Undercorrected refractive error in Singaporean Chinese adults: the Tanjong Pagar survey

Prevalence of refractive errors in population aged 50 years and over: The Gilan eye study

PURPOSE

To describe the prevalence of refractive error (RE) and its association with other environmental and health factors among population aged ≥50 years who lived in Gilan, Iran in 2014.

METHODS

In this population-based cross-sectional study, 3281 individuals aged ≥50 years living in Gilan for at least 6 months were enrolled. The prevalence of different types of REs including myopia (spherical equivalent (SE)≤-0.50D), high myopia (SE ≤ -6.00D), hyperopia (SE≥ + 0.50D), high hyperopia (SE≥ + 3.00D), astigmatism (cylinder < -0.50D) and high astigmatism (cylinder < -2.25D) were determined. Anisometropia was defined as the SE difference of ≥1.00D between the two eyes. Associated factors including age, body mass index (BMI) and education were also studied.

RESULTS

2587 eligible individuals (58% female subjects) with the mean age of 62.6 ± 8.8 years participated (87.6% response rate). The prevalence of myopia, hyperopia and astigmatism was 19.2%, 48.6% and 57.4%, respectively. 3.6% high hyperopia, 0.5% high myopia and 4.5% high astigmatism were identified. The positive simultaneous effects3 of older age (Odds Ratio (OR) = 3.14), nuclear (OR = 1.71) and posterior subcapsular (OR = 1.61) cataracts as well as the negative effects of higher levels of education (OR = 0.28) were obtained on myopia. Higher BMI was found as a risk factor for hyperopia (OR = 1.67), while older patients were less likely to be hyperopic (OR = 0.31).

CONCLUSION

Higher incidence of myopia and astigmatism was found in patients aged over 70 years. It was also found that patients at older ages who suffered with cataracts were at a higher risk of myopia, while elderly people with greater BMI were at a higher risk of hyperopia.

Barriers to the Utilization of Low-Vision Rehabilitation Services among Over-50-Year-Old People in East and Southeast Asian Regions: A Scoping Review

East and Southeast Asia (ESEA) are facing age-related eye health issues. Low-vision rehabilitation (LVR), which is a special rehabilitation service for individuals with vision impairment, is a promising solution for these health issues; however, poor accessibility to LVR services has been reported globally, including ESEA. Therefore, this scoping review aimed to summarize and understand the barriers to accessing LVR services in ESEA. In total, 20 articles were ultimately considered eligible for this scoping review after an electronic database search using MEDLINE (PubMed), Web of Science, Academic Search Ultimate (EBSCO), and Ichushi-Web (Japanese medical literature database), and an independent review by two reviewers. Twenty-one potential barrier factors were identified in the full-text review. Notably, age, education, economic status, "previous experience using eye care service", and "knowledge, information, and awareness" were the possible barrier factors that were examined for their association with LVR utilization, with supportive evidence in many eligible studies. We also identified research gaps relating to geographical and ethnic diversity, the scope of LVR services, and barriers among eligible articles. Therefore, by conducting further studies addressing the research gaps identified in this scoping review, these findings can be used to make LVR services more accessible to people in ESEA.

Improving Access to Refractive Services in Adults: A Health Examination Center-Based Model

Purpose: To assess the potential of a health examination center-based screening model in improving service for uncorrected refractive error. Methods: Individuals aged ≥18 years undergoing the routine physical examinations at a tertiary hospital in the northeast China were invited. Presenting visual acuity, noncycloplegic autorefraction, noncontact tonometry, fundus photography, and slit-lamp examination were performed. Refractive error was defined as having spherical equivalent ≤ -0.75 D or ≥ +1 D and uncorrected refractive error was considered as refractive error combined with presenting visual acuity < 6/12 in the better eye. Costs for the screening were assessed. Results: A total of 5,284 participants (61 ± 14 years) were included. The overall prevalence of myopia and hyperopia was 38.7% (95% CI, 37.4-40.0%) and 23.5% (95% CI, 22.3-24.6%), respectively. The prevalence of uncorrected refractive error was 7.85% (95% CI, 7.13-8.58%). Women (p < 0.001 and p = 0.003), those with age ≥ 70 years (p < 0.001 and p = 0.003), and myopia (p < 0.001 and p < 0.001) were at higher risk of uncorrected refractive error and uncorrected refractive error-related visual impairment. Spectacle coverage rate was 70.6% (95% CI, 68.2-73.0%). The cost to identify a single case of refractive error and uncorrected refractive error was US$3.2 and US$25.2, respectively. Conclusion: The prevalence of uncorrected refractive error is high in the urban Chinese adults. Health examination center-based refractive error screening is able to provide an efficient and low-cost model to improve the refractive services in China.

The prevalence and causes of visual impairment among children in Kenya - the Kenya eye study

Background

Visual impairment is the partial or complete loss of vision in which the presenting visual acuity lie between 6/18-no perceptions of light. In Kenya, little attention has been directed towards children vision and causes of visual impairment. Therefore, this study was designed to investigate the prevalence and causes of visual impairment in the children population of Kenya.

Methods

This cross-sectional population-based study included 3400 (1800, 52.9% female) randomly selected children with a mean age of 12 ± 2 years (range 5–16 years). Visual acuity was taken using Snellens chart at 6 m. Anterior and posterior segment was assessed using slit lamp and indirect ophthalmoscope. The World Health Organization definition formed the baseline for calculating the mean prevalence of visual impairment.

Results

Visual acuity measurements were available for 3240 (95.3%) participants. The mean prevalence of visual impairment based on pin-hole value was 1.7 ± 0.3% using World Health Organization definition. The prevalence of visual impairment based on presenting visual acuity value was 2.4 ± 0.7% using the World Health Organization definition. Multivariate analysis demonstrated that the presence of visual impairment on pin-hole increased significantly with increasing age (odds ratio 1.230, P = .021) and uncorrected refractive error (odds ratio 0.834, P = .032) according to World Health Organization definition. Cases of uncorrected refractive error remained the major cause for presenting visual impairment. Causes of visual impairment due to presenting visual acuity were nystagmus (14%), amblyopia (24%) and uncorrected refractive error (62%).

Conclusion

The prevalence of visual impairment in Kenya is associated with age. Uncorrected refractive error remains the major causes of visual impairment.

Visual impairment and social isolation, depression and life satisfaction among older adults in Ghana: analysis of the WHO's Study on global AGEing and adult health (SAGE) Wave 2

AIM

To estimate the prevalence of visual impairment (VI) and associated factors and further quantify its association with social isolation, depression and life satisfaction among older adults in Ghana.

METHODS

WHO Study on Global AGEing and Adult Health Ghana dataset for older adults 50 years and above was used for this study. Social isolation, depression and life satisfaction were our primary outcomes with VI being our secondary outcome. We employed negative binomial, Poisson and generalised negative binomial regression models individually modified with Coarsened Exact Matching method of analysis. All analysis was performed by adopting robust SE estimation using Stata V.15.

RESULTS

The prevalence of VI was 17.1% (95% CI14.3 to 20.2) and the factors associated include age groups, educational level, religion, region, where the participant was born, and difficulty in work/households activity (p<0.05). The inferential analysis shows that the significant log-likelihood score of social isolation and life satisfaction for older adults with VI was 0.25 more (95% CI 0.03 to 0.47) and 0.04 less (95% CI -0.08 to -0.01), respectively, compared with those without VI. The prevalence of depression among older adults with VI was significantly 90% higher compared with non-VI (adjusted prevalence ratio (95% CI) = 1.90 (1.17 to 3.09), p<0.001).

CONCLUSION

The prevalence of VI is associated with increasing age, educational level and self-rated health. VI was identified to be associated with social isolation, depression and diminishing life satisfaction. In order to achieve sustainable development goal #3, a national focus on geriatric care as part of the implementation of the National Ageing Policy will garner improvement in the quality of life of older adults with visual VI in Ghana. Eye health practitioners at all levels of the health systems should consider the psychosocial consequences of VI for the optimum care of the older adult client.

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.

Retinal Vascular Oxygen Saturation and Its Variation With Refractive Error and Axial Length

Purpose

To evaluate the relationships between refractive error, axial length (AL), and retinal vascular oxygen saturation in an adult population.

Methods

This was a hospital-based, prospective observational study. The left eyes of phakic adult subjects without media opacity were analyzed. Subjective undilated manifest refraction was performed, and refractive errors were defined as myopia (spherical equivalent [SE], <−1 D), emmetropia (SE between −1 D and +1 D) and hyperopia (SE >+1 D). Retinal oximetry was performed using the Oxymap system (Oxymap Inc., Reykjavik, Iceland). Multivariate linear regression models were constructed to assess the relationship between retinal vascular oxygen saturation, SE, and AL obtained with optical biometry, with adjustments for age, sex, race, blood pressure, hyperlipidemia, and diabetes mellitus.

Results

There were 85 subjects, with mean age of 66.1 ± 11.3 years. The majority were female (60%) and Chinese (84%). A total of 60% were myopic, 28% emmetropic, and 12% hyperopic. Mean SE was −5.29 ± 6.51 D and mean AL was 25.30 ± 2.99 mm. In multivariate analyses, more myopic SE and longer AL were associated with lower retinal arteriolar oxygen saturation (regression coefficient B = 0.61 [95% confidence interval, 0.28, 0.95], P = 0.001; and B = −1.13 [95% confidence interval, −1.71, −0.56], P < 0.001, respectively). Subjects with myopic SE and AL also had lower retinal arteriolar oxygen saturation than emmetropes and hyperopes (P = 0.03 and P = 0.02, respectively).

Conclusions

Eyes with more myopic SE and longer AL have lower retinal arteriolar oxygen saturation.

Translational Relevance

This study provides direct evidence of a link between retinal oxygenation and hypoxia and myopia by using a novel device that quantifies retinal vascular oxygenation in vivo.

Clinical safety of a minor eye conditions scheme in England delivered by community optometrists

OBJECTIVE

The aim of this study was to monitor the activity and evaluate the clinical safety of a minor eye conditions scheme (MECS) conducted by accredited community optometrists in Lambeth and Lewisham, London.

METHODS AND ANALYSIS

Optometrists underwent an accredited training programme, including attendance at hospital eye services (HES) clinics. Patients who satisfied certain inclusion criteria were referred to accredited MECS optometrists by their general practitioners (GPs) or could self-refer. Data were extracted from clinical records. A sample of MECS clinical records was graded to assess the quality of the MECS optometrists' clinical management decisions. Referrals to the HES were assessed by the collaborating ophthalmologists and feedback was provided.

RESULTS

A total of 2123 patients (mean age 47 years) were seen over 12 months. Two-thirds of the patients (67.3%) were referred by their GP. The most common reasons for patients needing a MECS assessment were 'red eye' (36.7% of patients), 'painful white eye' (11.1%), 'flashes and floaters' (10.2%); 8.7% of patients had a follow-up appointment. Of the patients seen, 75.1% were retained in the community, 5.7% were referred to their GP and 18.9% were referred to the HES. Of the HES referrals, 49.1% were routine, 22.6% urgent and 28.3% emergency. Of the records reviewed, 94.5% were rated as appropriately managed; 89.2% of the HES referrals were considered appropriate.

CONCLUSION

The findings of this study indicate that optometrists are in a good position to work very safely within the remits of the scheme and to assess risk.

Five-year visual outcome among people with correctable visual impairment: the Liwan Eye Study

IMPORTANCE

Longitudinal data on visual outcome of correctable visual impairments (VI) are of paramount importance for decision-maker to estimate burden and demand to treat avoidable VI.

BACKGROUND

To assess the 5-year visual outcome among participants with correctable VI and to identify associated risk factors.

DESIGN

Population-based longitudinal cohort study.

PARTICIPANTS

Participants with correctable VI at baseline attended the 5-year follow-up visit of the Liwan Eye Study.

METHODS

Presenting visual acuity (PVA) with habitual refractive correction was assessed using an Early Treatment Diabetic Retinopathy Study (ETDRS) chart. Then participants with PVA <6/12 in either eye underwent further non-cycloplegic subjective refraction to obtain their best-corrected visual acuity. Correctable VI was defined as having a PVA of <6/12 in the better eye which could be improved to ≥6/12 after refractive correction.

MAIN OUTCOME MEASURES

The 5-year visual outcome among participants with correctable VI.

RESULTS

Among 1405 participants at baseline examination, 188 (13.4%) had correctable VI, of whom 118 (62.8%) were re-examined at the 5-year follow-up, including 39 (33.9%) who progressed to non-correctable VI, 43 (37.4%) who had persistent correctable VI and 33 (28.7%) who were converted to normal vision. In multivariate logistic regression, compared with participants who were no longer visual impaired, significant risk factors for participants with persistent VI were older, had income <1000 RMB/month, and more myopia spherical equivalent.

CONCLUSIONS AND RELEVANCE

Over two of three participants with correctable VI remained to have VI after 5 years, among whom 50% are correctable by spectacles, highlighting the need to improve the refractive care accessibility to treat avoidable VI in China.

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

Background

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.

Methods

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.

Results

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.

Conclusion

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.

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

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.

Visual impairment and spectacle coverage rate in Baoshan district, China: population-based study

Background

To investigate the prevalence and risk factors of visual impairment associated with refractive error and the unmet need for spectacles in a special suburban senior population in Baoshan District of Shanghai, one of several rural areas undergoing a transition from rural to urban area, where data of visual impairment are limited.

Methods

The study was a population based survey of 4545 Chinese aged (age: >60 years or older ) at Baoshan, Shanghai, in 2009. One copy of questionnaire was completed for each subject. Examinations included a standardized refraction and measurement of presenting and best corrected visual acuity (BCVA) as well as tonometry, slit lamp biomicroscopy, and fundus photography.

Results

The prevalence of mild (6/12 to 6/18), moderate (6/18 to 6/60) and severe visual impairment was 12.59%, 8.38% and 0.44%, respectively, and 5.26%, 3.06% and 0.09% with refractive correction. Visual impairment was associated with age, gender, education and career, but not insurance . The prevalence of correctable visual impairment was 5.81% (using 6/18 cutoff) and 13.18% (using 6/12 cutoff). Senior people and women were significantly at a higher risk of correctable visual impairment, while the well-educated on the contrary. The prevalence of undercorrected refractive error (improves by 2 or more lines with refraction) was 24.84%, and the proportion with undercorrected refractive error for mild, moderate , severe and no visual impairment was 61.54%, 67.98%, 60.00% and 14.10%, respectively. The spectacle coverage rate was 44.12%. Greater unmet need for spectacles was observed among elderly people, females, non-peasant, and subjects with less education and astigmatism only.

Conclusions

High prevalence of visual impairment, visual impairment alleviated by refractive correction, and low spectacle coverage existed among the senior population in Baoshan District of Shanghai. Education for the public of the importance of regular examination and appropriate and accessible refraction service might be helpful to solve the problem.

Uncorrected refractive error in older British adults: the EPIC-Norfolk Eye Study

AIM

To investigate the prevalence of, and demographic associations with, uncorrected refractive error (URE) in an older British population.

METHODS

Data from 4428 participants, aged 48-89 years, who attended an eye examination in the third health check of the European Prospective Investigation into Cancer-Norfolk study and had also undergone an ophthalmic examination were assessed. URE was defined as ≥1 line improvement of visual acuity with pinhole-correction in the better eye in participants with LogMar presenting visual acuity (PVA) <0.3 (PVA <6/12). Refractive error was measured using an autorefractor without cycloplegia. Myopia was defined as spherical equivalent ≤-0.5 dioptre, and hypermetropia ≥0.5 dioptre.

RESULTS

Adjusted to the 2010 midyear British population, the prevalence of URE in this Norfolk population was 1.9% (95% CI 0.6% to 3.1%). Lower self-rated distance vision was correlated with higher prevalence of URE (p(trend)<0.001). In a multivariate logistic regression model adjusting for age, gender, retirement status, educational level and social class, independent significant associations with URE were increasing age (p(trend)<0.001) and having hypermetropic or myopic refractive error. Wearing distance spectacles was inversely associated with URE (OR 0.34, 95% CI 0.21 to 0.55, p<0.001). There were 3063 people (69.2%) who wore spectacles/contact lenses for distance vision. Spectacle wear differed according to type of refractive error (p<0.001), and use rose with increasing severity of refractive error (p(trend)<0.001).

CONCLUSION

Although refractive error is common, the prevalence of URE was found to be low in this population reflecting a low prevalence of PVA<0.3.

Unmet refractive need and its determinants in Shahroud, Iran

Uncorrected refractive error plays a significant role in poor vision and blindness, and its correction is the most cost-effective intervention in eye care. In this study, we report the status of the unmet refractive need and the role of economic inequality in determining the level of this need in Shahroud, Iran. This cross-sectional nested case-control study was performed on 5,190 individuals aged 40-64 years. Cases and controls were individuals with uncorrected visual acuity worse than 0.3 LogMAR in the better eye who showed at least 0.2 LogMAR improvement after correction. Cases were individuals whose presenting vision was worse than 0.3 in the better eye but improved by at least 0.2 LogMAR after correction. Controls were individuals in whom the difference between the presenting and corrected vision was less than 0.2 LogMAR. The prevalence of the unmet need was 5.7 % and it was more prevalent in women (6.5 %) than in men (4.6 %) (p = 0.003). There was a gap of 19.6 % between the two groups of high and low economic status. The Oaxaca-Blinder decomposition method revealed that differences in the education level of the two groups accounted for half of this gap. Spectacle usage is better in Iran than in some other developing countries; however, in this study, about 40 % of those who required spectacles did not have them.

Frequency, course, and impact of correctable visual impairment (uncorrected refractive error)

Uncorrected refractive error has been identified by the World Health Organization (WHO) as one of the priorities for Vision 2020 and a frequent cause of visual impairment. In the past, only the terms presenting visual impairment (PVI) and visual impairment after best refractive correction (BCVI) were used, so that PVI also included BCVI cases. In the more recent literature, visual impairment has been subdivided into two mutually exclusive entities: that which is correctable by refraction (which we now term correctable visual impairment, CVI) and that which cannot be corrected by refraction due to ocular or neurological disease (which we now term non-correctable visual impairment, NCVI, and which is identical to BCVI). PVI remains a useful concept as it includes both types of impairment. Although CVI is reported to be the major form of visual impairment worldwide, its impacts are not yet well understood. CVI has a higher prevalence among vulnerable groups such as older people, less well educated people and those living alone or in rural areas. Systematic data on barriers to refractive correction remain scant, but these may be present at the individual level, within the health service context, or at a social level. Our review indicates that research on CVI is at a relatively early stage and that more detailed research, particularly determining whether it has impacts on independent living and quality of life, is needed before CVI can be justifiably prioritized in health policy.

Change in function and spectacle-use 2 months after providing presbyopic spectacles in rural Tanzania

AIMS

To examine near vision spectacle retention and use, and changes in self-reported and performance-based near vision, 2 months after the provision of near vision spectacles.

METHODS

We conducted a 2-month follow-up of a population-based cohort of persons in rural Tanzania with near vision impairment who had received spectacles. Previously, residents age >or=40 years were examined for distance and near vision acuity. Those with presbyopia and hyperopia ('functional presbyopia') were given near vision spectacles. At baseline, subjects were asked to thread a needle; they were also asked questions on the perception of their near vision, ability to be independent and general health. At 2 months, subjects were again queried. Questions on the perceived affordability of replacement spectacles were also asked.

RESULTS

Of the 866 people provided with spectacles, 89% were seen at 2 months. Ninety-two per cent were still using the spectacles. Users were more likely to have any education (51.8%) than non-users (28.3%) (p<0.001). Only 31% had successfully threaded a needle at baseline, increasing to 91% at follow-up (p<0.001). Spectacle-users showed a significant improvement in satisfaction with near vision and ability to be independent, but no change in perception of general health, from baseline to follow-up. Men were more likely than women to be able to afford spectacles and to know where to get them.

CONCLUSIONS

Our cohort maintained their spectacles and reported tangible improvements associated with their use. The value of simple reading spectacles for those with near vision impairment suggests that a greater emphasis on near vision is needed in the Vision 2020 agenda.

Habitual vs optimal distance visual acuity

PURPOSE

The maintenance of a good level of vision is desirable for developmental and social reasons; it is also a requirement that should not be overlooked in the clinical research environment. This study set out to quantify and analyse any difference between 'habitual' (pre-sight test) and 'optimal' (post-refraction) distance visual acuity in an optometric population. It is intended that the outcome of this work will inform not only clinicians but also those undertaking vision research.

METHODS

Binocular logMAR visual acuity was determined at 6 m before and after optometric intervention in patients attending optometric practice for a routine sight test. Cases were recorded seriatim but restricted to the 'core' refraction range representative of typical optometric practice; three further exemption criteria included subject illiteracy, the necessity for a non-standard test distance and contact lens wear. Over a 12-month period, two-thirds of patients examined satisfied the study inclusion criteria; it is the clinical data of these 1288 individuals that are described and analysed here.

RESULTS

These data provide a quantitative demonstration that an optometric intervention will most likely improve the habitual distance visual acuity of subjects, irrespective of gender, age group, time interval since last test, refractive status and whether or not the subject is a habitual spectacle wearer. The improvement found was typically within one logMAR chart line (<5 letters), being greatest in spectacle-wearing teenagers and in individuals beyond retirement age (increasing to eight letters in elderly habitual non-spectacle wearers); also in non-wearers who left an interval of 2 years or more between sight tests.

CONCLUSIONS

Clinical and laboratory-based investigators are advised that a current and optimal refractive correction should be worn by subjects of all ages enrolled in vision-related studies. Refractive defocus may introduce or exaggerate test outcome variability.

Retinal redetachment after silicone oil removal in proliferative vitreoretinopathy: a prognostic factor analysis

PURPOSE

To determine the prognostic factors associated with retinal redetachment after 1300-centistokes silicone oil removal in rhegmatogenous retinal detachments (RDs) associated with grade C proliferative vitreoretinopathy (PVR).

DESIGN

Nonrandomized, retrospective, comparative interventional trial.

METHODS

One hundred and forty-seven eyes with RD and grade C PVR treated with silicone oil tamponade, with subsequent silicone oil removal, in an institutional setting. Main outcome measures included anatomic success, defined as complete retinal attachment after silicone oil removal, and best-corrected visual acuity (BCVA) after silicone oil removal.

RESULTS

Silicone oil was removed after a mean tamponade period of 12.4+/-9.8 months. The mean follow-up after silicone oil removal was 22.1+/-18.7 months (range, 6.0 to 71.0 months). The retina remained attached in 120 eyes after oil removal. The overall anatomic success rate was 81.6%+/-3.2%. Logistic regression showed that an increased number of previous unsuccessful RD surgeries (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.19 to 0.80; P=.010) and longer axial lengths (OR, 0.42; 95% CI, 0.15 to 0.87; P=.032) were associated with a lower anatomic success rate. Previous vitrectomy, previous scleral buckling procedure, 12% perfluoropropane-air exchange immediately after silicone oil removal, and duration of silicone oil tamponade were not statistically associated with the anatomic success rate. Anatomic success was associated with a significantly better BCVA (1.169+/-0.475 vs 1.520+/-0.381 logarithm of the minimum angle of resolution; P<.001).

CONCLUSIONS

The number of previous surgeries and axial length, rather than the nature of the previous surgical procedures, were significant prognostic factors for anatomic success after silicone oil removal.

Technical Note: A comparison of a novel direct ophthalmoscope, the OptyseTM, to conventional direct ophthalmoscopes

Despite the current popularity of binocular indirect ophthalmoscopy, direct ophthalmoscopes are still commonly used by clinicians for fundus examination. They are considered to be expensive, however, and it has been suggested that this cost can prevent their use by healthcare professionals in developing countries. The Optyse Lens Free Ophthalmoscope is a novel direct ophthalmoscope, without a lens focus system, that allows for comparatively inexpensive manufacture and supply. We compared the clarity of view with the Optyse to that with standard direct ophthalmoscopes, over a sequential cohort of patients with a variety of refractive errors and ocular conditions. The grade of clarity of view with the Optyse Lens Free Ophthalmoscope was less than conventional ophthalmoscopes (Wilcoxon signed rank test, p < 0.0001). This grade of clarity of view was not associated with the ametropia of the ophthalmoscopic observation (Spearman r < or = 0.03, p > or = 0.28) but was with the presence of cataracts (chi2 test, p < 0.0001) with both the Optyse and the conventional ophthalmoscopes. Despite its limitations, the retinal view with Optyse was often within acceptable clinical limits suggesting that this relatively inexpensive ophthalmoscope may have a place when cost prohibits any other type of ophthalmoscope use.

Pars plana vitrectomy and perfluoropropane (C3F8) tamponade for retinal detachment due to myopic macular hole: a prognostic factor analysis

PURPOSE

To determine the prognostic factors associated with anatomical success in the treatment of retinal detachment (RD) due to myopic macular hole by pars plana vitrectomy (PPV) and perfluoropropane (C3F8) gas tamponade.

DESIGN

Retrospective, interventional, comparative case series.

METHODS

In an institutional setting, 57 eyes with myopic macular hole RDs treated by PPV and C3F8 tamponade, with or without concomitant internal limiting membrane (ILM) peeling, endolaser photocoagulation, and/or phacoemulsification, were analyzed. Outcome measures were anatomical success, defined as closure of macular hole with reattachment of the surrounding retina, and postoperative best-corrected visual acuity (BCVA).

RESULTS

The mean postoperative follow-up was 26.9 +/- 16.5 months. The anatomical success rate after primary PPV and C3F8 tamponade was 63.2%. Regression analysis showed that shorter axial lengths (odds ratio [OR] = 6.73, 95% confidence interval [95% CI] 1.86 to 12.22, P = .010), concomitant ILM peeling (OR 1.59, 95% CI 1.14 to 2.38, P = .013), and shorter duration of macular hole RD (OR 0.81, 95% CI 0.67 to 0.98, P = .033) were associated with a higher anatomical success. The mean pre- and postoperative BCVAs were 1.430 +/- 0.273 (range, 0.523 to 1.700) and 1.403 +/- 0.271 (range, 0.699 to 1.800) logarithm of minimal angle of resolution units, respectively. The postoperative BCVA was significantly better in eyes with macular hole closure than in eyes without (P = .021).

CONCLUSIONS

Axial length, concomitant ILM peeling, and duration were important prognostic factors for PPV and C3F8 tamponade in the treatment of myopic macular hole RDs.

The epidemiology of age related eye diseases in Asia

In the past decade, several large population based studies have provided new information on the prevalence of visual impairment and the major age related eye diseases in Asia. These include epidemiological studies from India, Taiwan, Mongolia, Singapore, and Japan. In particular, the epidemiology of refractive errors and glaucoma has been well characterised, providing insights not only into the public health implications of these conditions, but also into anatomical changes of the eye with ageing. In contrast, there are few well conducted population based studies on diabetic retinopathy and age related macular degeneration in Asia, two conditions that are likely to be important causes of blindness in the future.

What is the global burden of visual impairment?

BACKGROUND

A recent estimate by the World Health Organization (WHO) suggests that 161 million persons worldwide have visual impairment, including 37 million blind (best-corrected visual acuity less than 3/60 in the better eye) and 124 million with visual impairment less severe than blindness (best-corrected acuity less than 6/18 to 3/60 in the better eye). This estimate is quoted widely, but because it is based on definitions using best-corrected visual acuity, uncorrected refractive error as a cause of visual impairment is excluded.

METHODS

We reviewed data from population-based surveys of visual impairment worldwide published 1996 onwards that included presenting visual acuity, and estimated the proportion of visual impairment caused by uncorrected refractive error in different sub-regions of the world. We then extrapolated these data to estimate the worldwide burden of visual impairment including that caused by uncorrected refractive error.

RESULTS

The total number of persons with visual impairment worldwide, including that due to uncorrected refractive error, was estimated as 259 million, 61% higher than the commonly quoted WHO estimate. This includes 42 million persons with blindness defined as presenting visual acuity less than 3/60 in the better eye, and 217 million persons with less severe visual impairment level defined as presenting visual acuity less than 6/18 to 3/60 in the better eye, 14% and 75% higher, respectively, than the WHO estimates based on best-corrected visual acuity. Sensitivity analysis, taking into account the uncertainty of the proportion of visual impairment caused by refractive error, revealed that the number of persons in the world with visual impairment due to uncorrected refractive error could range from 82 to 117 million.

CONCLUSION

The actual burden of visual impairment worldwide, including that caused by uncorrected refractive error, is substantially higher than the commonly quoted WHO estimate that is based on best-corrected visual acuity. We suggest that the indicative estimate of 259 million persons with visual impairment worldwide, which includes 42 million blind with visual acuity less than 3/60 in the better eye, be used for further planning of the VISION 2020 initiative instead of the often quoted 161 million estimate that includes 37 million blind.

Uncorrected refractive error in Singapore teenagers

AIM

To study the prevalence rate of uncorrected refractive error and associated risk factors among Singapore schoolchildren aged 12-16 years (grade 7).

METHODS

A cross sectional study of 628 participants (participation rate 99.8%) was conducted in two schools. An interviewer led questionnaire asking about sociodemographic variables and risk factors was administered. Refractive errors were measured using a table mounted autorefractor. Participants with habitual visual acuity (VA) of 0.2 logMAR or worse underwent subjective refraction. Uncorrected refractive error was defined as improvement of at least 0.2 logMAR in best corrected visual acuity after subjective refraction.

RESULTS

The prevalence rate of uncorrected refractive error was 22.3% (95% confidence interval (CI) 19.0% to 25.5%). The multivariate adjusted odds ratio of uncorrected refractive error in students with the lowest academic ability was 2.24 (95% CI 1.34 to 3.73). Increasing time interval since the last visit to an eye care provider increased the risk of uncorrected refractive error (trend p = 0.001).

CONCLUSION

Uncorrected refractive error was a significant problem among Singapore students aged 12-16 years (grade 7). Uncorrected refractive error was more common among students with low academic ability or those who had not visited an eye care provider for a long time.

Frequency of under-corrected refractive errors in elderly Chinese in Beijing

PURPOSE

The aim of the study was to evaluate the prevalence of under-corrected refractive error among elderly Chinese in the Beijing area.

METHODS

The population-based, cross-sectional, cohort study comprised 4,439 subjects out of 5,324 subjects asked to participate (response rate 83.4%) with an age of 40+ years. It was divided into a rural part [1,973 (44.4%) subjects] and an urban part [2,466 (55.6%) subjects]. Habitual and best-corrected visual acuity was measured. Under-corrected refractive error was defined as an improvement in visual acuity of the better eye of at least two lines with best possible refractive correction.

RESULTS

The rate of under-corrected refractive error was 19.4% (95% confidence interval, 18.2, 20.6). In a multiple regression analysis, prevalence and size of under-corrected refractive error in the better eye was significantly associated with lower level of education (P<0.001), female gender (P<0.001), and age (P=0.001).

CONCLUSIONS

Under-correction of refractive error is relatively common among elderly Chinese in the Beijing area when compared with data from other populations.