns at different gestational ages. One thousand two hundred three (1203) eyes were examined for refractive error by streak retinoscopy within the first week of life between June 2001 and September 2002. Tropicamide eye drops (0.8%) with phenylephrine 0.5% were used to achieve cycloplegia and mydriasis. The refractive error was measured in the vertical and horizontal meridia in both eyes and was recorded to the nearest dioptre (D). The neonates were grouped in five gestational age groups ranging from 24 weeks to 43 weeks. Extremely preterm babies were found to be myopic with a mean MSE (mean spherical equivalent) of -4.86 D. The MSE was found to progressively decrease (become less myopic) with increasing gestation and was +2.4 D at term. Astigmatism of more than 1 D spherical equivalent was seen in 67.8% of the eyes examined. Among newborns with > 1 D of astigmatism, the astigmatism was with-the-rule (vertical meridian having greater refractive power than horizontal) in 85% and against-the-rule in 15%. Anisometropia of more than 1 D spherical equivalent was seen in 31% babies. Term babies are known to be hypermetropic, and preterm babies with retinopathy of prematurity (ROP) are known to have myopia. This study provides data on the mean spherical equivalent, the degree of astigmatism, and incidence of anisometropia at different gestational ages. This is the largest study in world literature looking at refractive errors at birth against gestational age. It should help understand the norms of refractive errors in preterm babies.

Prevalence of uncorrected refractive errors, presbyopia and spectacle coverage in marine fishing communities in South India: Rapid Assessment of Visual Impairment (RAVI) project.

PubMed

Marmamula, Srinivas; Madala, Sreenivas R; Rao, Gullapalli N

2012-03-01

To investigate the prevalence of uncorrected refractive errors, presbyopia and spectacle coverage in subjects aged 40 years or more using a novel Rapid Assessment of Visual Impairment (RAVI) methodology. A population-based cross-sectional study was conducted using cluster random sampling to enumerate 1700 subjects from 34 clusters predominantly inhabited by marine fishing communities in the Prakasam district of Andhra Pradesh, India. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 m. Near vision was assessed using an N notation chart. Uncorrected refractive error was defined as presenting VA < 6/18 and improving to ≥6/18 with pinhole. Uncorrected presbyopia was defined as binocular near vision worse than N8 in subjects with binocular distance VA ≥ 6/18. 1560 subjects (response rate - 92%) were available for examination. Of these, 54.6% were female and 10.1% were ≥70 years of age. Refractive error was present in 250 individuals. It was uncorrected in 179 (unmet need) and corrected in 71 (met need) individuals. Among 1094 individuals with no distance visual impairment, presbyopia was present in 494 individuals. It was uncorrected in 439 (unmet need) and corrected in 55 individuals (met need). Spectacle coverage was 28.4% for refractive errors and 11.1% for presbyopia. There is a high unmet need for uncorrected refractive errors and presbyopia among marine fishing communities in the Prakasam district of South India. The data from this study can now be used as a baseline prior to the commencement of eye care services in this region. Ophthalmic & Physiological Optics © 2012 The College of Optometrists.

Refractive errors in patients with newly diagnosed diabetes mellitus.

PubMed

Yarbağ, Abdülhekim; Yazar, Hayrullah; Akdoğan, Mehmet; Pekgör, Ahmet; Kaleli, Suleyman

2015-01-01

Diabetes mellitus is a complex metabolic disorder that involves the small blood vessels, often causing widespread damage to tissues, including the eyes' optic refractive error. In patients with newly diagnosed diabetes mellitus who have unstable blood glucose levels, refraction may be incorrect. We aimed to investigate refraction in patients who were recently diagnosed with diabetes and treated at our centre. This prospective study was performed from February 2013 to January 2014. Patients were diagnosed with diabetes mellitus using laboratory biochemical tests and clinical examination. Venous fasting plasma glucose (fpg) levels were measured along with refractive errors. Two measurements were taken: initially and after four weeks. The last difference between the initial and end refractive measurements were evaluated. Our patients were 100 males and 30 females who had been newly diagnosed with type II DM. The refractive and fpg levels were measured twice in all patients. The average values of the initial measurements were as follows: fpg level, 415 mg/dl; average refractive value, +2.5 D (Dioptres). The average end of period measurements were fpg, 203 mg/dl; average refractive value, +0.75 D. There is a statistically significant difference between after four weeks measurements with initially measurements of fasting plasma glucose (fpg) levels (p<0.05) and there is a statistically significant relationship between changes in fpg changes with glasses ID (p<0.05) and the disappearance of blurred vision (to be greater than 50% success rate) were statistically significant (p<0.05). Also, were detected upon all these results the absence of any age and sex effects (p>0.05). Refractive error is affected in patients with newly diagnosed diabetes mellitus; therefore, plasma glucose levels should be considered in the selection of glasses.

Ciliary Body Thickness and Refractive Error in Children

PubMed Central

Bailey, Melissa D.; Sinnott, Loraine T.; Mutti, Donald O.

2010-01-01

Purpose To determine whether ciliary body thickness (CBT) is related to refractive error in school-age children. Methods Fifty-three children, 8 to 15 years of age, were recruited. CBT was measured from anterior segment OCT images (Visante; Carl Zeiss Meditec, Inc., Dublin, CA) at 1 (CBT1), 2 (CBT2) and 3 (CBT3) mm posterior to the scleral spur. Cycloplegic refractive error was measured with an autorefractor, and axial length was measured with an optical biometer. Multilevel regression models determined the relationship between CBT measurements and refractive error or axial length. A Bland-Altman analysis was used to assess the between-visit repeatability of the ciliary body measurements. Results The between-visits coefficients of repeatability for CBT1, -2, and -3 were 148.04, 165.68, and 110.90, respectively. Thicker measurements at CBT2 (r = −0.29, P = 0.03) and CBT3 (r = −0.38, P = 0.005) were associated with increasingly myopic refractive errors (multilevel model: P < 0.001). Thicker measurements at CBT2 (r = 0.40, P = 0.003) and CBT3 (r = 0.51, P < 0.001) were associated with longer axial lengths (multilevel model: P < 0.001). Conclusions Thicker ciliary body measurements were associated with myopia and a longer axial length. Future studies should determine whether this relationship is also present in animal models of myopia and determine the temporal relationship between thickening of the ciliary muscle and the onset of myopia. PMID:18566470

Corrective Techniques and Future Directions for Treatment of Residual Refractive Error Following Cataract Surgery.

PubMed

Moshirfar, Majid; McCaughey, Michael V; Santiago-Caban, Luis

2014-12-01

Postoperative residual refractive error following cataract surgery is not an uncommon occurrence for a large proportion of modern-day patients. Residual refractive errors can be broadly classified into 3 main categories: myopic, hyperopic, and astigmatic. The degree to which a residual refractive error adversely affects a patient is dependent on the magnitude of the error, as well as the specific type of intraocular lens the patient possesses. There are a variety of strategies for resolving residual refractive errors that must be individualized for each specific patient scenario. In this review, the authors discuss contemporary methods for rectification of residual refractive error, along with their respective indications/contraindications, and efficacies.

Corrective Techniques and Future Directions for Treatment of Residual Refractive Error Following Cataract Surgery

PubMed Central

Moshirfar, Majid; McCaughey, Michael V; Santiago-Caban, Luis

2015-01-01

Postoperative residual refractive error following cataract surgery is not an uncommon occurrence for a large proportion of modern-day patients. Residual refractive errors can be broadly classified into 3 main categories: myopic, hyperopic, and astigmatic. The degree to which a residual refractive error adversely affects a patient is dependent on the magnitude of the error, as well as the specific type of intraocular lens the patient possesses. There are a variety of strategies for resolving residual refractive errors that must be individualized for each specific patient scenario. In this review, the authors discuss contemporary methods for rectification of residual refractive error, along with their respective indications/contraindications, and efficacies. PMID:25663845

Refractive error among the elderly in rural Southern Harbin, China.

PubMed

Li, Zhijian; Sun, Dianjun; Cuj, Hao; Zhang, Liqiong; Lju, Ping; Yang, Hongbin; Baj, Jie

2009-01-01

To estimate the prevalence and associated factors of refractive errors among the elderly in a rural area of Southern Harbin, China. Five thousand and fifty seven subjects (age > or = 50 years) were enumerated for a population-based study. All participants underwent complete ophthalmic evaluation. Refraction was performed by ophthalmic personnel trained in the study procedures. Myopia was defined as spherical equivalent worse than -0.50 diopters (D) and hyperopia as spherical equivalent worse than +0.50 D. Astigmatism was defined as a cylindrical error worse than 0.75D. Association of refractive errors with age, sex, and education were analyzed. Of the 5,057 responders (91.0%), 4,979 were eligible. The mean age was 60.5 (range 50-96) years old. The prevalence of myopia was 9.5% (95% confidence interval [CI], 8.5-10.1) and of hyperopia was 8.9% (95% CI, 7.9-9.5). Astigmatism was evident in 7.6% of the subjects. Myopia, hyperopia and astigmatism increased with increasing age (p<0.001, respectively). Myopia and astigmatism were more common in males, whereas hyperopia was more common in females. We also found that prevalence of refractive error weas associated with education. Myopia was more common in those with higher degrees of education, whereas hyperopia and astigmatism were more common in those with no formal education. This report has provided details of the refractive status in a rural population of Harbin. The prevalence of refractive errors in this population is lower than those reported in other regions of the world.

Myopia, spectacle wear, and risk of bicycle accidents among rural Chinese secondary school students: the Xichang Pediatric Refractive Error Study report no. 7.

PubMed

Zhang, Mingzhi; Congdon, Nathan; Li, Liping; Song, Yue; Choi, Kai; Wang, Yunfei; Zhou, Zhongxia; Liu, Xiaojian; Sharma, Abhishek; Chen, Weihong; Lam, Dennis S C

2009-06-01

To study the effect of myopia and spectacle wear on bicycle-related injuries in rural Chinese students. Myopia is common among Chinese students but few studies have examined its effect on daily activities. Data on visual acuity, refractive error, current spectacle wear, and history of bicycle use and accidents during the past 3 years were sought from 1891 students undergoing eye examinations in rural Guangdong province. Refractive and accident data were available for 1539 participants (81.3%), among whom the mean age was 14.6 years, 52.5% were girls, 26.8% wore glasses, and 12.9% had myopia of less than -4 diopters in both eyes. More than 90% relied on bicycles to get to school daily. A total of 2931 accidents were reported by 423 participants, with 68 requiring medical attention. Male sex (odds ratio, 1.55; P < .001) and spectacle wear (odds ratio, 1.38; P = .04) were associated with a higher risk of accident, but habitual visual acuity and myopia were unassociated with the crash risk, after adjusting for age, sex, time spent riding, and risky riding behaviors. These results may be consistent with data on motor vehicle accidents implicating peripheral vision (potentially compromised by spectacle wear) more strongly than central visual acuity in mediating crash risk.

Reducing visual deficits caused by refractive errors in school and preschool children: results of a pilot school program in the Andean region of Apurimac, Peru.

PubMed

Latorre-Arteaga, Sergio; Gil-González, Diana; Enciso, Olga; Phelan, Aoife; García-Muñoz, Angel; Kohler, Johannes

2014-01-01

Refractive error is defined as the inability of the eye to bring parallel rays of light into focus on the retina, resulting in nearsightedness (myopia), farsightedness (Hyperopia) or astigmatism. Uncorrected refractive error in children is associated with increased morbidity and reduced educational opportunities. Vision screening (VS) is a method for identifying children with visual impairment or eye conditions likely to lead to visual impairment. To analyze the utility of vision screening conducted by teachers and to contribute to a better estimation of the prevalence of childhood refractive errors in Apurimac, Peru. Design : A pilot vision screening program in preschool (Group I) and elementary school children (Group II) was conducted with the participation of 26 trained teachers. Children whose visual acuity was<6/9 [20/30] (Group I) and ≤ 6/9 (Group II) in one or both eyes, measured with the Snellen Tumbling E chart at 6 m, were referred for a comprehensive eye exam. Specificity and positive predictive value to detect refractive error were calculated against clinical examination. Program assessment with participants was conducted to evaluate outcomes and procedures. A total sample of 364 children aged 3-11 were screened; 45 children were examined at Centro Oftalmológico Monseñor Enrique Pelach (COMEP) Eye Hospital. Prevalence of refractive error was 6.2% (Group I) and 6.9% (Group II); specificity of teacher vision screening was 95.8% and 93.0%, while positive predictive value was 59.1% and 47.8% for each group, respectively. Aspects highlighted to improve the program included extending training, increasing parental involvement, and helping referred children to attend the hospital. Prevalence of refractive error in children is significant in the region. Vision screening performed by trained teachers is a valid intervention for early detection of refractive error, including screening of preschool children. Program sustainability and improvements in education

Reducing visual deficits caused by refractive errors in school and preschool children: results of a pilot school program in the Andean region of Apurimac, Peru

PubMed Central

Latorre-Arteaga, Sergio; Gil-González, Diana; Enciso, Olga; Phelan, Aoife; García-Muñoz, Ángel; Kohler, Johannes

2014-01-01

Background Refractive error is defined as the inability of the eye to bring parallel rays of light into focus on the retina, resulting in nearsightedness (myopia), farsightedness (Hyperopia) or astigmatism. Uncorrected refractive error in children is associated with increased morbidity and reduced educational opportunities. Vision screening (VS) is a method for identifying children with visual impairment or eye conditions likely to lead to visual impairment. Objective To analyze the utility of vision screening conducted by teachers and to contribute to a better estimation of the prevalence of childhood refractive errors in Apurimac, Peru. Design A pilot vision screening program in preschool (Group I) and elementary school children (Group II) was conducted with the participation of 26 trained teachers. Children whose visual acuity was<6/9 [20/30] (Group I) and≤6/9 (Group II) in one or both eyes, measured with the Snellen Tumbling E chart at 6 m, were referred for a comprehensive eye exam. Specificity and positive predictive value to detect refractive error were calculated against clinical examination. Program assessment with participants was conducted to evaluate outcomes and procedures. Results A total sample of 364 children aged 3–11 were screened; 45 children were examined at Centro Oftalmológico Monseñor Enrique Pelach (COMEP) Eye Hospital. Prevalence of refractive error was 6.2% (Group I) and 6.9% (Group II); specificity of teacher vision screening was 95.8% and 93.0%, while positive predictive value was 59.1% and 47.8% for each group, respectively. Aspects highlighted to improve the program included extending training, increasing parental involvement, and helping referred children to attend the hospital. Conclusion Prevalence of refractive error in children is significant in the region. Vision screening performed by trained teachers is a valid intervention for early detection of refractive error, including screening of preschool children. Program

Refractive Amblyopia among children in Ibadan: the need for amblyopia screening programmes.

PubMed

Olusanya, B A; Ugalahi, M O; Okoli, C E; Baiyeroju, A M

2015-09-01

The prevalence and burden of amblyopia in developing countries is probably underestimated, and little is known about the pattern of amblyopia in West Africa. To determine the relative frequency and types of amblyopia among children with refractive errors seen in the eye clinic of a tertiary hospital over a 2 year period. A cross-sectional study conducted at the eye clinic of the University College Hospital, Ibadan, Nigeria between January 2012 and December 2013. Case notes of children with refractive errors seen during this period were retrieved and information including socio-demographic data, presenting visual acuity and visual acuity with correction were recorded. Amblyopia was defined as best corrected visual acuity worse than 6/9 or a difference of ≥ 2 Snellen chart lines between both eyes in the absence of any ocular pathology that could explain the visual impairment. A total of 250 eligible patients who had refractive errors were included in the study. Visual acuity was corrected to 6/9 or better in 224 (89.6%) children while 26 (10.4%) of them had amblyopia. Among the 26 children with amblyopia, 21 (80.8%) children had amblyopia in both eyes and majority (65.4%) had iso-ametropic amblyopia. Of the 47 amblyopic eyes, 36 (76.6%) eyes had moderate amblyopia while 11 (23.4%) eyes had severe amblyopia. There is a high relative frequency of amblyopia in this study and we recommend preschool eye examinations for all children to ensure early detection and management of amblyopia, thereby reducing the burden of amblyopia in our populace.

Refractive errors in a Brazilian population: age and sex distribution.

PubMed

Ferraz, Fabio H; Corrente, José E; Opromolla, Paula; Padovani, Carlos Roberto; Schellini, Silvana A

2015-01-01

To determine the prevalence of refractive errors and their distribution according to age and sex in a Brazilian population. This population-based cross-sectional study involved 7654 Brazilian inhabitants of nine municipalities of Sao Paulo State, Brazil, between March 2004 and July 2005. Participants aged >1 year were selected using a random, stratified, household cluster sampling technique, excluding individuals with previous refractive or cataract surgery. Myopia was defined as spherical equivalent (SE) ≤-0.5D, high myopia as SE ≤-3.0D, hyperopia as SE ≥+0.5D, high hyperopia as SE ≥+3D, astigmatism as ≤-0.5DC and anisometropia as ≥1.0D difference between eyes. Age, sex, complaints and a comprehensive eye examination including cycloplegic refraction test were collected and analysed using descriptive analysis, univariate and multivariate methods. The prevalence of astigmatism was 59.7%, hyperopia 33.8% and myopia was 25.3%. Astigmatism had a progressive increase with age. With-the-rule (WTR) axes of astigmatism were more frequently observed in the young participants and the against-the-rule (ATR) axes were more frequent in the older subjects. The onset of myopia occurred more frequently between the 2nd and 3rd decades of life. Anisometropia showed a prevalence of 13.2% (95% CI 12.4-13.9; p < 0.001). There was an association between age and all types of refractive error and hyperopia was also associated with sex. Hyperopia was associated with WTR axes (odds ratio 0.73; 95% CI: 0.6-0.8; p < 0.001) and myopia with ATR axes (odds ratio 0.66; 95% CI: 0.6-0.8; p < 0.001). Astigmatism was the most prevalent refractive error in a Brazilian population. There was a strong relationship between age and all refractive errors and between hyperopia and sex. WTR astigmatism was more frequently associated with hyperopia and ATR astigmatism with myopia. The vast majority of participants had low-grade refractive error, which favours planning aimed at correction of

Comparisons of refractive errors between twins and singletons in Chinese school-age samples.

PubMed

Hur, Yoon-Mi; Zheng, Yingfeng; Huang, Wenyong; Ding, Xiaohu; He, Mingguang

2009-02-01

Studies have reported that refractive errors are associated with premature births. As twins have higher prevalence of prematurity than singletons, it is important to assess similarity of the prevalence of refractive errors in twins and singletons for proper interpretations and generalizations of the findings from twin studies. We compared refractive errors and diopter hours between 561 pairs of twins and 3757 singletons who are representative of school-age children (7-15 years) residing in an urban area of southern China. We found that the means and variances of the continuous measurement of spherical equivalent refractive error and diopter hours were not significantly different between twins and singletons. Although the prevalence of myopia was comparable between twins and singletons, that of hyperopia and astigmatism was slightly but significantly higher in twins than in singletons. These results are inconsistent with those of adult studies that showed no differences in refractive errors between twins and singletons. Given that the sample size of twins is relatively small and that this study is the first to demonstrate minor differences in refractive errors between twins and singletons, future replications are necessary to determine whether the slightly higher prevalence of refractive errors in twins than in singletons found in this study was due to a sampling error or to the developmental delay often observed in twins in childhood.

Assumption-free estimation of the genetic contribution to refractive error across childhood.

PubMed

Guggenheim, Jeremy A; St Pourcain, Beate; McMahon, George; Timpson, Nicholas J; Evans, David M; Williams, Cathy

2015-01-01

Studies in relatives have generally yielded high heritability estimates for refractive error: twins 75-90%, families 15-70%. However, because related individuals often share a common environment, these estimates are inflated (via misallocation of unique/common environment variance). We calculated a lower-bound heritability estimate for refractive error free from such bias. Between the ages 7 and 15 years, participants in the Avon Longitudinal Study of Parents and Children (ALSPAC) underwent non-cycloplegic autorefraction at regular research clinics. At each age, an estimate of the variance in refractive error explained by single nucleotide polymorphism (SNP) genetic variants was calculated using genome-wide complex trait analysis (GCTA) using high-density genome-wide SNP genotype information (minimum N at each age=3,404). The variance in refractive error explained by the SNPs ("SNP heritability") was stable over childhood: Across age 7-15 years, SNP heritability averaged 0.28 (SE=0.08, p<0.001). The genetic correlation for refractive error between visits varied from 0.77 to 1.00 (all p<0.001) demonstrating that a common set of SNPs was responsible for the genetic contribution to refractive error across this period of childhood. Simulations suggested lack of cycloplegia during autorefraction led to a small underestimation of SNP heritability (adjusted SNP heritability=0.35; SE=0.09). To put these results in context, the variance in refractive error explained (or predicted) by the time participants spent outdoors was <0.005 and by the time spent reading was <0.01, based on a parental questionnaire completed when the child was aged 8-9 years old. Genetic variation captured by common SNPs explained approximately 35% of the variation in refractive error between unrelated subjects. This value sets an upper limit for predicting refractive error using existing SNP genotyping arrays, although higher-density genotyping in larger samples and inclusion of interaction effects

Refractive accuracy with light-adjustable intraocular lenses.

PubMed

Villegas, Eloy A; Alcon, Encarna; Rubio, Elena; Marín, José M; Artal, Pablo

2014-07-01

To evaluate efficacy, predictability, and stability of refractive treatments using light-adjustable intraocular lenses (IOLs). University Hospital Virgen de la Arrixaca, Murcia, Spain. Prospective nonrandomized clinical trial. Eyes with a light-adjustable IOL (LAL) were treated with spatial intensity profiles to correct refractive errors. The effective changes in refraction in the light-adjustable IOL after every treatment were estimated by subtracting those in the whole eye and the cornea, which were measured with a Hartmann-Shack sensor and a corneal topographer, respectively. The refractive changes in the whole eye and light-adjustable IOL, manifest refraction, and visual acuity were obtained after every light treatment and at the 3-, 6-, and 12-month follow-ups. The study enrolled 53 eyes (49 patients). Each tested light spatial pattern (5 spherical; 3 astigmatic) produced a different refractive change (P<.01). The combination of 2 light adjustments induced a maximum change in spherical power of the light-adjustable IOL of between -1.98 diopters (D) and +2.30 D and in astigmatism of up to -2.68 D with axis errors below 9 degrees. Intersubject variability (standard deviation) ranged between 0.10 D and 0.40 D. The 2 required lock-in procedures induced a small myopic shift (range +0.01 to +0.57 D) that depended on previous adjustments. Light-adjustable IOL implantation achieved accurate refractive outcomes (around emmetropia) with good uncorrected distance visual acuity, which remained stable over time. Further refinements in nomograms and in the treatment's protocol would improve the predictability of refractive and visual outcomes with these IOLs. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Nature of the Refractive Errors in Rhesus Monkeys (Macaca mulatta) with Experimentally Induced Ametropias

PubMed Central

Qiao-Grider, Ying; Hung, Li-Fang; Kee, Chea-su; Ramamirtham, Ramkumar; Smith, Earl L.

2010-01-01

We analyzed the contribution of individual ocular components to vision-induced ametropias in 210 rhesus monkeys. The primary contribution to refractive-error development came from vitreous chamber depth; a minor contribution from corneal power was also detected. However, there was no systematic relationship between refractive error and anterior chamber depth or between refractive error and any crystalline lens parameter. Our results are in good agreement with previous studies in humans, suggesting that the refractive errors commonly observed in humans are created by vision-dependent mechanisms that are similar to those operating in monkeys. This concordance emphasizes the applicability of rhesus monkeys in refractive-error studies. PMID:20600237

The GEnes in Myopia (GEM) study in understanding the aetiology of refractive errors.

PubMed

Baird, Paul N; Schäche, Maria; Dirani, Mohamed

2010-11-01

Refractive errors represent the leading cause of correctable vision impairment and blindness in the world with an estimated 2 billion people affected. Refractive error refers to a group of refractive conditions including hypermetropia, myopia, astigmatism and presbyopia but relatively little is known about their aetiology. In order to explore the potential role of genetic determinants in refractive error the "GEnes in Myopia (GEM) study" was established in 2004. The findings that have resulted from this study have not only provided greater insight into the role of genes and other factors involved in myopia but have also gone some way to uncovering the aetiology of other refractive errors. This review will describe some of the major findings of the GEM study and their relative contribution to the literature, illuminate where the deficiencies are in our understanding of the development of refractive errors and how we will advance this field in the future. Copyright © 2010 Elsevier Ltd. All rights reserved.

All-distance visual acuity and contrast visual acuity in eyes with a refractive multifocal intraocular lens with minimal added power.

PubMed

Hayashi, Ken; Yoshida, Motoaki; Hayashi, Hideyuki

2009-03-01

To compare visual acuity (VA) from far to near distances, photopic and mesopic contrast VA, and contrast VA in the presence of a glare source (glare VA), between eyes with a new refractive multifocal intraocular lens (IOL) with added power of only +3.0 diopters and those with a monofocal IOL. Comparative, nonrandomized, interventional study. Forty-four eyes of 22 patients who were scheduled for implantation of a refractive multifocal IOL (Hoya SFX MV1; Tokyo, Japan) and 44 eyes of 22 patients scheduled for implantation of a monofocal IOL. All patients underwent phacoemulsification with bilateral implantation of either multifocal or monofocal IOLs. At approximately 3 months after surgery, monocular and binocular VA from far to near distances was measured using the all-distance vision tester (Kowa AS-15; Tokyo, Japan), whereas photopic and mesopic contrast VA and glare VA were examined using the Contrast Sensitivity Accurate Tester (Menicon CAT-2000, Nagoya, Japan). Pupillary diameter and the degree of IOL decentration and tilt were correlated with VA at all distances. Mean VA in both the multifocal and monofocal IOL groups decreased gradually from far to near distances. When comparing the 2 groups, however, both uncorrected and best distance-corrected intermediate VA at 0.5 m and near VA at 0.3 m in the multifocal IOL group were significantly better than those in the monofocal IOL group (Prefractive multifocal IOL with minimal added power provides significantly better intermediate and near VA than does a monofocal IOL; contrast VA and glare VA are not impaired with this multifocal

Nature of the refractive errors in rhesus monkeys (Macaca mulatta) with experimentally induced ametropias.

PubMed

Qiao-Grider, Ying; Hung, Li-Fang; Kee, Chea-Su; Ramamirtham, Ramkumar; Smith, Earl L

2010-08-23

We analyzed the contribution of individual ocular components to vision-induced ametropias in 210 rhesus monkeys. The primary contribution to refractive-error development came from vitreous chamber depth; a minor contribution from corneal power was also detected. However, there was no systematic relationship between refractive error and anterior chamber depth or between refractive error and any crystalline lens parameter. Our results are in good agreement with previous studies in humans, suggesting that the refractive errors commonly observed in humans are created by vision-dependent mechanisms that are similar to those operating in monkeys. This concordance emphasizes the applicability of rhesus monkeys in refractive-error studies. Copyright 2010 Elsevier Ltd. All rights reserved.

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK.

PubMed

Kanellopoulos, Anastasios John

2016-01-01

To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Private clinical ophthalmology practice. A total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Mean refractive error was -5.5 D of myopia and -1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over -0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B ( P <0.01). The residual percentages in both groups were measured with refractive astigmatism of more than -0.5 diopters. Topography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

PubMed Central

Kanellopoulos, Anastasios John

2016-01-01

Purpose To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Setting Private clinical ophthalmology practice. Patients and methods A total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Results Mean refractive error was −5.5 D of myopia and −1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over −0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B (P<0.01). The residual percentages in both groups were measured with refractive astigmatism of more than −0.5 diopters. Conclusion Topography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction. PMID:27843292

Nature and Nurture: the complex genetics of myopia and refractive error

PubMed Central

Wojciechowski, Robert

2010-01-01

The refractive errors, myopia and hyperopia, are optical defects of the visual system that can cause blurred vision. Uncorrected refractive errors are the most common causes of visual impairment worldwide. It is estimated that 2.5 billion people will be affected by myopia alone with in the next decade. Experimental, epidemiological and clinical research has shown that refractive development is influenced by both environmental and genetic factors. Animal models have demonstrated that eye growth and refractive maturation during infancy are tightly regulated by visually-guided mechanisms. Observational data in human populations provide compelling evidence that environmental influences and individual behavioral factors play crucial roles in myopia susceptibility. Nevertheless, the majority of the variance of refractive error within populations is thought to be due to hereditary factors. Genetic linkage studies have mapped two dozen loci, while association studies have implicated more than 25 different genes in refractive variation. Many of these genes are involved in common biological pathways known to mediate extracellular matrix composition and regulate connective tissue remodeling. Other associated genomic regions suggest novel mechanisms in the etiology of human myopia, such as mitochondrial-mediated cell death or photoreceptor-mediated visual signal transmission. Taken together, observational and experimental studies have revealed the complex nature of human refractive variation, which likely involves variants in several genes and functional pathways. Multiway interactions between genes and/or environmental factors may also be important in determining individual risks of myopia, and may help explain the complex pattern of refractive error in human populations. PMID:21155761

Comparison of refractive errors and factors associated with spectacle use in a rural and urban South Indian population.

PubMed

Prema, Raju; George, Ronnie; Sathyamangalam Ve, Ramesh; Hemamalini, Arvind; Baskaran, Mani; Kumaramanickavel, Govindaswamy; Catherine, McCarty; Vijaya, Lingam

2008-01-01

To compare the prevalence of refractive errors and factors associated with spectacle use in a rural and urban south Indian population. Four thousand eight hundred subjects (age> 39 years) each from rural and urban Tamil Nadu were enumerated for a population-based study. All participants underwent a complete ophthalmic evaluation including best-corrected visual acuity (BCVA), objective and subjective refraction. Out of 3924 rural responders 63.91% and out of 3850 urban responders 81.64% were phakic in the right eye with BCVA of 20/40 or better and were included in the study. Association of spectacle use and refractive errors with different parameters were analysed using logistic regression. Chi square, t test, Chi square for trend and Pearson's correlation coefficient were used for analysis. Spectacle use was significantly higher and positively associated with literacy and employment in the urban population. The age and gender-adjusted prevalence of emmetropia, myopia of spherical equivalent (SE) < or =-0.50 diopter sphere (DS), high myopia (SE < or =-5.00DS), hyperopia (SE> 0.50DS) and astigmatism < or = 0.50 diopter cylinder (DC) were 46.8%, 31.0%, 4.3%, 17.9% and 60.4% respectively in the rural population and 29.0%, 17.6%, 1.5%, 51.9%, 59.1% respectively in the urban population. The prevalence of emmetropia decreased with age ( p p = 0.001) and were associated with nuclear sclerosis ( p = 0.001) in both populations. Hyperopia was commoner among women than men ( p = 0.001); was positively associated with diabetes mellitus ( p = 0.008) in the rural population and negatively with nuclear sclerosis ( p = 0.001) in both populations. Spectacle use was found to be significantly lower in the rural population. The pattern of refractive errors was significantly different between both populations.

Prevalence of uncorrected refractive errors among children aged 3-10 years in western Saudi Arabia

PubMed Central

Alrahili, Nojood Hameed R.; Jadidy, Esraa S.; Alahmadi, Bayan Sulieman H.; Abdula’al, Mohammed F.; Jadidy, Alaa S.; Alhusaini, Abdulaziz A.; Mojaddidi, Moaz A.; Al-Barry, Maan A.

2017-01-01

Objectives: To determine the prevalence of uncorrected refractive errors (URE) among children 3-10 years and to affirm the necessity of a national school-based visual screening program for school-aged children. Methods: This retrospective cross-sectional study was conducted in Medina, Saudi Arabia in 2015. Children were selected through a multistage stratified random sampling from 8 kindergarten and 8 primary schools. Those included were screened to diagnose UREs using a visual acuity chart and an auto refractometer according to American guidelines. The prevalence and types of UREs were estimated. Results: Of the 2121 children enumerated, 1893 were examined, yielding a response rate of 89.3%. The prevalence of UREs was 34.9% (95% CI = 32.8%-37.1%), with significant differences in different age groups. The prevalence of astigmatism (25.3%) was higher compared to that of anisometropia (7.4%), hypermetropia (1.5%), and myopia (0.7%). Risk of uncorrected refractive error was positively associated with age, and this was noted in astigmatism, myopia, and anisometropia. In addition, the risk of hypermetropia was associated with boys and that of myopia was associated with girls. Conclusions: The prevalence of UREs, particularly astigmatism, was high among children aged 3-10 years in Medina, with significant age differences. Vision screening programs targeting kindergarten and primary schoolchildren are crucial to lessen the risk of preventable visual impairment due to UREs. PMID:28762432

Prevalence of uncorrected refractive errors among children aged 3-10 years in western Saudi Arabia.

PubMed

Alrahili, Nojood Hameed R; Jadidy, Esraa S; Alahmadi, Bayan Sulieman H; Abdula'al, Mohammed F; Jadidy, Alaa S; Alhusaini, Abdulaziz A; Mojaddidi, Moaz A; Al-Barry, Maan A

2017-08-01

To determine the prevalence of uncorrected refractive errors (URE) among children 3-10 years and to affirm the necessity of a national school-based visual screening program for school-aged children. Methods: This retrospective cross-sectional study was conducted in Medina, Saudi Arabia in 2015. Children were selected through a multistage stratified random sampling from 8 kindergarten and 8 primary schools. Those included were screened to diagnose UREs using a visual acuity chart and an auto refractometer according to American guidelines. The prevalence and types of UREs were estimated. Results: Of the 2121 children enumerated, 1893 were examined, yielding a response rate of 89.3%. The prevalence of UREs was 34.9% (95% CI = 32.8%-37.1%), with significant differences in different age groups. The prevalence of astigmatism (25.3%) was higher compared to that of anisometropia (7.4%), hypermetropia (1.5%), and myopia (0.7%). Risk of uncorrected refractive error was positively associated with age, and this was noted in astigmatism, myopia, and anisometropia. In addition, the risk of hypermetropia was associated with boys and that of myopia was associated with girls. Conclusions: The prevalence of UREs, particularly astigmatism, was high among children aged 3-10 years in Medina, with significant age differences. Vision screening programs targeting kindergarten and primary schoolchildren are crucial to lessen the risk of preventable visual impairment due to UREs.

[Character of refractive errors in population study performed by the Area Military Medical Commission in Lodz].

PubMed

Nowak, Michał S; Goś, Roman; Smigielski, Janusz

2008-01-01

To determine the prevalence of refractive errors in population. A retrospective review of medical examinations for entry to the military service from The Area Military Medical Commission in Lodz. Ophthalmic examinations were performed. We used statistic analysis to review the results. Statistic analysis revealed that refractive errors occurred in 21.68% of the population. The most commen refractive error was myopia. 1) The most commen ocular diseases are refractive errors, especially myopia (21.68% in total). 2) Refractive surgery and contact lenses should be allowed as the possible correction of refractive errors for military service.

Refractive Errors and Amblyopia in the UCLA Preschool Vision Program; First Year Results.

PubMed

Hendler, Karen; Mehravaran, Shiva; Lu, Xiang; Brown, Stuart I; Mondino, Bartly J; Coleman, Anne L

2016-12-01

To report the outcomes of full ophthalmic examination for preschool children in LA County who failed screening with the Retinomax Autorefractor. Retrospective, cross-sectional study. Between August 2012 and May 2013, the University of California Los Angeles (UCLA) preschool vision program screened 11 260 preschool children aged 3-5 years in Los Angeles County using the Retinomax Autorefractor only. Of those, 1007 children who failed the screening were examined by an ophthalmologist on the UCLA Mobile Eye Clinic. Data from the eye examination were recorded for all children. Amblyopia was defined as unilateral if there was ≥2 line interocular difference in the best-corrected visual acuity (BCVA) and as bilateral if BCVA was <20/50 for children <4 years old and <20/40 for children ≥4 years old. Glasses were prescribed for 740 (74%) of those examined. Uncorrected visual acuity for all examined children was 0.4 ± 0.2 (logMAR mean ± SD), and BCVA was 0.2 ± 0.1. Of the 88% who underwent cycloplegia, 58% had hyperopia (spherical equivalent [SE] ≥+0.50 diopter [D]), mean of +2.50 D, and 21% had myopia (SE ≤-0.50 D), mean of -1.40 D. A total of 69% had astigmatism ≥1.50 D, mean of 1.97 D (range 0-5.75). Spherical and cylindrical anisometropia ≥1.00 D were each found in 26% of those examined. Refractive amblyopia was found in 9% of those examined, or 0.8% of the original population. Of the amblyopic subjects, 77% were unilateral. Screening of preschoolers with the Retinomax led to diagnosis and early treatment of uncorrected refractive errors and amblyopia. By treating children early, amblyopia may be prevented, quality of life improved, and academic achievements enhanced. Copyright © 2016 Elsevier Inc. All rights reserved.

A clinic-based study of refractive errors, strabismus, and amblyopia in pediatric age-group.

PubMed

Al-Tamimi, Elham R; Shakeel, Ayisha; Yassin, Sanaa A; Ali, Syed I; Khan, Umar A

2015-01-01

The purpose of this cross-sectional observational study was to determine the distribution and patterns of refractive errors, strabismus, and amblyopia in children seen at a pediatric eye care. The study was conducted in a Private Hospital in Dammam, Kingdom of Saudi Arabia, from March to July 2013. During this period, a total of 1350 children, aged 1-15 years were seen at this Center's Pediatric Ophthalmology Unit. All the children underwent complete ophthalmic examination with cycloplegic refraction. Refractive errors accounted for 44.4% of the cases, the predominant refractive error being hypermetropia which represented 83%. Strabismus and amblyopia were present in 38% and 9.1% of children, respectively. In this clinic-based study, the focus was on the frequency of refractive errors, strabismus, and amblyopia which were considerably high. Hypermetropia was the predominant refractive error in contrast to other studies in which myopia was more common. This could be attributed to the criteria for sample selection since it was clinic-based rather than a population-based study. However, it is important to promote public education on the significance of early detection of refractive errors, and have periodic screening in schools.

Visual Survey of Infantry Troops. Part 1. Visual Acuity, Refractive Status, Interpupillary Distance and Visual Skills

DTIC Science & Technology

1989-06-01

letters on one line and several letters on the next line, there is no accurate way to credit these extra letters for statistical analysis. The decimal and...contains the descriptive statistics of the objective refractive error components of infantrymen. Figures 8-11 show the frequency distributions for sphere...equivalents. Nonspectacle wearers Table 12 contains the idescriptive statistics for non- spectacle wearers. Based or these refractive error data, about 30

Prevalence of refractive errors in children in India: a systematic review.

PubMed

Sheeladevi, Sethu; Seelam, Bharani; Nukella, Phanindra B; Modi, Aditi; Ali, Rahul; Keay, Lisa

2018-04-22

Uncorrected refractive error is an avoidable cause of visual impairment which affects children in India. The objective of this review is to estimate the prevalence of refractive errors in children ≤ 15 years of age. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in this review. A detailed literature search was performed to include all population and school-based studies published from India between January 1990 and January 2017, using the Cochrane Library, Medline and Embase. The quality of the included studies was assessed based on a critical appraisal tool developed for systematic reviews of prevalence studies. Four population-based studies and eight school-based studies were included. The overall prevalence of refractive error per 100 children was 8.0 (CI: 7.4-8.1) and in schools it was 10.8 (CI: 10.5-11.2). The population-based prevalence of myopia, hyperopia (≥ +2.00 D) and astigmatism was 5.3 per cent, 4.0 per cent and 5.4 per cent, respectively. Combined refractive error and myopia alone were higher in urban areas compared to rural areas (odds ratio [OR]: 2.27 [CI: 2.09-2.45]) and (OR: 2.12 [CI: 1.79-2.50]), respectively. The prevalence of combined refractive errors and myopia alone in schools was higher among girls than boys (OR: 1.2 [CI: 1.1-1.3] and OR: 1.1 [CI: 1.1-1.2]), respectively. However, hyperopia was more prevalent among boys than girls in schools (OR: 2.1 [CI: 1.8-2.4]). Refractive error in children in India is a major public health problem and requires concerted efforts from various stakeholders including the health care workforce, education professionals and parents, to manage this issue. © 2018 Optometry Australia.

Relative Proportion Of Different Types Of Refractive Errors In Subjects Seeking Laser Vision Correction.

PubMed

Althomali, Talal A

2018-01-01

Refractive errors are a form of optical defect affecting more than 2.3 billion people worldwide. As refractive errors are a major contributor of mild to moderate vision impairment, assessment of their relative proportion would be helpful in the strategic planning of health programs. To determine the pattern of the relative proportion of types of refractive errors among the adult candidates seeking laser assisted refractive correction in a private clinic setting in Saudi Arabia. The clinical charts of 687 patients (1374 eyes) with mean age 27.6 ± 7.5 years who desired laser vision correction and underwent a pre-LASIK work-up were reviewed retrospectively. Refractive errors were classified as myopia, hyperopia and astigmatism. Manifest refraction spherical equivalent (MRSE) was applied to define refractive errors. Distribution percentage of different types of refractive errors; myopia, hyperopia and astigmatism. The mean spherical equivalent for 1374 eyes was -3.11 ± 2.88 D. Of the total 1374 eyes, 91.8% (n = 1262) eyes had myopia, 4.7% (n = 65) eyes had hyperopia and 3.4% (n = 47) had emmetropia with astigmatism. Distribution percentage of astigmatism (cylinder error of ≥ 0.50 D) was 78.5% (1078/1374 eyes); of which % 69.1% (994/1374) had low to moderate astigmatism and 9.4% (129/1374) had high astigmatism. Of the adult candidates seeking laser refractive correction in a private setting in Saudi Arabia, myopia represented greatest burden with more than 90% myopic eyes, compared to hyperopia in nearly 5% eyes. Astigmatism was present in more than 78% eyes.

Refractive errors and strabismus in Down's syndrome in Korea.

PubMed

Han, Dae Heon; Kim, Kyun Hyung; Paik, Hae Jung

2012-12-01

The aims of this study were to examine the distribution of refractive errors and clinical characteristics of strabismus in Korean patients with Down's syndrome. A total of 41 Korean patients with Down's syndrome were screened for strabismus and refractive errors in 2009. A total of 41 patients with an average age of 11.9 years (range, 2 to 36 years) were screened. Eighteen patients (43.9%) had strabismus. Ten (23.4%) of 18 patients exhibited esotropia and the others had intermittent exotropia. The most frequently detected type of esotropia was acquired non-accommodative esotropia, and that of exotropia was the basic type. Fifteen patients (36.6%) had hypermetropia and 20 (48.8%) had myopia. The patients with esotropia had refractive errors of +4.89 diopters (D, ±3.73) and the patients with exotropia had refractive errors of -0.31 D (±1.78). Six of ten patients with esotropia had an accommodation weakness. Twenty one patients (63.4%) had astigmatism. Eleven (28.6%) of 21 patients had anisometropia and six (14.6%) of those had clinically significant anisometropia. In Korean patients with Down's syndrome, esotropia was more common than exotropia and hypermetropia more common than myopia. Especially, Down's syndrome patients with esotropia generally exhibit clinically significant hyperopic errors (>+3.00 D) and evidence of under-accommodation. Thus, hypermetropia and accommodation weakness could be possible factors in esotropia when it occurs in Down's syndrome patients. Based on the results of this study, eye examinations of Down's syndrome patients should routinely include a measure of accommodation at near distances, and bifocals should be considered for those with evidence of under-accommodation.

High Prevalence of Refractive Errors in 7 Year Old Children in Iran.

PubMed

Hashemi, Hassan; Yekta, Abbasali; Jafarzadehpur, Ebrahim; Ostadimoghaddam, Hadi; Etemad, Koorosh; Asharlous, Amir; Nabovati, Payam; Khabazkhoob, Mehdi

2016-02-01

The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran. In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All children were tested by an optometrist for uncorrected and corrected vision, and non-cycloplegic and cycloplegic refraction. Refractive errors in this study were determined based on spherical equivalent (SE) cyloplegic refraction. From 4614 selected children, 89.0% participated in the study, and 4072 were eligible. The prevalence rates of myopia, hyperopia and astigmatism were 3.04% (95% CI: 2.30-3.78), 6.20% (95% CI: 5.27-7.14), and 17.43% (95% CI: 15.39-19.46), respectively. Prevalence of myopia (P=0.925) and astigmatism (P=0.056) were not statistically significantly different between the two genders, but the odds of hyperopia were 1.11 (95% CI: 1.01-2.05) times higher in girls (P=0.011). The prevalence of with-the-rule astigmatism was 12.59%, against-the-rule was 2.07%, and oblique 2.65%. Overall, 22.8% (95% CI: 19.7-24.9) of the schoolchildren in this study had at least one type of refractive error. One out of every 5 schoolchildren had some refractive error. Conducting multicenter studies throughout the Middle East can be very helpful in understanding the current distribution patterns and etiology of refractive errors compared to the previous decade.

Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

PubMed

Hastings, Gareth D; Marsack, Jason D; Nguyen, Lan Chi; Cheng, Han; Applegate, Raymond A

2017-05-01

To prospectively examine whether using the visual image quality metric, visual Strehl (VSX), to optimise objective refraction from wavefront error measurements can provide equivalent or better visual performance than subjective refraction and which refraction is preferred in free viewing. Subjective refractions and wavefront aberrations were measured on 40 visually-normal eyes of 20 subjects, through natural and dilated pupils. For each eye a sphere, cylinder, and axis prescription was also objectively determined that optimised visual image quality (VSX) for the measured wavefront error. High contrast (HC) and low contrast (LC) logMAR visual acuity (VA) and short-term monocular distance vision preference were recorded and compared between the VSX-objective and subjective prescriptions both undilated and dilated. For 36 myopic eyes, clinically equivalent (and not statistically different) HC VA was provided with both the objective and subjective refractions (undilated mean ± S.D. was -0.06 ± 0.04 with both refractions; dilated was -0.05 ± 0.04 with the objective, and -0.05 ± 0.05 with the subjective refraction). LC logMAR VA provided by the objective refraction was also clinically equivalent and not statistically different to that provided by the subjective refraction through both natural and dilated pupils for myopic eyes. In free viewing the objective prescription was preferred over the subjective by 72% of myopic eyes when not dilated. For four habitually undercorrected high hyperopic eyes, the VSX-objective refraction was more positive in spherical power and VA poorer than with the subjective refraction. A method of simultaneously optimising sphere, cylinder, and axis from wavefront error measurements, using the visual image quality metric VSX, is described. In myopic subjects, visual performance, as measured by HC and LC VA, with this VSX-objective refraction was found equivalent to that provided by subjective refraction, and was typically preferred

Is an objective refraction optimised using the visual Strehl ratio better than a subjective refraction?

PubMed Central

Hastings, Gareth D.; Marsack, Jason D.; Nguyen, Lan Chi; Cheng, Han; Applegate, Raymond A.

2017-01-01

Purpose To prospectively examine whether using the visual image quality metric, visual Strehl (VSX), to optimise objective refraction from wavefront error measurements can provide equivalent or better visual performance than subjective refraction and which refraction is preferred in free viewing. Methods Subjective refractions and wavefront aberrations were measured on 40 visually-normal eyes of 20 subjects, through natural and dilated pupils. For each eye a sphere, cylinder, and axis prescription was also objectively determined that optimised visual image quality (VSX) for the measured wavefront error. High contrast (HC) and low contrast (LC) logMAR visual acuity (VA) and short-term monocular distance vision preference were recorded and compared between the VSX-objective and subjective prescriptions both undilated and dilated. Results For 36 myopic eyes, clinically equivalent (and not statistically different) HC VA was provided with both the objective and subjective refractions (undilated mean ±SD was −0.06 ±0.04 with both refractions; dilated was −0.05 ±0.04 with the objective, and −0.05 ±0.05 with the subjective refraction). LC logMAR VA provided by the objective refraction was also clinically equivalent and not statistically different to that provided by the subjective refraction through both natural and dilated pupils for myopic eyes. In free viewing the objective prescription was preferred over the subjective by 72% of myopic eyes when not dilated. For four habitually undercorrected high hyperopic eyes, the VSX-objective refraction was more positive in spherical power and VA poorer than with the subjective refraction. Conclusions A method of simultaneously optimising sphere, cylinder, and axis from wavefront error measurements, using the visual image quality metric VSX, is described. In myopic subjects, visual performance, as measured by HC and LC VA, with this VSX-objective refraction was found equivalent to that provided by subjective refraction

[Epidemiologic study of refractive errors in schoolchildren in socioeconomically deprived regions in Tunisia].

PubMed

Ayed, T; Sokkah, M; Charfi, O; El Matri, L

2002-09-01

This study's purpose was to estimate the prevalence of common refractive errors in schoolchildren in low socioeconomic regions in Tunisia and to assess their effect on school performance. This was a cross-sectional study done from November 1999 to January 2000 within the context of health care screening campaigns carried out by volunteer ophthalmologists and opticians in low-end socioeconomic regions in Tunisia. The concerned population was schoolchildren living in the cities of Tunis and Tabarka (North), Kerkena (Center), and Tozeur (South). We examined a total of 708 children with a mean age of 11.9 +/-3.21 years (from 6 to 20 years) and a sex ratio of 0.84. A cycloplegic refraction examination was performed on all the children. Statistical analyses with the chi squared test and the Fisher exact test allowed us to calculate the prevalence of the refractive errors totally and separately as well as the distribution according to age, sex, and region. We also searched for a possible relation between refractive errors and academic failure. Among the 708 children, 57.2% [CI(95)=53.4-60] had refractive errors, of which 31.6% [CI(95)=28.2-35.2] were hyperopic, whereas 9.1% [CI(95)=7.1-11.5] were myopic. Astigmatism was found in 16.4% [CI(95)=13.7-19.3]. The prevalence of myopia was significantly higher after the age of fourteen. It increased significantly with age (P=0.0003). The prevalence of hyperopia was significantly higher between the ages of 8 and 11 (P=0.0004). Hyperopic astigmatism was significantly more frequent between 6 and 9 years of age (P=0.001). There was no significant difference regarding sex. However, the distribution of the refractive errors by region showed a significantly high level of myopia in Tunis, Kerkena, and Tozeur. This difference disappeared with increasing age. The study of the effect of these refractive errors on school performance of these children from poor areas showed a significant association between all types of refractive errors and

Relative Proportion Of Different Types Of Refractive Errors In Subjects Seeking Laser Vision Correction

PubMed Central

Althomali, Talal A.

2018-01-01

Background: Refractive errors are a form of optical defect affecting more than 2.3 billion people worldwide. As refractive errors are a major contributor of mild to moderate vision impairment, assessment of their relative proportion would be helpful in the strategic planning of health programs. Purpose: To determine the pattern of the relative proportion of types of refractive errors among the adult candidates seeking laser assisted refractive correction in a private clinic setting in Saudi Arabia. Methods: The clinical charts of 687 patients (1374 eyes) with mean age 27.6 ± 7.5 years who desired laser vision correction and underwent a pre-LASIK work-up were reviewed retrospectively. Refractive errors were classified as myopia, hyperopia and astigmatism. Manifest refraction spherical equivalent (MRSE) was applied to define refractive errors. Outcome Measures: Distribution percentage of different types of refractive errors; myopia, hyperopia and astigmatism. Results: The mean spherical equivalent for 1374 eyes was -3.11 ± 2.88 D. Of the total 1374 eyes, 91.8% (n = 1262) eyes had myopia, 4.7% (n = 65) eyes had hyperopia and 3.4% (n = 47) had emmetropia with astigmatism. Distribution percentage of astigmatism (cylinder error of ≥ 0.50 D) was 78.5% (1078/1374 eyes); of which % 69.1% (994/1374) had low to moderate astigmatism and 9.4% (129/1374) had high astigmatism. Conclusion and Relevance: Of the adult candidates seeking laser refractive correction in a private setting in Saudi Arabia, myopia represented greatest burden with more than 90% myopic eyes, compared to hyperopia in nearly 5% eyes. Astigmatism was present in more than 78% eyes. PMID:29872484

Distance versus near visual acuity in amblyopia

PubMed Central

Christoff, Alex; Repka, Michael X.; Kaminski, Brett M.; Holmes, Jonathan M.; Ch, B

2011-01-01

Purpose There are conflicting reports about whether distance and near visual acuity are similar in eyes with amblyopia. The purpose of this study is to compare monocular distance visual acuity with near visual acuity in amblyopic eyes of children. Methods Subjects 2 to 6 years of age were evaluated in a randomized trial of amblyopia therapy for moderate amblyopia (20/40 to 20/80) due to anisometropia, strabismus, or both. Prior to initiating the protocol-prescribed therapy, subjects had best-corrected visual acuity measured with standardized protocols at 3 meters and 0.4 meters using single-surrounded HOTV optotypes. Results A total of 129 subjects were included. The mean amblyopic eye visual acuity was similar at distance and near (mean, 0.45 logMAR at distance versus 0.45 logMAR at near; mean difference, +0.00, 95% CI, −0.03 to 0.03). Of the 129 subjects, 86 (67%) tested within one line at distance and near, 19 (15%) tested more than one logMAR line better at distance, and 24 (19%) tested more than one logMAR line better at near. The mean visual acuity difference between distance and near did not differ by cause of amblyopia, age, or spherical equivalent refractive error. Conclusions We found no systematic difference between distance and near visual acuity in 2- to 6-year-old children with moderate amblyopia associated with strabismus and/or anisometropia. Individual differences between distance and near visual acuity are likely due to test–retest variability. PMID:21907115

Refraction error correction for deformation measurement by digital image correlation at elevated temperature

NASA Astrophysics Data System (ADS)

Su, Yunquan; Yao, Xuefeng; Wang, Shen; Ma, Yinji

2017-03-01

An effective correction model is proposed to eliminate the refraction error effect caused by an optical window of a furnace in digital image correlation (DIC) deformation measurement under high-temperature environment. First, a theoretical correction model with the corresponding error correction factor is established to eliminate the refraction error induced by double-deck optical glass in DIC deformation measurement. Second, a high-temperature DIC experiment using a chromium-nickel austenite stainless steel specimen is performed to verify the effectiveness of the correction model by the correlation calculation results under two different conditions (with and without the optical glass). Finally, both the full-field and the divisional displacement results with refraction influence are corrected by the theoretical model and then compared to the displacement results extracted from the images without refraction influence. The experimental results demonstrate that the proposed theoretical correction model can effectively improve the measurement accuracy of DIC method by decreasing the refraction errors from measured full-field displacements under high-temperature environment.

Prevalence of Color Vision Deficiency and its Correlation with Amblyopia and Refractive Errors among Primary School Children.

PubMed

Rajavi, Zhale; Sabbaghi, Hamideh; Baghini, Ahmad Shojaei; Yaseri, Mehdi; Sheibani, Koroush; Norouzi, Ghazal

2015-01-01

To determine the prevalence of color vision deficiency (CVD) and its correlation with amblyopia and refractive errors among primary school children. In this population-based cross-sectional study, 2160 children were selected from 36 primary schools; 60 students were from each school (10 students in each grade), with equal sex distribution. A complete eye examination including refraction using a photorefractometer, determination of visual acuity (VA) and color vision using a Yang vision tester, and evaluation of ocular media opacity using a direct ophthalmoscope was performed. Children who could not answer at least 4 plates of the Ishihara color test were considered as color vision deficient subjects. Amblyopia was determined if pinhole VA was worse than 0.3 LogMAR (equal to 20/40). The prevalence of CVD was 2.2% (95% CI: 1.5% to 3%) which was higher in male subjects (37 [3.5%] boys vs. 11 [1.0%] girls, P < 0.001). Mean VA was lower among students with CVD as compared to normal color vision children (P = 0.035) and amblyopia was observed in 8.3% (95% CI: 0.2% to 16.4%) of patients with CVD versus 2.1% (95% CI: 1.5% to 2.08%) of children with normal color vision perception (P = 0.005). A statistically significant correlation between lower VA and CVD was observed (P = 0.023). Although CVD was correlated with lower VA and amblyopia, there was no relationship between CVD and the type of amblyopia, refractive error, anisometropia or strabismus.

High Prevalence of Refractive Errors in 7 Year Old Children in Iran

PubMed Central

HASHEMI, Hassan; YEKTA, Abbasali; JAFARZADEHPUR, Ebrahim; OSTADIMOGHADDAM, Hadi; ETEMAD, Koorosh; ASHARLOUS, Amir; NABOVATI, Payam; KHABAZKHOOB, Mehdi

2016-01-01

Background: The latest WHO report indicates that refractive errors are the leading cause of visual impairment throughout the world. The aim of this study was to determine the prevalence of myopia, hyperopia, and astigmatism in 7 yr old children in Iran. Methods: In a cross-sectional study in 2013 with multistage cluster sampling, first graders were randomly selected from 8 cities in Iran. All children were tested by an optometrist for uncorrected and corrected vision, and non-cycloplegic and cycloplegic refraction. Refractive errors in this study were determined based on spherical equivalent (SE) cyloplegic refraction. Results: From 4614 selected children, 89.0% participated in the study, and 4072 were eligible. The prevalence rates of myopia, hyperopia and astigmatism were 3.04% (95% CI: 2.30–3.78), 6.20% (95% CI: 5.27–7.14), and 17.43% (95% CI: 15.39–19.46), respectively. Prevalence of myopia (P=0.925) and astigmatism (P=0.056) were not statistically significantly different between the two genders, but the odds of hyperopia were 1.11 (95% CI: 1.01–2.05) times higher in girls (P=0.011). The prevalence of with-the-rule astigmatism was 12.59%, against-the-rule was 2.07%, and oblique 2.65%. Overall, 22.8% (95% CI: 19.7–24.9) of the schoolchildren in this study had at least one type of refractive error. Conclusion: One out of every 5 schoolchildren had some refractive error. Conducting multicenter studies throughout the Middle East can be very helpful in understanding the current distribution patterns and etiology of refractive errors compared to the previous decade. PMID:27114984

Managing residual refractive error after cataract surgery.

PubMed

Sáles, Christopher S; Manche, Edward E

2015-06-01

We present a review of keratorefractive and intraocular approaches to managing residual astigmatic and spherical refractive error after cataract surgery, including laser in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), arcuate keratotomy, intraocular lens (IOL) exchange, piggyback IOLs, and light-adjustable IOLs. Currently available literature suggests that laser vision correction, whether LASIK or PRK, yields more effective and predictable outcomes than intraocular surgery. Piggyback IOLs with a rounded-edge profile implanted in the sulcus may be superior to IOL exchange, but both options present potential risks that likely outweigh the refractive benefits except in cases with large residual spherical errors. The light-adjustable IOL may provide an ideal treatment to pseudophakic ametropia by obviating the need for secondary invasive procedures after cataract surgery, but it is not widely available nor has it been sufficiently studied. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Patient-reported Outcomes for Assessment of Quality of Life in Refractive Error: A Systematic Review.

PubMed

Kandel, Himal; Khadka, Jyoti; Goggin, Michael; Pesudovs, Konrad

2017-12-01

This review has identified the best existing patient-reported outcome (PRO) instruments in refractive error. The article highlights the limitations of the existing instruments and discusses the way forward. A systematic review was conducted to identify the types of PROs used in refractive error, to determine the quality of the existing PRO instruments in terms of their psychometric properties, and to determine the limitations in the content of the existing PRO instruments. Articles describing a PRO instrument measuring 1 or more domains of quality of life in people with refractive error were identified by electronic searches on the MEDLINE, PubMed, Scopus, Web of Science, and Cochrane databases. The information on content development, psychometric properties, validity, reliability, and responsiveness of those PRO instruments was extracted from the selected articles. The analysis was done based on a comprehensive set of assessment criteria. One hundred forty-eight articles describing 47 PRO instruments in refractive error were included in the review. Most of the articles (99 [66.9%]) used refractive error-specific PRO instruments. The PRO instruments comprised 19 refractive, 12 vision but nonrefractive, and 16 generic PRO instruments. Only 17 PRO instruments were validated in refractive error populations; six of them were developed using Rasch analysis. None of the PRO instruments has items across all domains of quality of life. The Quality of Life Impact of Refractive Correction, the Quality of Vision, and the Contact Lens Impact on Quality of Life have comparatively better quality with some limitations, compared with the other PRO instruments. This review describes the PRO instruments and informs the choice of an appropriate measure in refractive error. We identified need of a comprehensive and scientifically robust refractive error-specific PRO instrument. Item banking and computer-adaptive testing system can be the way to provide such an instrument.

Relationship between lenticular power and refractive error in children with hyperopia

PubMed Central

Tomomatsu, Takeshi; Kono, Shinjiro; Arimura, Shogo; Tomomatsu, Yoko; Matsumura, Takehiro; Takihara, Yuji; Inatani, Masaru; Takamura, Yoshihiro

2013-01-01

Objectives To evaluate the contribution of axial length, and lenticular and corneal power to the spherical equivalent refractive error in children with hyperopia between 3 and 13 years of age, using noncontact optical biometry. Methods There were 62 children between 3 and 13 years of age with hyperopia (+2 diopters [D] or more) who underwent automated refraction measurement with cycloplegia, to measure spherical equivalent refractive error and corneal power. Axial length was measured using an optic biometer that does not require contact with the cornea. The refractive power of the lens was calculated using the Sanders-Retzlaff-Kraff formula. Single regression analysis was used to evaluate the correlation among the optical parameters. Results There was a significant positive correlation between age and axial length (P = 0.0014); however, the degree of hyperopia did not decrease with aging (P = 0.59). There was a significant negative correlation between age and the refractive power of the lens (P = 0.0001) but not that of the cornea (P = 0.43). A significant negative correlation was observed between the degree of hyperopia and lenticular power (P < 0.0001). Conclusion Although this study is small scale and cross sectional, the analysis, using noncontact biometry, showed that lenticular power was negatively correlated with refractive error and age, indicating that lower lens power may contribute to the degree of hyperopia. PMID:23576859

Relationship between lenticular power and refractive error in children with hyperopia.

PubMed

Tomomatsu, Takeshi; Kono, Shinjiro; Arimura, Shogo; Tomomatsu, Yoko; Matsumura, Takehiro; Takihara, Yuji; Inatani, Masaru; Takamura, Yoshihiro

2013-01-01

To evaluate the contribution of axial length, and lenticular and corneal power to the spherical equivalent refractive error in children with hyperopia between 3 and 13 years of age, using noncontact optical biometry. There were 62 children between 3 and 13 years of age with hyperopia (+2 diopters [D] or more) who underwent automated refraction measurement with cycloplegia, to measure spherical equivalent refractive error and corneal power. Axial length was measured using an optic biometer that does not require contact with the cornea. The refractive power of the lens was calculated using the Sanders-Retzlaff-Kraff formula. Single regression analysis was used to evaluate the correlation among the optical parameters. There was a significant positive correlation between age and axial length (P = 0.0014); however, the degree of hyperopia did not decrease with aging (P = 0.59). There was a significant negative correlation between age and the refractive power of the lens (P = 0.0001) but not that of the cornea (P = 0.43). A significant negative correlation was observed between the degree of hyperopia and lenticular power (P < 0.0001). Although this study is small scale and cross sectional, the analysis, using noncontact biometry, showed that lenticular power was negatively correlated with refractive error and age, indicating that lower lens power may contribute to the degree of hyperopia.

Clear lens phacoemulsification in Alport syndrome: refractive results and electron microscopic analysis of the anterior lens capsule.

PubMed

Bayar, Sezin Akca; Pinarci, Eylem Yaman; Karabay, Gulten; Akman, Ahmet; Oto, Sibel; Yilmaz, Gursel

2014-01-01

To report the ocular findings of patients with Alport syndrome and the results of clear lens extraction in this patient group. Twenty-three eyes of 15 patients with a diagnosis of Alport syndrome were included in this study. Clear corneal phacoemulsification and intraocular foldable lens implantation was performed in eyes with indeterminate refractive errors and/or poor visual acuity and anterior capsule samples were analyzed with electron microscopy. All patients had a history of hereditary nephritis and/or deafness as systemic involvement. Ophthalmologic examination revealed anterior lenticonus with high myopia and/or irregular astigmatism in all patients. The mean best-corrected visual acuity (BCVA) was 0.67 ± 0.17 logMAR (range 1.0-0.4) preoperatively and 0.17 ± 0.08 logMAR (range 0.3-0.0) postoperatively. Postoperative refractive lenticular astigmatism dramatically decreased and no ocular complications arose during the follow-up period. Transmission electron microscopic analysis of the lens capsules supported the diagnosis of Alport syndrome. Clear lens phacoemulsification and foldable intraocular lens implantation is a safe and effective therapeutic choice for the management of uncorrectable refractive errors and low visual acuity due to anterior lenticonus in patients with Alport syndrome.

Prevalence of refractive error in Europe: the European Eye Epidemiology (E(3)) Consortium.

PubMed

Williams, Katie M; Verhoeven, Virginie J M; Cumberland, Phillippa; Bertelsen, Geir; Wolfram, Christian; Buitendijk, Gabriëlle H S; Hofman, Albert; van Duijn, Cornelia M; Vingerling, Johannes R; Kuijpers, Robert W A M; Höhn, René; Mirshahi, Alireza; Khawaja, Anthony P; Luben, Robert N; Erke, Maja Gran; von Hanno, Therese; Mahroo, Omar; Hogg, Ruth; Gieger, Christian; Cougnard-Grégoire, Audrey; Anastasopoulos, Eleftherios; Bron, Alain; Dartigues, Jean-François; Korobelnik, Jean-François; Creuzot-Garcher, Catherine; Topouzis, Fotis; Delcourt, Cécile; Rahi, Jugnoo; Meitinger, Thomas; Fletcher, Astrid; Foster, Paul J; Pfeiffer, Norbert; Klaver, Caroline C W; Hammond, Christopher J

2015-04-01

To estimate the prevalence of refractive error in adults across Europe. Refractive data (mean spherical equivalent) collected between 1990 and 2013 from fifteen population-based cohort and cross-sectional studies of the European Eye Epidemiology (E(3)) Consortium were combined in a random effects meta-analysis stratified by 5-year age intervals and gender. Participants were excluded if they were identified as having had cataract surgery, retinal detachment, refractive surgery or other factors that might influence refraction. Estimates of refractive error prevalence were obtained including the following classifications: myopia ≤-0.75 diopters (D), high myopia ≤-6D, hyperopia ≥1D and astigmatism ≥1D. Meta-analysis of refractive error was performed for 61,946 individuals from fifteen studies with median age ranging from 44 to 81 and minimal ethnic variation (98 % European ancestry). The age-standardised prevalences (using the 2010 European Standard Population, limited to those ≥25 and <90 years old) were: myopia 30.6 % [95 % confidence interval (CI) 30.4-30.9], high myopia 2.7 % (95 % CI 2.69-2.73), hyperopia 25.2 % (95 % CI 25.0-25.4) and astigmatism 23.9 % (95 % CI 23.7-24.1). Age-specific estimates revealed a high prevalence of myopia in younger participants [47.2 % (CI 41.8-52.5) in 25-29 years-olds]. Refractive error affects just over a half of European adults. The greatest burden of refractive error is due to myopia, with high prevalence rates in young adults. Using the 2010 European population estimates, we estimate there are 227.2 million people with myopia across Europe.

Comparison of refractive errors and factors associated with spectacle use in a rural and urban South Indian population

PubMed Central

Prema, Raju; Sathyamangalam Ve, Ramesh; Hemamalini, Arvind; Baskaran, Mani; Kumaramanickavel, Govindaswamy; Catherine, McCarty; Vijaya, Lingam

2008-01-01

Purpose: To compare the prevalence of refractive errors and factors associated with spectacle use in a rural and urban south Indian population. Materials and Methods: Four thousand eight hundred subjects (age >39 years) each from rural and urban Tamil Nadu were enumerated for a population-based study. All participants underwent a complete ophthalmic evaluation including best-corrected visual acuity (BCVA), objective and subjective refraction. Out of 3924 rural responders 63.91% and out of 3850 urban responders 81.64% were phakic in the right eye with BCVA of 20/40 or better and were included in the study. Association of spectacle use and refractive errors with different parameters were analysed using logistic regression. Statistical Analysis: Chi square, t test, Chi square for trend and Pearson′s correlation coefficient were used for analysis. Results: Spectacle use was significantly higher and positively associated with literacy and employment in the urban population. The age and gender-adjusted prevalence of emmetropia, myopia of spherical equivalent (SE) ≤-0.50 diopter sphere (DS), high myopia (SE ≤-5.00DS), hyperopia (SE >0.50DS) and astigmatism ≤ 0.50 diopter cylinder (DC) were 46.8%, 31.0%, 4.3%, 17.9% and 60.4% respectively in the rural population and 29.0%, 17.6%, 1.5%, 51.9%, 59.1% respectively in the urban population. The prevalence of emmetropia decreased with age (p < 0.001); prevalence of myopia and high myopia increased with age (p = 0.001) and were associated with nuclear sclerosis (p = 0.001) in both populations. Hyperopia was commoner among women than men (p = 0.001); was positively associated with diabetes mellitus (p = 0.008) in the rural population and negatively with nuclear sclerosis (p = 0.001) in both populations. Conclusion: Spectacle use was found to be significantly lower in the rural population. The pattern of refractive errors was significantly different between both populations. PMID:18292625

Prevalence of refractive errors in a Brazilian population: the Botucatu eye study.

PubMed

Schellini, Silvana Artioli; Durkin, Shane R; Hoyama, Erika; Hirai, Flavio; Cordeiro, Ricardo; Casson, Robert J; Selva, Dinesh; Padovani, Carlos Roberto

2009-01-01

To determine the prevalence and demographic associations of refractive error in Botucatu, Brazil. A population-based, cross-sectional prevalence study was conducted, which involved random, household cluster sampling of an urban Brazilian population in Botucatu. There were 3000 individuals aged 1 to 91 years (mean 38.3) who were eligible to participate in the study. Refractive error measurements were obtained by objective refraction. Objective refractive error examinations were performed on 2454 residents within this sample (81.8% of eligible participants). The mean age was 38 years (standard deviation (SD) 20.8 years, Range 1 to 91) and females comprised 57.5% of the study population. Myopia (spherical equivalent (SE) < -0.5 dropters (D)) was most prevalent among those aged 30-39 years (29.7%; 95% confidence interval (CI) 24.8-35.1) and least prevalent among children under 10 years (3.8%; 95% confidence interval (CI) 1.6-7.3). Conversely hypermetropia (SE > 0.5D) was most prevalent among participants under 10 years (86.9%; 95% CI 81.6-91.1) and least prevalent in the fourth decade (32.5%; 95% CI 28.2-37.0). Participants aged 70 years or older bore the largest burden of astigmatism (cylinder at least -0.5D) and anisometropia (difference in SE of > 0.5D) with a prevalence of 71.7% (95% CI 64.8-78.0) 55.0% (95% CI 47.6-62.2) respectively. Myopia and hypermetropia were significantly associated with age in a bimodal manner (P < 0.001), whereas anisometropia and astigmatism increased in line with age (P < 0.001). Multivariate modeling confirmed age-related risk factors for refractive error and revealed several gender, occupation and ethnic-related risk factors. These results represent previously unreported data on refractive error within this Brazilian population. They signal a need to continue to screen for refractive error within this population and to ensure that people have adequate access to optical correction.

Comparing the Impact of Refractive and Non-Refractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation

PubMed Central

Zebardast, Nazlee; Swenor, Bonnielin K.; van Landingham, Suzanne W.; Massof, Robert W.; Munoz, Beatriz; West, Sheila K.; Ramulu, Pradeep Y.

2015-01-01

Purpose To compare the effects of uncorrected refractive error (URE) and non-refractive visual impairment (VI) on performance and disability measures. Design Cross-sectional population-based study. Participants 2469 individuals with binocular presenting visual acuity (PVA) of 20/80 or better who participated in the first round of the Salisbury Eye Evaluation study. Methods URE was defined as binocular PVA of 20/30 or worse, improving to better than 20/30 with subjective refraction. VI was defined as post-refraction binocular best corrected visual acuity (BCVA) of 20/30 or worse. The visual acuity decrement attributable to VI was calculated as the difference between BCVA and 20/30 while that due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of 1) vision status (VI, URE, or normal vision) using the group with normal vision as reference, and 2) a one-line decrement in acuity due to VI or URE. Main Outcome Measures Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. ADV responses were analyzed using Rasch analysis to determine visual ability. Results Compared to individuals with normal vision, subjects with VI (n=191) had significantly poorer objective and subjective visual functioning in all metrics examined (p<0.05) while subjects with URE (n=132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation and lower ADV scores (p<0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a one-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared to a one-line VA decrement due to URE

[Use of Plusoptix as a screening method for refractive ambliopia].

PubMed

Bogdănici, T; Tone, Silvia; Miron, Mihaela; Boboc, Mihaela; Bogdănici, Camelia

2012-01-01

Highlighting the differences in the objective refraction using the Plusoptix AO9 comparing them with the refraction performed with TOPCON KR-8900 autorefractor. Prospective study for 3 months held in the Ophthalmology Clinic in Iasi, Hospital Sf. Spiridon on a total of 39 children (21 girls and 18 boys) with mean age of 10.61 +/- 5.67 years. Clinical parameters: sex, age, objective refraction obtained with Plusoptix and with autorefractor corrected visual acuity (with different methods depending on each patient age), ortoptic examination (strabic deviation, binocular vision), the presence of symetry/asymetry while measuring with Plusoptix. The results were statistically processed by F-TEST calculating the correlation coefficient, standard deviation, significance level (using the spherical equivalent of the obtained values). Age limits of the studied cases ranged between 2-23 years. Visual acuity of children who had cooperate was between 0.2-1 with correction, achieving best values on right eye than left eye. 8 cases (20.51%) had large differences between measurements made with Plusoptix and autorefractor, half of that (4 cases) had strabismus. Three of these cases were with small hypermetropia and one with small myopia (Plusoptix shows a lower value). In 2 cases occurred higher differences (about 2-2,5D) between the 2 measurements, in patients with average hypermetropia. Plusoptix refraction was not possible at high hypermetropia or high myopia. This type of determining objective refraction using Plusoptix is a useful method of screening for discovery of refractive errors that can cause refractive amblyopia in young children and in those cases with a difficult collaboration. Because there are differences betweeti this 2 methods, for children with refractive errors are recommended further exploration to determine the appropriate optical correction. Plusoptix is a limited method because it cannot detect the exact values in those cases with high hypermetropia or high

Prevalence of visual impairment due to uncorrected refractive error: Results from Delhi-Rapid Assessment of Visual Impairment Study.

PubMed

Senjam, Suraj Singh; Vashist, Praveen; Gupta, Noopur; Malhotra, Sumit; Misra, Vasundhara; Bhardwaj, Amit; Gupta, Vivek

2016-05-01

To estimate the prevalence of visual impairment (VI) due to uncorrected refractive error (URE) and to assess the barriers to utilization of services in the adult urban population of Delhi. A population-based rapid assessment of VI was conducted among people aged 40 years and above in 24 randomly selected clusters of East Delhi district. Presenting visual acuity (PVA) was assessed in each eye using Snellen's "E" chart. Pinhole examination was done if PVA was <20/60 in either eye and ocular examination to ascertain the cause of VI. Barriers to utilization of services for refractive error were recorded with questionnaires. Of 2421 individuals enumerated, 2331 (96%) individuals were examined. Females were 50.7% among them. The mean age of all examined subjects was 51.32 ± 10.5 years (standard deviation). VI in either eye due to URE was present in 275 individuals (11.8%, 95% confidence interval [CI]: 10.5-13.1). URE was identified as the most common cause (53.4%) of VI. The overall prevalence of VI due to URE in the study population was 6.1% (95% CI: 5.1-7.0). The elder population as well as females were more likely to have VI due to URE (odds ratio [OR] = 12.3; P < 0.001 and OR = 1.5; P < 0.02). Lack of felt need was the most common reported barrier (31.5%). The prevalence of VI due to URE among the urban adult population of Delhi is still high despite the availability of abundant eye care facilities. The majority of reported barriers are related to human behavior and attitude toward the refractive error. Understanding these aspects will help in planning appropriate strategies to eliminate VI due to URE.

Effects of refractive errors on visual evoked magnetic fields.

PubMed

Suzuki, Masaya; Nagae, Mizuki; Nagata, Yuko; Kumagai, Naoya; Inui, Koji; Kakigi, Ryusuke

2015-11-09

The latency and amplitude of visual evoked cortical responses are known to be affected by refractive states, suggesting that they may be used as an objective index of refractive errors. In order to establish an easy and reliable method for this purpose, we herein examined the effects of refractive errors on visual evoked magnetic fields (VEFs). Binocular VEFs following the presentation of a simple grating of 0.16 cd/m(2) in the lower visual field were recorded in 12 healthy volunteers and compared among four refractive states: 0D, +1D, +2D, and +4D, by using plus lenses. The low-luminance visual stimulus evoked a main MEG response at approximately 120 ms (M100) that reversed its polarity between the upper and lower visual field stimulations and originated from the occipital midline area. When refractive errors were induced by plus lenses, the latency of M100 increased, while its amplitude decreased with an increase in power of the lens. Differences from the control condition (+0D) were significant for all three lenses examined. The results of dipole analyses showed that evoked fields for the control (+0D) condition were explainable by one dipole in the primary visual cortex (V1), while other sources, presumably in V3 or V6, slightly contributed to shape M100 for the +2D or +4D condition. The present results showed that the latency and amplitude of M100 are both useful indicators for assessing refractive states. The contribution of neural sources other than V1 to M100 was modest under the 0D and +1D conditions. By considering the nature of the activity of M100 including its high sensitivity to a spatial frequency and lower visual field dominance, a simple low-luminance grating stimulus at an optimal spatial frequency in the lower visual field appears appropriate for obtaining data on high S/N ratios and reducing the load on subjects.

Comparison between refractometer and retinoscopy in determining refractive errors in children--false doubt.

PubMed

Pokupec, Rajko; Mrazovac, Danijela; Popović-Suić, Smiljka; Mrazovac, Visnja; Kordić, Rajko; Petricek, Igor

2013-04-01

Early detection of a refractive error and its correction are extremely important for the prevention of amblyopia (poor vision). The golden standard in the detection of refractive errors is retinoscopy--a method where the pupils are dilated in order to exclude accomodation. This results in a more accurate measurement of a refractive error. Automatic computer refractometer is also in use. The study included 30 patients, 15 boys, 15 girls aged 4-16. The first examination was conducted with refractometer on narrow pupils. Retinoscopy, followed by another examination with refractometer was performed on pupils dilated with mydriatic drops administered 3 times. The results obtained with three methods were compared. They indicate that in narrow pupils the autorefractometer revealed an increased diopter value in nearsightedness (myopia), the minus overcorrection, whereas findings obtained with retinoscopy and autorefractometer in mydriasis cycloplegia, were much more accurate. The results were statistically processed, which confirmed the differences between obtained measurements. These findings are consistent with the results of studies conducted by other authors. Automatic refractometry on narrow pupils has proven to be a method for detection of refractive errors in children. However, the exact value of the refractive error is obtained only in mydriasis--with retinoscopy or an automatic refractometer on dilated pupils.

Refractive errors in the adult pakistani population: the national blindness and visual impairment survey.

PubMed

Shah, Shaheen P; Jadoon, Mohammad Z; Dineen, Brendan; Bourne, Rupert R A; Johnson, Gordon J; Gilbert, Clare E; Khan, Mohammad D

2008-01-01

To determine the prevalence of refractive error (RE) and spectacle wear and to explore the need for spectacle correction in adults (30 years or older) in Pakistan. Multi-stage, cluster random sampling national survey. Each subject had their medical history taken, visual acuity measured, and underwent autorefraction, biometry and fundus examination. Those that presented with visual acuity of less than 6/12 in either eye underwent more detailed examination, including corrected distance visual acuity measurement (autorefraction results placed in a trial lens frame). Myopia was defined as a spherical equivalent of worse than -0.5D, hypermetropia as greater than +0.5D, and astigmatism as greater than 0.75D. Spectacle need (i.e., those that improved from unaided VA with spectacle correction) was determined along with the spectacle coverage, defined as the proportion of need that was met (by the participant's own spectacles). The crude prevalence of myopia, hypermetropia and astigmatism was 36.5%, 27.1%, and 37%, respectively. The prevalence of spectacle wear in phakic participants was 4.0%, significantly lower than for those who were pseudo/aphakic (41.7%). Just over a quarter (25.8%) of spectacle wearers presenting with visual impairment (< 6/12) were able to improve their vision when retested with their autorefraction prescription. The overall spectacle coverage (6/12 cutoff) was 15.1%. This survey provides the first reliable national estimates. RE services are not covering the majority of the population in need and the provision of spectacle correction, as a highly cost effective treatment for visual impairment, needs addressing within the country's national eye care program.

Simplified mathematics for customized refractive surgery.

PubMed

Preussner, Paul Rolf; Wahl, Jochen

2003-03-01

To describe a simple mathematical approach to customized corneal refractive surgery or customized intraocular lens (IOL) design that allows "hypervision" and to investigate the accuracy limits. University eye hospital, Mainz, Germany. Corneal shape and at least 1 IOL surface are approximated by the well-known Cartesian conic section curves (ellipsoid, paraboloid, or hyperboloid). They are characterized by only 2 parameters, the vertex radius and the numerical eccentricity. Residual refraction errors for this approximation are calculated by numerical ray tracing. These errors can be displayed as a 2-dimensional refraction map across the pupil or by blurring the image of a Landolt ring superimposed on the retinal receptor grid, giving an overall impression of the visual outcome. If the eye is made emmetropic for paraxial rays and if the numerical eccentricities of the cornea and lens are appropriately fitted to each other, the residual refractive errors are small enough to allow hypervision. Visual acuity of at least 2.0 (20/10) appears to be possible, particularly for mesopic pupil diameters. However, customized optics may have limited application due to their sensitivity to misalignment errors such as decentrations or rotations. The mathematical approach described by Descartes 350 years ago is adequate to calculate hypervision optics for the human eye. The availability of suitable mathematical tools should, however, not be viewed with too much optimism as long as the accuracy of the implementation in surgical procedures is limited.

Prevalence of refractive errors in the European adult population: the Gutenberg Health Study (GHS).

PubMed

Wolfram, Christian; Höhn, René; Kottler, Ulrike; Wild, Philipp; Blettner, Maria; Bühren, Jens; Pfeiffer, Norbert; Mirshahi, Alireza

2014-07-01

To study the distribution of refractive errors among adults of European descent. Population-based eye study in Germany with 15010 participants aged 35-74 years. The study participants underwent a detailed ophthalmic examination according to a standardised protocol. Refractive error was determined by an automatic refraction device (Humphrey HARK 599) without cycloplegia. Definitions for the analysis were myopia <-0.5 dioptres (D), hyperopia >+0.5 D, astigmatism >0.5 cylinder D and anisometropia >1.0 D difference in the spherical equivalent between the eyes. Exclusion criterion was previous cataract or refractive surgery. 13959 subjects were eligible. Refractive errors ranged from -21.5 to +13.88 D. Myopia was present in 35.1% of this study sample, hyperopia in 31.8%, astigmatism in 32.3% and anisometropia in 13.5%. The prevalence of myopia decreased, while the prevalence of hyperopia, astigmatism and anisometropia increased with age. 3.5% of the study sample had no refractive correction for their ametropia. Refractive errors affect the majority of the population. The Gutenberg Health Study sample contains more myopes than other study cohorts in adult populations. Our findings do not support the hypothesis of a generally lower prevalence of myopia among adults in Europe as compared with East Asia.

Visual function of police officers who have undergone refractive surgery.

PubMed

Hovis, Jeffery K; Ramaswamy, Shankaran

2006-11-01

The visual acuity and contrast sensitivity of police recruits and officers was evaluated in both normal and dim illumination conditions to determine whether officers who have had refractive surgery have compromised night vision. The control group consisted of 76 officers and recruits who have not had refractive surgery and the refractive surgery group consisted of 22 officers and recruits who had refractive surgery. Visual acuity and contrast sensitivity were measured under both room illumination and dim illumination. The room illumination test series included high contrast acuity, low contrast acuity and Pelli-Robson contrast sensitivity. The dim illumination test series included high contrast acuity, low contrast acuity, Pelli-Robson contrast sensitivity, license plate number acuity (with and without glare) and the Mesotest. The general findings were that the refractive surgery group had lower acuity scores on low contrast targets in both room and dim light levels along with a reduction in the Mesotest scores with a glare source compared to the control group. Although refractive surgery police recruits and officers had reduced performance on some vision tests, these reductions were small and it is unlikely that their performance on vision related tasks would be compromised, on average. The major concern is the small number of refractive surgery candidates whose results were well outside the range of the non-surgical candidates. Their vision may be unacceptable for policing. Copyright (c) 2006 Wiley-Liss, Inc.

Evaluation of Visual Acuity Measurements after Autorefraction versus Manual Refraction in Eyes with and without Diabetic Macular Edema

PubMed Central

Sun, Jennifer K.; Qin, Haijing; Aiello, Lloyd Paul; Melia, Michele; Beck, Roy W.; Andreoli, Christopher M.; Edwards, Paul A.; Glassman, Adam R.; Pavlica, Michael R.

2012-01-01

Objective To compare visual acuity (VA) scores after autorefraction versus research protocol manual refraction in eyes of patients with diabetes and a wide range of VA. Methods Electronic Early Treatment Diabetic Retinopathy Study (E-ETDRS) VA Test© letter score (EVA) was measured after autorefraction (AR-EVA) and after Diabetic Retinopathy Clinical Research Network (DRCR.net) protocol manual refraction (MR-EVA). Testing order was randomized, study participants and VA examiners were masked to refraction source, and a second EVA utilizing an identical manual refraction (MR-EVAsupl) was performed to determine test-retest variability. Results In 878 eyes of 456 study participants, median MR-EVA was 74 (Snellen equivalent approximately 20/32). Spherical equivalent was often similar for manual and autorefraction (median difference: 0.00, 5th and 95th percentiles −1.75 to +1.13 Diopters). However, on average, MR-EVA results were slightly better than AR-EVA results across the entire VA range. Furthermore, variability between AR-EVA and MR-EVA was substantially greater than the test-retest variability of MR-EVA (P<0.001). Variability of differences was highly dependent on autorefractor model. Conclusions Across a wide range of VA at multiple sites using a variety of autorefractors, VA measurements tend to be worse with autorefraction than manual refraction. Differences between individual autorefractor models were identified. However, even among autorefractor models comparing most favorably to manual refraction, VA variability between autorefraction and manual refraction is higher than the test-retest variability of manual refraction. The results suggest that with current instruments, autorefraction is not an acceptable substitute for manual refraction for most clinical trials with primary outcomes dependent on best-corrected VA. PMID:22159173

Ocular manifestations of sickle cell disease and genetic susceptibility for refractive errors

PubMed Central

Shukla, Palak; Verma, Henu; Patel, Santosh; Patra, P. K.; Bhaskar, L. V. K. S.

2017-01-01

PURPOSE: Sickle cell disease (SCD) is the most common and serious form of an inherited blood disorder that lead to higher risk of early mortality. SCD patients are at high risk for developing multiorgan acute and chronic complications linked with significant morbidity and mortality. Some of the ophthalmological complications of SCD include retinal changes, refractive errors, vitreous hemorrhage, and abnormalities of the cornea. MATERIALS AND METHODS: The present study includes 96 SCD patients. A dilated comprehensive eye examination was performed to know the status of retinopathy. Refractive errors were measured in all patients. In patients with >10 years of age, cycloplegia was not performed before autorefractometry. A subset of fifty patients’ genotyping was done for NOS3 27-base pair (bp) variable number of tandem repeat (VNTR) and IL4 intron-3 VNTR polymorphisms using polymerase chain reaction-electrophoresis. Chi-square test was performed to test the association between the polymorphisms and refractive errors. RESULTS: The results of the present study revealed that 63.5% of patients have myopia followed by 19.8% hyperopia. NOS3 27-bp VNTR genotypes significantly deviated from Hardy–Weinberg equilibrium (P < 0.0001). Although IL4 70-bp VNTR increased the risk of developing refractive errors, it is not statistically significant. However, NOS3 27-bp VNTR significantly reduced the risk of development of myopia. CONCLUSION: In summary, our study documents the prevalence of refractive errors along with some retinal changes in Indian SCD patients. Further, this study demonstrates that the NOS3 VNTR contributes to the susceptibility to development of myopia in SCD cases. PMID:29018763

Ocular manifestations of sickle cell disease and genetic susceptibility for refractive errors.

PubMed

Shukla, Palak; Verma, Henu; Patel, Santosh; Patra, P K; Bhaskar, L V K S

2017-01-01

Sickle cell disease (SCD) is the most common and serious form of an inherited blood disorder that lead to higher risk of early mortality. SCD patients are at high risk for developing multiorgan acute and chronic complications linked with significant morbidity and mortality. Some of the ophthalmological complications of SCD include retinal changes, refractive errors, vitreous hemorrhage, and abnormalities of the cornea. The present study includes 96 SCD patients. A dilated comprehensive eye examination was performed to know the status of retinopathy. Refractive errors were measured in all patients. In patients with >10 years of age, cycloplegia was not performed before autorefractometry. A subset of fifty patients' genotyping was done for NOS3 27-base pair (bp) variable number of tandem repeat (VNTR) and IL4 intron-3 VNTR polymorphisms using polymerase chain reaction-electrophoresis. Chi-square test was performed to test the association between the polymorphisms and refractive errors. The results of the present study revealed that 63.5% of patients have myopia followed by 19.8% hyperopia. NOS3 27-bp VNTR genotypes significantly deviated from Hardy-Weinberg equilibrium ( P < 0.0001). Although IL4 70-bp VNTR increased the risk of developing refractive errors, it is not statistically significant. However, NOS3 27-bp VNTR significantly reduced the risk of development of myopia. In summary, our study documents the prevalence of refractive errors along with some retinal changes in Indian SCD patients. Further, this study demonstrates that the NOS3 VNTR contributes to the susceptibility to development of myopia in SCD cases.

Prevalence of Visual Impairment and Refractive Errors in Children of South Sinai, Egypt.

PubMed

Yamamah, Gamal Abdel Naser; Talaat Abdel Alim, Ahmed Ahmed; Mostafa, Yehia Salah El Din; Ahmed, Rania Ahmed Abdel Salam; Mohammed, Asmaa Mahmoud; Mahmoud, Asmaa Mohammed

2015-01-01

To assess the prevalence and causes of visual impairment in children of South Sinai, and to evaluate outcomes of rehabilitation programs. Population-based, cross-sectional analysis of 2070 healthy school children screened for visual impairment from 2009 through 2010 in cities of South Sinai and their surrounding Bedouin settlements. Visual acuity (VA) was tested using Snellen charts followed by cycloplegic autorefractometry for cases with presenting VA ≤ 6/9. Appropriate eyeglasses were prescribed and VA re-evaluated. This study included 1047 boys and 1023 girls, mean age 10.7 ± 3.1 years. Visual impairment (uncorrected VA ≤ 6/9) was detected in 29.4% of children, while 2.0% had moderate-severe visual impairment (uncorrected VA ≤ 6/24). There were statistically significant differences in prevalence of visual impairment between the studied cities (p < 0.05), with the highest prevalence in Abu Redis. Prevalence of visual impairment was significantly higher among girls (p < 0.05) and those with positive consanguinity (p < 0.05). Bedouin children showed significantly lower prevalences of visual impairment. Only age was a reliable predictor of visual impairment (odds ratio 0.94, p < 0.0001). Ophthalmic examination revealed other disorders, e.g. dry eye (4.74%), squint (2.37%), exophthalmos (1.58%) and ptosis (0.79%). VA significantly improved in children who received spectacles (p < 0.001). A total of 29.4% of South Sinai children had some form of visual impairment, 90.32% of which comprised refractive errors (mainly astigmatism) which were significantly corrected with eyeglasses. VA screening and correction of refractive errors are of the utmost importance for ensuring better visual outcomes and improved school performance.

The prevalence of refractive errors among adult rural populations in Iran.

PubMed

Hashemi, Hassan; Nabovati, Payam; Yekta, Abbasali; Shokrollahzadeh, Fereshteh; Khabazkhoob, Mehdi

2018-01-01

The aim was to determine the prevalence of myopia and hyperopia and related factors in underserved rural areas in Iran. Under random cluster sampling, two rural regions were randomly selected in the north and southwest of the country, and 3,061 persons over 15 years of age were invited into the study. After selecting samples, all participants had refraction, measurement of uncorrected vision and visual acuity and ocular health examination by slitlamp biomicroscopy. Of the 3,061 invitees, 2,575 participated in the study (response rate: 84.1 per cent). After excluding those who met the exclusion criteria or had missing refractive data, eventually there were 2,518 subjects available for this analysis. The mean age of the participants was 44.3 ± 17.5 years (range: 16 to 93 years) and 1,460 of them (58.0 per cent) were female. The overall prevalence of myopia and hyperopia in this study was 25.2 per cent (95 per cent CI: 23.2 to 27.2) and 22.5 per cent (95 per cent CI: 20.6 to 24.4), respectively. The prevalence of myopia increased from 20.9 per cent in participants 16 to 20 years to 32.9 per cent in the 21 to 30 years age group, declined up to the age of 60 years and increased again afterwards. The lowest prevalence was 6.8 per cent observed in the 16 to 20 years age group and the highest was 45.8 per cent in 61- to 70-year-olds. In the final logistic regression model, myopia significantly associated with age, higher education levels and cataracts, while hyperopia associated with age, lower education levels and male gender. In our study, the prevalence of myopia was lower and the prevalence of hyperopia was higher compared to most previous studies. The findings of this study imply that refractive errors vary by age. © 2017 Optometry Australia.

Prevalence of refractive errors in the Slovak population calculated using the Gullstrand schematic eye model.

PubMed

Popov, I; Valašková, J; Štefaničková, J; Krásnik, V

2017-01-01

A substantial part of the population suffers from some kind of refractive errors. It is envisaged that their prevalence may change with the development of society. The aim of this study is to determine the prevalence of refractive errors using calculations based on the Gullstrand schematic eye model. We used the Gullstrand schematic eye model to calculate refraction retrospectively. Refraction was presented as the need for glasses correction at a vertex distance of 12 mm. The necessary data was obtained using the optical biometer Lenstar LS900. Data which could not be obtained due to the limitations of the device was substituted by theoretical data from the Gullstrand schematic eye model. Only analyses from the right eyes were presented. The data was interpreted using descriptive statistics, Pearson correlation and t-test. The statistical tests were conducted at a level of significance of 5%. Our sample included 1663 patients (665 male, 998 female) within the age range of 19 to 96 years. Average age was 70.8 ± 9.53 years. Average refraction of the eye was 2.73 ± 2.13D (males 2.49 ± 2.34, females 2.90 ± 2.76). The mean absolute error from emmetropia was 3.01 ± 1.58 (males 2.83 ± 2.95, females 3.25 ± 3.35). 89.06% of the sample was hyperopic, 6.61% was myopic and 4.33% emmetropic. We did not find any correlation between refraction and age. Females were more hyperopic than males. We did not find any statistically significant hypermetopic shift of refraction with age. According to our estimation, the calculations of refractive errors using the Gullstrand schematic eye model showed a significant hypermetropic shift of more than +2D. Our results could be used in future for comparing the prevalence of refractive errors using same methods we used.Key words: refractive errors, refraction, Gullstrand schematic eye model, population, emmetropia.

The ipRGC-Driven Pupil Response with Light Exposure, Refractive Error, and Sleep.

PubMed

Abbott, Kaleb S; Queener, Hope M; Ostrin, Lisa A

2018-04-01

We investigated links between the intrinsically photosensitive retinal ganglion cells, light exposure, refractive error, and sleep. Results showed that morning melatonin was associated with light exposure, with modest differences in sleep quality between myopes and emmetropes. Findings suggest a complex relationship between light exposure and these physiological processes. Intrinsically photosensitive retinal ganglion cells (ipRGCs) signal environmental light, with pathways to the midbrain to control pupil size and circadian rhythm. Evidence suggests that light exposure plays a role in refractive error development. Our goal was to investigate links between light exposure, ipRGCs, refractive error, and sleep. Fifty subjects, aged 17-40, participated (19 emmetropes and 31 myopes). A subset of subjects (n = 24) wore an Actiwatch Spectrum for 1 week. The Pittsburgh Sleep Quality Index (PSQI) was administered, and saliva samples were collected for melatonin analysis. The post-illumination pupil response (PIPR) to 1 s and 5 s long- and short-wavelength stimuli was measured. Pupil metrics included the 6 s and 30 s PIPR and early and late area under the curve. Subjects spent 104.8 ± 46.6 min outdoors per day over the previous week. Morning melatonin concentration (6.9 ± 3.5 pg/ml) was significantly associated with time outdoors and objectively measured light exposure (P = .01 and .002, respectively). Pupil metrics were not significantly associated with light exposure or refractive error. PSQI scores indicated good sleep quality for emmetropes (score 4.2 ± 2.3) and poor sleep quality for myopes (5.6 ± 2.2, P = .04). We found that light exposure and time outdoors influenced morning melatonin concentration. No differences in melatonin or the ipRGC-driven pupil response were observed between refractive error groups, although myopes exhibited poor sleep quality compared to emmetropes. Findings suggest that a complex relationship between light exposure, ipRGCs, refractive

Refractive errors in 3-6 year-old Chinese children: a very low prevalence of myopia?

PubMed

Lan, Weizhong; Zhao, Feng; Lin, Lixia; Li, Zhen; Zeng, Junwen; Yang, Zhikuan; Morgan, Ian G

2013-01-01

To examine the prevalence of refractive errors in children aged 3-6 years in China. Children were recruited for a trial of a home-based amblyopia screening kit in Guangzhou preschools, during which cycloplegic refractions were measured in both eyes of 2480 children. Cycloplegic refraction (from 3 to 4 drops of 1% cyclopentolate to ensure abolition of the light reflex) was measured by both autorefraction and retinoscopy. Refractive errors were defined as followed: myopia (at least -0.50 D in the worse eye), hyperopia (at least +2.00 D in the worse eye) and astigmatism (at least 1.50 D in the worse eye). Different definitions, as specified in the text, were also used to facilitate comparison with other studies. The mean spherical equivalent refractive error was at least +1.22 D for all ages and both genders. The prevalence of myopia for any definition at any age was at most 2.5%, and lower in most cases. In contrast, the prevalence of hyperopia was generally over 20%, and declined slightly with age. The prevalence of astigmatism was between 6% and 11%. There was very little change in refractive error with age over this age range. Previous reports of less hyperopic mean spherical equivalent refractive error, and more myopia and less hyperopia in children of this age may be due to problems with achieving adequate cycloplegia in children with dark irises. Using up to 4 drops of 1% cyclopentolate may be necessary to accurately measure refractive error in paediatric studies of such children. Our results suggest that children from all ethnic groups may follow a similar pattern of early refractive development, with little myopia and a hyperopic mean spherical equivalent over +1.00 D up to the age of 5-6 years in most conditions.

Corneal epithelium, visual acuity, and laser refractive keratectomy

NASA Astrophysics Data System (ADS)

Simon, Gabriel; Parel, Jean-Marie A.; Kervick, Gerard N.; Rol, Pascal O.; Hanna, Khalil; Thompson, Keith P.

1991-06-01

Photorefractive keratectomy (PRK) using an argon fluoride excimer laser for photoablation of the cornea shows potential for the precise correction of refractive errors in patients. Usually, the epithelium is mechanically removed, and Bowman's layer and stromal tissue are photoablated to precomputed depths and shapes that are based on known ablation rates for these tissues. After four day's time, the epithelium has regrown. Assuming the epithelium to be preoperatively uniform in thickness across the central optical zone, and assuming that it regrows to the same thickness, a theoretical precision of +/- 0.05 diopters is achievable with PRK. Keratometric measurements of the epithelium and of Bowman's layer were made at the 2.0 and 3.6 mm optical zones on 10 fresh cadaver eyes (<21 hours postmortem). In the eyes studied, the epithelium thickness was found to vary across the central optical zone, accounting for the measured refractive differences of 0.5 to 1.8 diopters. Bowman's layer was found to be more prolated than the epithelial surface (ratios: 1.005 compared to 1.033). In addition, the surface of Bowman's layer had a larger degree of astigmatism. Other studies have shown that the epithelium regrowth is a function of the newly exposed corneal topography as the wing cells compensate for irregularities in Bowman's surface. As the preoperative topography of the epithelium cannot be used as a reference surface when computing photoablation depth, intraoperative keratometry of Bowman's surface becomes a necessity in PRK.

Refractive improvements and safety with topography-guided corneal crosslinking for keratoconus: 1-year results.

PubMed

Nordström, Maria; Schiller, Maria; Fredriksson, Anneli; Behndig, Anders

2017-07-01

To assess the refractive improvements and the corneal endothelial safety of an individualised topography-guided regimen for corneal crosslinking in progressive keratoconus. An open-label prospective randomised clinical trial was performed at the Department of Clinical Sciences, Ophthalmology, Umeå University Hospital, Umeå, Sweden. Thirty-seven patients (50 eyes) with progressive keratoconus planned for corneal crosslinking were included. The patients were randomised to topography-guided crosslinking (photorefractive intrastromal crosslinking (PiXL); n=25) or uniform 9 mm crosslinking (corneal collagen crosslinking (CXL); n=25). Visual acuity, refraction, keratometry (K1, K2 and K max ) and corneal endothelial morphometry were assessed preoperatively and at 1, 3, 6 and 12 months postoperatively. The PiXL treatment involved an asymmetrical treatment zone centred on the area of maximum corneal steepness with treatment energies ranging from 7.2 to 15.0 J/cm 2 ; the CXL treatment was a uniform 9 mm 5.4 J/cm 2 pulsed crosslinking. The main outcome measures were changes in refractive errors and corneal endothelial cell density. The spherical refractive errors decreased (p<0.05) and the visual acuity improved (p<0.01) at 3, 6 and 12 months after PiXL, but not after CXL. The between-groups differences, however, were not significant. K2 and K max decreased at 3, 6 and 12 months after PiXL (p<0.01), but not after CXL (p<0.01 when comparing the two treatments). No corneal endothelial cell loss was seen after either treatment. Individualised topography-based crosslinking treatment centred on the ectatic cone has the potential to improve the corneal shape in keratoconus with decreased spherical refractive errors and improved visual acuity, without damage to the corneal endothelium. NCT02514200, Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Risk factors for refractive errors in primary school children (6-12 years old) in Nakhon Pathom Province.

PubMed

Yingyong, Penpimol

2010-11-01

Refractive error is one of the leading causes of visual impairment in children. An analysis of risk factors for refractive error is required to reduce and prevent this common eye disease. To identify the risk factors associated with refractive errors in primary school children (6-12 year old) in Nakhon Pathom province. A population-based cross-sectional analytic study was conducted between October 2008 and September 2009 in Nakhon Pathom. Refractive error, parental refractive status, and hours per week of near activities (studying, reading books, watching television, playing with video games, or working on the computer) were assessed in 377 children who participated in this study. The most common type of refractive error in primary school children was myopia. Myopic children were more likely to have parents with myopia. Children with myopia spend more time at near activities. The multivariate odds ratio (95% confidence interval)for two myopic parents was 6.37 (2.26-17.78) and for each diopter-hour per week of near work was 1.019 (1.005-1.033). Multivariate logistic regression models show no confounding effects between parental myopia and near work suggesting that each factor has an independent association with myopia. Statistical analysis by logistic regression revealed that family history of refractive error and hours of near-work were significantly associated with refractive error in primary school children.

Statistics of the residual refraction errors in laser ranging data

NASA Technical Reports Server (NTRS)

Gardner, C. S.

1977-01-01

A theoretical model for the range error covariance was derived by assuming that the residual refraction errors are due entirely to errors in the meteorological data which are used to calculate the atmospheric correction. The properties of the covariance function are illustrated by evaluating the theoretical model for the special case of a dense network of weather stations uniformly distributed within a circle.

[Extreme (complicated, ultra-high) refractive errors: terminological misconceptions!?

PubMed

Avetisov, S E

2018-01-01

The article reviews development mechanisms of different refractive errors accompanied by marked defocus of light rays reaching the retina. Terminology used for such ametropias includes terms extreme, ultra-high and complicated. Justification of their usage for primary ametropias, whose symptom complex is based on changes in axial eye length, is an ongoing discussion. To comply with thesaurus definitions of 'diagnosis' and 'pathogenesis', to characterize refractive and anatomical-functional disorders in patients with primary ametropias it is proposed to use the terms 'hyperaxial and hypoaxial syndromes' with elaboration of specific symptoms instead of such expressions as extreme (ultra-high) myopia and hypermetropia.

Correlations between Preoperative Angle Parameters and Postoperative Unpredicted Refractive Errors after Cataract Surgery in Open Angle Glaucoma (AOD 500).

PubMed

Lee, Wonseok; Bae, Hyoung Won; Lee, Si Hyung; Kim, Chan Yun; Seong, Gong Je

2017-03-01

To assess the accuracy of intraocular lens (IOL) power prediction for cataract surgery with open angle glaucoma (OAG) and to identify preoperative angle parameters correlated with postoperative unpredicted refractive errors. This study comprised 45 eyes from 45 OAG subjects and 63 eyes from 63 non-glaucomatous cataract subjects (controls). We investigated differences in preoperative predicted refractive errors and postoperative refractive errors for each group. Preoperative predicted refractive errors were obtained by biometry (IOL-master) and compared to postoperative refractive errors measured by auto-refractometer 2 months postoperatively. Anterior angle parameters were determined using swept source optical coherence tomography. We investigated correlations between preoperative angle parameters [angle open distance (AOD); trabecular iris surface area (TISA); angle recess area (ARA); trabecular iris angle (TIA)] and postoperative unpredicted refractive errors. In patients with OAG, significant differences were noted between preoperative predicted and postoperative real refractive errors, with more myopia than predicted. No significant differences were recorded in controls. Angle parameters (AOD, ARA, TISA, and TIA) at the superior and inferior quadrant were significantly correlated with differences between predicted and postoperative refractive errors in OAG patients (-0.321 to -0.408, p<0.05). Superior quadrant AOD 500 was significantly correlated with postoperative refractive differences in multivariate linear regression analysis (β=-2.925, R²=0.404). Clinically unpredicted refractive errors after cataract surgery were more common in OAG than in controls. Certain preoperative angle parameters, especially AOD 500 at the superior quadrant, were significantly correlated with these unpredicted errors.

Five-Year Progression of Refractive Errors and Incidence of Myopia in School-Aged Children in Western China.

PubMed

Zhou, Wen-Jun; Zhang, Yong-Ye; Li, Hua; Wu, Yu-Fei; Xu, Ji; Lv, Sha; Li, Ge; Liu, Shi-Chun; Song, Sheng-Fang

2016-07-05

To determine the change in refractive error and the incidence of myopia among school-aged children in the Yongchuan District of Chongqing City, Western China. A population-based cross-sectional survey was initially conducted in 2006 among 3070 children aged 6 to 15 years. A longitudinal follow-up study was then conducted 5 years later between November 2011 and March 2012. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression of refractive error and incidence of myopia. Longitudinal data were available for 1858 children (60.5%). The cumulative mean change in refractive error was -2.21 (standard deviation [SD], 1.87) diopters (D) for the entire study population, with an annual progression of refraction in a myopic direction of -0.43 D. Myopic progression of refractive error was associated with younger age, female sex, and higher myopic or hyperopic refractive error at baseline. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of -0.50 D or more, among initial emmetropes and hyperopes was 54.9% (95% confidence interval [CI], 45.2%-63.5%), with an annual incidence of 10.6% (95% CI, 8.7%-13.1%). Myopia was found more likely to happen in female and older children. In Western China, both myopic progression and incidence of myopia were higher than those of children from most other locations in China and from the European Caucasian population. Compared with a previous study in China, there was a relative increase in annual myopia progression and annual myopia incidence, a finding which is consistent with the increasing trend on prevalence of myopia in China.

Agreement Between Autorefraction and Subjective Refraction in Keraring-Implanted Keratoconic Eyes.

PubMed

Al-Tuwairqi, Waleed S; Ogbuehi, Kelechi C; Razzouk, Haya; Alanazi, Mana A; Osuagwu, Uchechukwu L

2017-03-01

To assess the agreement between subjective refraction and autorefraction and to explore the relationship between the magnitude of higher order aberration, and visual acuity and refraction, before and after keraring implantation. This prospective, randomized, interventional study enrolled 27 subjects (mean age 28.1±6.5 years) with keratoconus. Noncycloplegic refraction was performed subjectively by one clinician and with an autorefractor by another clinician, before and 6 months after surgery. The limit of agreement (LoA) between methods was assessed, and the relationships between the corrected distance visual acuity, logMAR on the one hand and refraction measurements and higher-order aberrations on the other, were examined. The agreement in mean spherical equivalent refraction (MSER) between methods was good postoperatively but poor preoperatively. The autorefractor gave a more myopic refraction than subjective refraction preoperatively (-3.28±3.06 D; LoA -9.27 to +2.71 D, P<0.0001) and postoperatively (-0.63±1.64 D; LoA -3.85 to +2.58 D, P=0.055), and returned higher negative cylinders preoperatively (-1.10±1.17 D; LoA -3.40 to +1.19 D, P<0.0001) and postoperatively (-1.08±1.27 D; LoA -3.60 to +1.41 D, P<0.0001) in keratoconic eyes. The difference in MSER between methods was significantly related to the refractive error at both visits (P<0.05) and to the magnitude of higher-order aberrations in keratoconic eyes preoperatively (P<0.05). The logMAR visual acuity achieved subjectively worsened as the magnitude of higher-order aberrations increased preoperatively (P<0.001). The autorefractor returns values that are significantly more myopic in MSER and higher negative cylinders than subjective refraction, preoperatively, but the MSER was similar between devices postoperatively. The autorefactor seems a valid starting point for subjective refraction in keratoconic eyes treated with keraring, but the cylinder should be corrected by about +1 D. The instruments agree

Visual symptoms associated with refractive errors among Thangka artists of Kathmandu valley.

PubMed

Dhungel, Deepa; Shrestha, Gauri Shankar

2017-12-21

Prolong near work, especially among people with uncorrected refractive error is considered a potential source of visual symptoms. The present study aims to determine the visual symptoms and the association of those with refractive errors among Thangka artists. In a descriptive cross-sectional study, 242 (46.1%) participants of 525 thangka artists examined, with age ranged between 16 years to 39 years which comprised of 112 participants with significant refractive errors and 130 absolutely emmetropic participants, were enrolled from six Thangka painting schools. The visual symptoms were assessed using a structured questionnaire consisting of nine items and scoring from 0 to 6 consecutive scales. The eye examination included detailed anterior and posterior segment examination, objective and subjective refraction, and assessment of heterophoria, vergence and accommodation. Symptoms were presented in percentage and median. Variation in distribution of participants and symptoms was analysed using the Kruskal Wallis test for mean, and the correlation with the Pearson correlation coefficient. A significance level of 0.05 was applied for 95% confidence interval. The majority of participants (65.1%) among refractive error group (REG) were above the age of 30 years, with a male predominance (61.6%), compared to the participants in the normal cohort group (NCG), where majority of them (72.3%) were below 30 years of age (72.3%) and female (51.5%). Overall, the visual symptoms are high among Thangka artists. However, blurred vision (p = 0.003) and dry eye (p = 0.004) are higher among the REG than the NCG. Females have slightly higher symptoms than males. Most of the symptoms, such as sore/aching eye (p = 0.003), feeling dry (p = 0.005) and blurred vision (p = 0.02) are significantly associated with astigmatism. Thangka artists present with significant proportion of refractive error and visual symptoms, especially among females. The most commonly reported

Prevalence of Amblyopia in School-Aged Children and Variations by Age, Gender, and Ethnicity in a Multi-Country Refractive Error Study.

PubMed

Xiao, Ou; Morgan, Ian G; Ellwein, Leon B; He, Mingguang

2015-09-01

To estimate the age-, gender-, and ethnicity-specific prevalence of amblyopia in children aged 5 to 15 years using data from the multi-country Refractive Error Study in Children (RESC). Population-based, cross-sectional study. Among 46 260 children aged 5 to 15 years who were enumerated from 8 sites in the RESC study, 39 551 had a detailed ocular examination and a reliable visual acuity (VA) measurement in 1 or both eyes. Information on ethnicity was available for 39 321 of these participants. This study focused on findings from the 39 321 children. The examination included VA measurements, evaluation of ocular alignment and refractive error under cycloplegia, and examination of the external eye, anterior segment, media, and fundus. The proportion of children aged 5 to 15 years with amblyopia in different ethnic cohorts. Amblyopia was defined as best-corrected visual acuity (BCVA) of ≤20/40 in either eye, with tropia, anisometropia (≥2 spherical equivalent diopters [D]), or hyperopia (≥+6 spherical equivalent D), after excluding children with fundus or anterior segment abnormalities. The overall prevalence of amblyopia was 0.74% (95% confidence interval, 0.64-0.83) with significant (P < 0.001) variation across ethnic groups: 1.43% in Hispanic, 0.93% in Chinese, 0.62% in Indian, 0.52% in Malay, 0.35% in Nepali, and 0.28% in African children. Amblyopia was not associated with age or gender. The most common cause of amblyopia was anisometropia. In this study, the prevalence of amblyopia varied with ethnicity and was highest in Hispanic children and lowest in African children. Most cases were unilateral and developed before the age of 5 years. The impact of changes of definitions on prevalence estimates is discussed. Copyright © 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Prevalence of Refractive Errors in Students with and without Color Vision Deficiency

PubMed Central

Ostadimoghaddam, Hadi; Yekta, Abbas Ali; Heravian, Javad; Azimi, Abbas; Hosseini, Seyed Mahdi Ahmadi; Vatandoust, Sakineh; Sharifi, Fatemeh; Abolbashari, Fereshteh

2014-01-01

Purpose: To evaluate refractive errors in school age children with color vision deficiency (CVD) and those with normal color vision (NCV) in order to make a better understanding of the emmetropization process. Methods: A total of 4,400 primary school students aged 7–12 years were screened for color vision using Ishihara pseudoisochromatic color vision plate sets. Of these, 160 (3.6%) students had CVD. A total of 400 age- and sex-matched students with NCV were selected as controls. Refractive status was evaluated using objective cyclorefraction. Results: The CVD group included 136 male (85%) and 24 female (15%) subjects with mean age of 10.1 ± 1.8 years. The NCV group comprised of 336 male (84%) and 64 female (16%) subjects with mean age of 10.5 ± 1.2 years. The prevalence of myopia (7.7% vs. 13.9%, P < 0.001) and hyperopia (41% vs. 57.4%, P = 0.03) was significantly lower in the CVD group. Furthermore, subjects with CVD subjects demonstrated a lower magnitude of refractive errors as compared to the CVD group (mean refractive error: +0.54 ± 0.19 D versus + 0.74 ± 1.12 D, P < 0.001). Conclusion: Although the lower prevalence of myopia in subjects with CVD group supports the role of longitudinal chromatic aberration in the development of refractive errors; the lower prevalence of hyperopia in this group is an opposing finding. Myopia is a multifactorial disorder and longitudinal chromatic aberration is not the only factor influencing the emmetropization process. PMID:25709775

The patterns of refractive errors among the school children of rural and urban settings in Nepal.

PubMed

Pokharel, A; Pokharel, P K; Das, H; Adhikari, S

2010-01-01

The uncorrected refractive error is an important cause of childhood blindness and visual impairment. To study the patterns of refractive errors among the urban and rural school going children of Nepal. A total of 440 school children of urban and rural schools within the age range of 7-15 years were selected for this study using multi-stage randomization technique. The overall prevalance of refractive error in school children was 19.8 %. The commonest refractive error among the students was myopia (59.8 %), followed by hypermetropia (31.0 %). The children of age group 12-15 years had the higher prevalence of myopia as compared to the younger counterparts (42.5 % vs 17.2 %). The prevalence of myopia was 15.5 % among the urban students as compared to 8.2 % among the rural ones (RR = 1.89, 95 % CI = 1.1-3.24). The hypermetropia was more common in urban students than in rural ones (6.4 %) vs 5.9 %, RR = 1.08 (95 % CI: 0.52-2.24). The prevalence of refractive error in the school children of Nepal is 19.8 %. The students from urban settings are more likely to have refractive error than their rural counterparts. © Nepal Ophthalmic Society.

Changes in refractive errors related to spectacle correction of hyperopia.

PubMed

Yang, Hee Kyung; Choi, Jung Yeon; Kim, Dae Hyun; Hwang, Jeong-Min

2014-01-01

Hyperopic undercorrection is a common clinical practice. However, less is known of its effect on the change in refractive errors and emmetropization throughout the later years of childhood. To evaluate the effect of spectacle correction on the change in refractive errors in hyperopic children less than 12 years of age with or without strabismus. A retrospective cohort study was performed by a computer based search of the hospital database of patients with hyperopia, accommodative esotropia or exotropia. A total of 150 hyperopic children under 12 years of age were included. Patients were classified into four groups: 1) accommodative esotropia with full correction of hyperopia, 2) exotropia with undercorrection of hyperopia, 3) orthotropia with full correction of hyperopia, 4) orthotropia with undercorrection of hyperopia. The 4 groups were matched by initial age on examination and spherical equivalent refractive errors (SER). The main outcome measure was the change in SER (Diopter/year) in both eyes after two years of follow-up. An overall negative shift in SER was noted during the follow-up period in all groups, except for the group with esotropia and full correction. The mean negative shift of hyperopia was more rapid in groups receiving undercorrection of hyperopia with or without strabismus. The amount of undercorrection of hyperopia was positively correlated to the magnitude of decrease in hyperopia in all patients (r = 0.289, P<0.001) and in the subgroup of patients with orthotropia (r = 0.304, P = 0.011). The amount of undercorrection of hyperopia was the only factor associated with a more negative shift in SER (OR, 2.414; 95% CI, 1.202-4.849; P = 0.013). The amount of undercorrection is significantly correlated to the change in hyperopic refractive errors. Full correction of hyperopia may inhibit emmetropization during early and late childhood.

Correlations between Preoperative Angle Parameters and Postoperative Unpredicted Refractive Errors after Cataract Surgery in Open Angle Glaucoma (AOD 500)

PubMed Central

Lee, Wonseok; Bae, Hyoung Won; Lee, Si Hyung; Kim, Chan Yun

2017-01-01

Purpose To assess the accuracy of intraocular lens (IOL) power prediction for cataract surgery with open angle glaucoma (OAG) and to identify preoperative angle parameters correlated with postoperative unpredicted refractive errors. Materials and Methods This study comprised 45 eyes from 45 OAG subjects and 63 eyes from 63 non-glaucomatous cataract subjects (controls). We investigated differences in preoperative predicted refractive errors and postoperative refractive errors for each group. Preoperative predicted refractive errors were obtained by biometry (IOL-master) and compared to postoperative refractive errors measured by auto-refractometer 2 months postoperatively. Anterior angle parameters were determined using swept source optical coherence tomography. We investigated correlations between preoperative angle parameters [angle open distance (AOD); trabecular iris surface area (TISA); angle recess area (ARA); trabecular iris angle (TIA)] and postoperative unpredicted refractive errors. Results In patients with OAG, significant differences were noted between preoperative predicted and postoperative real refractive errors, with more myopia than predicted. No significant differences were recorded in controls. Angle parameters (AOD, ARA, TISA, and TIA) at the superior and inferior quadrant were significantly correlated with differences between predicted and postoperative refractive errors in OAG patients (-0.321 to -0.408, p<0.05). Superior quadrant AOD 500 was significantly correlated with postoperative refractive differences in multivariate linear regression analysis (β=-2.925, R2=0.404). Conclusion Clinically unpredicted refractive errors after cataract surgery were more common in OAG than in controls. Certain preoperative angle parameters, especially AOD 500 at the superior quadrant, were significantly correlated with these unpredicted errors. PMID:28120576

Five-Year Progression of Refractive Errors and Incidence of Myopia in School-Aged Children in Western China

PubMed Central

Zhou, Wen-Jun; Zhang, Yong-Ye; Li, Hua; Wu, Yu-Fei; Xu, Ji; Lv, Sha; Li, Ge; Liu, Shi-Chun; Song, Sheng-Fang

2016-01-01

Background To determine the change in refractive error and the incidence of myopia among school-aged children in the Yongchuan District of Chongqing City, Western China. Methods A population-based cross-sectional survey was initially conducted in 2006 among 3070 children aged 6 to 15 years. A longitudinal follow-up study was then conducted 5 years later between November 2011 and March 2012. Refractive error was measured under cycloplegia with autorefraction. Age, sex, and baseline refractive error were evaluated as risk factors for progression of refractive error and incidence of myopia. Results Longitudinal data were available for 1858 children (60.5%). The cumulative mean change in refractive error was −2.21 (standard deviation [SD], 1.87) diopters (D) for the entire study population, with an annual progression of refraction in a myopic direction of −0.43 D. Myopic progression of refractive error was associated with younger age, female sex, and higher myopic or hyperopic refractive error at baseline. The cumulative incidence of myopia, defined as a spherical equivalent refractive error of −0.50 D or more, among initial emmetropes and hyperopes was 54.9% (95% confidence interval [CI], 45.2%–63.5%), with an annual incidence of 10.6% (95% CI, 8.7%–13.1%). Myopia was found more likely to happen in female and older children. Conclusions In Western China, both myopic progression and incidence of myopia were higher than those of children from most other locations in China and from the European Caucasian population. Compared with a previous study in China, there was a relative increase in annual myopia progression and annual myopia incidence, a finding which is consistent with the increasing trend on prevalence of myopia in China. PMID:26875599

Near work, outdoor activity, and their association with refractive error.

PubMed

Lin, Zhong; Vasudevan, Balamurali; Jhanji, Vishal; Mao, Guang Yun; Gao, Tie Ying; Wang, Feng Hua; Rong, Shi Song; Ciuffreda, Kenneth J; Liang, Yuan Bo

2014-04-01

To assess the relationship between near work, outdoor activity, and refractive error in schoolchildren in Beijing. The Beijing Myopia Progression Study is a hospital-based myopia study, in which 386 students from primary (aged 6 to 12 years) and secondary (aged 13 to 17 years) schools in the inner city of Beijing were enrolled. Cycloplegic refraction and a detailed questionnaire probing near, intermediate, and distance visual activities were completed. Three hundred seventy (95.9%) of 386 students with complete cycloplegic autorefraction and myopia questionnaire data were enrolled in this study. Children with more near work time did not exhibit a significantly more myopic refraction in both the primary and secondary school levels after adjusting for the children's gender, outdoor activity time, and average parental refractive error. A significant association between outdoor activity time (in hours per day) and the children's spherical equivalent (in diopters) was found in the primary school students (β = 0.27, p = 0.03) but not in the secondary school students (β = 0.04, p = 0.70) after adjusting for similar confounders. The time spent on outdoor sports and outdoor leisure in the primary school students was also significantly associated with the children's spherical equivalent (β = 0.46, p = 0.04 and β = 0.31, p = 0.02, respectively). Primary school students with more time outdoors exhibited relatively less myopic refraction than their peers (ptrend = 0.0003), but this relation was not demonstrated in the secondary school children (ptrend = 0.53) after adjusting for similar confounders. Higher levels of outdoor activity were associated with less myopic refraction in primary school students in the inner city of Beijing. Near work activity was not found to be associated with refraction at either school level.

Refractive outcomes after multifocal intraocular lens exchange.

PubMed

Kim, Eric J; Sajjad, Ahmar; Montes de Oca, Ildamaris; Koch, Douglas D; Wang, Li; Weikert, Mitchell P; Al-Mohtaseb, Zaina N

2017-06-01

To evaluate the refractive outcomes after multifocal intraocular lens (IOL) exchange. Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA. Retrospective case series. Patients had multifocal IOL explantation followed by IOL implantation. Outcome measures included type of IOL, surgical indication, corrected distance visual acuity (CDVA), and refractive prediction error. The study comprised 29 patients (35 eyes). The types of IOLs implanted after multifocal IOL explantation included in-the-bag IOLs (74%), iris-sutured IOLs (6%), sulcus-fixated IOLs with optic capture (9%), sulcus-fixated IOLs without optic capture (9%), and anterior chamber IOLs (3%). The surgical indication for exchange included blurred vision (60%), photic phenomena (57%), photophobia (9%), loss of contrast sensitivity (3%), and multiple complaints (29%). The CDVA was 20/40 or better in 94% of eyes before the exchange and 100% of eyes after the exchange (P = .12). The mean refractive prediction error significantly decreased from 0.22 ± 0.81 diopter (D) before the exchange to -0.09 ± 0.53 D after the exchange (P < .05). The median absolute refractive prediction error significantly decreased from 0.43 D before the exchange to 0.23 D after the exchange (P < .05). Multifocal IOL exchange can be performed safely with good visual outcomes using different types of IOLs. A lower refractive prediction error and a higher likelihood of 20/40 or better vision can be achieved with the implantation of the second IOL compared with the original multifocal IOL, regardless of the final IOL position. Copyright © 2017 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Femtosecond-LASIK outcomes using the VisuMax®-MEL® 80 platform for mixed astigmatism refractive surgery.

PubMed

Stanca, Horia Tudor; Munteanu, Mihnea; Jianu, Dragoş Cătălin; Motoc, Andrei Gheorghe Marius; Jecan, Cristian Radu; Tăbăcaru, Bogdana; Stanca, Simona; Preda, Maria Alexandra

2018-01-01

To evaluate the predictability, efficacy and safety of Femtosecond-laser-assisted in situ keratomileusis (LASIK) procedure for mixed astigmatism. We prospectively evaluated for 12 months 74 eyes (52 patients) with mixed astigmatism that underwent Femtosecond-LASIK treatment. The preoperative mean refractive sphere value was +1.879±1.313 diopters (D) and the mean refractive cylinder value was -4.169±1.091 D. The anterior corneal flap was cut using the VisuMax® femtosecond laser and then the stromal ablation was done using the MEL® 80 excimer laser. Mean age was 30.22±6.421 years with 61.53% female patients. Postoperative spherical equivalent at 12 months was within ±0.5D of emmetropia in 75.8% of eyes and within ±1D in 97.3% of eyes. Postoperative uncorrected distance visual acuity was equivalent to or better than the preoperative corrected distance visual acuity in 91.9% of eyes. Compared to the preoperative corrected distance visual acuity (CDVA), 8.1% of eyes gained one line, 2.7% gained two lines and 2.7% gained three lines of visual acuity. Femtosecond-LASIK using the VisuMax®-MEL® 80 platform appears to have safe, effective and predictable results in mixed astigmatic eyes. The results are impressive for high refractive error treatment and for improvement of both uncorrected and corrected distance visual acuity.

Refractive Errors in 3–6 Year-Old Chinese Children: A Very Low Prevalence of Myopia?

PubMed Central

Lin, Lixia; Li, Zhen; Zeng, Junwen; Yang, Zhikuan; Morgan, Ian G.

2013-01-01

Purpose To examine the prevalence of refractive errors in children aged 3–6 years in China. Methods Children were recruited for a trial of a home-based amblyopia screening kit in Guangzhou preschools, during which cycloplegic refractions were measured in both eyes of 2480 children. Cycloplegic refraction (from 3 to 4 drops of 1% cyclopentolate to ensure abolition of the light reflex) was measured by both autorefraction and retinoscopy. Refractive errors were defined as followed: myopia (at least −0.50 D in the worse eye), hyperopia (at least +2.00 D in the worse eye) and astigmatism (at least 1.50 D in the worse eye). Different definitions, as specified in the text, were also used to facilitate comparison with other studies. Results The mean spherical equivalent refractive error was at least +1.22 D for all ages and both genders. The prevalence of myopia for any definition at any age was at most 2.5%, and lower in most cases. In contrast, the prevalence of hyperopia was generally over 20%, and declined slightly with age. The prevalence of astigmatism was between 6% and 11%. There was very little change in refractive error with age over this age range. Conclusions Previous reports of less hyperopic mean spherical equivalent refractive error, and more myopia and less hyperopia in children of this age may be due to problems with achieving adequate cycloplegia in children with dark irises. Using up to 4 drops of 1% cyclopentolate may be necessary to accurately measure refractive error in paediatric studies of such children. Our results suggest that children from all ethnic groups may follow a similar pattern of early refractive development, with little myopia and a hyperopic mean spherical equivalent over +1.00 D up to the age of 5–6 yearsin most conditions. PMID:24205064

Relative Peripheral Refractive Error and the Risk of Onset and Progression of Myopia in Children

PubMed Central

Sinnott, Loraine T.; Mitchell, G. Lynn; Jones-Jordan, Lisa A.; Moeschberger, Melvin L.; Cotter, Susan A.; Kleinstein, Robert N.; Manny, Ruth E.; Twelker, J. Daniel; Zadnik, Karla

2011-01-01

Purpose. To investigate whether relative peripheral hyperopia is a risk factor for either the onset of myopia in children or the rate of myopic progression. Methods. The risk of myopia onset was assessed in 2043 nonmyopic third-grade children (mean age ± SD = 8.8 ± 0.52 years) participating in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study between 1995 and 2007, 324 of whom became myopic by the eighth grade. Progression analyses used data from 774 myopic children in grades 1 to 8. Foveal and relative peripheral refractive error 30° in the nasal visual field was measured annually by using cycloplegic autorefraction. Axial length was measured by A-scan ultrasonography. Results. The association between more hyperopic relative peripheral refractive error in the third grade and the risk of the onset of myopia by the eighth grade varied by ethnic group (Asian children odds ratio [OR] = 1.56, 95% confidence interval [CI] = 1.06–2.30; African-American children OR = 0.75, 95% CI = 0.58–0.96; Hispanics, Native Americans, and whites showed no significant association). Myopia progression was greater per diopter of more hyperopic relative peripheral refractive error, but only by a small amount (−0.024 D per year; P = 0.02). Axial elongation was unrelated to the average relative peripheral refractive error (P = 0.77), regardless of ethnicity. Conclusions. Relative peripheral hyperopia appears to exert little consistent influence on the risk of the onset of myopic refractive error, on the rate of myopia progression, or on axial elongation. PMID:20739476

From unseen to seen: tackling the global burden of uncorrected refractive errors.

PubMed

Durr, Nicholas J; Dave, Shivang R; Lage, Eduardo; Marcos, Susana; Thorn, Frank; Lim, Daryl

2014-07-11

Worldwide, more than one billion people suffer from poor vision because they do not have the eyeglasses they need. Their uncorrected refractive errors are a major cause of global disability and drastically reduce productivity, educational opportunities, and overall quality of life. The problem persists most prevalently in low-resource settings, even though prescription eyeglasses serve as a simple, effective, and largely affordable solution. In this review, we discuss barriers to obtaining, and approaches for providing, refractive eye care. We also highlight emerging technologies that are being developed to increase the accessibility of eye care. Finally, we describe opportunities that exist for engineers to develop new solutions to positively impact the diagnosis and treatment of correctable refractive errors in low-resource settings.

Analysis of ionospheric refraction error corrections for GRARR systems

NASA Technical Reports Server (NTRS)

Mallinckrodt, A. J.; Parker, H. C.; Berbert, J. H.

1971-01-01

A determination is presented of the ionospheric refraction correction requirements for the Goddard range and range rate (GRARR) S-band, modified S-band, very high frequency (VHF), and modified VHF systems. The relation ships within these four systems are analyzed to show that the refraction corrections are the same for all four systems and to clarify the group and phase nature of these corrections. The analysis is simplified by recognizing that the range rate is equivalent to a carrier phase range change measurement. The equation for the range errors are given.

Modeling of mouse eye and errors in ocular parameters affecting refractive state

NASA Astrophysics Data System (ADS)

Bawa, Gurinder

Rodents eye are particularly used to study refractive error state of an eye and development of refractive eye. Genetic organization of rodents is similar to that of humans, which makes them interesting candidates to be researched upon. From rodents family mice models are encouraged over rats because of availability of genetically engineered models. Despite of extensive work that has been performed on mice and rat models, still no one is able to quantify an optical model, due to variability in the reported ocular parameters. In this Dissertation, we have extracted ocular parameters and generated schematics of eye from the raw data from School of Medicine, Detroit. In order to see how the rays would travel through an eye and the defects associated with an eye; ray tracing has been performed using ocular parameters. Finally we have systematically evaluated the contribution of various ocular parameters, such as radii of curvature of ocular surfaces, thicknesses of ocular components, and refractive indices of ocular refractive media, using variational analysis and a computational model of the rodent eye. Variational analysis revealed that variation in all the ocular parameters does affect the refractive status of the eye, but depending upon the magnitude of the impact those parameters are listed as critical or non critical. Variation in the depth of the vitreous chamber, thickness of the lens, radius of the anterior surface of the cornea, radius of the anterior surface of the lens, as well as refractive indices for the lens and vitreous, appears to have the largest impact on the refractive error and thus are categorized as critical ocular parameters. The radii of the posterior surfaces of the cornea and lens have much smaller contributions to the refractive state, while the radii of the anterior and posterior surfaces of the retina have no effect on the refractive error. These data provide the framework for further refinement of the optical models of the rat and mouse

Refractive error characteristics of early and advanced presbyopic individuals.

DOT National Transportation Integrated Search

1977-07-01

The frequency and distribution of ocular refractive errors among middle-aged and older people were obtained from a nonclinical population holding a variety of blue-collar, clerical, and technical jobs. The 422 individuals ranged in age from 35 to 69 ...

Baseline peripheral refractive error and changes in axial refraction during one year in a young adult population.

PubMed

Hartwig, Andreas; Charman, William Neil; Radhakrishnan, Hema

2016-01-01

To determine whether the initial characteristics of individual patterns of peripheral refraction relate to subsequent changes in refraction over a one-year period. 54 myopic and emmetropic subjects (mean age: 24.9±5.1 years; median 24 years) with normal vision were recruited and underwent conventional non-cycloplegic subjective refraction. Peripheral refraction was also measured at 5° intervals over the central 60° of horizontal visual field, together with axial length. After one year, measurements of subjective refraction and axial length were repeated on the 43 subjects who were still available for examination. In agreement with earlier studies, higher myopes tended to show greater relative peripheral hyperopia. There was, however, considerable inter-subject variation in the pattern of relative peripheral refractive error (RPRE) at any level of axial refraction. Across the group, mean one-year changes in axial refraction and axial length did not differ significantly from zero. There was no correlation between changes in these parameters for individual subjects and any characteristic of their RPRE. No evidence was found to support the hypothesis that the pattern of RPRE is predictive of subsequent refractive change in this age group. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Prevalence of the refractive errors by age and gender: the Mashhad eye study of Iran.

PubMed

Ostadimoghaddam, Hadi; Fotouhi, Akbar; Hashemi, Hassan; Yekta, Abbasali; Heravian, Javad; Rezvan, Farhad; Ghadimi, Hamidreza; Rezvan, Bijan; Khabazkhoob, Mehdi

2011-11-01

Refractive errors are a common eye problem. Considering the low number of population-based studies in Iran in this regard, we decided to determine the prevalence rates of myopia and hyperopia in a population in Mashhad, Iran. Cross-sectional population-based study. Random cluster sampling. Of 4453 selected individuals from the urban population of Mashhad, 70.4% participated. Refractive error was determined using manifest (age > 15 years) and cycloplegic refraction (age ≤ 15 years). Myopia was defined as a spherical equivalent of -0.5 diopter or worse. An spherical equivalent of +0.5 diopter or worse for non-cycloplegic refraction and an spherical equivalent of +2 diopter or worse for cycloplegic refraction was used to define hyperopia. Prevalence of refractive errors. The prevalence of myopia and hyperopia in individuals ≤ 15 years old was 3.64% (95% CI: 2.19-5.09) and 27.4% (95% CI: 23.72-31.09), respectively. The same measurements for subjects > 15 years of age was 22.36% (95% CI: 20.06-24.66) and 34.21% (95% CI: 31.57-36.85), respectively. Myopia was found to increase with age in individuals ≤ 15 years and decrease with age in individuals > 15 years of age. The rate of hyperopia showed a significant increase with age in individuals > 15 years. The prevalence of astigmatism was 25.64% (95% CI: 23.76-27.51). In children and the elderly, hyperopia is the most prevalent refractive error. After hyperopia, astigmatism is also of importance in older ages. Age is the most important demographic factor associated with different types of refractive errors. © 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists.

Macular Pigment Optical Density and Ocular Pulse Amplitude in Subjects with Different Axial Lengths and Refractive Errors.

PubMed

Czepita, Maciej; Karczewicz, Danuta; Safranow, Krzysztof; Czepita, Damian

2015-06-13

The purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP). This study included 140 eyes of 70 subjects - 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant. The following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=-0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL. (1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP.

MONOCULAR DIPLOPIA DUE TO SPHEROCYLINDRICAL REFRACTIVE ERRORS (AN AMERICAN OPHTHALMOLOGICAL SOCIETY THESIS)

PubMed Central

Archer, Steven M.

2007-01-01

Purpose Ordinary spherocylindrical refractive errors have been recognized as a cause of monocular diplopia for over a century, yet explanation of this phenomenon using geometrical optics has remained problematic. This study tests the hypothesis that the diffraction theory treatment of refractive errors will provide a more satisfactory explanation of monocular diplopia. Methods Diffraction theory calculations were carried out for modulation transfer functions, point spread functions, and line spread functions under conditions of defocus, astigmatism, and mixed spherocylindrical refractive errors. Defocused photographs of inked and projected black lines were made to demonstrate the predicted consequences of the theoretical calculations. Results For certain amounts of defocus, line spread functions resulting from spherical defocus are predicted to have a bimodal intensity distribution that could provide the basis for diplopia with line targets. Multimodal intensity distributions are predicted in point spread functions and provide a basis for diplopia or polyopia of point targets under conditions of astigmatism. The predicted doubling effect is evident in defocused photographs of black lines, but the effect is not as robust as the subjective experience of monocular diplopia. Conclusions Monocular diplopia due to ordinary refractive errors can be predicted from diffraction theory. Higher-order aberrations—such as spherical aberration—are not necessary but may, under some circumstances, enhance the features of monocular diplopia. The physical basis for monocular diplopia is relatively subtle, and enhancement by neural processing is probably needed to account for the robustness of the percept. PMID:18427616

Population-based assessment of sensitivity and specificity of a pinhole for detection of significant refractive errors in the community.

PubMed

Marmamula, Srinivas; Keeffe, Jill E; Narsaiah, Saggam; Khanna, Rohit C; Rao, Gullapalli N

2014-11-01

Measurements of refractive errors through subjective or automated refraction are not always possible in rapid assessment studies and community vision screening programs; however, measurements of vision with habitual correction and with a pinhole can easily be made. Although improvements in vision with a pinhole are assumed to mean that a refractive error is present, no studies have investigated the magnitude of improvement in vision with pinhole that is predictive of refractive error. The aim was to measure the sensitivity and specificity of 'vision improvement with pinhole' in predicting the presence of refractive error in a community setting. Vision and vision with pinhole were measured using a logMAR chart for 488 of 582 individuals aged 15 to 50 years. Refractive errors were measured using non-cycloplegic autorefraction and subjective refraction. The presence of refractive error was defined using spherical equivalent refraction (SER) at two levels: SER greater than ± 0.50 D sphere (DS) and SER greater than ±1.00 DS. Three definitions for significant improvement in vision with a pinhole were used: 1. Presenting vision less than 6/12 and improving to 6/12 or better, 2. Improvement in vision of more than one logMAR line and 3. Improvement in vision of more than two logMAR lines. For refractive error defined as spherical equivalent refraction greater than ± 0.50 DS, the sensitivities and specificities for the pinhole test predicting the presence of refractive error were 83.9 per cent (95% CI: 74.5 to 90.9) and 98.8 per cent (95% CI: 97.1 to 99.6), respectively for definition 1. Definition 2 had a sensitivity 89.7 per cent (95% CI: 81.3 to 95.2) and specificity 88.0 per cent (95% CI: 4.4 to 91.0). Definition 3 had a sensitivity of 75.9 per cent (95% CI: 65.5 to 84.4) and specificity of 97.8 per cent (95% CI: 95.8 to 99.0). Similar results were found with spherical equivalent refraction greater than ±1.00 DS, when tested against the three pinhole

Genome-wide association study for refractive astigmatism reveals genetic co-determination with spherical equivalent refractive error: the CREAM consortium.

PubMed

Li, Qing; Wojciechowski, Robert; Simpson, Claire L; Hysi, Pirro G; Verhoeven, Virginie J M; Ikram, Mohammad Kamran; Höhn, René; Vitart, Veronique; Hewitt, Alex W; Oexle, Konrad; Mäkelä, Kari-Matti; MacGregor, Stuart; Pirastu, Mario; Fan, Qiao; Cheng, Ching-Yu; St Pourcain, Beaté; McMahon, George; Kemp, John P; Northstone, Kate; Rahi, Jugnoo S; Cumberland, Phillippa M; Martin, Nicholas G; Sanfilippo, Paul G; Lu, Yi; Wang, Ya Xing; Hayward, Caroline; Polašek, Ozren; Campbell, Harry; Bencic, Goran; Wright, Alan F; Wedenoja, Juho; Zeller, Tanja; Schillert, Arne; Mirshahi, Alireza; Lackner, Karl; Yip, Shea Ping; Yap, Maurice K H; Ried, Janina S; Gieger, Christian; Murgia, Federico; Wilson, James F; Fleck, Brian; Yazar, Seyhan; Vingerling, Johannes R; Hofman, Albert; Uitterlinden, André; Rivadeneira, Fernando; Amin, Najaf; Karssen, Lennart; Oostra, Ben A; Zhou, Xin; Teo, Yik-Ying; Tai, E Shyong; Vithana, Eranga; Barathi, Veluchamy; Zheng, Yingfeng; Siantar, Rosalynn Grace; Neelam, Kumari; Shin, Youchan; Lam, Janice; Yonova-Doing, Ekaterina; Venturini, Cristina; Hosseini, S Mohsen; Wong, Hoi-Suen; Lehtimäki, Terho; Kähönen, Mika; Raitakari, Olli; Timpson, Nicholas J; Evans, David M; Khor, Chiea-Chuen; Aung, Tin; Young, Terri L; Mitchell, Paul; Klein, Barbara; van Duijn, Cornelia M; Meitinger, Thomas; Jonas, Jost B; Baird, Paul N; Mackey, David A; Wong, Tien Yin; Saw, Seang-Mei; Pärssinen, Olavi; Stambolian, Dwight; Hammond, Christopher J; Klaver, Caroline C W; Williams, Cathy; Paterson, Andrew D; Bailey-Wilson, Joan E; Guggenheim, Jeremy A

2015-02-01

To identify genetic variants associated with refractive astigmatism in the general population, meta-analyses of genome-wide association studies were performed for: White Europeans aged at least 25 years (20 cohorts, N = 31,968); Asian subjects aged at least 25 years (7 cohorts, N = 9,295); White Europeans aged <25 years (4 cohorts, N = 5,640); and all independent individuals from the above three samples combined with a sample of Chinese subjects aged <25 years (N = 45,931). Participants were classified as cases with refractive astigmatism if the average cylinder power in their two eyes was at least 1.00 diopter and as controls otherwise. Genome-wide association analysis was carried out for each cohort separately using logistic regression. Meta-analysis was conducted using a fixed effects model. In the older European group the most strongly associated marker was downstream of the neurexin-1 (NRXN1) gene (rs1401327, P = 3.92E-8). No other region reached genome-wide significance, and association signals were lower for the younger European group and Asian group. In the meta-analysis of all cohorts, no marker reached genome-wide significance: The most strongly associated regions were, NRXN1 (rs1401327, P = 2.93E-07), TOX (rs7823467, P = 3.47E-07) and LINC00340 (rs12212674, P = 1.49E-06). For 34 markers identified in prior GWAS for spherical equivalent refractive error, the beta coefficients for genotype versus spherical equivalent, and genotype versus refractive astigmatism, were highly correlated (r = -0.59, P = 2.10E-04). This work revealed no consistent or strong genetic signals for refractive astigmatism; however, the TOX gene region previously identified in GWAS for spherical equivalent refractive error was the second most strongly associated region. Analysis of additional markers provided evidence supporting widespread genetic co-susceptibility for spherical and astigmatic refractive errors.

Femtosecond laser-assisted LASIK versus PRK for high myopia: comparison of 18-month visual acuity and quality.

PubMed

Hashemi, Hassan; Ghaffari, Reza; Miraftab, Mohammad; Asgari, Soheila

2017-08-01

To compare 18-month outcomes between femtosecond laser-assisted LASIK (femto-LASIK) and photorefractive keratectomy with mitomycin-C (PRK-MMC) for myopia of more than 7.0 D in terms of visual acuity and quality. In this comparative nonrandomized clinical trial, 60 eyes from 30 patients (30 eyes in each group) were enrolled. The two procedures were compared in terms of 18-month changes in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction spherical equivalent, ocular and corneal higher order aberrations (HOAs), and contrast sensitivity (CS). Mean myopia was -8.65 ± 1.51 and -8.04 ± 1.70 D (P = 0.149) and mean ablation depth was 109.37 ± 9.07 and 105.09 ± 12.59 µm (P = 0.138), in the femto-LASIK and PRK-MMC groups, respectively. Baseline parameters were not significantly different between the two groups (all P > 0.05). At 18 months postoperatively, 75 % in the femto-LASIK, versus 57.1 % in the PRK-MMC group, had 20/20 UDVA (P = 0.017). CDVA remained similarly unchanged in both groups (P = 0.616). No case had residual refractive error more than 1.0 D in the femto-LASIK group, while 33.5 % in the other group had more than 1.0 D residual error (P = 0.390). Changes in corneal HOA were not significantly different between the two groups (P = 0.260). Cases in the femto-LASIK group showed more increase in ocular HOA (P = 0.032) and coma (P = 0.083, power = 72 %). CS remained similarly unchanged in all spatial frequencies in both groups (all P > 0.05). Although femto-LASIK induces more HOA compared to PRK-MMC, considering outcomes in terms of 20/20 UDVA, residual refractive error, and CS stability, femto-LASIK provides more favorable results than PRK-MMC in high myopia.

An optomechanical model eye for ophthalmological refractive studies.

PubMed

Arianpour, Ashkan; Tremblay, Eric J; Stamenov, Igor; Ford, Joseph E; Schanzlin, David J; Lo, Yuhwa

2013-02-01

To create an accurate, low-cost optomechanical model eye for investigation of refractive errors in clinical and basic research studies. An optomechanical fluid-filled eye model with dimensions consistent with the human eye was designed and fabricated. Optical simulations were performed on the optomechanical eye model, and the quantified resolution and refractive errors were compared with the widely used Navarro eye model using the ray-tracing software ZEMAX (Radiant Zemax, Redmond, WA). The resolution of the physical optomechanical eye model was then quantified with a complementary metal-oxide semiconductor imager using the image resolution software SFR Plus (Imatest, Boulder, CO). Refractive, manufacturing, and assembling errors were also assessed. A refractive intraocular lens (IOL) and a diffractive IOL were added to the optomechanical eye model for tests and analyses of a 1951 U.S. Air Force target chart. Resolution and aberrations of the optomechanical eye model and the Navarro eye model were qualitatively similar in ZEMAX simulations. Experimental testing found that the optomechanical eye model reproduced properties pertinent to human eyes, including resolution better than 20/20 visual acuity and a decrease in resolution as the field of view increased in size. The IOLs were also integrated into the optomechanical eye model to image objects at distances of 15, 10, and 3 feet, and they indicated a resolution of 22.8 cycles per degree at 15 feet. A life-sized optomechanical eye model with the flexibility to be patient-specific was designed and constructed. The model had the resolution of a healthy human eye and recreated normal refractive errors. This model may be useful in the evaluation of IOLs for cataract surgery. Copyright 2013, SLACK Incorporated.

Trial Frame Refraction versus Autorefraction among New Patients in a Low-Vision Clinic

PubMed Central

DeCarlo, Dawn K.; McGwin, Gerald; Searcey, Karen; Gao, Liyan; Snow, Marsha; Waterbor, John; Owsley, Cynthia

2013-01-01

Purpose. To determine the relationship between refractive error as measured by autorefraction and that measured by trial frame refraction among a sample of adults with vision impairment seen in a university-based low-vision clinic and to determine if autorefraction might be a suitable replacement for trial frame refraction. Methods. A retrospective chart review of all new patients 19 years or older seen over an 18-month period was conducted and the following data collected: age, sex, primary ocular diagnosis, entering distance visual acuity, habitual correction, trial frame refraction, autorefraction, and distance visual acuity measured after trial frame refraction. Trial frame refraction and autorefraction were compared using paired t-tests, intraclass correlations, and Bland-Altman plots. Results. Final analyses included 440 patients for whom both trial frame refraction and autorefraction data were available for the better eye. Participants were mostly female (59%) with a mean age of 68 years (SD = 20). Age-related macular degeneration was the most common etiology for vision impairment (44%). Values for autorefraction and trial frame refraction were statistically different, but highly correlated for the spherical equivalent power (r = 0.92), the cylinder power (r = 0.80) and overall blurring strength (0.89). Although the values of the cross-cylinders J0 and J45 were similar, they were poorly correlated (0.08 and 0.15, respectively). The range of differences in spherical equivalent power was large (−8.6 to 4.9). Conclusions. Autorefraction is highly correlated with trial frame refraction. Differences are sometimes substantial, making autorefraction an unsuitable substitute for trial frame refraction. PMID:23188726

Trial frame refraction versus autorefraction among new patients in a low-vision clinic.

PubMed

DeCarlo, Dawn K; McGwin, Gerald; Searcey, Karen; Gao, Liyan; Snow, Marsha; Waterbor, John; Owsley, Cynthia

2013-01-02

To determine the relationship between refractive error as measured by autorefraction and that measured by trial frame refraction among a sample of adults with vision impairment seen in a university-based low-vision clinic and to determine if autorefraction might be a suitable replacement for trial frame refraction. A retrospective chart review of all new patients 19 years or older seen over an 18-month period was conducted and the following data collected: age, sex, primary ocular diagnosis, entering distance visual acuity, habitual correction, trial frame refraction, autorefraction, and distance visual acuity measured after trial frame refraction. Trial frame refraction and autorefraction were compared using paired t-tests, intraclass correlations, and Bland-Altman plots. Final analyses included 440 patients for whom both trial frame refraction and autorefraction data were available for the better eye. Participants were mostly female (59%) with a mean age of 68 years (SD = 20). Age-related macular degeneration was the most common etiology for vision impairment (44%). Values for autorefraction and trial frame refraction were statistically different, but highly correlated for the spherical equivalent power (r = 0.92), the cylinder power (r = 0.80) and overall blurring strength (0.89). Although the values of the cross-cylinders J(0) and J(45) were similar, they were poorly correlated (0.08 and 0.15, respectively). The range of differences in spherical equivalent power was large (-8.6 to 4.9). Autorefraction is highly correlated with trial frame refraction. Differences are sometimes substantial, making autorefraction an unsuitable substitute for trial frame refraction.

[Prevalence of low visual acuity and ophthalmological disorders in six-year-old children from Santa Fe city].

PubMed

Verrone, Pablo J; Simi, Marcelo R

2008-08-01

Changes in children visual acuity that are not treated carry a high risk of irreversible consequences. To determine the prevalence of low visual acuity and to diagnose the ophthalmologic diseases that cause it in six-year-old children from Santa Fe City, Argentina. Observational, descriptive and transversal design. Visual acuity is defined as the eye's capacity to distinguish separate points and to recognize shapes. It was determined using the Snellen table for farsighted vision on 177 six-year-old children who attended four elementary schools in Santa Fe City. An ophthalmologic examination was performed on those who had low visual acuity and their mothers were interviewed to ascertain the pathological background of their children. The prevalence of low visual acuity was 10.7% (n= 19). The prevalence of amblyopia was 3.9%. Refraction errors were the only cause of low visual acuity. Astigmatism was predominantly frequent. The most frequent pathological backgrounds were: ocular infections, premature birth, history of malnutrition and maternal use of tobacco. The prevalence of low visual acuity found in this study is lower than the one informed in most other studies. This data require confirmation by further studies.

The prevalence rates of refractive errors among children, adolescents, and adults in Germany.

PubMed

Jobke, Sandra; Kasten, Erich; Vorwerk, Christian

2008-09-01

The prevalence rates of myopia vary between 5% in Australian Aborigines to 84% in Hong Kong and Taiwan, 30% in Norwegian adults, and 49.5% in Swedish schoolchildren. The aim of this study was to determine the prevalence of refractive errors in German children, adolescents, and adults. The parents (aged 24-65 years) and their children (516 subjects aged 2-35 years) were asked to fill out a questionnaire about their refractive error and spectacle use. Emmetropia was defined as refractive status between +0.25D and -0.25D. Myopia was characterized as /=+0.5D. All information concerning refractive error were controlled by asking their opticians. The prevalence rates of myopia differed significantly between all investigated age groups: it was 0% in children aged 2-6 years, 5.5% in children aged 7-11 years, 21.0% in adolescents (aged 12-17 years) and 41.3% in adults aged 18-35 years (Pearson's Chi-square, p = 0.000). Furthermore, 9.8% of children aged 2-6 years were hyperopic, 6.4% of children aged 7-11 years, 3.7% of adolescents, and 2.9% of adults (p = 0.380). The prevalence of myopia in females (23.6%) was significantly higher than in males (14.6%, p = 0.018). The difference between the self-reported and the refractive error reported by their opticians was very small and was not significant (p = 0.850). In Germany, the prevalence of myopia seems to be somewhat lower than in Asia and Europe. There are few comparable studies concerning the prevalence rates of hyperopia.

The Effect of Age, Accommodation and Refractive Error on the Adult Human Eye

PubMed Central

Richdale, Kathryn; Bullimore, Mark A.; Sinnott, Loraine T.; Zadnik, Karla

2015-01-01

Purpose To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects. Methods The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error and accommodation. Results With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/y) and lens equivalent refractive index decreased (0.001 /y) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D) and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D), and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03). Conclusions Refractive error is significantly correlated with not only the axial dimensions, but the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients’ preoperative refractive error. PMID:26703933

Strategies to improve the accuracy of vision measurement by teachers in rural Chinese secondary schoolchildren: Xichang Pediatric Refractive Error Study (X-PRES) report no. 6.

PubMed

Sharma, Abhishek; Li, Liping; Song, Yue; Choi, Kai; Lam, Dennis S C; Zhang, Mingzhi; Zheng, Mingwei; Zhou, Zhongxia; Liu, Xiaojian; Wu, Bin; Congdon, Nathan

2008-10-01

To assess and improve the accuracy of lay screeners compared with vision professionals in detecting visual impairment in secondary schoolchildren in rural China. After brief training, 32 teachers and a team of vision professionals independently measured vision in 1892 children in Xichang. The children also underwent vision measurement by health technicians in a concurrent government screening program. Of 32 teachers, 28 (87.5%) believed that teacher screening was worthwhile. Sensitivity (93.5%) and specificity (91.2%) of teachers detecting uncorrected presenting visual acuity of 20/40 or less were better than for presenting visual acuity (sensitivity, 85.2%; specificity, 84.8%). Failure of teachers to identify children owning but not wearing glasses and teacher bias toward better vision in children wearing glasses explain the worse results for initial vision. Wearing glasses was the student factor most strongly predictive of inaccurate teacher screening (P < .001). The sensitivity and specificity of the government screening program detecting low presenting visual acuity were 86.7% and 28.7%, respectively. Teacher vision screening after brief training can achieve accurate results in this setting, and there is support among teachers for screening. Screening of uncorrected rather than presenting visual acuity is recommended in settings with a high prevalence of corrected and uncorrected refractive error. Low specificity in the government program renders it ineffective.

Ray tracing evaluation of a technique for correcting the refraction errors in satellite tracking data

NASA Technical Reports Server (NTRS)

Gardner, C. S.; Rowlett, J. R.; Hendrickson, B. E.

1978-01-01

Errors may be introduced in satellite laser ranging data by atmospheric refractivity. Ray tracing data have indicated that horizontal refractivity gradients may introduce nearly 3-cm rms error when satellites are near 10-degree elevation. A correction formula to compensate for the horizontal gradients has been developed. Its accuracy is evaluated by comparing it to refractivity profiles. It is found that if both spherical and gradient correction formulas are employed in conjunction with meteorological measurements, a range resolution of one cm or less is feasible for satellite elevation angles above 10 degrees.

Self-refraction accuracy with adjustable spectacles among children in Ghana.

PubMed

Ilechie, Alex Azuka; Abokyi, Samuel; Owusu-Ansah, Andrew; Boadi-Kusi, Samuel Bert; Denkyira, Andrew Kofi; Abraham, Carl Halladay

2015-04-01

To determine the accuracy of self-refraction (SR) in myopic teenagers, we compared visual and refractive outcomes of self-refracting spectacles (FocusSpecs) with those obtained using cycloplegic subjective refraction (CSR) as a gold standard. A total of 203 eligible schoolchildren (mean [±SD] age, 13.8 [±1.0] years; 59.1% were female) completed an examination consisting of SR with FocusSpecs adjustable spectacles, visual acuity with the logMAR (logarithm of the minimum angle of resolution) chart, cycloplegic retinoscopy, and CSR. Examiners were masked to the SR findings. Wilcoxon signed rank test and paired Student t test were used to compare measures across refraction methods (95% confidence intervals [CIs]). The mean (±SD) spherical equivalent refractive error measured by CSR and SR was -1.22 (±0.49) diopters (D) and -1.66 (±0.73) D, respectively, a statistically significant difference of -0.44 D (p < 0.001, t = 15.517). The greatest proportion of participants was correctable to visual acuity greater than or equal to 6/7.5 (logMAR 0.1) in the better eye by CSR (99.0%; 95% CI, 96.5 to 99.7%), followed by cycloplegic retinoscopy (94.1%; 95% CI, 90.0 to 96.6%) and SR (85.2%; 95% CI, 79.7 to 89.5%). These proportions differed significantly from each other (p < 0.001, Wilcoxon signed rank test). Myopic inaccuracy of greater than 0.50 D and greater than or equal to -1.00 D was present in 29 (15.3%) and 16 (8.4%) right eyes, respectively, with SR. In logistic regression models, failure to achieve visual acuity greater than or equal to 6/7.5 in right eyes with SR was significantly associated with age (odds ratio, 1.92; 95% CI, 1.12 to 3.28; p = 0.017) and spherical power (odds ratio, 0.017; 95% CI, 0.005 to 0.056; p < 0.001). Self-refraction offers acceptable visual and refractive results for young people in a rural setting in Ghana, although myopic inaccuracy in the more negative direction occurred in some children.

Visual acuity of commercial motor drivers in Ogun State of Nigeria.

PubMed

Onabolu, O O; Bodunde, O T; Otulana, T O; Ajibode, H A; Awodein, O G; Onadipe, O J; Jagun, O A

2012-12-01

To objectively assess the visual acuity of commercial motor drivers (CMD) in 3 Local Government Areas (LGA) of Ogun State of Nigeria in order to determine their eligibility to drive. The visual acuities of CMDs in 3 LGAS of Ogun state in Nigeria (selected using a multistage sampling technique) were tested with Snellens acuity charts and the eyes examined with bright pen torches and ophthamoscopes. Visual acuity 6/12 or better in the worse eye was taken as adequate to obtain a driving license. The drivers with worse visual acuities were further examined to find the cause of decreased vision. The visual acuities of 524 drivers were determined and analyzed. Their ages ranged from 19-66 years with a mean of 46.8 ±7.2 years. Two hundred and twenty (41.9%) of the drivers were between 40 and 49 years old. Four hundred and four (77.1%) did not have any form of eye test prior to this study. Four hundred and sixty three drivers (88.4%) were eligible to drive while 61 drivers (11.6%) were not eligible. Decreased visual acuity was caused by refractive error in 22(36.1%), cataract in 19(31.2%), glaucoma in 12(19.7%), corneal scar in 5(8.2%) and posterior segment lesions in 3(4.9%). Objective assessment of vision should be an essential component of licensure. Middle aged and elderly drivers are prone to age related ocular diseases and require reassessment of visual status every 3 years when licenses are renewed.

Corrective lens use and refractive error among United States Air Force aircrew.

PubMed

Wright, Steve T; Ivan, Douglas J; Clark, Patrick J; Gooch, John M; Thompson, William

2010-03-01

Corrective lens use by military aviators is an important consideration in the design of head-mounted equipment. The United States Air Force (USAF) has periodically monitored lens use by aviators; however, it has been over a decade since the last study. We provide an update on the prevalence of corrective lenses and refractive error among USAF aircrew based on eyeglass orders processed through the Spectacle Request Transmission System (SRTS). Currently, 41% of active duty USAF pilots and 54% of other aircrew require corrective lenses to perform flight duties. Refractive errors are characterized by low to moderate levels of myopia with a mean spherical equivalent power of -1.01 diopters (D) for pilots and -1.68 D for others. Contact lenses, and more recently refractive surgery, reduce the number of aircrew that must rely on spectacles when flying; however, spectacle compatibility remains an important consideration in the cockpit.

Refractive optics to compensate x-ray mirror shape-errors

NASA Astrophysics Data System (ADS)

Laundy, David; Sawhney, Kawal; Dhamgaye, Vishal; Pape, Ian

2017-08-01

Elliptically profiled mirrors operating at glancing angle are frequently used at X-ray synchrotron sources to focus X-rays into sub-micrometer sized spots. Mirror figure error, defined as the height difference function between the actual mirror surface and the ideal elliptical profile, causes a perturbation of the X-ray wavefront for X- rays reflecting from the mirror. This perturbation, when propagated to the focal plane results in an increase in the size of the focused beam. At Diamond Light Source we are developing refractive optics that can be used to locally cancel out the wavefront distortion caused by figure error from nano-focusing elliptical mirrors. These optics could be used to correct existing optical components on synchrotron radiation beamlines in order to give focused X-ray beam sizes approaching the theoretical diffraction limit. We present our latest results showing measurement of the X-ray wavefront error after reflection from X-ray mirrors and the translation of the measured wavefront into a design for refractive optical elements for correction of the X-ray wavefront. We show measurement of the focused beam with and without the corrective optics inserted showing reduction in the size of the focus resulting from the correction to the wavefront.

Region-Specific Relationships Between Refractive Error and Ciliary Muscle Thickness in Children

PubMed Central

Pucker, Andrew D.; Sinnott, Loraine T.; Kao, Chiu-Yen; Bailey, Melissa D.

2013-01-01

Purpose. To determine if there is a relationship between refractive error and ciliary muscle thickness in different muscle regions. Methods. An anterior segment optical coherence tomographer was used to measure cycloplegic ciliary muscle thicknesses at 1 mm (CMT1), 2 mm (CMT2), and 3 mm (CMT3) posterior to the scleral spur; maximum (CMTMAX) thickness was also assessed. An autorefractor was used to determine cycloplegic spherical equivalent refractive error (SPHEQ). Apical ciliary muscle fibers were obtained by subtracting corresponding CMT2 values from CMT1 and CMTMAX. Multilevel regression models were used to determine the relationship between ciliary muscle thickness in various regions of the muscle and refractive error. Results. Subjects included 269 children with a mean age of 8.71 ± 1.51 years and a mean refractive error of +0.41 ± 1.29 diopters. In linear models with ciliary muscle thicknesses and SPHEQ, SPHEQ was significantly associated only with CMT2 (β = −11.34, P = 0.0008) and CMT 3 (β = −6.97, P = 0.007). When corresponding values of CMT2 were subtracted from CMT1 and CMTMAX, apical fibers at CMT1 (β = 14.75, P < 0.0001) and CMTMAX (β = 18.16, P < 0.0001) had a significant relationship with SPHEQ. Conclusions. These data indicated that in children the posterior ciliary muscle fibers are thicker in myopia (CMT2 and CMT3), but paradoxically, the apical ciliary muscle fibers are thicker in hyperopia (CMTMAX and CMT1). This may be the first evidence that hyperopia is associated with a thicker apical ciliary muscle region. PMID:23761093

Prevalence of visual impairment and refractive errors among different ethnic groups in schoolchildren in Turpan, China.

PubMed

Chin, Man Pan; Siong, Kar Ho; Chan, Ka Ho; Do, Chi Wai; Chan, Henry Ho Lung; Cheong, Allen Ming Yan

2015-05-01

There is currently limited information about ethnic differences in myopia prevalence within mainland China, especially in rural or semi-rural areas. We examined the prevalence of refractive errors, visual impairment and spectacle coverage in school children of varying ethnicity in Turpan, Xinjiang province. A community eye care service was provided for five schools. Presenting monocular distance and near visual acuity (VA), and ocular alignment were assessed. Retinoscopy and cycloplegic subjective refraction were performed for participants with presenting visual impairment (distance VA worse than 0.3 logMAR; Snellen 6/12 or 20/40) or abnormal binocular vision. Questionnaires administered prior to the eye examinations were used to collect information regarding personal lifestyle and parental myopia. A total of 646 out of 690 (94%) subjects aged four to 19 years (11.9 ± 2.6; mean ± S.D.) completed the eye examination. Three hundred and eighty-two (59%) of participants were of Uyghur ethnicity, followed by Han, 176 (27%) and Hui, 74 (12%). The mean age of Uyghur, Han and Hui students was 12.3 ± 2.7, 11.4 ± 2.6 and 11.4 ± 2.3 years respectively, in which the Uyghur students were significantly older than the Han and Hui students (F(3,631) = 5.58 p < 0.001). In total, 170 (27%) and 85 (13%) subjects failed the screening examination for one eye or both eyes, respectively. The prevalence of presenting visual impairment was not significantly different among the ethnic groups (p = 0.26). After cycloplegic refraction, most subjects' VA (98%) improved to better than 0.3 logMAR (Snellen 6/12 or 20/40). The prevalence of "clinically-significant myopia" (≤-0.50 dioptres) was 27%, 18% and 13% in Han, Hui and Uyghur children, respectively (p < 0.001). In contrast, Uyghur students had the highest prevalence of astigmatism (Uyghur 12%, Han 5%, Hui 4%). The overall spectacle coverage was 36%, while spectacle coverage among ethnic groups were similar (Han, 41%; Uyghur, 32%; Hui

Profile of refractive errors in European Caucasian children with Autistic Spectrum Disorder; increased prevalence and magnitude of astigmatism.

PubMed

Anketell, Pamela M; Saunders, Kathryn J; Gallagher, Stephen; Bailey, Clare; Little, Julie-Anne

2016-07-01

Autistic Spectrum Disorder (ASD) is a common neurodevelopmental disorder characterised by impairment of communication, social interaction and repetitive behaviours. Only a small number of studies have investigated fundamental clinical measures of vision including refractive error. The aim of this study was to describe the refractive profile of a population of children with ASD compared to typically developing (TD) children. Refractive error was assessed using the Shin-Nippon NVision-K 5001 open-field autorefractor following the instillation of cyclopentolate hydrochloride 1% eye drops. A total of 128 participants with ASD (mean age 10.9 ± 3.3 years) and 206 typically developing participants (11.5 ± 3.1 years) were recruited. There was no significant difference in median refractive error, either by spherical equivalent or most ametropic meridian between the ASD and TD groups (Spherical equivalent, Mann-Whitney U307 = 1.15, p = 0.25; Most Ametropic Meridian, U305 = 0.52, p = 0.60). Median refractive astigmatism was -0.50DC (range 0.00 to -3.50DC) for the ASD group and -0.50DC (Range 0.00 to -2.25DC) for the TD group. Magnitude and prevalence of refractive astigmatism (defined as astigmatism ≥1.00DC) was significantly greater in the ASD group compared to the typically developing group (ASD 26%, TD 8%, magnitude U305 = 3.86, p = 0.0001; prevalence (χ12=17.71 , p < 0.0001). This is the first study to describe the refractive profile of a population of European Caucasian children with ASD compared to a TD population of children. Unlike other neurodevelopmental conditions, there was no increased prevalence of spherical refractive errors in ASD but astigmatic errors were significantly greater in magnitude and prevalence. This highlights the need to examine refractive errors in this population. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Eye laterality: a comprehensive analysis in refractive surgery candidates.

PubMed

Linke, Stephan J; Druchkiv, Vasyl; Steinberg, Johannes; Richard, Gisbert; Katz, Toam

2013-08-01

To explore eye laterality (higher refractive error in one eye) and its association with refractive state, spherical/astigmatic anisometropia, age and sex in refractive surgery candidates. Medical records of 12 493 consecutive refractive surgery candidates were filtered. Refractive error (subjective and cycloplegic) was measured in each subject and correlated with eye laterality. Only subjects with corrected distance visual acuity (CDVA) of >20/22 in each eye were enrolled to exclude amblyopia. Associations between eye laterality and refractive state were analysed by means of t-test, chi-squared test, Spearman's correlation and multivariate logistic regression analysis, respectively. There was no statistically significant difference in spherical equivalent between right (-3.47 ± 2.76 D) and left eyes (-3.47 ± 2.76 D, p = 0.510; Pearson's r = 0.948, p < 0.001). Subgroup analysis revealed (I) right eye laterality for anisometropia >2.5 D in myopic (-5.64 ± 2.5 D versus -4.92 ± 2.6 D; p = 0.001) and in hyperopic (4.44 ± 1.69 D versus 3.04 ± 1.79 D; p = 0.025) subjects, (II) a tendency for left eye cylindrical laterality in myopic subjects, and (III) myopic male subjects had a higher prevalence of left eye laterality. (IV) Age did not show any significant impact on laterality. Over the full refractive spectrum, this study confirmed previously described strong interocular refractive correlation but revealed a statistically significant higher rate of right eye laterality for anisometropia >2.5 D. In general, our results support the use of data from one eye only in studies of ocular refraction. © 2013 The Authors. Acta Ophthalmologica © 2013 Acta Ophthalmologica Scandinavica Foundation.

Pattern of refractive errors among patients at a tertiary hospital in Kathmandu.

PubMed

Rizyal, A; Ghising, R; Shrestha, R K; Kansakar, I

2011-09-01

A hospital based cross sectional study was carried out to determine the pattern of refractive errors among patients attending the out patient department, Department of Ophthalmology, Nepal Medical College Teaching Hospital. A total of 1100 patients were evaluated, (male 43.67%; female 56.33%). Simple myopic astigmatism was the most prevalent type of refractive error accounting for 27.18% followed by simple myopia (21.66%) and compound myopic astigmatism (19.48%). Simple hypermetropia (15.03%) and mixed astigmatism (4.3%) were also noted. Simple myopia was prevalent among the younger age group in the first to third decades, whereas hypermetropia was seen in the older patients in the third to fifth decades.

Prevalence of Refractive Error among Preschool Children in an Urban Population: The Baltimore Pediatric Eye Disease Study

PubMed Central

Giordano, Lydia; Friedman, David S.; Repka, Michael X.; Katz, Joanne; Ibironke, Josephine; Hawes, Patricia; Tielsch, James M.

2009-01-01

Purpose To determine the age-specific prevalence of refractive errors in White and African-American preschool children. Design The Baltimore Pediatric Eye Disease Study is a population-based evaluation of the prevalence of ocular disorders in children aged six through 71 months in Baltimore, Maryland, United States. Participants Among 4,132 children identified, 3,990 eligible children (97%) were enrolled and 2,546 children (62%) were examined. Methods Cycloplegic autorefraction was attempted on all children using a Nikon Retinomax K-Plus 2. If a reliable autorefraction could not be obtained after three attempts, cycloplegic streak retinoscopy was performed. Main Outcome Measures Mean spherical equivalent (SE) refractive error, astigmatism, and prevalence of higher refractive errors among African American and White children. Results The mean spherical equivalent (SE) of right eyes was +1.49 diopter (D) (standard deviation (SD) =1.23) in White and +0.71D (SD=1.35) in African-American children (mean difference of 0.78D, 95% CI: 0.67, 0.89). Mean SE refractive error did not decline with age in either group. The prevalence of myopia of 1.00 D or more in the eye with the lesser refractive error was 0.7% in White and 5.5% in African-American children (RR: 8.01 95% confidence interval (CI): 3.70, 17.35). The prevalence of hyperopia of +3D or more in the eye with the lesser refractive error was 8.9% in White and 4.4% in African-American children (relative risk (RR): 0.49, 95% CI: 0.35, 0.68). The prevalence of emmetropia (less than −1.00 D to less than +1.00 D) was 35.6% in Whites and 58.0 % in African-Americans (RR: 1.64, 95% CI: 1.49, 1.80). Based on published prescribing guidelines 5.1% of the children would have benefited from spectacle correction. However, only 1.3% had been previously prescribed correction. Conclusions Significant refractive errors are uncommon in this population of urban preschool children. There was no evidence for a myopic shift over this age

Prevalence of refractive error among preschool children in an urban population: the Baltimore Pediatric Eye Disease Study.

PubMed

Giordano, Lydia; Friedman, David S; Repka, Michael X; Katz, Joanne; Ibironke, Josephine; Hawes, Patricia; Tielsch, James M

2009-04-01

To determine the age-specific prevalence of refractive errors in white and African-American preschool children. The Baltimore Pediatric Eye Disease Study is a population-based evaluation of the prevalence of ocular disorders in children aged 6 to 71 months in Baltimore, Maryland. Among 4132 children identified, 3990 eligible children (97%) were enrolled and 2546 children (62%) were examined. Cycloplegic autorefraction was attempted in all children with the use of a Nikon Retinomax K-Plus 2 (Nikon Corporation, Tokyo, Japan). If a reliable autorefraction could not be obtained after 3 attempts, cycloplegic streak retinoscopy was performed. Mean spherical equivalent (SE) refractive error, astigmatism, and prevalence of higher refractive errors among African-American and white children. The mean SE of right eyes was +1.49 diopters (D) (standard deviation [SD] = 1.23) in white children and +0.71 D (SD = 1.35) in African-American children (mean difference of 0.78 D; 95% confidence interval [CI], 0.67-0.89). Mean SE refractive error did not decline with age in either group. The prevalence of myopia of 1.00 D or more in the eye with the lesser refractive error was 0.7% in white children and 5.5% in African-American children (relative risk [RR], 8.01; 95% CI, 3.70-17.35). The prevalence of hyperopia of +3 D or more in the eye with the lesser refractive error was 8.9% in white children and 4.4% in African-American children (RR, 0.49; 95% CI, 0.35-0.68). The prevalence of emmetropia (<-1.00 D to <+1.00 D) was 35.6% in white children and 58.0% in African-American children (RR, 1.64; 95% CI, 1.49-1.80). On the basis of published prescribing guidelines, 5.1% of the children would have benefited from spectacle correction. However, only 1.3% had been prescribed correction. Significant refractive errors are uncommon in this population of urban preschool children. There was no evidence for a myopic shift over this age range in this cross-sectional study. A small proportion of

Prevalence of refractive error and visual impairment among rural school-age children of Goro District, Gurage Zone, Ethiopia.

PubMed

Kedir, Jafer; Girma, Abonesh

2014-10-01

Refractive error is one of the major causes of blindness and visual impairment in children; but community based studies are scarce especially in rural parts of Ethiopia. So, this study aims to assess the prevalence of refractive error and its magnitude as a cause of visual impairment among school-age children of rural community. This community-based cross-sectional descriptive study was conducted from March 1 to April 30, 2009 in rural villages of Goro district of Gurage Zone, found south west of Addis Ababa, the capital of Ethiopia. A multistage cluster sampling method was used with simple random selection of representative villages in the district. Chi-Square and t-tests were used in the data analysis. A total of 570 school-age children (age 7-15) were evaluated, 54% boys and 46% girls. The prevalence of refractive error was 3.5% (myopia 2.6% and hyperopia 0.9%). Refractive error was the major cause of visual impairment accounting for 54% of all causes in the study group. No child was found wearing corrective spectacles during the study period. Refractive error was the commonest cause of visual impairment in children of the district, but no measures were taken to reduce the burden in the community. So, large scale community level screening for refractive error should be conducted and integrated with regular school eye screening programs. Effective strategies need to be devised to provide low cost corrective spectacles in the rural community.

Refractive errors in an older population: the Blue Mountains Eye Study.

PubMed

Attebo, K; Ivers, R Q; Mitchell, P

1999-06-01

To determine prevalence and associations with refractive errors in a defined older population. Cross-sectional study. A total of 3654 residents, aged 49-97, of the Blue Mountains, west of Sydney, Australia. Comprehensive questionnaire and detailed eye examination, including refraction. Refractive error of phakic eyes, age, gender, and education. Prevalence rates were determined for myopia (15%), hyperopia (57%), and emmetropia (28%). Hyperopia prevalence was age-related, increasing from 36% in persons aged <60 years to 71 % of persons aged > or = 80 (P < 0.0001), whereas myopia prevalence decreased with age, from 21 % in persons aged <60 years to 10% of persons aged > or = 80 years (P < 0.0001). Younger myopic subjects in this population reported first wearing distance correction at a significantly younger age than older subjects, P < 0.0001. After adjustment for age, women were slightly more hyperopic (mean +0.75 diopters [D]) than men (mean +0.59 D, P = 0.0012. The gender-adjusted mean spherical error increased with age from +0.03 D in persons aged <60 years to +1.2 D in persons aged > or = 80 years (P < 0.0001). The gender-adjusted mean cylinder power also increased with age, from -0.6 D in persons aged <60 years to -1.2 D in persons aged > or = 80 years (P < 0.0001). The mean axis of astigmatism was "against the rule" in all age groups. Anisometropia increased with age, from a mean of 0.4 D in persons aged <60 to 0.9 D in persons aged > or = 80 years (P < 0.0001). Higher education was associated with myopia in men (P = 0.009) but not in women (P = 0.21) after adjustment for age. This report has documented the detailed refractive status of an older population, confirming previously described trends but also finding an apparent higher prevalence of myopia among younger members of this community.

Proportion of refractive errors in a Polish immigrant population in Chicago.

PubMed

Allison, Christine L

2010-08-01

This retrospective record review was conducted to investigate the proportion of patients with refractive error in a Polish immigrant population residing in an urban environment. Illinois has more than 1 million people of Polish descent as citizens, and Chicago is considered to have the second largest population of Polish descent in the world, outside of Warsaw, Poland. Six hundred seventy-five records (271 men/404 women) of Polish immigrants were reviewed from a practice with >92% Polish immigrants in the patient base. The patients ranged in age from 3 to 94 years. Refractive status for each eye, and the existence of any strabismus or amblyopia, was recorded. The proportion of myopia [spherical equivalent at least -0.75 diopter (D)] was found to be 35.1%, whereas the proportion of hyperopia (spherical equivalent > or =+0.75 D) was found to be 38.4%. Fifteen percent of the patients exhibited astigmatism > or =1.00 D. Amblyopia was present in 9% of the patients, whereas the prevalence of strabismus was found to be 3%, with 76% of the strabismics exhibiting esotropia. In the 0- to 18-year age range and the 19- to 45-year age range, the most common refractive error was low myopia (43.9 and 36.9%), whereas in the patients >45 years of age, it was low hyperopia (31.2%). Refractive error data are presented for a population base that has not been previously reported, although Polish Americans comprise 3% of the US population. Myopia is more common in young Polish patients than in the general US population. The strong hyperopic shift in older patients may either be normal aging or the product of increased near work in the young. The high rates of amblyopia call for more aggressive education and treatment.

Relation of anthropometric measurements to ocular biometric changes and refractive error in children with thalassemia.

PubMed

Elkitkat, Rania S; El-Shazly, Amany A; Ebeid, Weam M; Deghedy, Marwa R

2018-03-01

To evaluate and correlate anthropometric, biometric, and refractive error changes in thalassemia major (TM). One hundred children with TM and another hundred healthy controls were recruited. Height, weight, body mass index (BMI), and occipitofrontal circumference (OFC) were the anthropometric parameters recorded. Full ophthalmologic examination was performed, including best-corrected visual acuity, cycloplegic refraction, slit-lamp examination, Goldmann applanation tonometry, indirect ophthalmoscopy, keratometry (K readings), and ocular biometry. Compared to controls, children with TM were shorter and lighter, with a smaller BMI (p<0.001); however, no significant difference existed in OFC. Regarding ocular biometric data, patients with thalassemia had steeper mean K readings (p = 0.03), shorter axial length (AXL) (p = 0.005), shorter vitreous chamber depth (p<0.001), and thicker crystalline lens (p<0.001) than controls. Patients with thalassemia had a significant myopic shift (p = 0.003). Multiple regression analyses only showed a significant correlation between corneal astigmatism and both weight and height (β = -0.05 and p = 0.03 and β = 0.06 and p = 0.04, respectively). Spherical equivalent was significantly correlated to K readings, lens thickness, and anterior chamber depth (p<0.0001 for all parameters). Compared to controls, children with TM have significant retardation in general and ocular growth (smaller BMI and shorter AXL). Ocular growth changes probably resulted in compensatory biometric changes (steeper corneas and thicker lenses) to reach emmetropization, with an exaggerated response and subsequent myopic shift. However, growth retardation is not directly related to ocular growth changes, myopic shift, or variations in biometric parameters.

Visual Impairment, Undercorrected Refractive Errors, and Activity Limitations in Older Adults: Findings From the Three-City Alienor Study.

PubMed

Naël, Virginie; Pérès, Karine; Carrière, Isabelle; Daien, Vincent; Scherlen, Anne-Catherine; Arleo, Angelo; Korobelnik, Jean-Francois; Delcourt, Cécile; Helmer, Catherine

2017-04-01

As vision is required in almost all activities of daily living, visual impairment (VI) may be one of the major treatable factors for preventing activity limitations. We aimed to evaluate the attributable risk of VI associated with activity limitations and the extent to which limitations are avoidable with optimal optical correction of undercorrected refractive errors. We analyzed 709 older adults from the Three-City-Alienor population-based study. VI was defined by presenting distance visual acuity in the better-seeing eye. Multivariate modified Poisson regressions were used to estimate the associations between vision, activity limitations, and social participation restrictions. Population attributable risk (PAR) and generalized impact fraction (GIF) were estimated. Bootstrapping was used to estimate 95% confidence intervals (CI). After adjustment for potential confounders, VI was associated with each domain of activity limitations, except basic activities of daily living (ADL) limitations. These associations were found for even minimal levels of VI. PAR was estimated at 10.1% (95% CI: 5.2-10.6) for mobility limitations, at 26.0% (95% CI: 13.5-41.2) for instrumental ADL (IADL) limitations, and at 24.9% (95% CI: 10.5-47.1) for social participation restrictions. GIF for improvement of undercorrected refractive errors was 6.1% (95% CI: 3.8-8.5) for mobility limitations, 15.8% (95% CI: 11.5-20.1) for IADL limitations and 21.4% (95% CI: 13.8-28.5) for social participation restrictions. About one-sixth of IADL limitations and one-fifth of social participation restrictions could be prevented by an optimal optical correction. These results underline the importance of eye examinations in older adults to prevent disability.

Decision support system for determining the contact lens for refractive errors patients with classification ID3

NASA Astrophysics Data System (ADS)

Situmorang, B. H.; Setiawan, M. P.; Tosida, E. T.

2017-01-01

Refractive errors are abnormalities of the refraction of light so that the shadows do not focus precisely on the retina resulting in blurred vision [1]. Refractive errors causing the patient should wear glasses or contact lenses in order eyesight returned to normal. The use of glasses or contact lenses in a person will be different from others, it is influenced by patient age, the amount of tear production, vision prescription, and astigmatic. Because the eye is one organ of the human body is very important to see, then the accuracy in determining glasses or contact lenses which will be used is required. This research aims to develop a decision support system that can produce output on the right contact lenses for refractive errors patients with a value of 100% accuracy. Iterative Dichotomize Three (ID3) classification methods will generate gain and entropy values of attributes that include code sample data, age of the patient, astigmatic, the ratio of tear production, vision prescription, and classes that will affect the outcome of the decision tree. The eye specialist test result for the training data obtained the accuracy rate of 96.7% and an error rate of 3.3%, the result test using confusion matrix obtained the accuracy rate of 96.1% and an error rate of 3.1%; for the data testing obtained accuracy rate of 100% and an error rate of 0.

Trachoma, cataracts and uncorrected refractive error are still important contributors to visual morbidity in two remote indigenous communities of the Northern Territory, Australia.

PubMed

Wright, Heathcote R; Keeffe, Jill E; Taylor, Hugh R

2009-08-01

To assess the contribution of trachoma, cataract and refractive error to visual morbidity among Indigenous adults living in two remote communities of the Northern Territory. Cross-sectional survey of all adults aged 40 and over within a desert and coastal community. Visual acuity, clinical signs of trachoma using the simplified WHO grading system and assessment of cataract through a non-dilated pupil. Two hundred and sixty individuals over the age of 40 years participated in the study. The prevalence of visual impairment (<6/12) was 17%. The prevalence of blindness (<3/60) was 2%, 40-fold higher than seen in an urban Australian population when adjusted for age. In total, 78% of adults who grew up in a desert community had trachomatous scarring compared with 26% of those who grew up in a coastal community (P < or = 0.001). In the desert community the prevalence of trachomatous trichiasis was 10% and corneal opacity was 6%. No trachomatous trichiasis or corneal opacity was seen in the coastal community. Trachoma, cataract and uncorrected refractive error remain significant contributors to visual morbidity in at least two remote indigenous communities. A wider survey is required to determine if these findings represent a more widespread pattern and existing eye care services may need to be re-assessed to determine the cause of this unmet need.

Global cost of correcting vision impairment from uncorrected refractive error.

PubMed

Fricke, T R; Holden, B A; Wilson, D A; Schlenther, G; Naidoo, K S; Resnikoff, S; Frick, K D

2012-10-01

To estimate the global cost of establishing and operating the educational and refractive care facilities required to provide care to all individuals who currently have vision impairment resulting from uncorrected refractive error (URE). The global cost of correcting URE was estimated using data on the population, the prevalence of URE and the number of existing refractive care practitioners in individual countries, the cost of establishing and operating educational programmes for practitioners and the cost of establishing and operating refractive care facilities. The assumptions made ensured that costs were not underestimated and an upper limit to the costs was derived using the most expensive extreme for each assumption. There were an estimated 158 million cases of distance vision impairment and 544 million cases of near vision impairment caused by URE worldwide in 2007. Approximately 47 000 additional full-time functional clinical refractionists and 18 000 ophthalmic dispensers would be required to provide refractive care services for these individuals. The global cost of educating the additional personnel and of establishing, maintaining and operating the refractive care facilities needed was estimated to be around 20 000 million United States dollars (US$) and the upper-limit cost was US$ 28 000 million. The estimated loss in global gross domestic product due to distance vision impairment caused by URE was US$ 202 000 million annually. The cost of establishing and operating the educational and refractive care facilities required to deal with vision impairment resulting from URE was a small proportion of the global loss in productivity associated with that vision impairment.

Ionospheric refraction effects on orbit determination using the orbit determination error analysis system

NASA Technical Reports Server (NTRS)

Yee, C. P.; Kelbel, D. A.; Lee, T.; Dunham, J. B.; Mistretta, G. D.

1990-01-01

The influence of ionospheric refraction on orbit determination was studied through the use of the Orbit Determination Error Analysis System (ODEAS). The results of a study of the orbital state estimate errors due to the ionospheric refraction corrections, particularly for measurements involving spacecraft-to-spacecraft tracking links, are presented. In current operational practice at the Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF), the ionospheric refraction effects on the tracking measurements are modeled in the Goddard Trajectory Determination System (GTDS) using the Bent ionospheric model. While GTDS has the capability of incorporating the ionospheric refraction effects for measurements involving ground-to-spacecraft tracking links, such as those generated by the Ground Spaceflight Tracking and Data Network (GSTDN), it does not have the capability to incorporate the refraction effects for spacecraft-to-spacecraft tracking links for measurements generated by the Tracking and Data Relay Satellite System (TDRSS). The lack of this particular capability in GTDS raised some concern about the achievable accuracy of the estimated orbit for certain classes of spacecraft missions that require high-precision orbits. Using an enhanced research version of GTDS, some efforts have already been made to assess the importance of the spacecraft-to-spacecraft ionospheric refraction corrections in an orbit determination process. While these studies were performed using simulated data or real tracking data in definitive orbit determination modes, the study results presented here were obtained by means of covariance analysis simulating the weighted least-squares method used in orbit determination.

Atmospheric microwave refractivity and refraction

NASA Technical Reports Server (NTRS)

Yu, E.; Hodge, D. B.

1980-01-01

The atmospheric refractivity can be expressed as a function of temperature, pressure, water vapor content, and operating frequency. Based on twenty-year meteorological data, statistics of the atmospheric refractivity were obtained. These statistics were used to estimate the variation of dispersion, attenuation, and refraction effects on microwave and millimeter wave signals propagating along atmospheric paths. Bending angle, elevation angle error, and range error were also developed for an exponentially tapered, spherical atmosphere.

[The history of correction of refractive errors: spectacles].

PubMed

Wojtyczkak, E

2000-01-01

An historical analysis of discoveries related to the treatment of defects of vision is described. Opinions on visual processes, optics and methods of treating myopia, hypermetropia and astigmatism from ancient times through the Middle Ages, the renaissance and the following centuries are presented in particular. The beginning of the usage of glasses is discussed. Examples of the techniques which have been used to improve the subjective and objective methods of measuring refractive errors are also presented.

Comparison of visual acuity estimates using three different letter charts under two ambient room illuminations

PubMed Central

Chen, Ai-Hong; Norazman, Fatin Nur Najwa; Buari, Noor Halilah

2012-01-01

Background: Visual acuity is an essential estimate to assess ability of the visual system and is used as an indicator of ocular health status. Aim: The aim of this study is to investigate the consistency of acuity estimates from three different clinical visual acuity charts under two levels of ambient room illumination. Materials and Methods: This study involved thirty Malay university students aged between 19 and 23 years old (7 males, 23 females), with their spherical refractive error ranging between plano and –7.75D, astigmatism ranging from plano to –1.75D, anisometropia less than 1.00D and with no history of ocular injury or pathology. Right eye visual acuity (recorded in logMAR unit) was measured with Snellen letter chart (Snellen), wall mounted letter chart (WM) and projected letter chart (PC) under two ambient room illuminations, room light on and room light off. Results: Visual acuity estimates showed no statistically significant difference when measured with the room light on and with the room light off (F1,372 = 0.26, P = 0.61). Post-hoc analysis with Tukey showed that visual acuity estimates were significantly different between the Snellen and PC (P = 0.009) and between Snellen and WM (P = 0.002). Conclusions: Different levels of ambient room illumination had no significant effect on visual acuity estimates. However, the discrepancies in estimates of visual acuity noted in this study were purely due to the type of letter chart used. PMID:22446903

Refractive Errors in Koreans: The Korea National Health and Nutrition Examination Survey 2008-2012.

PubMed

Rim, Tyler Hyungtaek; Kim, Seung-Hyun; Lim, Key Hwan; Choi, Moonjung; Kim, Hye Young; Baek, Seung-Hee

2016-06-01

Our study provides epidemiologic data on the prevalence of refractive errors in all age group ≥5 years in Korea. In 2008 to 2012, a total of 33,355 participants aged ≥5 years underwent ophthalmologic examinations. Using the right eye, myopia was defined as a spherical equivalent (SE) less than -0.5 or -1.0 diopters (D) in subjects aged 19 years and older or as an SE less than -0.75 or -1.25 D in subjects aged 5 to 18 years according to non-cycloplegic refraction. Other refractive errors were defined as follows: high myopia as an SE less than -6.0 D; hyperopia as an SE larger than +0.5 D; and astigmatism as a cylindrical error less than -1.0 D. The prevalence and risk factors of myopia were evaluated. Prevalence rates with a 95% confidence interval were determined for myopia (SE <-0.5 D, 51.9% [51.2 to 52.7]; SE <-1.0 D, 39.6% [38.8 to 40.3]), high myopia (5.0% [4.7 to 5.3]), hyperopia (13.4% [12.9 to 13.9]), and astigmatism (31.2% [30.5 to 32.0]). The prevalence of myopia demonstrated a nonlinear distribution with the highest peak between the ages of 19 and 29 years. The prevalence of hyperopia decreased with age in subjects aged 39 years or younger and then increased with age in subjects aged 40 years or older. The prevalence of astigmatism gradually increased with age. Education was associated with all refractive errors; myopia was more prevalent and hyperopia and astigmatism were less prevalent in the highly educated groups. In young generations, the prevalence of myopia in Korea was much higher compared to the white or black populations in Western countries and is consistent with the high prevalence found in most other Asian countries. The overall prevalence of hyperopia was much lower compared to that of the white Western population. Age and education level were significant predictive factors associated with all kinds of refractive errors.

Refractive Errors in Koreans: The Korea National Health and Nutrition Examination Survey 2008-2012

PubMed Central

Rim, Tyler Hyungtaek; Kim, Seung-Hyun; Lim, Key Hwan; Choi, Moonjung

2016-01-01

Purpose Our study provides epidemiologic data on the prevalence of refractive errors in all age group ≥5 years in Korea. Methods In 2008 to 2012, a total of 33,355 participants aged ≥5 years underwent ophthalmologic examinations. Using the right eye, myopia was defined as a spherical equivalent (SE) less than -0.5 or -1.0 diopters (D) in subjects aged 19 years and older or as an SE less than -0.75 or -1.25 D in subjects aged 5 to 18 years according to non-cycloplegic refraction. Other refractive errors were defined as follows: high myopia as an SE less than -6.0 D; hyperopia as an SE larger than +0.5 D; and astigmatism as a cylindrical error less than -1.0 D. The prevalence and risk factors of myopia were evaluated. Results Prevalence rates with a 95% confidence interval were determined for myopia (SE <-0.5 D, 51.9% [51.2 to 52.7]; SE <-1.0 D, 39.6% [38.8 to 40.3]), high myopia (5.0% [4.7 to 5.3]), hyperopia (13.4% [12.9 to 13.9]), and astigmatism (31.2% [30.5 to 32.0]). The prevalence of myopia demonstrated a nonlinear distribution with the highest peak between the ages of 19 and 29 years. The prevalence of hyperopia decreased with age in subjects aged 39 years or younger and then increased with age in subjects aged 40 years or older. The prevalence of astigmatism gradually increased with age. Education was associated with all refractive errors; myopia was more prevalent and hyperopia and astigmatism were less prevalent in the highly educated groups. Conclusions In young generations, the prevalence of myopia in Korea was much higher compared to the white or black populations in Western countries and is consistent with the high prevalence found in most other Asian countries. The overall prevalence of hyperopia was much lower compared to that of the white Western population. Age and education level were significant predictive factors associated with all kinds of refractive errors. PMID:27247521

Effects of Head-Mounted Display on the Oculomotor System and Refractive Error in Normal Adolescents.

PubMed

Ha, Suk-Gyu; Na, Kun-Hoo; Kweon, Il-Joo; Suh, Young-Woo; Kim, Seung-Hyun

2016-07-01

To investigate the clinical effects of head-mounted display on the refractive error and oculomotor system in normal adolescents. Sixty volunteers (age: 13 to 18 years) watched a three-dimensional movie and virtual reality application of head-mounted display for 30 minutes. The refractive error (diopters [D]), angle of deviation (prism diopters [PD]) at distance (6 m) and near (33 cm), near point of accommodation, and stereoacuity were measured before, immediately after, and 10 minutes after watching the head-mounted display. The refractive error was presented as spherical equivalent (SE). Refractive error was measured repeatedly after every 10 minutes when a myopic shift greater than 0.15 D was observed after watching the head-mounted display. The mean age of the participants was 14.7 ± 1.3 years and the mean SE before watching head-mounted display was -3.1 ± 2.6 D. One participant in the virtual reality application group was excluded due to motion sickness and nausea. After 30 minutes of watching the head-mounted display, the SE, near point of accommodation, and stereoacuity in both eyes did not change significantly (all P > .05). Immediately after watching the head-mounted display, esophoric shift was observed (0.6 ± 1.5 to 0.2 ± 1.5 PD), although it was not significant (P = .06). Transient myopic shifts of 17.2% to 30% were observed immediately after watching the head-mounted display in both groups, but recovered fully within 40 minutes after watching the head-mounted display. There were no significant clinical effects of watching head-mounted display for 30 minutes on the normal adolescent eye. Transient changes in refractive error and binocular alignment were noted, but were not significant. [J Pediatr Ophthalmol Strabismus. 2016;53(4):238-245.]. Copyright 2016, SLACK Incorporated.

Change in over-refraction after scleral lens settling on average corneas.

PubMed

Bray, Chelsea; Britton, Stephanie; Yeung, Debby; Haines, Lacey; Sorbara, Luigina

2017-07-01

The purpose of this study was to determine the change in over-refraction, if any, after a scleral lens settled on the eye for 6-8 h. Sixteen patients of varying refractive errors and normal corneal curvatures (measured with Pentacam ™ Oculus) were fitted with trial Mini-Scleral Design (MSD) scleral lenses (15.8 mm diameter) in one eye. The sagittal depths of the scleral lenses were selected by adding 350 μm to the corneal sagittal heights measured at a chord length of 15 mm with the Visante ™ optical coherence tomographer (OCT) anterior segment scans and picking the closest available trial lens in the set. Initial measurements were taken 30 min after lens insertion and included an auto-refraction, subjective refraction, and best sphere refraction over the contact lens. Visual acuities and Visante ™ OCT anterior segment scans were also taken. These measurements were repeated after 6-8 h of lens wear. Over the trial wearing period, the average change in the spherical component of the over-refraction was +0.06 D (S.D. 0.17) (p = 0.16). The average change in cylinder was +0.04 D (S.D. 0.19) (p = 0.33). The average absolute change in axis was 1.06° (S.D. 12.11) (p = 0.74). The average change in best sphere was +0.13 ± 0.30 D (p = 0.12). There was no significant change in visual acuity with the best sphere over-refraction over the 6-8 h wearing period. There was a significant change in central corneal clearance over the wearing period of 83 μm (S.D. 22) (p < 0.0001). Despite a significant change in the central corneal clearance due to thinning of the fluid reservoir as the scleral lens settled (an average decrease of 83 μm after wearing the lenses for 6-8 h), there was not a statistically significant change in the subjective over-refraction (sphere, cylinder, and axis) or best sphere or visual acuity. This study has confirmed that there is no link between reduction in central corneal clearance and change in over-refraction for average

Indication of advanced orthokeratology as an additional treatment after refractive surgeries

NASA Astrophysics Data System (ADS)

Mitsui, Iwane; Yamada, Yoshida

2005-04-01

Ortho-K was indicated for twenty-three eyes of thirteen patients after refractive surgeries such as RK(1) ,PRK(2), and LASIK(3). The average of their Uncorrective Visual Acuity (UCVA) after surgeries was 20/30 or worse, and mean spherical equivalent (SE) was -2.42D. They were followed at least two years wearing of Advanced Ortho-K lenses during night. The following studies were examined on their auto-refraction, auto-keratometry, uncorrected and corrected visual acuity, intra-ocular pressure, corneal endothelium, corneal thickness, corneal curvature, and corneal shape for more than two years. 95% of the patients improved in UCVA up to 20/20 or better, 86% of them improved up to 20/15 or better, and 76% of them improved up to 20/10. The mean SEs improved to -1.20+/-1.02D during six months, - 1.03+/-0.83D during one year, and -0.73+/-0.64D during two years. Astigmatism also slightly decreased. Ophthalmologic examinations showed no abnormalities including flap formation, intra-ocular pressure, and endothelium. Among the refractive surgeries as well as RK and PRK, LASIK has been most popularly spread all over the world. However, patient's quality of vision is not always satisfied during and/or after refractive surgeries, because of several complications such as instability of flap formation, unexpected keratoectasia, diffuse lamellar keratitis, epithelial ingrowth, irregularity of corneal surface which caused myopia regression. In such cases, additional surgical procedures should not be indicated easily. However, Ortho-K is safe and effective enough to correct refractive errors still remained or re-appeared after refractive surgeries. It enables to restore the corneal irregularity to the ideal shape.

APLP2 Regulates Refractive Error and Myopia Development in Mice and Humans

PubMed Central

Verhoeven, Virginie J. M.; Hysi, Pirro G.; Wojciechowski, Robert; Singh, Pawan Kumar; Kumar, Ashok; Thinakaran, Gopal; Williams, Cathy

2015-01-01

Myopia is the most common vision disorder and the leading cause of visual impairment worldwide. However, gene variants identified to date explain less than 10% of the variance in refractive error, leaving the majority of heritability unexplained (“missing heritability”). Previously, we reported that expression of APLP2 was strongly associated with myopia in a primate model. Here, we found that low-frequency variants near the 5’-end of APLP2 were associated with refractive error in a prospective UK birth cohort (n = 3,819 children; top SNP rs188663068, p = 5.0 × 10−4) and a CREAM consortium panel (n = 45,756 adults; top SNP rs7127037, p = 6.6 × 10−3). These variants showed evidence of differential effect on childhood longitudinal refractive error trajectories depending on time spent reading (gene x time spent reading x age interaction, p = 4.0 × 10−3). Furthermore, Aplp2 knockout mice developed high degrees of hyperopia (+11.5 ± 2.2 D, p < 1.0 × 10−4) compared to both heterozygous (-0.8 ± 2.0 D, p < 1.0 × 10−4) and wild-type (+0.3 ± 2.2 D, p < 1.0 × 10−4) littermates and exhibited a dose-dependent reduction in susceptibility to environmentally induced myopia (F(2, 33) = 191.0, p < 1.0 × 10−4). This phenotype was associated with reduced contrast sensitivity (F(12, 120) = 3.6, p = 1.5 × 10−4) and changes in the electrophysiological properties of retinal amacrine cells, which expressed Aplp2. This work identifies APLP2 as one of the “missing” myopia genes, demonstrating the importance of a low-frequency gene variant in the development of human myopia. It also demonstrates an important role for APLP2 in refractive development in mice and humans, suggesting a high level of evolutionary conservation of the signaling pathways underlying refractive eye development. PMID:26313004

Frequency and Distribution of Refractive Error in Adult Life: Methodology and Findings of the UK Biobank Study

PubMed Central

Cumberland, Phillippa M.; Bao, Yanchun; Hysi, Pirro G.; Foster, Paul J.; Hammond, Christopher J.; Rahi, Jugnoo S.

2015-01-01

Purpose To report the methodology and findings of a large scale investigation of burden and distribution of refractive error, from a contemporary and ethnically diverse study of health and disease in adults, in the UK. Methods U K Biobank, a unique contemporary resource for the study of health and disease, recruited more than half a million people aged 40–69 years. A subsample of 107,452 subjects undertook an enhanced ophthalmic examination which provided autorefraction data (a measure of refractive error). Refractive error status was categorised using the mean spherical equivalent refraction measure. Information on socio-demographic factors (age, gender, ethnicity, educational qualifications and accommodation tenure) was reported at the time of recruitment by questionnaire and face-to-face interview. Results Fifty four percent of participants aged 40–69 years had refractive error. Specifically 27% had myopia (4% high myopia), which was more common amongst younger people, those of higher socio-economic status, higher educational attainment, or of White or Chinese ethnicity. The frequency of hypermetropia increased with age (7% at 40–44 years increasing to 46% at 65–69 years), was higher in women and its severity was associated with ethnicity (moderate or high hypermetropia at least 30% less likely in non-White ethnic groups compared to White). Conclusions Refractive error is a significant public health issue for the UK and this study provides contemporary data on adults for planning services, health economic modelling and monitoring of secular trends. Further investigation of risk factors is necessary to inform strategies for prevention. There is scope to do this through the planned longitudinal extension of the UK Biobank study. PMID:26430771

Recovery of Peripheral Refractive Errors and Ocular Shape in Rhesus Monkeys (Macaca mulatta) with Experimentally Induced Myopia

PubMed Central

Huang, Juan; Hung, Li-Fang; Smith, Earl L.

2012-01-01

This study aimed to investigate the changes in ocular shape and relative peripheral refraction during the recovery from myopia produced by form deprivation (FD) and hyperopic defocus. FD was imposed in 6 monkeys by securing a diffuser lens over one eye; hyperopic defocus was produced in another 6 monkeys by fitting one eye with -3D spectacle. When unrestricted vision was re-established, the treated eyes recovered from the vision-induced central and peripheral refractive errors. The recovery of peripheral refractive errors was associated with corresponding changes in the shape of the posterior globe. The results suggest that vision can actively regulate ocular shape and the development of central and peripheral refractions in infant primates. PMID:23026012

Genome-wide association meta-analysis highlights light-induced signaling as a driver for refractive error.

PubMed

Tedja, Milly S; Wojciechowski, Robert; Hysi, Pirro G; Eriksson, Nicholas; Furlotte, Nicholas A; Verhoeven, Virginie J M; Iglesias, Adriana I; Meester-Smoor, Magda A; Tompson, Stuart W; Fan, Qiao; Khawaja, Anthony P; Cheng, Ching-Yu; Höhn, René; Yamashiro, Kenji; Wenocur, Adam; Grazal, Clare; Haller, Toomas; Metspalu, Andres; Wedenoja, Juho; Jonas, Jost B; Wang, Ya Xing; Xie, Jing; Mitchell, Paul; Foster, Paul J; Klein, Barbara E K; Klein, Ronald; Paterson, Andrew D; Hosseini, S Mohsen; Shah, Rupal L; Williams, Cathy; Teo, Yik Ying; Tham, Yih Chung; Gupta, Preeti; Zhao, Wanting; Shi, Yuan; Saw, Woei-Yuh; Tai, E-Shyong; Sim, Xue Ling; Huffman, Jennifer E; Polašek, Ozren; Hayward, Caroline; Bencic, Goran; Rudan, Igor; Wilson, James F; Joshi, Peter K; Tsujikawa, Akitaka; Matsuda, Fumihiko; Whisenhunt, Kristina N; Zeller, Tanja; van der Spek, Peter J; Haak, Roxanna; Meijers-Heijboer, Hanne; van Leeuwen, Elisabeth M; Iyengar, Sudha K; Lass, Jonathan H; Hofman, Albert; Rivadeneira, Fernando; Uitterlinden, André G; Vingerling, Johannes R; Lehtimäki, Terho; Raitakari, Olli T; Biino, Ginevra; Concas, Maria Pina; Schwantes-An, Tae-Hwi; Igo, Robert P; Cuellar-Partida, Gabriel; Martin, Nicholas G; Craig, Jamie E; Gharahkhani, Puya; Williams, Katie M; Nag, Abhishek; Rahi, Jugnoo S; Cumberland, Phillippa M; Delcourt, Cécile; Bellenguez, Céline; Ried, Janina S; Bergen, Arthur A; Meitinger, Thomas; Gieger, Christian; Wong, Tien Yin; Hewitt, Alex W; Mackey, David A; Simpson, Claire L; Pfeiffer, Norbert; Pärssinen, Olavi; Baird, Paul N; Vitart, Veronique; Amin, Najaf; van Duijn, Cornelia M; Bailey-Wilson, Joan E; Young, Terri L; Saw, Seang-Mei; Stambolian, Dwight; MacGregor, Stuart; Guggenheim, Jeremy A; Tung, Joyce Y; Hammond, Christopher J; Klaver, Caroline C W

2018-06-01

Refractive errors, including myopia, are the most frequent eye disorders worldwide and an increasingly common cause of blindness. This genome-wide association meta-analysis in 160,420 participants and replication in 95,505 participants increased the number of established independent signals from 37 to 161 and showed high genetic correlation between Europeans and Asians (>0.78). Expression experiments and comprehensive in silico analyses identified retinal cell physiology and light processing as prominent mechanisms, and also identified functional contributions to refractive-error development in all cell types of the neurosensory retina, retinal pigment epithelium, vascular endothelium and extracellular matrix. Newly identified genes implicate novel mechanisms such as rod-and-cone bipolar synaptic neurotransmission, anterior-segment morphology and angiogenesis. Thirty-one loci resided in or near regions transcribing small RNAs, thus suggesting a role for post-transcriptional regulation. Our results support the notion that refractive errors are caused by a light-dependent retina-to-sclera signaling cascade and delineate potential pathobiological molecular drivers.

Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus.

PubMed

Schedin, Staffan; Hallberg, Per; Behndig, Anders

2016-01-20

We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on- and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.

The refractive index in electron microscopy and the errors of its approximations.

PubMed

Lentzen, M

2017-05-01

In numerical calculations for electron diffraction often a simplified form of the electron-optical refractive index, linear in the electric potential, is used. In recent years improved calculation schemes have been proposed, aiming at higher accuracy by including higher-order terms of the electric potential. These schemes start from the relativistically corrected Schrödinger equation, and use a second simplified form, now for the refractive index squared, being linear in the electric potential. The second and higher-order corrections thus determined have, however, a large error, compared to those derived from the relativistically correct refractive index. The impact of the two simplifications on electron diffraction calculations is assessed through numerical comparison of the refractive index at high-angle Coulomb scattering and of cross-sections for a wide range of scattering angles, kinetic energies, and atomic numbers. Copyright © 2016 Elsevier B.V. All rights reserved.

The prevalence of refractive errors among adults in the United States, Western Europe, and Australia.

PubMed

Kempen, John H; Mitchell, Paul; Lee, Kristine E; Tielsch, James M; Broman, Aimee T; Taylor, Hugh R; Ikram, M Kamran; Congdon, Nathan G; O'Colmain, Benita J

2004-04-01

To estimate the prevalence of refractive errors in persons 40 years and older. Counts of persons with phakic eyes with and without spherical equivalent refractive error in the worse eye of +3 diopters (D) or greater, -1 D or less, and -5 D or less were obtained from population-based eye surveys in strata of gender, race/ethnicity, and 5-year age intervals. Pooled age-, gender-, and race/ethnicity-specific rates for each refractive error were applied to the corresponding stratum-specific US, Western European, and Australian populations (years 2000 and projected 2020). Six studies provided data from 29 281 persons. In the US, Western European, and Australian year 2000 populations 40 years or older, the estimated crude prevalence for hyperopia of +3 D or greater was 9.9%, 11.6%, and 5.8%, respectively (11.8 million, 21.6 million, and 0.47 million persons). For myopia of -1 D or less, the estimated crude prevalence was 25.4%, 26.6%, and 16.4% (30.4 million, 49.6 million, and 1.3 million persons), respectively, of whom 4.5%, 4.6%, and 2.8% (5.3 million, 8.5 million, and 0.23 million persons), respectively, had myopia of -5 D or less. Projected prevalence rates in 2020 were similar. Refractive errors affect approximately one third of persons 40 years or older in the United States and Western Europe, and one fifth of Australians in this age group.

Longitudinal Development of Refractive Error in Children With Accommodative Esotropia: Onset, Amblyopia, and Anisometropia

PubMed Central

Wang, Jingyun; Morale, Sarah E.; Ren, Xiaowei; Birch, Eileen E.

2016-01-01

Purpose We investigated longitudinal changes of refractive error in children with accommodative esotropia (ET) throughout the first 12 years of life, its dependence on age at onset of ET, and whether amblyopia or anisometropia are associated with defective emmetropization. Methods Longitudinal refractive errors in children with accommodative ET were analyzed retrospectively. Eligibility criteria included: initial hyperopia ≥+4.00 diopters (D), initial cycloplegic refraction before 4 years, at least 3 visits, and at least one visit between 7 and 12 years. Children were classified as having infantile (N = 30; onset ≤12 months) or late-onset (N = 78; onset at 18–48 months) accommodative ET. Cycloplegic refractions culled from medical records were converted into spherical equivalent (SEQ). Results Although the initial visit right eye SEQ was similar for the infantile and late-onset groups (+5.86 ± 1.28 and +5.67 ± 1.26 D, respectively), there were different developmental changes in refractive error. Neither group had a significant decrease in hyperopia before age 7 years, but after 7 years, the infantile group experienced a myopic shift of −0.43 D/y. The late-onset group did not experience a myopic shift at 7 to 12 years. Among amblyopic children, a slower myopic shift was observed for the amblyopic eye. Among anisometropic children, the more hyperopic eye experienced more myopic shift than the less hyperopic eye. Conclusions Children with infantile accommodative ET experienced prolonged hyperopia followed by a myopic shift after 7 years of age, consistent with dissociation between infantile emmetropization and school age myopic shift. In contrast, children with late-onset accommodative ET had little myopic shift before or after 7 years. PMID:27116548

The quality of systematic reviews about interventions for refractive error can be improved: a review of systematic reviews.

PubMed

Mayo-Wilson, Evan; Ng, Sueko Matsumura; Chuck, Roy S; Li, Tianjing

2017-09-05

Systematic reviews should inform American Academy of Ophthalmology (AAO) Preferred Practice Pattern® (PPP) guidelines. The quality of systematic reviews related to the forthcoming Preferred Practice Pattern® guideline (PPP) Refractive Errors & Refractive Surgery is unknown. We sought to identify reliable systematic reviews to assist the AAO Refractive Errors & Refractive Surgery PPP. Systematic reviews were eligible if they evaluated the effectiveness or safety of interventions included in the 2012 PPP Refractive Errors & Refractive Surgery. To identify potentially eligible systematic reviews, we searched the Cochrane Eyes and Vision United States Satellite database of systematic reviews. Two authors identified eligible reviews and abstracted information about the characteristics and quality of the reviews independently using the Systematic Review Data Repository. We classified systematic reviews as "reliable" when they (1) defined criteria for the selection of studies, (2) conducted comprehensive literature searches for eligible studies, (3) assessed the methodological quality (risk of bias) of the included studies, (4) used appropriate methods for meta-analyses (which we assessed only when meta-analyses were reported), (5) presented conclusions that were supported by the evidence provided in the review. We identified 124 systematic reviews related to refractive error; 39 met our eligibility criteria, of which we classified 11 to be reliable. Systematic reviews classified as unreliable did not define the criteria for selecting studies (5; 13%), did not assess methodological rigor (10; 26%), did not conduct comprehensive searches (17; 44%), or used inappropriate quantitative methods (3; 8%). The 11 reliable reviews were published between 2002 and 2016. They included 0 to 23 studies (median = 9) and analyzed 0 to 4696 participants (median = 666). Seven reliable reviews (64%) assessed surgical interventions. Most systematic reviews of interventions for

Nature versus nurture: A systematic approach to elucidate gene-environment interactions in the development of myopic refractive errors.

PubMed

Miraldi Utz, Virginia

2017-01-01

Myopia is the most common eye disorder and major cause of visual impairment worldwide. As the incidence of myopia continues to rise, the need to further understand the complex roles of molecular and environmental factors controlling variation in refractive error is of increasing importance. Tkatchenko and colleagues applied a systematic approach using a combination of gene set enrichment analysis, genome-wide association studies, and functional analysis of a murine model to identify a myopia susceptibility gene, APLP2. Differential expression of refractive error was associated with time spent reading for those with low frequency variants in this gene. This provides support for the longstanding hypothesis of gene-environment interactions in refractive error development.

Association between Refractive Errors and Ocular Biometry in Iranian Adults

PubMed Central

Hashemi, Hassan; Khabazkhoob, Mehdi; Emamian, Mohammad Hassan; Shariati, Mohammad; Miraftab, Mohammad; Yekta, Abbasali; Ostadimoghaddam, Hadi; Fotouhi, Akbar

2015-01-01

Purpose: To investigate the association between ocular biometrics such as axial length (AL), anterior chamber depth (ACD), lens thickness (LT), vitreous chamber depth (VCD) and corneal power (CP) with different refractive errors. Methods: In a cross-sectional study on the 40 to 64-year-old population of Shahroud, random cluster sampling was performed. Ocular biometrics were measured using the Allegro Biograph (WaveLight AG, Erlangen, Germany) for all participants. Refractive errors were determined using cycloplegic refraction. Results: In the first model, the strongest correlations were found between spherical equivalent with axial length and corneal power. Spherical equivalent was strongly correlated with axial length in high myopic and high hyperopic cases, and with corneal power in high hyperopic cases; 69.5% of variability in spherical equivalent was attributed to changes in these variables. In the second model, the correlations between vitreous chamber depth and corneal power with spherical equivalent were stronger in myopes than hyperopes, while the correlations between lens thickness and anterior chamber depth with spherical equivalent were stronger in hyperopic cases than myopic ones. In the third model, anterior chamber depth + lens thickness correlated with spherical equivalent only in moderate and severe cases of hyperopia, and this index was not correlated with spherical equivalent in moderate to severe myopia. Conclusion: In individuals aged 40-64 years, corneal power and axial length make the greatest contribution to spherical equivalent in high hyperopia and high myopia. Anterior segment biometric components have a more important role in hyperopia than myopia. PMID:26730304

Refractive errors and strabismus in Asian patients with Down syndrome.

PubMed

Kim, U; Hwang, J-M

2009-07-01

The purpose of this study was to investigate the prevalence and patterns of refractive errors and strabismus in Asian patients with Down syndrome, as they relate to age.MethodsA total of 261 Korean patients with Down syndrome were examined between March 1999 and May 2007. Eighty-nine patients were excluded from the study. The remaining 172 patients were divided into four age groups (<3 years, 3-<6 years, 6-<9 years, and >or=9 years). Full ophthalmologic examinations and strabismus assessments were performed. Refractive errors were defined as follows: myopia >or=-1.00 D, hyperopia >or=+1.00 D, astigmatism >or=+/-1.00 D, and anisometropia as a refractive difference between the two eyes >or=1.00 D. Hyperopia (46.5%) was slightly more common than myopia (40.1%). The prevalence of myopia increased with age, whereas that of hyperopia decreased. Astigmatism was found in 66.8% of patients, and astigmatism >or=2 D was found in 16.8% of patients. Anisometropia was identified in 29.7% of patients, and the incidence of anisometropia correlated significantly with age as well as with astigmatism. Esotropia (22.1%) was twice as common as exotropia (10.5%). The prevalence of esotropia increased with age, but that of exotropia decreased. Fifty patients were found to have nystagmus (29.1%). In Asian patients with Down syndrome, esotropia was more common than exotropia and hyperopia was more common than myopia. The prevalence of exotropia and astigmatism was much higher in this study than has been previously reported.

Effects of tropospheric and ionospheric refraction errors in the utilization of GEOS-C altimeter data

NASA Technical Reports Server (NTRS)

Goad, C. C.

1977-01-01

The effects of tropospheric and ionospheric refraction errors are analyzed for the GEOS-C altimeter project in terms of their resultant effects on C-band orbits and the altimeter measurement itself. Operational procedures using surface meteorological measurements at ground stations and monthly means for ocean surface conditions are assumed, with no corrections made for ionospheric effects. Effects on the orbit height due to tropospheric errors are approximately 15 cm for single pass short arcs (such as for calibration) and 10 cm for global orbits of one revolution. Orbit height errors due to neglect of the ionosphere have an amplitude of approximately 40 cm when the orbits are determined from C-band range data with predominantly daylight tracking. Altimeter measurement errors are approximately 10 cm due to residual tropospheric refraction correction errors. Ionospheric effects on the altimeter range measurement are also on the order of 10 cm during the GEOS-C launch and early operation period.

Enhanced visual acuity and image perception following correction of highly aberrated eyes using an adaptive optics visual simulator.

PubMed

Rocha, Karolinne Maia; Vabre, Laurent; Chateau, Nicolas; Krueger, Ronald R

2010-01-01

To evaluate the changes in visual acuity and visual perception generated by correcting higher order aberrations in highly aberrated eyes using a large-stroke adaptive optics visual simulator. A crx1 Adaptive Optics Visual Simulator (Imagine Eyes) was used to correct and modify the wavefront aberrations in 12 keratoconic eyes and 8 symptomatic postoperative refractive surgery (LASIK) eyes. After measuring ocular aberrations, the device was programmed to compensate for the eye's wavefront error from the second order to the fifth order (6-mm pupil). Visual acuity was assessed through the adaptive optics system using computer-generated ETDRS opto-types and the Freiburg Visual Acuity and Contrast Test. Mean higher order aberration root-mean-square (RMS) errors in the keratoconus and symptomatic LASIK eyes were 1.88+/-0.99 microm and 1.62+/-0.79 microm (6-mm pupil), respectively. The visual simulator correction of the higher order aberrations present in the keratoconus eyes improved their visual acuity by a mean of 2 lines when compared to their best spherocylinder correction (mean decimal visual acuity with spherocylindrical correction was 0.31+/-0.18 and improved to 0.44+/-0.23 with higher order aberration correction). In the symptomatic LASIK eyes, the mean decimal visual acuity with spherocylindrical correction improved from 0.54+/-0.16 to 0.71+/-0.13 with higher order aberration correction. The visual perception of ETDRS letters was improved when correcting higher order aberrations. The adaptive optics visual simulator can effectively measure and compensate for higher order aberrations (second to fifth order), which are associated with diminished visual acuity and perception in highly aberrated eyes. The adaptive optics technology may be of clinical benefit when counseling patients with highly aberrated eyes regarding their maximum subjective potential for vision correction. Copyright 2010, SLACK Incorporated.

Visual acuity, endothelial cell density and polymegathism after iris-fixated lens implantation.

PubMed

Nassiri, Nader; Ghorbanhosseini, Saeedeh; Jafarzadehpur, Ebrahim; Kavousnezhad, Sara; Nassiri, Nariman; Sheibani, Kourosh

2018-01-01

The purpose of this study was to evaluate the visual acuity as well as endothelial cell density (ECD) and polymegathism after iris-fixated lens (Artiflex ® AC 401) implantation for correction of moderate to high myopia. In this retrospective cross-sectional study, 55 eyes from 29 patients undergoing iris-fixated lens implantation for correction of myopia (-5.00 to -15.00 D) from 2007 to 2014 were evaluated. Uncorrected visual acuity, best spectacle-corrected visual acuity, refraction, ECD and polymegathism (coefficient of variation [CV] in the sizes of endothelial cells) were measured preoperatively and 6 months postoperatively. In the sixth month of follow-up, the uncorrected vision acuity was 20/25 or better in 81.5% of the eyes. The best-corrected visual acuity was 20/30 or better in 96.3% of the eyes, and more than 92% of the eyes had a refraction score of ±1 D from the target refraction. The mean corneal ECD of patients before surgery was 2,803±339 cells/mm 2 , which changed to 2,744±369 cells/mm 2 six months after surgery ( p =0.142). CV in the sizes of endothelial cells before the surgery was 25.7%±7.1% and six months after surgery it was 25.9%±5.4% ( p =0.857). Artiflex iris-fixated lens implantation is a suitable and predictable method for correction of moderate to high myopia. There was no statistically significant change in ECD and polymegathism (CV in the sizes of endothelial cells) after 6 months of follow-up.

A survey of the criteria for prescribing in cases of borderline refractive errors

PubMed Central

Shneor, Einat; Evans, Bruce John William; Fine, Yael; Shapira, Yehudit; Gantz, Liat; Gordon-Shaag, Ariela

2015-01-01

Purpose This research investigated the reported optometric prescribing criteria of Israeli optometrists. Methods An online questionnaire based on previous studies was distributed via email and social networking sites to optometrists in Israel. The questionnaire surveyed the level of refractive error at which respondents would prescribe for different types of refractive error at various ages with and without symptoms. Results 124 responses were obtained, yielding a response rate of approximately 12–22%, 92% of whom had trained in Israel. For all refractive errors, the presence of symptoms strongly influenced prescribing criteria. For example, for 10–20 year old patients the degree of hyperopia for which 50% of practitioners would prescribe is +0.75 D in the presence of symptoms but twice this value (+1.50 D) in the absence of symptoms. As might be expected, optometrists prescribed at lower degrees of hyperopia for older compared with younger patients. There was a trend for more experienced practitioners to be less likely to prescribe for lower degrees of myopia and presbyopia. Practitioner gender, country of training, the type of practice environment, and financial incentives were not strongly related to prescribing criteria. Conclusions The prescribing criteria found in this study are broadly comparable with those in previous studies and with published prescribing guidelines. Subtle indications suggest that optometrists may become more conservative in their prescribing criteria with experience. PMID:26520884

Correlation between dry eye and refractive error in Saudi young adults using noninvasive Keratograph 4

PubMed Central

Fahmy, Rania M; Aldarwesh, Amal

2018-01-01

Purpose: The purpose is to study the correlation between dry eye and refractive errors in young adults using noninvasive Keratograph. Methods: In this cross sectional study, a total of 126 participants in the age range of 19–25 years and who were free of ocular surface disease, were recruited from King Saud University Campus. Refraction was defined by the spherical equivalent (SE) as the following: 49 emmetropic eyes (±0.50 SE), 48 myopic eyes (≤−0.75 SE and above), and 31 hyperopic eyes (>+0.75 SE). All participants underwent full ophthalmic examinations assessing their refractive status and dryness level including noninvasive breakup time (NIBUT) and tear meniscus height using Keratograph 4. Results: The prevalence of dry eye was 24.6%, 36.5%, and 17.4% in emmetropes, myopes, and hypermetropes, respectively. NIBUT has a negative correlation with hyperopia and a positive correlation with myopia with a significant reduction in the average NIBUT in myopes and hypermetropes in comparison to emmetropes. Conclusion: The current results succeeded to demonstrate a correlation between refractive errors and dryness level. PMID:29676308

Comparing sports vision among three groups of soft tennis adolescent athletes: Normal vision, refractive errors with and without correction.

PubMed

Chang, Shih-Tsun; Liu, Yen-Hsiu; Lee, Jiahn-Shing; See, Lai-Chu

2015-09-01

The effect of correcting static vision on sports vision is still not clear. To examine whether sports vision (depth perception [DP], dynamic visual acuity [DVA], eye movement [EM], peripheral vision [PV], and momentary vision [MV],) were different among soft tennis adolescent athletes with normal vision (Group A), with refractive error and corrected with (Group B) and without eyeglasses (Group C). A cross-section study was conducted. Soft tennis athletes aged 10-13 who played softball tennis for 2-5 years, and who were without any ocular diseases and without visual training for the past 3 months were recruited. DPs were measured in an absolute deviation (mm) between a moving rod and fixing rod (approaching at 25 mm/s, receding at 25 mm/s, approaching at 50 mm/s, receding at 50 mm/s) using electric DP tester. A smaller deviation represented better DP. DVA, EM, PV, and MV were measured on a scale from 1 (worse) to 10 (best) using ATHLEVISION software. Chi-square test and Kruskal-Wallis test was used to compare the data among the three study groups. A total of 73 athletes (37 in Group A, 8 in Group B, 28 in Group C) were enrolled in this study. All four items of DP showed significant difference among the three study groups (P = 0.0051, 0.0004, 0.0095, 0.0021). PV displayed significant difference among the three study groups (P = 0.0044). There was no significant difference in DVA, EM, and MV among the three study groups. Significant better DP and PV were seen among soft tennis adolescent athletes with normal vision than those with refractive error regardless whether they had eyeglasses corrected. On the other hand, DVA, EM, and MV were similar among the three study groups.

Comparing sports vision among three groups of soft tennis adolescent athletes: Normal vision, refractive errors with and without correction

PubMed Central

Chang, Shih-Tsun; Liu, Yen-Hsiu; Lee, Jiahn-Shing; See, Lai-Chu

2015-01-01

Background: The effect of correcting static vision on sports vision is still not clear. Aim: To examine whether sports vision (depth perception [DP], dynamic visual acuity [DVA], eye movement [EM], peripheral vision [PV], and momentary vision [MV],) were different among soft tennis adolescent athletes with normal vision (Group A), with refractive error and corrected with (Group B) and without eyeglasses (Group C). Setting and Design: A cross-section study was conducted. Soft tennis athletes aged 10–13 who played softball tennis for 2–5 years, and who were without any ocular diseases and without visual training for the past 3 months were recruited. Materials and Methods: DPs were measured in an absolute deviation (mm) between a moving rod and fixing rod (approaching at 25 mm/s, receding at 25 mm/s, approaching at 50 mm/s, receding at 50 mm/s) using electric DP tester. A smaller deviation represented better DP. DVA, EM, PV, and MV were measured on a scale from 1 (worse) to 10 (best) using ATHLEVISION software. Statistical Analysis: Chi-square test and Kruskal–Wallis test was used to compare the data among the three study groups. Results: A total of 73 athletes (37 in Group A, 8 in Group B, 28 in Group C) were enrolled in this study. All four items of DP showed significant difference among the three study groups (P = 0.0051, 0.0004, 0.0095, 0.0021). PV displayed significant difference among the three study groups (P = 0.0044). There was no significant difference in DVA, EM, and MV among the three study groups. Conclusions: Significant better DP and PV were seen among soft tennis adolescent athletes with normal vision than those with refractive error regardless whether they had eyeglasses corrected. On the other hand, DVA, EM, and MV were similar among the three study groups. PMID:26632127

Rasch Analysis of the Student Refractive Error and Eyeglass Questionnaire

PubMed Central

Crescioni, Mabel; Messer, Dawn H.; Warholak, Terri L.; Miller, Joseph M.; Twelker, J. Daniel; Harvey, Erin M.

2014-01-01

Purpose To evaluate and refine a newly developed instrument, the Student Refractive Error and Eyeglasses Questionnaire (SREEQ), designed to measure the impact of uncorrected and corrected refractive error on vision-related quality of life (VRQoL) in school-aged children. Methods. A 38 statement instrument consisting of two parts was developed: Part A relates to perceptions regarding uncorrected vision and Part B relates to perceptions regarding corrected vision and includes other statements regarding VRQoL with spectacle correction. The SREEQ was administered to 200 Native American 6th through 12th grade students known to have previously worn and who currently require eyeglasses. Rasch analysis was conducted to evaluate the functioning of the SREEQ. Statements on Part A and Part B were analyzed to examine the dimensionality and constructs of the questionnaire, how well the items functioned, and the appropriateness of the response scale used. Results Rasch analysis suggested two items be eliminated and the measurement scale for matching items be reduced from a 4-point response scale to a 3-point response scale. With these modifications, categorical data were converted to interval level data, to conduct an item and person analysis. A shortened version of the SREEQ was constructed with these modifications, the SREEQ-R, which included the statements that were able to capture changes in VRQoL associated with spectacle wear for those with significant refractive error in our study population. Conclusions While the SREEQ Part B appears to be a have less than optimal reliability to assess the impact of spectacle correction on VRQoL in our student population, it is also able to detect statistically significant differences from pretest to posttest on both the group and individual levels to show that the instrument can assess the impact that glasses have on VRQoL. Further modifications to the questionnaire, such as those included in the SREEQ-R, could enhance its functionality

Visual outcomes after spectacles treatment in children with bilateral high refractive amblyopia.

PubMed

Lin, Pei-Wen; Chang, Hsueh-Wen; Lai, Ing-Chou; Teng, Mei-Ching

2016-11-01

The aim was to investigate the visual outcomes of treatment with spectacles for bilateral high refractive amblyopia in children three to eight years of age. Children with previously untreated bilateral refractive amblyopia were enrolled. Bilateral high refractive amblyopia was defined as visual acuity (VA) being worse than 6/9 in both eyes in the presence of 5.00 D or more of hyperopia, 5.00 D or more of myopia and 2.00 D or more of astigmatism. Full myopic and astigmatic refractive errors were corrected, and the hyperopic refractive errors were corrected within 1.00 D of the full correction. All children received visual assessments at four-weekly intervals. VA, Worth four-dot test and Randot preschool stereotest were assessed at baseline and every four weeks for two years. Twenty-eight children with previously untreated bilateral high refractive amblyopia were enrolled. The mean VA at baseline was 0.39 ± 0.24 logMAR and it significantly improved to 0.21, 0.14, 0.11, 0.05 and 0.0 logMAR at four, eight, 12, 24 weeks and 18 months, respectively (all p = 0.001). The mean stereoacuity (SA) was 1,143 ± 617 arcsec at baseline and it significantly improved to 701, 532, 429, 211 and 98 arcsec at four, eight, 12, 24 weeks and 18 months, respectively (all p = 0.001). The time interval for VA achieving 6/6 was significantly shorter in the eyes of low spherical equivalent (SE) (-2.00 D < SE < +2.00 D) than in those of high SE (SE > +2.00 D) (3.33 ± 2.75 months versus 8.11 ± 4.56 months, p = 0.0005). All subjects had normal fusion on Worth four-dot test at baseline and all follow-up visits. Refractive correction with good spectacles compliance improves VA and SA in young children with bilateral high refractive amblyopia. Patients with greater amounts of refractive error will achieve resolution of amblyopia with a longer time. © 2016 Optometry Australia.

The incidence and visual acuity outcomes of children identified with ametropic amblyopia by vision screening.

PubMed

Maqsud, Mohammed Aftab; Arblaster, Gemma E

2015-04-01

To determine the incidence of ametropic amblyopia within a vision screening program's population and report the visual acuity outcomes of children identified with the condition. The medical records of children who underwent vision screening as their first assessment at 4-5 years of age between September 1, 2005 and August 31, 2006, were retrospectively reviewed. Children referred with ≤0.30 logMAR in each eye with at least 1 year of follow-up had their hospital notes reviewed and data on final visual acuity, refractive error, and follow-up period collected. A total of 33 children identified as having ametropic amblyopia with a follow-up of at least 1 year. The incidence of ametropic amblyopia was 2%-3.2%, depending on the definition used. The mean visual acuity achieved after treatment was 0.12 logMAR, which is significantly less than the age-appropriate mean of 0.00 logMAR (P < 0.01). Ametropic amblyopia responds to treatment, but most children demonstrate persistent reduced visual acuity at age 7 years. The incidence of ametropic amblyopia within a routine vision screening population shows that significant numbers fail to self-present. Copyright © 2015 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Assessing the accuracy and feasibility of a refractive error screening program conducted by school teachers in pre-primary and primary schools in Thailand.

PubMed

Teerawattananon, Kanlaya; Myint, Chaw-Yin; Wongkittirux, Kwanjai; Teerawattananon, Yot; Chinkulkitnivat, Bunyong; Orprayoon, Surapong; Kusakul, Suwat; Tengtrisorn, Supaporn; Jenchitr, Watanee

2014-01-01

As part of the development of a system for the screening of refractive error in Thai children, this study describes the accuracy and feasibility of establishing a program conducted by teachers. To assess the accuracy and feasibility of screening by teachers. A cross-sectional descriptive and analytical study was conducted in 17 schools in four provinces representing four geographic regions in Thailand. A two-staged cluster sampling was employed to compare the detection rate of refractive error among eligible students between trained teachers and health professionals. Serial focus group discussions were held for teachers and parents in order to understand their attitude towards refractive error screening at schools and the potential success factors and barriers. The detection rate of refractive error screening by teachers among pre-primary school children is relatively low (21%) for mild visual impairment but higher for moderate visual impairment (44%). The detection rate for primary school children is high for both levels of visual impairment (52% for mild and 74% for moderate). The focus group discussions reveal that both teachers and parents would benefit from further education regarding refractive errors and that the vast majority of teachers are willing to conduct a school-based screening program. Refractive error screening by health professionals in pre-primary and primary school children is not currently implemented in Thailand due to resource limitations. However, evidence suggests that a refractive error screening program conducted in schools by teachers in the country is reasonable and feasible because the detection and treatment of refractive error in very young generations is important and the screening program can be implemented and conducted with relatively low costs.

Refraction test

MedlinePlus

... purpose is to determine whether you have a refractive error (a need for glasses or contact lenses). For ... glasses or contact lenses) is normal, then the refractive error is zero (plano) and your vision should be ...

Young Public’s Awareness to Refractive Error Deficiency

PubMed Central

Aldebasi, Yousef

2011-01-01

Background: Visual impairment due to uncorrected refractive error affects 200 – 250 million people in the world. Uncorrected vision represents the 2nd or the 3rd blinding condition in many developing countries. The importance of awareness in dealing with this problem has been shown to reduce the risks of blindness and improve the quality of vision. Methods: Survey questionnaires have been distributed to 2500 randomly selected people from 6 different locations in Riyadh area between late 2003 and early 2004. Only 2039 data sheets (58% female and 42% male) have been analyzed; the remaining 461 data sheets were cancelled whether for biased responses or for ages those were outside the limited range (15–45 years). The questionnaire was designed to show responses according to three levels of education: basic, intermediate and high. Results: 8% of the sample individuals wear spectacle. Of these, 2/3 acknowledges the importance of wearing spectacles. For those who don’t, intellect is a determining factor in how people consider optical correction (21% of basic intellectual backgrounds only think it is important to wear glasses against some 40% of higher intellect). Most of the other results showed the effect of education in increasing the level of awareness in vision related questions. People with higher education are more aware than those with basic intellect in acknowledging: visual symptoms that need care (37% against only 26%), presbyopia condition (23% against 11%), urgency to seek eye care (85% against 29%), factors aggravating refractive errors in children (45% against 29%). Knowledge about the different forms of optical correction showed higher preference for spectacles against both contact lenses and refractive surgery. Conclusion: There is an overall tendency to show that the general public is not aware about most of the problems that concern their visual health. This is even more so in those with basic intellectual levels. In order to reduce the impact of

A survey of the criteria for prescribing in cases of borderline refractive errors.

PubMed

Shneor, Einat; Evans, Bruce John William; Fine, Yael; Shapira, Yehudit; Gantz, Liat; Gordon-Shaag, Ariela

2016-01-01

This research investigated the reported optometric prescribing criteria of Israeli optometrists. An online questionnaire based on previous studies was distributed via email and social networking sites to optometrists in Israel. The questionnaire surveyed the level of refractive error at which respondents would prescribe for different types of refractive error at various ages with and without symptoms. 124 responses were obtained, yielding a response rate of approximately 12-22%, 92% of whom had trained in Israel. For all refractive errors, the presence of symptoms strongly influenced prescribing criteria. For example, for 10-20 year old patients the degree of hyperopia for which 50% of practitioners would prescribe is +0.75 D in the presence of symptoms but twice this value (+1.50 D) in the absence of symptoms. As might be expected, optometrists prescribed at lower degrees of hyperopia for older compared with younger patients. There was a trend for more experienced practitioners to be less likely to prescribe for lower degrees of myopia and presbyopia. Practitioner gender, country of training, the type of practice environment, and financial incentives were not strongly related to prescribing criteria. The prescribing criteria found in this study are broadly comparable with those in previous studies and with published prescribing guidelines. Subtle indications suggest that optometrists may become more conservative in their prescribing criteria with experience. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Characteristics of Refractive Errors in a Population of Adults in the Central Region of Poland.

PubMed

Nowak, Michal S; Jurowski, Piotr; Grzybowski, Andrzej; Smigielski, Janusz

2018-01-08

Background : To investigate the distribution of refractive errors and their characteristics in older adults from a Polish population. Methods : The study design was a cross-sectional study. A total of 1107 men and women were interviewed and underwent detailed ophthalmic examinations, 998 subjects underwent refraction. Myopia was defined as spherical equivalent (SER) refraction ≤-0.5 dioptres (D) and hyperopia was defined as SER ≥+0.5 dioptres (D). Results : Among those who were refracted the distribution of myopia and hyperopia was 24.1% (95% CI 21.4-26.7) and 37.5% (95% CI 34.5-40.5), respectively. Myopia decreased from 28.7% in subjects aged 35-59 years to 19.3% in those aged 60 years or older and hyperopia increased from 21.8% at 35-59 years of age to 53.3% in subjects aged ≥60 years. Multiple regression analysis showed decreasing age (OR 0.98, 95% CI 0.96-1.00), female gender (OR 1.87, 95% CI 1.18-2.95) and presence of cataract (OR 2.40, 95% CI 1.24-4.63) were independent risk factors associated with myopia. Conclusions : The distribution of refractive errors found in our study is similar to those reported in other Caucasian populations and differs from Asian populations. Myopia was positively associated with younger age, female gender and presence of cataract.

Potential lost productivity resulting from the global burden of uncorrected refractive error.

PubMed

Smith, T S T; Frick, K D; Holden, B A; Fricke, T R; Naidoo, K S

2009-06-01

To estimate the potential global economic productivity loss associated with the existing burden of visual impairment from uncorrected refractive error (URE). Conservative assumptions and national population, epidemiological and economic data were used to estimate the purchasing power parity-adjusted gross domestic product (PPP-adjusted GDP) loss for all individuals with impaired vision and blindness, and for individuals with normal sight who provide them with informal care. An estimated 158.1 million cases of visual impairment resulted from uncorrected or undercorrected refractive error in 2007; of these, 8.7 million were blind. We estimated the global economic productivity loss in international dollars (I$) associated with this burden at I$ 427.7 billion before, and I$ 268.8 billion after, adjustment for country-specific labour force participation and employment rates. With the same adjustment, but assuming no economic productivity for individuals aged > 50 years, we estimated the potential productivity loss at I$ 121.4 billion. Even under the most conservative assumptions, the total estimated productivity loss, in $I, associated with visual impairment from URE is approximately a thousand times greater than the global number of cases. The cost of scaling up existing refractive services to meet this burden is unknown, but if each affected individual were to be provided with appropriate eyeglasses for less than I$ 1000, a net economic gain may be attainable.

Potential lost productivity resulting from the global burden of uncorrected refractive error

PubMed Central

Frick, KD; Holden, BA; Fricke, TR; Naidoo, KS

2009-01-01

Abstract Objective To estimate the potential global economic productivity loss associated with the existing burden of visual impairment from uncorrected refractive error (URE). Methods Conservative assumptions and national population, epidemiological and economic data were used to estimate the purchasing power parity-adjusted gross domestic product (PPP-adjusted GDP) loss for all individuals with impaired vision and blindness, and for individuals with normal sight who provide them with informal care. Findings An estimated 158.1 million cases of visual impairment resulted from uncorrected or undercorrected refractive error in 2007; of these, 8.7 million were blind. We estimated the global economic productivity loss in international dollars (I$) associated with this burden at I$ 427.7 billion before, and I$ 268.8 billion after, adjustment for country-specific labour force participation and employment rates. With the same adjustment, but assuming no economic productivity for individuals aged ≥ 50 years, we estimated the potential productivity loss at I$ 121.4 billion. Conclusion Even under the most conservative assumptions, the total estimated productivity loss, in $I, associated with visual impairment from URE is approximately a thousand times greater than the global number of cases. The cost of scaling up existing refractive services to meet this burden is unknown, but if each affected individual were to be provided with appropriate eyeglasses for less than I$ 1000, a net economic gain may be attainable. PMID:19565121

Image sensor for testing refractive error of eyes

NASA Astrophysics Data System (ADS)

Li, Xiangning; Chen, Jiabi; Xu, Longyun

2000-05-01

It is difficult to detect ametropia and anisometropia for children. Image sensor for testing refractive error of eyes does not need the cooperation of children and can be used to do the general survey of ametropia and anisometropia for children. In our study, photographs are recorded by a CCD element in a digital form which can be directly processed by a computer. In order to process the image accurately by digital technique, formula considering the effect of extended light source and the size of lens aperture has been deduced, which is more reliable in practice. Computer simulation of the image sensing is made to verify the fineness of the results.

[One-year longitudinal change in parameters of myopic school children trained by a new accommodative training device--uncorrected visual acuity, refraction, axial length, accommodation, and pupil reaction].

PubMed

Watanabe, Kumiko; Hara, Naoto; Kimijima, Masumi; Kotegawa, Yasue; Ohno, Koji; Arimoto, Ako; Mukuno, Kazuo; Hisahara, Satoru; Horie, Hidenori

2012-10-01

School children with myopia were trained using a visual stimulation device that generated an isolated blur stimulus on a visual target, with a constant retinal image size and constant brightness. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and papillary reaction were measured to investigate the effectiveness of the training. There were 45 school children with myopia without any other ophthalmic diseases. The mean age of the children was 8.9 +/- 2.0 years (age range; 6-16)and the mean refraction was -1.56 +/- 0.58 D (mean +/- standard deviation). As a visual stimulus, a white ring on a black background with a constant ratio of visual target size to retinal image size, irrespective of the distance, was displayed on a liquid crystal display (LCD), and the LCD was quickly moved from a proximal to a distal position to produce an isolated blur stimulus. Training with this visual stimulus was carried out in the relaxation phase of accommodation. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and pupillary reaction were investigated before training and every 3 months during the training. Of the 45 subjects, 42 (93%) could be trained for 3 consecutive months, 33 (73%) for 6 months, 23 (51%) for 9 months, and 21 (47%) for 12 months. The mean refraction decreased by 0.83 +/- 0.56 D (mean +/- standard deviation) and the mean axial length increased by 0.47 +/- 0.16 mm at 1 year, showing that the training bad some effect in improving the visual acuity. In the tests of the dynamic accommodative responses, the latency of the accommodative-phase decreased from 0.4 +/- 0.2 sec to 0.3 +/- 0.1 sec at 1 year, the gain of the accommodative-phase improved from 69.0 +/- 27.0% to 93.3 +/- 13.4%, the maximum speed of the accommodative-phase increased from 5.1 +/- 2.2 D/sec to 6.8 +/- 2.2 D/sec and the gain of the relaxation-phase significantly improved from 52.1 +/- 26.0% to 72.7 +/- 13.7% (corresponding t

Computed estimation of visual acuity after laser refractive keratectomy

NASA Astrophysics Data System (ADS)

Rol, Pascal O.; Parel, Jean-Marie A.; Hanna, Khalil

1991-06-01

A number of surgical techniques has been developed to correct ametropia (refractive defaults) of the eye by changing the anterior corneal radius. Because the air-cornea interface makes up for about two-third of the refractive power of the eye, a refractive correction is obtained by a suitable photoablation of the cornea. For this purpose, e.g., an ArF excimer laser which emits a wavelength of 193 nm is being used. After a mechanical removal of the epithelium, the Bowman's layer and the corneal stroma are photoablated on typically 50% of the central surface of the cornea with various precomputed shapes. Methods using a variable diaphragm1 or a scanning slit2 are being utilized. After regrowth of the epithelium, a smooth interface with air develops itself, which can be attributed to a mechanical equilibration. Yet, SEM studies have shown that with such kind of treatments, irregularities can remain in the new stromal surface (Fig. 1). A possible explanation for this effect is associated with an inhomogeneous energy distribution of the laser beam profile3. To some extent, the stromal surface is equalized by the epithelial layer during healing& However, as the corneal epithelium and stroma have different refractive indices, a scatter of the incident light may result causing a haze in the cornea and a blur of the image at the retina. In such a case the resolution and the contrast performance of the eye which is expected from a successful operation, may be reduced. This study is an attempt to quantify the vision blur as a function of the deformation observed at the epithelium-stroma interface.

Refractive Error and Visual Functions in Children with Special Needs Compared with the First Grade School Students in Oman

PubMed Central

Vora, Urmi; Khandekar, Rajiv; Natrajan, Sarvanan; Al-Hadrami, Khalfan

2010-01-01

Background: We evaluated the refractive status and visual function of children with special needs (other handicap) in 2010 and compared them with healthy 1st grade school students in Oman. Materials and Methods: This was a cohort study. Optometrists recorded vision using a logarithm of minimum angle of resolution (LogMAR) chart. Preferential looking method was used for testing 31 children. Cycloplegic refraction was performed on all children. Contrast sensitivity was tested using 2.5%, 10%, and 100% contrast charts. Ocular movement, alignment, and anterior segment were also assessed. A pediatrician reviewed the health records of all the children at the time of their enrollment in this study to determine if the child had been diagnosed with a systemic condition or syndromes. The visual functions were assessed by study investigators. We estimated the rates and the risk of different visual function defects in children with special needs. Result: The prevalence of refractive error in 70 children (4.7 ± 0.8 years) with special needs (group 1) and 175 normal healthy first grade students (group 2) were 58.5% and 2.9%, respectively. The risk of refractive error was significantly higher in children with special needs [relative risk, 48.1 (95% confidence interval, 17.54–131.8)]. Hyperopia (>1.00 D), myopia (≥ 1.00D) and astigmatism (≥ ±1.00 D) were found in 18.6%, 24.3%, and 27.1%, respectively, in group 1. Six children in this group had defective near vision. Sixteen (80%) children with Down syndrome had refractive error. Seven (50%) children with developmental disorder showed decreased contrast sensitivity. Conclusion: Prevalence of uncorrected refractive error was much higher in children with special needs. Prevalence of strabismus, nystagmus, and reduced contrast sensitivity was also higher in children with special needs. Early vision screening, visual function assessment, correction of refractive error, and frequent follow-up are recommended. PMID:21180428

Prevalence and risk factors for refractive errors in the Singapore Malay Eye Survey.

PubMed

Saw, Seang-Mei; Chan, Yiong-Huak; Wong, Wan-Ling; Shankar, Anoop; Sandar, Mya; Aung, Tin; Tan, Donald T H; Mitchell, Paul; Wong, Tien Yin

2008-10-01

To describe the prevalence and risk factors for myopia and other refractive errors in an urban Malay population in Singapore. Population-based, cross-sectional study. Persons of Malay ethnicity, between 40 and 80 years of age, living in Singapore. Refractive error was determined by subjective refraction and if unavailable by autorefraction. Data were analyzed for 2974 adults without previous cataract surgery and who had right eye refraction data. Risk factor data, such as education levels and near work activity, were obtained from a face-to-face interview. Myopia, defined as spherical equivalent (SE) refraction less than -0.5 diopters (D), astigmatism as cylinder less than -0.5 D, hyperopia as SE greater than 0.5 D, and anisometropia as the difference in SE greater than 1.0 D. The prevalence of myopia in the right eye was 30.7% (9.4% unilateral myopia and 21.3% bilateral myopia), the prevalence of astigmatism in the right eye was 33.3% (95% confidence interval [CI, 33.0-33.5), the prevalence of hyperopia in the right eye was 27.4% (95% CI, 24.7-27.6), and the prevalence of anisometropia was 9.9% (95% CI, 9.7-10.0). There was a U-shaped relationship between increasing age and the prevalence of myopia, which was partially explained by the age-related increase in the prevalence of cataract. In a multiple logistic regression model, female sex, age, higher educational level, and cataract were associated with myopia. Adults with myopia were more likely to have astigmatism (P<0.001) in multivariate analyses. A quarter of older adult Malay people in Singapore had myopia. Compared with previous reports of similarly aged Singapore Chinese adults, the prevalence of myopia, astigmatism, and anisometropia was lower, whereas the prevalence of hyperopia was similar.

Refractive Errors and Academic Achievements of Primary School Children.

PubMed

Joseph, Lucyamma

2014-01-01

The current study was conducted among school children of selected schools of Thiruvananthapuram district of Kerala. It was designed to investigate the effect of refractive errors on academic achievement of primary school children. Experimental method was used in the study and the study used a sample of 185 children. An equated sample without myopia were selected as control group. Academic achievement tests based on the study syllabus were prepared and administered to both groups. The children with myopia were given corrective devices such as glasses prescribed by the ophthalmologist. After five months academic achievement tests were again given to both groups and the results of the scores between two groups as well as the scores before and after correction of errors were compared, which showed a significant influence of myopia on academic achievement and examination anxiety of children.

Decreasing Uncorrected Refractive Error in the Classroom through a Multifactorial Pilot Intervention

ERIC Educational Resources Information Center

Kodjebacheva, Gergana; Maliski, Sally; Yu, Fei; Oelrich, Faye; Coleman, Anne L.

2014-01-01

The study assessed the effectiveness of a pilot intervention to promote the use of eyeglasses in one school in California. The intervention used a one-group pretest, posttest design. Between January and June 2011, during the intervention, all first- and second-grade children received eye evaluations and the children with refractive error received…

Ocular wavefront aberration and refractive error in pre-school children

NASA Astrophysics Data System (ADS)

Thapa, Damber; Fleck, Andre; Lakshminarayanan, Vasudevan; Bobier, William R.

2011-11-01

Hartmann-Shack images taken from an archived collection of SureSight refractive measurements of pre-school children in Oxford County, Ontario, Canada were retrieved and re-analyzed. Higher-order aberrations were calculated over the age range of 3 to 6 years. These higher-order aberrations were compared with respect to magnitudes of ametropia. Subjects were classified as emmetropic (range -0.5 to + 0.5D), low hyperopic (+ 0.5 to +2D) and high hyperopic (+2D or more) based upon the resulting spherical equivalent. Higher-order aberrations were found to increase with higher levels of hyperopia (p < 0.01). The strongest effect was for children showing more than +2.00D of hyperopia. The correlation coefficients were small in all of the higher-order aberrations; however, they were significant (p < 0.01). These analyses indicate a weak association between refractive error and higher-order aberrations in pre-school children.

Optical correction of refractive error for preventing and treating eye symptoms in computer users.

PubMed

Heus, Pauline; Verbeek, Jos H; Tikka, Christina

2018-04-10

Computer users frequently complain about problems with seeing and functioning of the eyes. Asthenopia is a term generally used to describe symptoms related to (prolonged) use of the eyes like ocular fatigue, headache, pain or aching around the eyes, and burning and itchiness of the eyelids. The prevalence of asthenopia during or after work on a computer ranges from 46.3% to 68.5%. Uncorrected or under-corrected refractive error can contribute to the development of asthenopia. A refractive error is an error in the focusing of light by the eye and can lead to reduced visual acuity. There are various possibilities for optical correction of refractive errors including eyeglasses, contact lenses and refractive surgery. To examine the evidence on the effectiveness, safety and applicability of optical correction of refractive error for reducing and preventing eye symptoms in computer users. We searched the Cochrane Central Register of Controlled Trials (CENTRAL); PubMed; Embase; Web of Science; and OSH update, all to 20 December 2017. Additionally, we searched trial registries and checked references of included studies. We included randomised controlled trials (RCTs) and quasi-randomised trials of interventions evaluating optical correction for computer workers with refractive error for preventing or treating asthenopia and their effect on health related quality of life. Two authors independently assessed study eligibility and risk of bias, and extracted data. Where appropriate, we combined studies in a meta-analysis. We included eight studies with 381 participants. Three were parallel group RCTs, three were cross-over RCTs and two were quasi-randomised cross-over trials. All studies evaluated eyeglasses, there were no studies that evaluated contact lenses or surgery. Seven studies evaluated computer glasses with at least one focal area for the distance of the computer screen with or without additional focal areas in presbyopic persons. Six studies compared computer

Comparing the Impact of Refractive and Nonrefractive Vision Loss on Functioning and Disability: The Salisbury Eye Evaluation.

PubMed

Zebardast, Nazlee; Swenor, Bonnielin K; van Landingham, Suzanne W; Massof, Robert W; Munoz, Beatriz; West, Sheila K; Ramulu, Pradeep Y

2015-06-01

To compare the effects of uncorrected refractive error (URE) and nonrefractive visual impairment (VI) on performance and disability measures. Cross-sectional, population-based study. A total of 2469 individuals with binocular presenting visual acuity (PVA) of ≥ 20/80 who participated in the first round of the Salisbury Eye Evaluation study. The URE was defined as binocular PVA of ≤ 20/30, improving to >20/30 with subjective refraction. The VI was defined as post-refraction binocular best-corrected visual acuity (BCVA) of ≤ 20/30. The visual acuity decrement due to VI was calculated as the difference between BCVA and 20/30, whereas visual acuity due to URE was taken as the difference between PVA and BCVA. Multivariable regression analyses were used to assess the disability impact of (1) vision status (VI, URE, or normal vision) using the group with normal vision as reference and (2) a 1-line decrement in acuity due to VI or URE. Objective measures of visual function were obtained from timed performance of mobility and near vision tasks, self-reported driving cessation, and self-reported visual difficulty measured by the Activities of Daily Vision (ADV) scale. The ADV responses were analyzed using Rasch analysis to determine visual ability. Compared with individuals with normal vision, subjects with VI (n = 191) had significantly poorer objective and subjective visual functioning in all metrics examined (P < 0.05), whereas subjects with URE (n = 132) demonstrated slower walking speeds, slower near task performance, more frequent driving cessation, and lower ADV scores (P < 0.05), but did not demonstrate slower stair climbing or descent speed. For all functional metrics evaluated, the impact of VI was greater than the impact of URE. The impact of a 1-line VA decrement due to VI was associated with greater deficits in mobility measures and driving cessation when compared with a 1-line VA decrement due to URE. Visual impairment is associated with greater

Characteristics of Refractive Errors in a Population of Adults in the Central Region of Poland

PubMed Central

Jurowski, Piotr; Grzybowski, Andrzej; Smigielski, Janusz

2018-01-01

Background: To investigate the distribution of refractive errors and their characteristics in older adults from a Polish population. Methods: The study design was a cross-sectional study. A total of 1107 men and women were interviewed and underwent detailed ophthalmic examinations, 998 subjects underwent refraction. Myopia was defined as spherical equivalent (SER) refraction ≤−0.5 dioptres (D) and hyperopia was defined as SER ≥+0.5 dioptres (D). Results: Among those who were refracted the distribution of myopia and hyperopia was 24.1% (95% CI 21.4–26.7) and 37.5% (95% CI 34.5–40.5), respectively. Myopia decreased from 28.7% in subjects aged 35–59 years to 19.3% in those aged 60 years or older and hyperopia increased from 21.8% at 35–59 years of age to 53.3% in subjects aged ≥60 years. Multiple regression analysis showed decreasing age (OR 0.98, 95% CI 0.96–1.00), female gender (OR 1.87, 95% CI 1.18–2.95) and presence of cataract (OR 2.40, 95% CI 1.24–4.63) were independent risk factors associated with myopia. Conclusions: The distribution of refractive errors found in our study is similar to those reported in other Caucasian populations and differs from Asian populations. Myopia was positively associated with younger age, female gender and presence of cataract. PMID:29316688

Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia.

PubMed

Verhoeven, Virginie J M; Hysi, Pirro G; Wojciechowski, Robert; Fan, Qiao; Guggenheim, Jeremy A; Höhn, René; MacGregor, Stuart; Hewitt, Alex W; Nag, Abhishek; Cheng, Ching-Yu; Yonova-Doing, Ekaterina; Zhou, Xin; Ikram, M Kamran; Buitendijk, Gabriëlle H S; McMahon, George; Kemp, John P; Pourcain, Beate St; Simpson, Claire L; Mäkelä, Kari-Matti; Lehtimäki, Terho; Kähönen, Mika; Paterson, Andrew D; Hosseini, S Mohsen; Wong, Hoi Suen; Xu, Liang; Jonas, Jost B; Pärssinen, Olavi; Wedenoja, Juho; Yip, Shea Ping; Ho, Daniel W H; Pang, Chi Pui; Chen, Li Jia; Burdon, Kathryn P; Craig, Jamie E; Klein, Barbara E K; Klein, Ronald; Haller, Toomas; Metspalu, Andres; Khor, Chiea-Chuen; Tai, E-Shyong; Aung, Tin; Vithana, Eranga; Tay, Wan-Ting; Barathi, Veluchamy A; Chen, Peng; Li, Ruoying; Liao, Jiemin; Zheng, Yingfeng; Ong, Rick T; Döring, Angela; Evans, David M; Timpson, Nicholas J; Verkerk, Annemieke J M H; Meitinger, Thomas; Raitakari, Olli; Hawthorne, Felicia; Spector, Tim D; Karssen, Lennart C; Pirastu, Mario; Murgia, Federico; Ang, Wei; Mishra, Aniket; Montgomery, Grant W; Pennell, Craig E; Cumberland, Phillippa M; Cotlarciuc, Ioana; Mitchell, Paul; Wang, Jie Jin; Schache, Maria; Janmahasatian, Sarayut; Janmahasathian, Sarayut; Igo, Robert P; Lass, Jonathan H; Chew, Emily; Iyengar, Sudha K; Gorgels, Theo G M F; Rudan, Igor; Hayward, Caroline; Wright, Alan F; Polasek, Ozren; Vatavuk, Zoran; Wilson, James F; Fleck, Brian; Zeller, Tanja; Mirshahi, Alireza; Müller, Christian; Uitterlinden, André G; Rivadeneira, Fernando; Vingerling, Johannes R; Hofman, Albert; Oostra, Ben A; Amin, Najaf; Bergen, Arthur A B; Teo, Yik-Ying; Rahi, Jugnoo S; Vitart, Veronique; Williams, Cathy; Baird, Paul N; Wong, Tien-Yin; Oexle, Konrad; Pfeiffer, Norbert; Mackey, David A; Young, Terri L; van Duijn, Cornelia M; Saw, Seang-Mei; Bailey-Wilson, Joan E; Stambolian, Dwight; Klaver, Caroline C; Hammond, Christopher J

2013-03-01

Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness. Myopia affects over 30% of Western populations and up to 80% of Asians. The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and 8,376 from 5 Asian cohorts. We identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians. Combined analysis identified 8 additional associated loci. The new loci include candidate genes with functions in neurotransmission (GRIA4), ion transport (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2 and BMP2) and eye development (SIX6 and PRSS56). We also confirmed previously reported associations with GJD2 and RASGRF1. Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for individuals carrying the highest genetic load. Our results, based on a large meta-analysis across independent multiancestry studies, considerably advance understanding of the mechanisms involved in refractive error and myopia.

Exceptionally low prevalence of refractive error and visual impairment in schoolchildren from Lao People's Democratic Republic.

PubMed

Casson, Robert J; Kahawita, Shyalle; Kong, Aimee; Muecke, James; Sisaleumsak, Siphetthavong; Visonnavong, Vithoune

2012-10-01

Vientiane Province is an urbanizing region in Southeast Asia. We aimed to determine the prevalence of refractive error and visual impairment in primary school-aged children in this region. Prospective, cross-sectional survey. A total of 2899 schoolchildren from Vientiane Province, Lao People's Democratic Republic (Lao PDR). Ten districts from Vientiane were randomly selected and 2 primary schools were randomly selected from each district. All children aged 6 to 11 years at selected schools were eligible to participate. The examination included visual acuity (VA) testing, cycloplegic retinoscopy with subjective refinement if indicated, ocular motility testing, and anterior segment and fundus examinations in visually impaired children. Cycloplegic refraction and VA. There was an estimated total of 3330 children who were eligible to participate, and data were recorded from 2899 (87%) of these children. Complete refractive data were available on 2842 children (85% of eligible population). The mean spherical equivalent (SE) in the right eyes was +0.60 diopter (D) (95% confidence interval [CI], 0.49-0.72), and the mean SE in the left eyes was +0.59 (95% CI, 0.50-0.68). The prevalence of hyperopia was 2.8% (95% CI, 1.9-3.7; 88 subjects), and the prevalence of myopia was 0.8% (95% CI, 0.3-1.4; 24 subjects). The majority of children (98%; 95% CI, 97.0-99.0) had normal unaided binocular VA (at least 20/32 in their better eye). The overall prevalence of any visual impairment (presenting VA <20/32 in the better eye) was 1.9% (95% CI, 1.0-2.9; 55 subjects). In multivariate logistic regression analysis, age (P = 0.001) was a significant predictor, and female gender (P = 0.08) and Yao ethnicity (P = 0.09) were borderline significant predictors of the presence of any visual impairment. Visual impairment is not a public health concern in this primary school-aged population; however, visually impaired children in the community were not studied. From this baseline, future surveys

The prevalence of refractive conditions in Puerto Rican adults attending an eye clinic system

PubMed Central

Rodriguez, Neisha M.; Romero, Angel. F.

2014-01-01

Purpose To determine the prevalence of refractive conditions in the adult population that visited primary care optometry clinics in Puerto Rico. Methods A retrospective cross-sectional study of patients examined at the Inter American University of Puerto Rico School of Optometry Eye Institute Clinics between 2004 and 2010. Subjects considered had best corrected visual acuity by standardized subjective refraction of 20/40 or better. The refractive errors were classified by the spherical equivalent (SE): sphere+½ cylinder. Myopia was classified as a SE>−0.50 D, hyperopia as a SE>+0.50  D, and emmetropia as a SE between −0.50 and +0.50, both included. Astigmatism equal or higher than 0.25 D in minus cylinder form was used. Patients with documented history of cataract extraction (pseudophakia or aphakia), amblyopia, refractive surgery or other corneal/ocular surgery were excluded from the study. Results A total of 784 randomly selected subjects older than 40 years of age were selected. The estimated prevalence (95%, confidence interval) among all subjects was hyperopia 51.5% (48.0–55.0), emmetropia 33.8% (30.5–37.2), myopia 14.7% (12.1–17.2) and astigmatism 69.6% (68.8–73.3). Hyperopia was more common in females than males although the difference was not statistically significant. The mean spherical equivalent values was hyperopic until 70 y/o and decreased slightly as the population ages. Conclusion Hyperopia is the most common refractive error and its prevalence and seems to increase among the aging population who visited the clinics. Further programs and studies must be developed to address the refractive errors needs of the adult Puerto Rican population. PMID:25000872