Uncorrected refractive errors

An Innovative Virtual Reality System for Measuring Refractive Error

In this study, we aimed to validate a novel light field virtual reality (LFVR) system for estimating refractive errors in the human eye. Fifty participants with an average age of 22.12 ± 2.2 years (range 20-30 years) were enrolled. The present study compared spherical equivalent (SE) and focal line measurements (F1 and F2) obtained by the LFVR system with those obtained by established methods, including closed-field and open-field autorefractors, retinoscopy, and subjective refraction. The results showed substantial agreement between the LFVR system and the traditional methods, with intraclass correlation coefficients (ICC) for SE ranging from 82.7% to 86.7% (p < 0.01), and for F1 and F2 from 80.7% to 86.4% (p < 0.01). Intra-repeatability for F1 and F2 demonstrated strong agreement, with ICC values of 88.8% and 97.5%, respectively. These findings suggest that the LFVR system holds potential as a primary tool for refractive error measurement in optical care, offering high agreement and repeatability compared to conventional methods.

National prevalence of vision impairment and blindness and associated risk factors in adults aged 40 years and older with known or undiagnosed diabetes: results from the SMART-India cross-sectional study

BACKGROUND

National estimates of the prevalence of vision impairment and blindness in people with diabetes are required to inform resource allocation. People with diabetes are more susceptible to conditions such as diabetic retinopathy that can impair vision; however, these are often missed in national studies. This study aims to determine the prevalence and risk factors of vision impairment and blindness in people with diabetes in India.

METHODS

Data from the SMART-India study, a cross-sectional survey with national coverage of 42 147 Indian adults aged 40 years and older, collected using a complex sampling design, were used to obtain nationally representative estimates for the prevalence of vision impairment and blindness in people with diabetes in India. Vulnerable adults (primarily those who did not have capacity to provide consent); pregnant and breastfeeding women; anyone deemed too ill to be screened; those who did not provide consent; and people with type 1 diabetes, gestational diabetes, or secondary diabetes were excluded from the study. Vision impairment was defined as presenting visual acuity of 0·4 logMAR or higher and blindness as presenting a visual acuity of 1·0 logMAR or higher in the better-seeing eye. Demographic, anthropometric, and laboratory data along with geographic distribution were analysed in all participants with available data. Non-mydriatic retinal images were used to grade diabetic retinopathy, and risk factors were also assessed.

FINDINGS

A total of 7910 people with diabetes were included in the analysis, of whom 5689 had known diabetes and 2221 were undiagnosed. 4387 (55·5%) of 7909 participants with available sex data were female and 3522 (44·5%) participants were male. The estimated national prevalence of vision impairment was 21·1% (95% CI 15·7-27·7) and blindness 2·4% (1·7-3·4). A higher prevalence of any vision impairment (29·2% vs 19·6%; p=0·016) and blindness (6·7% vs 1·6%; p<0·0001) was observed in those with ungradable images. In known diabetes, diabetic retinopathy (adjusted odds ratio [aOR] 3·06 [95% CI 1·25-7·51]), vision-threatening diabetic retinopathy (aOR 7·21 [3·52-14·75]), and diabetic macular oedema (aOR 5·41 [2·20-13·33]) were associated with blindness in adjusted analysis. Common sociodemographic risk factors for vision impairment and blindness include older age, lower educational attainment, and unemployment.

INTERPRETATION

Based on the estimated 101 million people with diabetes in 2021 and the interpretation of the data from this study, approximately 21 million people with diabetes have vision impairment in India, of whom 2·4 million are blind. Higher prevalence is observed in those from lower socio-economic strata and policy makers should focus on these groups to reduce inequalities in health care.

FUNDING

Global Challenge Research Fund of United Kingdom Research and Innovation through the Medical Research Council.

Striving Toward Better Eye Health Beyond Our Waiting Rooms: The LXXX Edward Jackson Memorial Lecture

PURPOSE

Visual impairment (VI) negatively impacts the quality of lives of individuals and the optimal health of populations, creating both human and financial costs. Yet, VI has not risen to a level that is considered a priority in population health. This analysis assesses the evidence currently available for strengthening the value proposition for eye health, particularly the demographic characteristics and patient-centered outcomes found in clinical research.

DESIGN

Retrospective cross-sectional analysis.

METHOD

Two searches of the AJO database were performed using relevant key words: Search 1 (S1): NEI-sponsored clinical trials (1970-2023); and Search 2 (S2): Quality of life (2018-2023). The Scopus Cite Score was used as a filter for each search, specifically ≥50 for S1 and ≥20 for S2.

RESULTS

Of the initial 466 articles found, 100 met the preestablished criteria. Age, sex, and race/ancestry/ethnicity were reported across glaucoma, retina, uveitis, cornea, and pediatrics subspecialties in 56% ± 9.7% of the articles; 37% ± 9.5% listed either age only or age, sex, or gender. The characterizations varied and subcategories were rarely reported. Only 2% of S1 and 25% of S2 noted patient-centered outcomes.

CONCLUSIONS

The characterization of study populations in the ophthalmic literature is limited by underreporting of patient-centered outcomes, useful for reaffirming the value of eye and vision health in population health. This analysis highlights the need for paying greater attention to more specific demographic categories and focusing more on patient-centered outcomes in clinical research.

Quality of life and depression among patients with high myopia in Nigeria: a cross sectional study

AIM

To evaluate the quality of life (QOL) and level of depression among participants with high myopia in Nigeria and the demographic factors associated with these outcomes.

METHODS

This cross-sectional study was conducted on 100 adult participants with high myopia (defined as refractive error ≤-5.00 D or worse, and uncorrected visual acuity worse than 6/18 in the better seeing eye) attending ophthalmology centres in Nigeria from 2 October 2021 to 30 August 2022. The means and standard deviations were calculated for each of the four domains of World Health Organization Quality of life scale (WHOQOL-BREF) using the transformed scores. The Beck Depression Inventory (BDI) scale was used to assess the level of depression.

RESULTS

The highest and the lowest mean scores of WHOQOL-BREF domains were found for the psychological and physical health domains (mean percentage scores were 67.0 [95% confidence intervals (CI) 64.1-68.9] and 55.3 (95%CI 51.8-58.8, P<0.001), respectively. One-way analysis of variance (ANOVA) revealed significant differences in physical health with educational status (higher among those with tertiary education: mean difference 0.9, 95%CI -0.2-2.1; P=0.049), differences in psychological health with working status (higher among those who were working 1.2, 95%CI 0.3-2.1; P=0.012). Also, the result showed a statistically significant association between environmental health and marital status (higher among non-married: 1.7, 95%CI -0.9-2.3; P=0.012) while overall health was associated with place of residence (higher in urban areas: 2.3, 95%CI 1.2-3.5; P=0.024). For depression, one in every nine participants reported major depressive symptom, mostly younger people (aged 16-29 vs 30-49y: 17.0% vs 0, P=0.019), and slightly more women than men (14.3% vs 0, P=0.064). There were significant negative correlations between the depression scores and psychological health (r=-0.48, P<0.001), physical health (r=-0.29, P=0.002), social and relationship (r=-0.49, P<0.001), environmental (r=-0.48, P<0.001) and overall health (r=-0.49, P<0.001).

CONCLUSION

People with high myopia have a relatively moderate QOL, but poor physical health, particularly the younger age group, and women who are more likely to experience clinically relevant depression. Eye care professionals should consider possible referrals for counselling for people with high myopia.

Design and delivery of the Refractive Errors Among Children (REACH) school-based eye health programme in India

CLINICAL RELEVANCE

Optimisation of vision screening programmes can result the detection of refractive anomalies in a high proportion of school children.

BACKGROUND

The Refractive Errors Among Children (REACH) programme aims to optimise outcomes of school-based vision screening in India by collaborating with hospitals and monitoring eye care throughout school attendance.

METHODS

REACH delivers school vision screening using pocket vision screeners (cards presenting rows of seven 0.2 logMAR Sloan letters at a 3 m viewing distance) in five states across India. Children who fail screening are referred for detailed evaluation including refraction, those requiring cycloplegic refraction are referred to partner hospitals. Spectacles are dispensed as needed and compliance is assessed. All data are recorded electronically.

RESULTS

Out of 2,240,805 children aged 5 to 18 (mean 11.5; SD ±3.3) years, 2,024,053 have undergone REACH screening in 10,309 schools predominantly in rural locations (78.7%) and government-funded (76%). Of those screened, 174,706 (8.6%) underwent detailed evaluation. A higher proportion of children in private or urban schools (11.8% and 10.4% respectively) were referred for detailed evaluation than those in government-funded or rural schools (5.9% and 7.2%, respectively; p < 0.001). The proportion referred for detailed evaluation differed by state (p < 0.001), from 4.0% in West Bengal to 14.4% in Kerala.

CONCLUSION

The REACH programme screened a high proportion of school children, providing further care and follow-up to optimise visual outcomes.

Determinants of Health Care Needs in Relation to Vision Correction among Adolescents in the United Arab Emirates: A Cross-Sectional Study

BACKGROUND

Uncorrected refractive error has been suggested to affect children's development, educational performance, and socialization. Sociodemographic and environmental differences among individuals may impact their accessibility to utilizing appropriate services, impacting their vision-dependent activities.

METHODS

Guided by the population health framework, this retrospective study assessed the prevalence of self-reported vision correction needs and its determinants for a sample of adolescents (n = 6363) from the United Arab Emirates (UAE) aged 13 to 20 years between 2007 to 2009.

RESULTS

The findings suggest a relatively high prevalence of self-reported vision correction needs (26.8%), with among 24.8% males and 31.7% among females. Factors that were significantly associated with vision correction needs included age, biological sex, location of residence (emirate), nationality, parental education and employment level, household financial status, screen time use, visiting an eye specialist in the past year, and daily functional capacity.

CONCLUSION

Reporting the vision correction needs of the adolescent population and identifying its determinants may help identify and resolve modifiable barriers to accessing the appropriate vision care resources. Further research in assessing the type of refractive error, potential genetic and environmental factors, and vision care services in each emirate may help decision-makers set appropriate policies to improve the overall quality of eye health.

Pediatric Eye Care Treatment Rates and Community Compliance to a Spectacle Provision Program in an Underserved School District in San Diego, CA

Significance

The need for early identification and treatment of young children's refractive error needs has become a public health concern. The UCSD Eyemobile for Children (EyeMobile) provides vision screenings and comprehensive eye exams on the Eyemobile among a population of underserved, predominantly Hispanic preschool and elementary school children. The program also provides spectacles for children who fail eye exams due to refractive error.

Methods

We performed a retrospective cross-sectional analysis of all children screened from 2011 to 2017 by the Eyemobile across 10 San Diego elementary schools. We examined demographics, distance and near visual acuity, autorefraction, stereopsis, and color vision. To measure compliance to our spectacle program, we checked if children who were prescribed spectacles were wearing them, as instructed, at the following year's screening. Differences between compliance measures with respect to school, age, ethnicity, and gender were determined using chi-square analysis, while all other measures were fit to a binary logistic regression to determine statistically significant factors.

Results

A total of 12,176 elementary school children were screened between 2011 and 2017. Of these children, 5269 (43.3%) were referred for a comprehensive eye examination. Across six years, 3163 (60.0%) of the children referred completed their eye examinations. There was a significant increase (p < 0.001) in exam completion in the successive years. Exam completion was significantly higher in ten-year-olds (p = 0.0278) and in 3 of the 10 schools (p < 0.0001, p = 0.0027, and p = 0.0309). A total of 1089 (8.9% of screened) children were prescribed spectacles. Of the 409 children that were recorded with the compliance method, 342 (83.6%) were found to be fully compliant and wearing their spectacles as prescribed.

Conclusion

The Eyemobile program demonstrated high levels of compliance for both eye examination completion and prescribed spectacle wear in underserved populations in the San Diego region, compared to similar national programs.

A Study to Analyze Refractive Errors in Relation to Age and Sex

Background and objective Refractive defects should be detected and treated early to avoid irreversible vision loss and other potential problems in the future. In this study, we aimed to analyze the refractive errors (REs) and their relationship with gender and age. Methods This study was conducted at the Northern Border University Health Center, Arar, Saudi Arabia. REs were analyzed using spherical equivalents (SEs), cylinders, and their orientations. SEs of REs were taken as half the cylinder plus the spherical component. Emmetropia was defined as SE between -0.50 and +0.50 diopter sphere (DS), myopia as SE ≤0.50 DS, and hyperopia as SE ≥0.50 DS for adults and SE ≥1.0 for children (up to 10 years). Statistical analysis was performed using the IBM SPSS Statistics software package (IBM, Armonk, NY). Qualitative data were presented as frequency and percentage while quantitative data were presented as mean and standard deviation (SD). Chi-square was used as a significant test and a p-value <0.05 was considered statistically significant. Results A total of 240 patients were included in the study. There were 138 men and 102 females aged 3-60 years (57.5 and 42.5%, respectively). The mean age of males was 24.4 years and that of females was 25.5 years. The p-value was statistically significant in terms of analysis with age. The study found an association between age and RE magnitude and variability. Conclusion Based on our findings, RE is a common problem that affects individuals of all ages. Regular screenings are advised for individuals in order to detect REs early.

Epidemiology and Burden of Astigmatism: A Systematic Literature Review

SIGNIFICANCE

This is the first literature review to report the epidemiology, patient burden, and economic burden of astigmatism in the general adult population. The unmet needs of astigmatism patients with coexisting ocular conditions (cataract, glaucoma, dry eye, presbyopia, or macular degeneration) and risks associated with untreated astigmatism are also reviewed and reported.

PURPOSE

This study aimed to identify, report, and summarize the published literature on epidemiology, patient burden, and economic burden of astigmatism using a systematic literature review.

METHODS

MEDLINE, EMBASE, and Cochrane Library databases were searched (January 1996 to May 2021). Search results were limited to the English language. Proceedings (2018 to 2021) from ophthalmology congresses were searched along with gray literature using the Google Scholar platform.

RESULTS

The literature search yielded 6804 citations, of which 125 met the inclusion criteria (epidemiology, 68; patient burden, 60; economic burden, 6). Astigmatism prevalence in the general population varied from 8 to 62%, with higher rates in individuals 70 years or older. The prevalence of with-the-rule astigmatism was higher in individuals 40 years or younger, whereas rates of against-the-rule and oblique astigmatism increased with age. Astigmatic patients experienced decreased vision quality, increased glare (53 to 77%), haloes (28 to 80%), night-time driving difficulties (66%), falls, and spectacle dependence (45 to 85%). Astigmatic patients performed vision-related tasks slower (1 D, 9% slower; 2 D, 29% slower) and made more errors (1 D, 38% more errors; 2 D, 370% more errors) compared with fully corrected individuals. In cataract patients with astigmatism, the annual mean per-patient productivity loss costs ranged from €55 ($71) to €84 ($108), and mean informal care costs ranged from €30 ($39) to €55 ($71) with a mean of 2.3 to 4.1 hours spent on informal care.

CONCLUSIONS

Uncorrected astigmatism decreases patients' vision-related quality of life, decreases productivity among working-age adults, and poses an economic burden on patients and their families.

Intrasession repeatability and agreement of a new method to measure the foveal fixation axis

Purpose

Ophthalmic lens adaptation, particularly with progressive addition lenses, requires accurate measurements of the patient nasopupillary distance (NPD) and interpupillary distance (IPD), which are usually collected using the pupil centre as a reference. However, differences between the pupil centre and visual or foveal axis could induce some subsidiary effects of correcting lenses. This study aimed to assess the intrasession repeatability of a new prototype (Ergofocus®; Lentitech, Barakaldo, Spain) that can measure the foveal fixation axis (FFA) distance and assess the agreement with the NPD measurements collected using a traditional method (frame ruler).

Methods

The FFA at far and near distances was measured three consecutive times in 39 healthy volunteers to determine the intrasession repeatability according to the British Standards Institute and International Organization for Standardization. Additionally, the FFA and NPD (standard frame ruler) were measured in 71 healthy volunteers and compared using Bland-Altman analysis. Two blinded experienced practitioners conducted each FFA and NPD measurement.

Results

The FFA measurements showed acceptable repeatability at far distances (right eye (RE): Sw = 1.16 ± 0.76 mm and coefficient of variation (CV) = 3.92 ± 2.51%; left eye (LE) Sw = 1.11 ± 0.79 mm and CV = 3.76 ± 2.51%) and at near distances (RE: Sw = 0.97 ± 0.85 mm and CV = 3.52 ± 3.02%; LE: Sw = 1.17 ± 0.96 mm and CV = 4.54 ± 3.72%). Additionally, agreement with the NPD showed large differences at far distances (RE: -2.15 ± 2.34, LoA = -6.73 to 2.43 mm (P < 0.001); LE: -0.61 ± 2.62, LoA = -5.75 to 4.53 mm (P = 0.052)) and near distances (RE: -3.08 ± 2.80, LoA -8.57 to 2.42 mm (P < 0.001); LE: -2.97 ± 3.97, LoA: -10.75 to 4.80 mm (P < 0.001)).

Conclusions

FFA measurements showed clinically acceptable repeatability at both far and near distances. Agreement with the NPD measured using a standard frame ruler showed significant differences, suggesting that both measurements are not interchangeable in clinical practice to prescribe and center ophthalmic lenses. Further research is necessary to assess the impact of FFA measurement in ophthalmic lens prescriptions.

Cycloplegic Autorefraction as a Substitute for Cycloplegic Retinoscopy in the Pediatric Population

PURPOSE

To evaluate whether cycloplegic autorefraction can provide similar results as cycloplegic retinoscopy, allowing more comprehensive ophthalmologists to be comfortable in managing pediatric refractive error and refractive amblyopia.

METHODS

This retrospective chart review was performed to determine the mean difference in sphere, cylinder, and axis between cycloplegic autorefraction and retinoscopy, both of which were obtained on the same eye at least 30 minutes after cycloplegia and dilation with a mixed solution of tropicamide, cyclopentolate, and phenylephrine.

RESULTS

A total of 34 eyes (18 right, 16 left) from 18 patients were included in the analysis. Mean sphere difference between cycloplegic autorefraction and retinoscopy was 0.044 ± 0.278 diopters (D) (95% CI: -1.275 to 1.363 D), mean cylinder difference was -0.081 ± 0.236 D (95% CI: -0.706 to 0.544 D), and mean axis difference was 7.059 ± 19.676 degrees (95% CI: -32.527 to 38.878 degrees). Mean differences in sphere, cylinder, and axis were not statistically significant (P = .362, .0541, and .377, respectively).

CONCLUSIONS

In this small sample population, cycloplegic autorefraction was comparable to cycloplegic retinoscopy. Recognition of amblyopia should still prompt evaluation by a pediatric ophthalmologist. Further research is necessary to confirm whether uncomplicated refractive error in children may be sufficiently detected and managed by a comprehensive ophthalmologist. [J Pediatr Ophthalmol Strabismus. 2022:59(6):422-427.].

Habitual visual acuity and visual acuity threshold demands in Nigerian school classrooms

This study was designed to estimate the burden of blindness and vision impairment in school children, and to determine the proportion of students meeting the visual acuity (VA) demand for their classrooms. From 148 primary and secondary school classrooms in Edo State, Nigeria, the habitual distance and near VA of over 2000 students were measured. Values obtained were compared with the calculated distance VA demand and actual near VA demand for their classrooms. Measures used to calculate the VA demand were working distance and smallest text size on learning materials, at both distance and near. We also determined the relationship between age and calculated VA demand and the effect of factors such as school ownership and school type on the VA  demand. Habitual distance vision impairment was found in 0.8% of pupils, including 2 (0.10%) who met the WHO criteria for blindness. The average VA demand at the furthest and nearest sitting position to the board was 0.21 ± 0.23 and 0.65 ± 0.33LogMAR, respectively. Near working distance of students ranged from 15.00 to 37.20 cm, and the near VA demand as well as actual near VA demand (using a 2.5 times acuity reserve) was 0.60 ± 0.17 and 0.20 ± 1.7LogMAR, respectively. LogMAR VA demand increased (size of print decreases) with increasing age, at both distance (r =  - 0.549, p = 0.070) and near (r =  - 0.921, p < 0.0001). The VA demand at maximum distance and the actual near VA demand differed significantly by school ownership and between primary and secondary schools. Most students had VA better, but up to 11% of students per class had VA poorer than their classroom demands. Although the majority of students had better VA than their classroom demands, for students with reduced vision, learning could be negatively impacted. It is important to continually screen students for vision impairment and ensure prompt referral and treatment. These findings have implications for managing vision problems in children, as well as enabling appropriate classroom arrangements for those with vision impairment.

Prevalence of visual impairment due to refractive error among children and adolescents in Ethiopia: A systematic review and meta-analysis

Introduction

Globally, the prevalence of refractive error was 12%, and visual impairment due to refractive error was 2.1%. In sub-Saharan Africa, the prevalence of refractive error and visual impairment due to refractive error was 12.6% and 3.4%, respectively. In Ethiopia, the prevalence of visual impairment due to refractive error varies from 2.5% in the Gurage zone to 12.3% in Hawassa city. Hence, this Meta-analysis aimed to summarize the pooled prevalence of visual impairment due to refractive error in Ethiopia.

Methods

A systematic search of the literature was conducted by the authors to identify all relevant primary studies. All articles on the prevalence of visual impairment due to refractive error in Ethiopia were identified through a literature search. The databases used to search for studies were PubMed, Science Direct, POPLINE, HENARI, Google Scholar, and grey literature was searched on Google until December 15, 2021. In this meta-analysis, the presence of publication bias was evaluated using funnel plots and Begg’s tests at a significance level of less than 0.05. The sensitivity analysis was conducted to check for a single study’s effect on the overall prevalence of refractive error.

Result

About 1664 studies were retrieved from initial electronic searches using international databases and google searches. A total number of 20,088 children and adolescents were included in this meta-analysis. The pooled prevalence of visual impairment due to refractive error in Ethiopia using the random effects model was estimated to be 6% (95% CI, 5–7) with a significant level of heterogeneity (I² = 94.4%; p < 0.001). The pooled prevalence of visual impairment due to refractive was analyzed by subtypes, and pooled prevalence was estimated to be 4%, 5.2%, and 1% for myopia, hyperopia, and astigmatism, respectively.

Conclusion

The pooled prevalence of visual impairment due to refractive error was high in Ethiopia. About one in twenty-five Ethiopian children and adolescents are affected by visual impairment due to myopia.

Demographic Characteristics and Causes of Visual Impairment in the White Nile State of Sudan: A Hospital-based Study

Abstract: BACKGROUND: The World Health Organization (WHO) states that visual impairment (VI) is a reduction of vision functions due to eye diseases, trauma, and congenital eye conditions. Current estimates indicate that more than 90% of people with vision impairment live in rural and developing countries. AIM: This study aimed to determine demographic characteristics and causes of visual impairment in the White Nile State of Sudan METHODS: A cross-sectional retrospective hospital-based study, including all patients attending Kosti and Rabak eye hospitals from January to December 2017, was conducted. A total of 1000 records were reviewed, 300 of them met the required criteria and then included in this study, with a mean age of 59.8 ± 18.5 (ranging from 10 to 95) years old. Visual impairment was classified according to the International Classification of Diseases, 11th revision, 2018 (ICD-11). RESULTS: The prevalence of VI was found at 28.5 %. Based on best-corrected visual acuity (BCVA), 6 participants (2.0%) were mild VI, 32 (10.7%) had moderate VI, 152 (50.7%) had severe VI, and 110 (36.7%) were blind. VI was associated with patients' age in children (3.6%) and reached (48.3) in older age (P=0.001). VI was more common among males 158 (52.7%) than females but was statistically not significant (P=0.35). The main causes of VI were cataract (52%), refractive errors (20.7%), glaucoma (16.3%), corneal disorders (5.3%), diabetic retinopathy (1.7 %), and other causes (4%). Conclusion Visual impairment was high in the community and more prevalent among older age. Cataract was the leading cause of VI, then refractive errors and glaucoma. Among children, uncorrected refractive errors and cataracts were the common leading causes of VI. In adults, the main causes were cataracts, uncorrected refractive errors, and glaucoma.

A situational analysis of clinical refraction services in the capital city of the Maldives

Background

Uncorrected refractive error is a leading cause of visual impairment globally. This study aimed to determine the current state of clinical refraction services and barriers to service provision in the capital city of the Maldives.

Methods

This cross-sectional, descriptive-analytical study used a purposive sampling technique. The list of facilities providing refraction services in the city of Malé was compiled through a desk review and finalized after verification by personnel from the Ministry of Health. The availability of human resources and infrastructure was measured using a pre-coded questionnaire that also listed barriers to service provision, followed by on-site observations and subsequent data analysis.

Results

Three clinical ophthalmology departments within hospitals, two ophthalmology hospitals, and nine primary eye care centers were selected for this study. The private sector (n = 12, 85.7%) was the primary provider of refractive error services. All facilities possessed the essential equipment required for refraction. Only optometrists and ophthalmologists conducted refraction. Contact lens assessment and low vision services were not available at any facility. The number of refractions conducted in Malé annually was 145,392. Human resources and management-related factors were the major barriers to the provision of clinical refraction services (n = 21, 44.7%).

Conclusions

Accessibility to refractive error management and low vision services is needed in Malé to meet current population needs. Existing resources, including humans and equipment, require augmentation regarding service provision and enhancement. Knowledge of these barriers could lead to the upscaling of refraction services in Malé, Maldives by health policy makers.

Prevalence of refractive errors among school students in Ethiopia: A systematic review and meta-analysis

Objective:

Refractive errors are most common ocular disorders among children and adolescents. They remain as secondary causes of avoidable blindness in impoverished areas in Africa, most notably in Ethiopia. The problem worsens if it is not managed and addressed early. The aim of this systematic review and meta-analysis was to determine the prevalence of refractive errors among school students in Ethiopia.

Methods:

We searched international databases such as PubMed/Medline, Web of Science, CINAHL, Embase, Scopus, Cochrane Library, Google Scholar, and Science Direct for relevant articles. Data were extracted using Microsoft Excel and exported to Stata version 14.0 software for analysis. The Cochrane Q and I2 tests were used to assess heterogeneity. Funnel plot, Egger’s, and Begg’s tests were used to assess reporting bias. Random effect meta-analysis model was employed to estimate pooled prevalence of refractive errors. A regional subgroup analysis was carried out.

Results:

We reviewed 22 qualified studies with 23,355 study participants. The overall prevalence of refractive errors among school students was 7.36% (95% confidence interval = 6.05, 8.67). The prevalence of myopia, hyperopia, and astigmatism was 5.10% (95% confidence interval = 3.79, 6.40), 0.95% (95% confidence interval = 0.59, 1.31), and 0.01% (95% confidence interval = 0.01, 0.04), respectively. From subgroup analysis, the highest prevalence of refractive errors was reported in Amhara Region (9.18%, 95% confidence interval = 6.63, 11.74), followed by Southern Nations, Nationalities, and Peoples’ region (6.78%, 95% confidence interval = 4.65, 8.92) while the lowest prevalence of refractive errors was reported in Addis Ababa (3.93%, 95% confidence interval = 3.30, 4.56).

Conclusion:

In Ethiopia, the prevalence of refractive errors among school students is higher (7.36%) compared to what it was 5 years (7.05%) ago. Amhara Region has the highest prevalence of refractive errors among school students in Ethiopia with myopia being the most common type of refractive error.

Parents' reasons for nonadherence to referral to follow-up eye care for schoolchildren who failed school-based vision screening in Cross River State, Nigeria-A descriptive qualitative study

BACKGROUND

Uncorrected refractive error (URE) is a major cause of vision impairment in children worldwide. Cases are often detected through a school-based vision screening program and then treated in a follow-up appointment. This requires parents or guardians ('parents') to adhere to referrals for the eye exam and care plan. We aim to understand the reasons for parents' referral non-adherence in Cross River State, Nigeria, using qualitative methods.

METHODS

Ten focus groups were held with parents who had not adhered to the referral for a follow-up eye examination. Participants were recruited with help from staff in schools hosting the vision screening programme. Interviews were conducted using a semi-structured interview guide, audio taped and transcribed verbatim. After identifying relevant quotes, the researchers labelled each one with a descriptive code/subcode label. Then they clustered the data into categories and overarching themes.

RESULTS

Forty-four parents participated in 10 focus group discussions with 28 women and 16 men. Three themes and participated in the focus group discussions with 28 women (63%). Twelve themes were generated. The three megathemes were Modifiable Factors (with 4 themes), Contextual Factors (with 6 themes), and Recommendations (with 2 themes).

CONCLUSION

Participants identified modifiable barriers that make it difficult for parents to adhere to a referral for a follow-up eye exam. These include not believing their child has a vision problem or the screening test, and issues with the referral letter. They also described important contextual factors such as poverty, logistical problems, parental attitudes towards their children and beliefs about appropriate care. Many of these issues could be addressed by following their recommendation to educate the public on the importance of child eye care and correct parents' misconceptions. These themes will be used by the Nigerian government to enhance and scale up its child eye health programme.

Accuracy of Noncycloplegic Refraction for Detecting Refractive Errors in School-aged African Children

SIGNIFICANCE

Cycloplegia is often restricted in screening settings. Previous studies have evaluated noncycloplegic refraction for screening, but their data are not fully applicable to school-aged African children. This article adds to the literature by investigating this in school-aged African children.

PURPOSE

The purpose of this study was to evaluate the ability of noncycloplegic autorefraction (NCA) and noncycloplegic retinoscopy (NCR) to detect refractive errors in school-aged African children and quantify differences between noncycloplegic and cycloplegic refraction measures.

METHODS

Autorefraction and retinoscopy were performed on 150 children aged 6 to 15 years before and after cyclopentolate cycloplegia. Subjective refraction was performed by the same examiner after cycloplegia. Noncycloplegic and cycloplegic measurements were compared, and the data were assessed with receiver operating characteristic curves and Bland-Altman plots.

RESULTS

With the exception of cylindrical vector J0 (P = .17) and J45 (P = .08) obtained with NCR, all mean measures of NCA and NCR significantly differed from mean cycloplegic subjective refraction measurements by -0.71 ± 0.67 (P ≤ .001; 95% confidence interval, -2.02 to +0.60) and -0.75 ± 0.68 (P ≤ .001; 95% confidence interval, -2.08 to +0.58), respectively. Mean spherical power between the two tests did not differ (NCA -NCR, mean bias of -0.037 ± 0.675 and 95% limits of agreement of -1.36 to 1.286; P = .51). The sensitivities for detecting any refractive error for NCR and NCA were 86.8 and 82.9%, respectively, and the specificities were 82.0% for NCR and 82.4% for NCA. Performance of both tests was excellent for myopia (area under the curve, >0.90; sensitivity, ≥90%) and similar (P = .13), but the specificities for detecting hyperopia were 78.0% for NCR and 80.0% for NCA.

CONCLUSIONS

Noncycloplegic refraction may accurately detect astigmatism and myopia in this population but may elicit higher myopic values and lower hyperopic values than using cycloplegic refraction.

Prevalence and time trends of refractive error in Chinese children: A systematic review and meta-analysis

Background

To investigate the prevalence and time trends of refractive error (RE) among Chinese children under 18 years old.

Methods

PubMed, Embase, Web of Science were searched for articles that estimated prevalence of RE in Chinese children. Data of identified eligible studies was extracted by two investigators independently. Pooled prevalence of RE and its 95% confidence interval (95% CI) and the time trends of RE were investigated using Meta-analysis methods.

Results

Of the 41 studies covering 1 051 784 subjects, the pooled prevalence of myopia, high myopia, hyperopia and astigmatism in Chinese children was 38.0% (95% confidence interval (CI) = 35.1%-41.1%), 2.8% (95% CI = 2.3%-3.4%), 5.2% (95% CI = 3.1%-8.6%) and 16.5% (95% CI = 12.3%-21.8%), respectively. Subgroup analysis show that children living in urban were at higher risk of RE. Prevalence of myopia and hyperopia were higher in Northern China compared with Southern China and high myopia and astigmatism were higher in Hong Kong, Macau and Taiwan than in mainland China. Regression analysis showed an upward trend in myopia and hyperopia and a downward trend in high myopia and astigmatism with years.

Conclusions

The prevalence of RE is higher in urban areas than in rural for Chinese children. The much higher prevalence of myopia and astigmatism in China compared with foreign countries indicates the important role played by environment and genetic factors. Considering the large magnitude of refractive errors, much more attention should still be paid to RE prevention and treatment strategy development in China.

Prevalence of Refractive Errors among Children in Saudi Arabia: A Systemic Review

Introduction:

The aim of this review was to estimate the prevalence of refractive errors (RE) and uncorrected refractive error (URE) in school-aged children of 4 to 14 years of age in Saudi Arabia.

Methods:

An extensive search was performed for peer-reviewed studies with data from the Saudi population during the past 20 years. The Cochrane Library, Pubmed, and Embase databases were used. Two independent reviewers evaluated publications and extracted the data. The quality of the studies was evaluated based on a critical appraisal tool designed for systematic reviews. The pooled prevalence of refractive error, uncorrected refractive error and different types of refractive error were estimated by using the random-effects meta-analysis.

Results and Discussion:

Eight school-based studies were included in this review. Among the overall pooled population of 12,247childern, the estimated prevalence of refractive error was 17.5% (95% CI: 11.1- 25). In the five studies that reported uncorrected refractive error (N=10,198), the pooled prevalence was 16.8% (95% CI: 11.4 – 21.3). The overall prevalence of refractive errors was very similar among boys, 16.8 (95% CI: 10.8- 24.1), and girls, 17.7% (95% CI: 10.2 – 25.9). Myopia was the most prevalent refractive error and was present in 40.8% (95% CI: 16.1 – 69.9) followed by astigmatism 29.7% (95% CI: 6.1- 61.7) and hyperopia 28.3% (95% CI: 16.9 – 41.2).

Conclusion:

This review highlights the high prevalence of refractive errors and uncorrected refractive error among children in Saudi Arabia. More studies are required using standardised methods in different regions where there is a lack of information on UREs. It is recommended that vision screening programs of children for RE should be implemented at the community level and integrated into school health programmes in order to detect UREs and prevent amblyopia, which is one of the debilitating consequences of URE.

Prevalence of Uncorrected Refractive Error and Its Risk Factors; Tehran Geriatric Eye Study (TGES)

Purpose: To determine the age-sex-standardized prevalence of uncorrected refractive error and its determinantsMethods: This population-based cross-sectional study was conducted on 3310 people aged≥ 60 years in Tehran, Iran in 2019. Need for spectacles was defined as uncorrected visual acuity worse than 20/40 in better eye that could be corrected to more than 20/40 with suitable spectacles. Met need was defined as proportion of individuals with need for spectacles whose visual acuity was 20/40 or better with current spectacles. Unmet need was defined as proportion of individuals with need for spectacles who needed but did not have spectacles or their visual acuity was worse than 20/40 with current spectacles while suitable spectacles improved their visual acuity to 20/40 or better.Results: The age-sex-standardized prevalence of need for spectacles, met need, and unmet need was 16.67% (95% CI: 15.33-18.09), 7.81% (95% CI: 6.95-8.78), and 8.85% (95% CI: 7.77-10.07), respectively. Myopic subjects had the highest prevalence of need for spectacles (24.06%, 95% CI: 21.47-26.87). The odds ratio of met and unmet need in subjects≥ 80 years versus those aged 60-65 years was 0.36 (p-value: 0.009) and 2.34 (p-value: <0.001), respectively. The odds ratio of met and unmet need in subjects with a university education versus illiterate subjects was 1.72 (p-value: 0.045) and 0.42 (p-value: 0.007), respectively.Conclusion: The prevalence of uncorrected refractive error was lower in this study compared to previous studies. The met need rate was lower in subjects with older age and lower education levels.

A realist evaluation of the implementation of a large-scale school eye health programme in India: a qualitative study

PURPOSE

This study investigates how and in what circumstances a school-based eye health programme, the Refractive Errors Among CHildren (REACH) programme, achieved its desired outcomes: accessibility, standards of refractive care, fidelity and availability of comprehensive services, for over 2 million school children in six districts across India.

METHODS

We conducted a realist evaluation to identify programme aspects and their causal relationships with outcomes. Deductive and inductive thematic analysis of qualitative data included three phases: 1. theory gleaning, 2. eliciting programme theory, 3. revisiting programme theory. The Initial Programme Theories (IPTs) were developed and revised through review of the literature, programme documents and field notes. We reviewed informal and formal discussions from the participatory advisory workshops and conducted semi-structured interviews with key stakeholders for the development and refinement of the IPTs. We based our analysis on the programme designers' perspective; used contexts, mechanisms and outcomes configuration for the analysis and presentation of the findings and reported the revised IPTs for the REACH programme.

RESULTS

We identified four major programme aspects of the REACH programme for evaluation: programme governing unit, human resource, innovation and technology and funding. Based on the intended outcomes of the programme, themes and contexts were sorted and IPTs were defined. We revised the IPTs based on the analysis of the interviews (n = 19). The contexts and mechanisms that were reported to have potential influence on the attainment of favourable programme outcomes were identified. The revisions to the IPTs included: co-designing a collaborative model and involving local government officials to reinforce trust, community partnerships; local well-trained staff to encourage participation; use of the web-based data capturing system with built-in quality control measures and continued technical support; pre-determined costs and targets for the outputs promoted transparency and adherence with costs.

CONCLUSION

This process provided a comprehensive understanding of the opportunities and possibilities for a large-scale school eye health programme in diverse local contexts in India. This illustrated the importance of embracing principles of system thinking and considering contextual factors for School Eye Health programmes in low and middle-income countries.

Parents' willingness to pay for children's spectacles in Cambodia

Background/aim

To determine willingness to pay for children's spectacles, and barriers to purchasing children's spectacles in Cambodia.

Methods

We conducted vision screenings, and eye examinations as indicated, for all consenting children at 21 randomly selected secondary schools. We invited parents/guardians of children found to have refractive problems to complete a willingness to pay for spectacles survey, using a binary-with-follow-up technique.

Results

We conducted vision screenings on 12 128 secondary schoolchildren, and willingness to pay for spectacles surveys with 491 parents/guardians (n=491) from Kandal and Phnom Penh provinces in Cambodia. We found 519 children with refractive error, 7 who had pre-existing spectacles and 14 recommended spectacles for lower ametropias. About half (53.2%; 95% CI 44.0% to 62.1%) of parents/guardians were willing to pay KHR70 000 (US$17.5; average market price) or more for spectacles. Mean willingness-to-pay price was KHR74 595 (US$18.6; 95% CI KHR64 505 to 86 262; 95% CI US$16.1 to US$21.6) in Phnom Penh and KHR55 651 (US$13.9; 95% CI KHR48 021 to 64 494; 95% CI US$12.0 to US$16.1) in Kandal province. Logistic regression suggested parents/guardians with college education (OR 6.8; p<0.001), higher household incomes (OR 8.0; p=0.006) and those wearing spectacles (OR 2.2; p=0.01) were more likely to be willing to pay ≥US$17.5. The most common reasons for being unwilling to pay US$17.5 were related to cost (58.8%). The most common barrier to spectacle wear was fear that spectacles weaken children's eyes (36.0%).

Conclusions

With almost half of parents/guardians unwilling to pay for spectacles at the current average market price, financial support through a subsidised spectacle scheme might be required for children to access spectacles in Cambodia.

The Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) Study-Defining a Threshold for Non-Cycloplegic Myopia Prevalence in Children

The aim of this study was to investigate the agreement between cycloplegic and non-cycloplegic autorefraction with an open-field auto refractor in a school vision screening set up, and to define a threshold for myopia that agrees with the standard cycloplegic refraction threshold. The study was conducted as part of the Sankara Nethralaya Tamil Nadu Essilor Myopia (STEM) study, which investigated the prevalence, incidence, and risk factors for myopia among children in South India. Children from two schools aged 5 to 15 years, with no ocular abnormalities and whose parents gave informed consent for cycloplegic refraction were included in the study. All the children underwent visual acuity assessment (Pocket Vision Screener, Elite school of Optometry, India), followed by non-cycloplegic and cycloplegic (1% tropicamide) open-field autorefraction (Grand Seiko, WAM-5500). A total of 387 children were included in the study, of whom 201 were boys. The mean (SD) age of the children was 12.2 (±2.1) years. Overall, the mean difference between cycloplegic and non-cycloplegic spherical equivalent (SE) open-field autorefraction measures was 0.34 D (limits of agreement (LOA), 1.06 D to −0.38 D). For myopes, the mean difference between cycloplegic and non-cycloplegic SE was 0.13 D (LOA, 0.63D to −0.36D). The prevalence of myopia was 12% (95% CI, 8% to 15%) using the threshold of cycloplegic SE ≤ −0.50 D, and was 14% (95% CI, 11% to 17%) with SE ≤ −0.50 D using non-cycloplegic refraction. When myopia was defined as SE of ≤−0.75 D under non-cycloplegic conditions, there was no difference between cycloplegic and non-cycloplegic open-field autorefraction prevalence estimates (12%; 95% CI, 8% to 15%; p = 1.00). Overall, non-cycloplegic refraction underestimates hyperopia and overestimates myopia; but for subjects with myopia, this difference is minimal and not clinically significant. A threshold of SE ≤ −0.75 D agrees well for the estimation of myopia prevalence among children when using non-cycloplegic refraction and is comparable with the standard definition of cycloplegic myopic refraction of SE ≤ −0.50 D.

School-based vision screening in Quetta, Pakistan: a qualitative study of experiences of teachers and eye care providers

Background

Visual impairment in children is a significant public health problem affecting millions of children globally. Many eye problems experienced by children can be easily diagnosed and treated. We conducted a qualitative study with teachers and optometrists involved in a school-based vision screening programme in Quetta district of Pakistan to explore their experiences of training, vision screening and referrals and to identify factors impacting on the effectiveness of the programme.

Methods

Between April 2018 and June 2018, we conducted semi-structured in-depth interviews with 14 teachers from eight purposefully selected schools with high rates of inaccurate (false positive) referrals. Interviews were also conducted with three optometrists from a not-for profit private eye care hospital that had trained the teachers. Interviews were audio recorded and professionally transcribed. NVIVO software version 12 was used to code and thematically analyze the data.

Results

Findings suggest that the importance of school-based vision screening was well understood and appreciated by the teachers and optometrists. Most participants felt that there was a strong level of support for the vision screening programme within the participating schools. However, there were a number of operational issues undermining the quality of screening. Eight teachers felt that the duration of the training was insufficient; the training was rushed; six teachers said that the procedures were not sufficiently explained, and the teachers had no time to practice. The screening protocol was not always followed by the teachers. Additionally, many teachers reported being overburdened with other work, which affected both their levels of participation in the training and the time they spent on the screening.

Conclusions

School-based vision screening by teachers is a cost-effective strategy to detect and treat children’s vision impairment early on. In the programme reviewed here however, a significant number of teachers over referred children to ophthalmic services, overwhelming their capacity and undermining the efficiency of the approach. To maximise the effectiveness and efficiency of school-based screening, future initiatives should give sufficient attention to the duration of the teacher training, experience of trainers, support supervision, refresher trainings, regular use of the screening guidelines, and the workload and motivation of those trained.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10404-9.

Is an integrated model of school eye health delivery more cost-effective than a vertical model? An implementation research in Zanzibar

Objective

To review and compare the cost-effectiveness of the integrated model (IM) and vertical model (VM) of school eye health programme in Zanzibar.

Methods and analysis

This 6-month implementation research was conducted in four districts in Zanzibar. Nine and ten schools were recruited into the IM and VM, respectively. In the VM, teachers conducted eye health screening and education only while these eye health components were added to the existing school feeding programme (IM). The number of children aged 6–13 years old screened and identified was collected monthly. A review of project account records was conducted with 19 key informants. The actual costs were calculated for each cost categories, and costs per child screened and cost per child identified were compared between the two models.

Results

Screening coverage was 96% and 90% in the IM and VM with 297 children (69.5%) from the IM and 130 children (30.5%) from VM failed eye health screening. The 6-month eye health screening cost for VM and IM was US$6 728 and US$7 355. The cost per child screened for IM and VM was US$1.23 and US$1.31, and the cost per child identified was US$24.76 and US$51.75, respectively.

Conclusion

Both models achieved high coverage of eye health screening with the IM being a more cost-effective school eye health delivery screening compared with VM with great opportunities for cost savings.

Economic Inequality in Unmet Refractive Error Need in Deprived Rural Population of Iran

Purpose:

To determine economic inequality in unmet refractive error (RE) need and its determinants in deprived rural population of Iran.

Methods:

In this population-based study, two villages were randomly selected from among underserved villages of Iran. After selecting the participants, optometric examinations, including uncorrected and corrected visual acuity and subjective and manifest refraction, were done for all the participants. Then, unmet need for glasses was determined. Concentration index (C) was used to assess inequality, and Oaxaca–Blinder decomposition method was applied to decompose the gap between the two groups based on the determinants.

Results:

Of 3851 samples, 3314 participated in the study (response rate = 86.05%). The data of 3255 participants were used for analysis. The value of C and 95% confidence interval (CI) was −0.088 (−0.157 to −0.020), indicating a pro-poor inequality in unmet need. The prevalence (95% CI) of unmet need was 11.74% (9.25–14.22) in the poor and 6.51% (4.96–8.06) in the rich, with a gap of about 5% in favor of the rich (P < 0.001). A marked percentage of the gap was due to the explained portion (b = 5.73; P = 0.031). In the explained portion, the variable of economic status (b = 3.48; P = 0.004) and myopia (b = 0.88; P = 0.031) caused inequality in favor of the rich and against the poor, respectively. In the unexplained portion (b = −0.51; P = 0.372), the variables of education (P = 0.002) and place (P = 0.001) had statistically significant effects on inequality.

Conclusions:

There is a significant pro-poor economic inequality in the prevalence of unmet need in rural areas of Iran. Although part of this inequality is related to variables such as education and myopia, a major portion (two thirds) of this inequality may be due to the direct effect of economic inequality.

Temporal trends in the prevalence of spectacle use and spectacle coverage in India

BACKGROUND

This study aims to assess the temporal trends in the prevalence of spectacle use and spectacle coverage for refractive errors in population-based studies conducted during 2011-2012 and 2017 among those aged ≥ 40 years in the state of Telangana, India. An intervention in the form of 10 vision centres and a secondary centre was established in one district (Khammam) after the 2011-2012 study and another district (Warangal) was left to secular trends.

METHODS

In both the studies, multi-stage cluster random sampling methodology was used to select the participants. In addition to a clinical examination, a questionnaire was used for collecting information on current and previous use of spectacles, type of spectacles and details of the spectacle providers. The same questionnaire was used in both the studies.

RESULTS

In total, 2,485 participants were examined in the 2011-2012 study and 2,711 participants were examined in the 2017 study in Khammam. Similarly, 2,438 and 2,646 participants were examined in Warangal in the two studies, respectively. In Khammam, the age and gender-adjusted prevalence of current spectacle use increased from 30.0 per cent (95% CI 28.2-31.9) to 34.8 per cent (95% CI 33.0-36.6) in the 2011-2012 and 2017 studies, respectively (p < 0.01). However, in the Warangal district, the age and gender-adjusted prevalence of current spectacle use declined from 32.8 per cent (95% CI 31.0-34.7) to 27.6 per cent (95% CI 25.9-29.3) during the 2011-2012 and 2017 studies, respectively (p < 0.01). In Khammam, the spectacle coverage increased from 26.9 per cent to 35.6 per cent, but it declined from 43.8 per cent to 35.7 per cent in Warangal between the studies in 2011-2012 and 2017.

CONCLUSIONS

An increase in spectacle use and coverage was observed in Khammam where the secondary centre and vision centres were established, compared to Warangal where there was no such intervention. The results suggest a positive impact of the intervention in the Khammam district and suggest replication of the model to address the burden of uncorrected refractive errors.

Prevalence of visual impairment and refractive errors in an urban area of Mexico

AIM

To determine the distribution of refractive errors in a school-age population in Quintana Roo (Mexico) in the framework of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 2647 school-age children (ranging from 5 to 14 years old) with a mean age of 9.1±1.9 years old were tested by trained volunteers for distance visual acuity (VA) and refractive errors. The first screening examination included uncorrected distance visual acuity (UDVA) and VA with a +2.00 D lens. Inclusion criteria for a second complete cycloplegic eye examination performed by an optometrist were UDVA <20/25 (0.10 logMAR or 0.8 decimal) and/or VA with +2.00 D ≥20/25.

RESULTS

A total of 633 (23.9%) children underwent the second complete eye examination. Mean logMAR UDVA was 0.035±0.094 (range 1.00 to 0.00 logMAR) for the right eyes and 0.036±0.160 (range 1.00 to 0.00 logMAR) for the left eyes. Bilateral amblyopia was found in 17 children (2.7% of refracted eyes; 0.64% of the total). The main reason for visual impairment (VI) in the sample analyzed was found to be refractive errors. In 12 children (1.9% of refracted eyes; 0.45% of the total) the VI was bilateral and 9 (1.4% of refracted eyes; 0.34% of the total) achieved a corrected distance visual acuity of 20/25 or better in both eyes. Mean magnitude of sphere and refractive cylinder was +0.20±0.96 D and -0.43±0.85 D in right eyes, and +0.24±1.08 and -0.43±0.83 D in left eyes. The proportion of myopic eyes [standard equivalent (SE) ≤-0.50 D] was 4.6% of the whole sample (5290 eyes). The mean magnitude of myopia was -0.84±3.44 D for the right eyes and -0.82±5.21 D for the left eyes. The proportion of hyperopic patients (SE≥+2.00 D) was 2.4% (15/633), which corresponded to 0.60% of the whole sample (32/5290 eyes). No statistically significant correlation of age to manifest sphere or cylinder was found.

CONCLUSION

VI due to uncorrected refractive errors can be easily corrected with glasses but it is still a burden to be treated. Myopia is prevalent in this sample. More efforts towards correcting uncorrected refractive errors are needed.

Adults visual impairment and blindness - An overview of prevalence and causes in Saudi Arabia

BACKGROUND

A major socio-economic development in Saudi Arabia affected the pattern and causes of visual impairment for the past 40 years. Moreover, an up-to-date summary of available data is vital for planning, monitoring, and evaluating national blindness prevention program.

AIM

This study conducted to provide a summary overview of prevalence, causes, and changes in the pattern of blindness and visual impairment for the past 40 years among Saudi adults, with brief discussion of the related socio-economic and ecological factors.

METHODS

The review was confined to the published epidemiological studies performed in Saudi Arabia covering the age group 18 year and older from 1985 onwards.

RESULTS

Six epidemiological studies were included from 1985 onwards. In1986, the prevalence of blindness and visual impairment in Saudi Arabia were 1.5% and 7.8%, respectively which is 20 times the magnitude of blindness in the United States. Multiple regional population based studies conducted later in areas with disparate ecological and socio-economical determinants at different time intervals showed variable prevalence of blindness 3.3% Eastern Province 1986, 0.7% Bisha 1993. Recently, in older than 50 year population the reported prevalence was 2.6% Taif 2012 and 5.7% Jazan 2015 and 6.4% in Ahsa. Since 1986, the single leading cause of adult blindness in Saudi Arabia is cataract. Although, Trachoma reported to be the second primary cause of blindness on 1986, its burden is reduced in Jizan (2015) and minimal in Taif (2012) which is replaced by chronic diseases related etiologies i.e Diabetic Retinopathy.

CONCLUSION

Ecological and socio-economical determinants play critical role in the magnitude and causes of blindness and visual impairment in Saudi Arabia. Significant data gaps obscure monitoring and evaluation of the eye health. Eye health indicators should be integrated into the national health information system for dynamic monitoring and evaluation.

Constructing Item Banks for Measuring Quality of Life in Refractive Error

SIGNIFICANCE

Existing patient-reported outcome instruments in refractive error are paper-based questionnaires. They are not comprehensive and psychometrically robust. This study has identified the content of the refractive error-specific item banks that aim to provide comprehensive and scientific measurement of refractive error-specific quality of life.

PURPOSE

The purpose of this study was to identify minimally representative, optimally informative, and efficient sets of items for measuring quality of life in people with refractive error.

METHODS

First, items were identified from existing patient-reported outcome instruments. Second, items were developed from qualitative studies with people with refractive error (48 and 101 in-depth interviews in Australia and Nepal, respectively). Third, classification and selection of items were done based on a set of systematic criteria using an iterative process of binning and winnowing. The resulting items underwent cognitive testing with people with refractive error in Australia and in Nepal. Each step was guided by an expert panel consensus.

RESULTS

We retrieved 792 items from the existing patient-reported outcome instruments. From the interviews conducted in Australia, a total of 2367 comments were coded into 807 initial items. Similarly, from the interviews conducted in Nepal, 3477 comments were coded into 914 initial items. After binning and winnowing, followed by cognitive testing, a final set of items comprising 337 items for the Item-pool (Australia) and 308 items for the Item-pool (Nepal), both spanning 12 domains, was obtained. Forty-seven percent of items were common across the two item pools. In the Item-pool (Nepal), 65% items were common for corrected and uncorrected refractive error.

CONCLUSIONS

We identified the content of two different sets of item banks to comprehensively measure the impact of refractive error on quality of life for people in Australia and Nepal, which may be applicable to high-income country settings and low- and middle-income country settings, respectively. Future work aims to develop computer-adaptive testing system to administer the item banks, resulting in useful measurement tools for researchers, clinicians, and policy planners.

Prevalence of refractive errors, uncorrected refractive error, and presbyopia in adults in India: A systematic review

Purpose:

The objective of this review is to estimate the prevalence of refractive errors, uncorrected refractive error (URE), and uncorrected presbyopia in adults aged ≥30 years in India.

Methods:

The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were followed. A detailed literature search was performed to include all studies published from India from the year 1990 using the Cochrane Library, Medline, and Embase. Refractive error was defined by >0.50 D ametropia. URE was defined by presenting visual acuity (PVA) worse than 6/18 improving with pinhole or spectacle correction, and uncorrected presbyopia by near vision <N8 improving with correction in the absence of distance URE.

Results:

Fifteen studies were included from South India, one each from Western and Central India, and one study covered 15 states across India. The prevalence of RE of at least 0.50 D of spherical equivalent ametropia was 53.1% [(95% confidence interval (CI): 37.2–68.5), of which myopia and hyperopia was 27.7% and 22.9%, respectively. The prevalence of URE was 10.2% (95% CI: 6.9–14.8), but heterogeneity in these estimates was very high. The prevalence of uncorrected presbyopia was 33% (95% CI: 19.1–51.0).

Conclusion:

This review highlights the magnitude of refractive errors among adults in India. More studies are needed using standard methods in regions where there is a lack of information on UREs. Programs delivering spectacles for adults in India will need to primarily focus on reading glasses to correct presbyopia along with spectacles for hyperopia and myopia.

Visual problems: a review of prevalence studies on visual impairment in school-age children

Childhood visual impairment (VI) have a significant impact on the educational achievement, career choices and social life of affected individual, and in children, is mainly due to either preventable or treatable causes. Reliable data on the prevalence and causes of VI in children will guide the development of a systematic vision screening program for its early detection and successful treatment of possible causes. The purpose of this literature review is to summarize the available data on prevalence and causes of VI in school-age children from various regions globally. A discussion on the major findings highlighting the definition criteria, classifications and limitations for further studies is also presented.

Quality of eyeglass prescriptions from a low-cost wavefront autorefractor evaluated in rural India: results of a 708-participant field study

Objective

To assess the quality of eyeglass prescriptions provided by an affordable wavefront autorefractor operated by a minimally trained technician in a low-resource setting.

Methods and Analysis

708 participants were recruited from consecutive patients registered for routine eye examinations at Aravind Eye Hospital in Madurai, India, or an affiliated rural satellite vision centre. Visual acuity (VA) and patient preference were compared between trial lenses set to two eyeglass prescriptions from (1) a novel wavefront autorefractor and (2) subjective refraction by an experienced refractionist.

Results

The mean±SD VA was 0.30±0.37, –0.02±0.14 and −0.04±0.11 logarithm of the minimum angle of resolution units before correction, with autorefractor correction and with subjective refraction correction, respectively (all differences p<0.01). Overall, 25% of participants had no preference, 33% preferred eyeglass prescriptions from autorefraction, and 42% preferred eyeglass prescriptions from subjective refraction (p<0.01). Of the 438 patients 40 years old and younger, 96 had no preference and the remainder had no statistically significant difference in preference for subjective refraction prescriptions (51%) versus autorefractor prescriptions (49%) (p=0.52).

Conclusion

Average VAs from autorefractor-prescribed eyeglasses were one letter worse than those from subjective refraction. More than half of all participants either had no preference or preferred eyeglasses prescribed by the autorefractor. This marginal difference in quality may warrant autorefractor-based prescriptions, given the portable form factor, short measurement time, low cost and minimal training required to use the autorefractor evaluated here.

Large dynamic range autorefraction with a low-cost diffuser wavefront sensor

Wavefront sensing with a thin diffuser has emerged as a potential low-cost alternative to a lenslet array for aberrometry. Here we show that displacement of caustic patterns can be tracked for estimating wavefront gradient in a diffuser wavefront sensor (DWFS), enabling large dynamic-range wavefront measurements with sufficient accuracy for eyeglass prescription measurements. We compare the dynamic range, repeatability, precision, and number of resolvable prescriptions of a DWFS to a Shack-Hartmann wavefront sensor (SHWFS) for autorefraction measurement. We induce spherical and cylindrical errors in a model eye and use a multi-level Demon's non-rigid registration algorithm to estimate caustic displacements relative to an emmetropic model eye. When compared to spherical error measurements with the SHWFS using a laser diode with a laser speckle reducer, the DWFS demonstrates a ∼5-fold improvement in dynamic range (-4.0 to +4.5 D vs. -22.0 to +19.5 D) with less than half the reduction in resolution (0.072 vs. 0.116 D), enabling a ∼3-fold increase in the number of resolvable prescriptions (118 vs. 358). In addition to being lower-cost, the unique, non-periodic nature of the caustic pattern formed by a diffuser enables a larger dynamic range of aberration measurements compared to a lenslet array.

Perception of primary school teachers on pupils’ eye health in the Ga West Municipality, Greater Accra Region, Ghana

Background:

Eye health education is lacking in low- and middle-income countries due to limited availability of eye care personnel in the school setting. Teachers have been considered possible human resource for maintaining eye health in schoolchildren.

Objective:

The aim of this article is to determine the knowledge of teachers on the nature of eye problems among schoolchildren and their ability to recognize visual disorders.

Materials and Methods:

This was a descriptive cross-sectional survey among primary school teachers in the Ga West Municipality. Cluster sampling was used to select 140 teachers from 12 public and private schools. A structured questionnaire was used in assessing teachers’ knowledge about the features of a healthy and diseased eyes, common causes of visual impairment (VI) and blindness, and recognizing and preventing eye problems in the children. Aggregate scores were computed for correct responses concerning healthy and diseased eyes, and scores were categorized into poor (0–25%), fair (26–50%), good (51–75%), and very good (76–100%) knowledge.

Results:

Eighty-six (61.4%) of the teachers were females. The mean age was 33 ± 9.1 years. Most teachers were found to have good knowledge about healthy and diseased eyes (75.0% and 60.0%). Hypermetropia, red eye, allergy, and cataract were cited by 50.0–57.9% as the most common causes of VI and blindness. Between 27.1% and 92.1% of teachers identified difficulties seeing the writing board, inability to concentrate in class, holding the book close to the eye to read, and squinting as ways of recognizing eye problems. Most respondents, 132 (94.3%), were of the view that teachers should be involved in screening schoolchildren for ocular morbidities.

Conclusion:

Teachers in the Ga West Municipality had good knowledge of the characteristics of healthy eyes and a fair knowledge of the causes of VI in primary schoolchildren. Teachers require further training if they are to serve as focal persons for vision screening and eye health education in primary schools.

Burden of vision loss in the Eastern Mediterranean region, 1990-2015: findings from the Global Burden of Disease 2015 study

OBJECTIVES

To report the estimated trend in prevalence and years lived with disability (YLDs) due to vision loss (VL) in the Eastern Mediterranean region (EMR) from 1990 to 2015.

METHODS

The estimated trends in age-standardized prevalence and the YLDs rate due to VL in 22 EMR countries were extracted from the Global Burden of Disease (GBD) 2015 study. The association of Socio-demographic Index (SDI) with changes in prevalence and YLDs of VL was evaluated using a multilevel mixed model.

RESULTS

The age-standardized prevalence of VL in the EMR was 18.2% in 1990 and 15.5% in 2015. The total age-standardized YLDs rate attributed to all-cause VL in EMR was 536.9 per 100,000 population in 1990 and 482.3 per 100,000 population in 2015. For each 0.1 unit increase in SDI, the age-standardized prevalence and YLDs rate of VL showed a reduction of 1.5% (p < 0.001) and 23.9 per 100,000 population (p < 0.001), respectively.

CONCLUSIONS

The burden of VL is high in the EMR; however, it shows a descending trend over the past 25 years. EMR countries need to establish comprehensive eye care programs in their health care systems.

Attitudes and perceptions of Sudanese high-school students and their parents towards spectacle wear

Background: Uncorrected refractive error is a major cause of avoidable vision impairment and may have significant impact on social life, education and economic prospects of people. This condition could be easily treated by wearing spectacles, but because of attitudes and misconceptions of some communities towards spectacle wear and eye care, such methods are underutilised.Aim: To assess the attitudes and perceptions of Sudanese high-school students and their parents towards spectacle wear.Setting: The study was conducted in eight randomly selected high schools from the South Darfur state of Sudan.Methods: A cross-sectional school-based study comprising 387 high-school students with age ranging from 12 to 17 years together with 47 students’ parents with age ranging from 32 to 52 years. Quantitative and qualitative methods were used to collect data from eight high schools. Semi-structured questionnaires were distributed to collect the quantitative data, and seven focus group meetings were held in the schools with students’ parents to derive the qualitative data.Results: The findings revealed that 39%, 32% and 27.1% of the students believed that wearing spectacles affected their opportunities for education, employment and marriage, respectively. A total of 36.4% of the students believed that wearing spectacles could lead to making the eyes weaker or could damage the eyes, resulting in early blindness, and 22.5% of the respondents believed that spectacles were only for older people. In general, the perception towards spectacle wear was different between genders, with females appearing to be more vulnerable to social and psychological distress when wearing spectacles compared to males. A total of 79% of the parents were aware that wearing spectacles would improve vision if an eye doctor prescribed the spectacles. However, parents reported that the disadvantages of wearing spectacles were that they reduced the power of the eyes and spectacle wear had psychological effects, particularly among females. Parents felt that their children had lost an important asset, that the community looked at them as handicapped and that their children would be blind in future.Conclusion: The fear and stigma related to the use of spectacles are widely experienced among students and their parents in Sudan, and particularly among females. Eye health education programmes should be broadcast through the public media to promote awareness and benefits about spectacle wear and eye care.

Prevalence and causes of visual impairment amongst older adults in a rural area of North India: a cross-sectional study

OBJECTIVES

To determine the prevalence, causes and associated factors for visual impairment (VI) in rural population of Jhajjar district, Haryana, north India.

METHODS

A community-based, cross-sectional study was conducted in two blocks of Jhajjar district. A total of 34 villages were selected using probability proportionate to size sampling method. Adults aged 50 years and above were selected using compact segment cluster sampling approach. Presenting visual acuity using LogMAR E chart was measured along with collection of other demographic details as part of the house-to-house survey. Subjective refraction and torch light examination were performed at a clinic site within the village to ascertain VI and its cause. VI was considered when presenting visual acuity was less than 6/18 in the better eye. Common causes of VI viz uncorrected refractive errors, cataract, central corneal opacity and others were noted by optometrists. Descriptive analysis was undertaken. Multivariate logistic regression analysis was performed for determining associated factors with VI.

RESULTS

Out of 2025 enumerated adults, 1690 (83.5%) were examined at the household level and 1575 (78%) completed all study procedures. The prevalence of VI was found to be 24.5% (95% CI 21.1 to 26.3) and blindness was 5% (95% CI 3.9 to 6.1). The most common causes of VI were uncorrected refractive errors (50%) and cataract (37%). The VI in study participants was found to be associated with age, gender, marital and educational status.

CONCLUSIONS

VI is still a public health problem in rural population of Jhajjar district, Haryana. Provision of spectacles and cataract surgical services are simple interventions to address this issue.

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

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.

Recognition of a Virtual Scene via Simulated Prosthetic Vision

In order to effectively aid the blind with optimal low-resolution vision and visual recovery training, pathfinding and recognition tests were performed using a simulated visual prosthetic scene. Simple and complex virtual scenes were built using 3DMAX and Unity, and pixelated to three different resolutions (32 × 32, 64 × 64, and 128 × 128) for real-time pixel processing. Twenty subjects were recruited to complete the pathfinding and object recognition tasks within the scene. The recognition accuracy and time required were recorded and analyzed after the trials. In the simple simulated prosthetic vision (SPV) scene, when the resolution was increased from 32 × 32 to 48 × 48, the object recognition time decreased from 92.19 ± 6.97 to 43.05 ± 6.08 s, and the recognition accuracy increased from 51.22 ± 8.53 to 85.52 ± 4.93%. Furthermore, the number of collisions decreased from 10.00 ± 2.31 to 3.00 ± 0.68. When the resolution was increased from 48 × 48 to 64 × 64, the object recognition time further decreased from 43.05 ± 6.08 to 19.46 ± 3.71 s, the recognition accuracy increased from 85.52 ± 4.93 to 96.89 ± 2.06%, and the number of collisions decreased from 3.00 ± 0.68 to 1.00 ± 0.29. In complex scenes, the time required to recognize the room type decreased from 115.00 ± 23.02 to 68.25 ± 17.23 s, and object recognition accuracy increased from 65.69 ± 9.61 to 80.42 ± 7.70% when the resolution increased from 48 × 48 to 64 × 64. When the resolution increased from 64 × 64 to 128 × 128, the time required to recognize the room type decreased from 68.25 ± 17.23 to 44.88 ± 9.94 s, and object recognition accuracy increased from 80.42 ± 7.71 to 85.69 ± 7.39%. Therefore, one can conclude that there are correlations between pathfinding and recognition. When the resolution increased, the time required for recognition decreased, the recognition accuracy increased, and the number of collisions decreased. Although the subjects could partially complete the recognition task at a resolution of 32 × 32, the recognition time was too long and recognition accuracy was not good enough to identify simple scenes. Complex scenes required a resolution of at least 48 × 48 for complete recognition. In addition, increasing the resolution shortened the time required to identify the type of room, and improved the recognition accuracy.

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

AIM

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.

MATERIALS AND METHODS

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.

RESULTS

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%).

CONCLUSIONS

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.

Knowledge, usage and barriers associated with contact lens wear in Ghana

BACKGROUND

Despite findings that contact lens wear for vision correction provides better quality of life than spectacles, contact lens use in developing countries is low. This study evaluated knowledge, usage and barriers associated with contact lens wear among spectacle wearers in Cape Coast, Ghana.

METHOD

A cross-sectional survey using a structured questionnaire was conducted on an adult population of spectacle wearers to assess their knowledge of contact lens wear for vision correction. The participants were proportionately sampled from three eye clinics in the Cape Coast Metropolis, Ghana. Questionnaires were either self-administered or completed with the help of a research assistant.

RESULTS

Of the 422 participants, only 147 (34.8%) knew of contact lens wear for vision correction. The proportion of spectacle wearers reporting history of contact lens wear was 14 (3.3%). Barriers to contact lens wear reported were satisfaction with vision through spectacles 102 (25.0%), lack of adequate information 111 (27.2%), fear of side effects 94 (23.0%) and cost 78 (19.1%). The younger adults and those with higher number of changes of spectacles were more likely to know of contact lenses.

CONCLUSION

Knowledge and usage of contact lenses among spectacle wearers was low. Contact lens education and demonstration of visual performance through fitting of trial contact lenses on potential candidates may help overcome barriers to contact lens wear.

Impact of refractive error on quality of life: a qualitative study

IMPORTANCE

This study qualitatively explores the impact of refractive error on adults, particularly after correction.

BACKGROUND

The study aimed to explore the impact of refractive error on quality of life.

DESIGN

Cross-sectional; in-depth telephone and face-to-face semistructured interviews; qualitative study with inductive and deductive processes.

PARTICIPANTS

Forty-eight adults with refractive error (including presbyopia) were recruited from the Flinders Vision, the Ashford Advanced Eye Care and among Flinders University staff and students, in South Australia.

METHODS

The interviews were audio-recorded, transcribed verbatim, coded and analysed using thematic analysis.

MAIN OUTCOME MEASURES

Themes and categories RESULTS: The median age of the participants was 49 years (min: 22 years; max: 76 years). Most of them were female: (29; 59%). Most of them (36; 75.0%) had myopia followed by hyperopia (12; 25.0%). Twenty-two (45.8%) participants had astigmatism. Similarly, 23 (47.9%) of them were presbyopes. Most of the participants (39; 81.3%) wore glasses; 17 (35.4%) used contact lenses, and 17 (35.4%) had undergone refractive surgery. A total of 2367 comments were coded. Thematic analysis resulted into six themes that informed about quality of life issues in people with refractive error. Concerns about cosmetic appearance, personal health and safety, difficulties in day-to-day activities and inconveniences rendered in daily life were identified as the most important themes.

CONCLUSIONS AND RELEVANCE

The findings of this study enrich the understanding on the issues important in people with refractive error. The quality of life issues identified will be used to develop a refractive error-specific item bank.

Refractive error study in young subjects: results from a rural area in Paraguay

AIM

To evaluate the distribution of refractive error in young subjects in a rural area of Paraguay in the context of an international cooperation campaign for the prevention of blindness.

METHODS

A sample of 1466 young subjects (ranging from 3 to 22 years old), with a mean age of 11.21±3.63 years old, were examined to assess their distance visual acuity (VA) and refractive error. The first screening examination performed by trained volunteers, included visual acuity testing, autokeratometry and non-cycloplegic autorefraction. Inclusion criteria for a second complete cycloplegic eye examination by an optometrist were VA <20/25 (0.10 logMAR or 0.8 decimal) and/or corneal astigmatism ≥1.50 D.

RESULTS

An uncorrected distance VA of 0 logMAR (1.0 decimal) was found in 89.2% of children. VA <20/25 and/or corneal astigmatism ≥1.50 D was found in 3.9% of children (n=57), with a prevalence of hyperopia of 5.2% (0.2% of the total) in this specific group. Furthermore, myopia (spherical equivalent ≤-0.5 D) was found in 37.7% of the refracted children (0.5% of the total). The prevalence of refractive astigmatism (cylinder ≤-1.50 D) was 15.8% (0.6% of the total). Visual impairment (VI) (0.05≤VA≤0.3) was found in 12/114 (0.4%) of the refracted eyes. Main causes for VI were refractive error (58%), retinal problems (17%, 2/12), albinism (17%, 2/12) and unknown (8%, 1/12).

CONCLUSION

A low prevalence of refractive error has been found in this rural area of Paraguay, with higher prevalence of myopia than of hyperopia.

Magnitude and Determinants of the Ratio between Prevalence of Low Vision and Blindness in Rapid Assessment of Avoidable Blindness Surveys

PURPOSE

To determine the magnitude and determinants of the ratio between prevalence of low vision and prevalence of blindness in rapid assessment of avoidable blindness (RAAB) surveys globally.

METHODS

Standard RAAB reports were downloaded from the repository or requested from principal investigators. Potential predictor variables included prevalence of uncorrected refractive error (URE) as well as gross domestic product (GDP) per capita, health expenditure per capita of the country across World Bank regions. Univariate and multivariate linear regression were used to investigate the correlation between potential predictor variables and the ratio.

RESULTS

The results of 94 surveys from 43 countries showed that the ratio ranged from 1.35 in Mozambique to 11.03 in India with a median value of 3.90 (Interquartile range 3.06;5.38). Univariate regression analysis showed that prevalence of URE (p = 0.04), logarithm of GDP per capita (p = 0.01) and logarithm of health expenditure per capita (p = 0.03) were significantly associated with the higher ratio. However, only prevalence of URE was found to be significant in multivariate regression analysis (p = 0.03).

CONCLUSION

There is a wide variation in the ratio of the prevalence of low vision to the prevalence of blindness. Eye care service utilization indicators such as the prevalence of URE may explain some of the variation across the regions.