The first rapid assessment of avoidable blindness (RAAB) in Thailand

Rapid survey for assessing effective cataract surgical coverage (eCSC) and effective refractive error coverage (eREC)-Novel indicators of universal eye health

PURPOSE

As per the recent World Health Organization estimates, approximately 2.2 billion people have near and distance vision impairment (VI) globally, and out of this almost 50% is avoidable.

METHODS

The Rapid Assessment of Avoidable Visual Impairment survey was a cross-sectional study conducted in September 2021, using cluster random sampling in 42 clusters with a cluster size of 140, giving a total of 6000 participants. Two teams comprising of trained optometrists and social workers conducted the ocular examination which included unaided, pinhole, and aided visual acuity assessments followed by examination of the anterior segment and lens. Distance visual acuity was measured using simplified tumbling "E" charts of different sizes for VA of 6/12, 6/18, and 6/60. The lens assessment was done in an un-dilated pupil with torch light by the optometrist.

RESULTS

Overall, 6520 individuals aged 6 years and above were enumerated, of whom 5440 (83.4%) were examined. The response rate for examination was better among females (93.1%) than males (73.9%), and it decreased from 93.8% in the age group 6-15 years to 77.1% in the 45+ age group. The prevalence of blindness and VI were 0.18% (95% CI: 0.06-0.29) and 4.19% (95%CI: 3.65-4.72), respectively. The major causes of VI in all age groups were uncorrected refractive error (65.4%), cataract (23.7%), cataract surgical complications (2.6%), corneal opacity (0.4%), and other posterior segment diseases (7.5%). The effective cataract surgical coverage (eCSC) was 61.8%, effective refractive error coverage (eREC) for distance vision was 59.8%, and eREC for near vision was 47.0%.

CONCLUSION

The RAAVI methodology is suitable to measure effective coverage in the general population, both for baseline measurement and periodic monitoring. The 2030 targets for the surveyed district are 90% eCSC and 100% eREC. Such exercises need to be conducted in each district of the country to determine the baseline and target values of effective coverage.

Evaluating the efficacy of UNav: A computer vision-based navigation aid for persons with blindness or low vision

UNav is a computer-vision-based localization and navigation aid that provides step-by-step route instructions to reach selected destinations without any infrastructure in both indoor and outdoor environments. Despite the initial literature highlighting UNav's potential, clinical efficacy has not yet been rigorously evaluated. Herein, we assess UNav against standard in-person travel directions (SIPTD) for persons with blindness or low vision (PBLV) in an ecologically valid environment using a non-inferiority design. Twenty BLV subjects (age = 38 ± 8.4; nine females) were recruited and asked to navigate to a variety of destinations, over short-range distances (<200 m), in unfamiliar spaces, using either UNav or SIPTD. Navigation performance was assessed with nine dependent variables to assess travel confidence, as well as spatial and temporal performances, including path efficiency, total time, and wrong turns. The results suggest that UNav is not only non-inferior to the standard-of-care in wayfinding (SIPTD) but also superior on 8 out of 9 metrics, as compared to SIPTD. This study highlights the range of benefits computer vision-based aids provide to PBLV in short-range navigation and provides key insights into how users benefit from this systematic form of computer-aided guidance, demonstrating transformative promise for educational attainment, gainful employment, and recreational participation.

Effect of a self-care promoting program on engagement in self-care behaviors and health-related outcomes among persons with type 2 diabetes and diabetic retinopathy: A single-blind randomized controlled trial

Background

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes, leading to visual impairment and eventual blindness. Promoting self-care behaviors is crucial in controlling DR progression and preventing blindness.

Objective

This study aimed to investigate the effects of a Self-Care Promoting Program (SCPP) on engagement in self-care behaviors, HbA1c levels, visual acuity (VA), severity of DR, and vision-related quality of life (VRQoL) among individuals with type 2 diabetes and DR.

Methods

This study employed a single-blind randomized controlled trial design to compare SCPP with conventional diabetic care interventions (standard care). The SCPP was based on the Self-Care of Chronic Illness Theory, Self-efficacy theory, and the Association of Diabetic Care and Education Specialist (ADCES) guidelines incorporating health education, self-care maintenance, monitoring, and management skills training over 12 weeks. Ninety-eight participants were randomly allocated to the experimental or control group (n = 49 per group). While the experimental group received SCPP alongside standard care, the control group received standard care alone. Data collection occurred between May 2022 and March 2023 and included demographic information, the Self-Care of Diabetes Index questionnaire (SCODI), the self-care for diabetes eye care questionnaire (SCFDE), the impact of visual impairment questionnaire (IVI-Thai version), and retinal images for DR severity grading. Data analysis utilized descriptive statistics, Chi-Square tests, t-tests, and MANOVA.

Results

Following 8 and 16 weeks of SCPP, the experimental group had significantly higher mean scores in engagement with self-care and eye-care behaviors compared to the control group (p <0.001). The highest scores were observed in self-care and eye-care confidence behaviors, followed by maintenance, monitoring, and management. Furthermore, HbA1c levels and VRQoL significantly decreased and were lower than those of the control group at week 16 (p <0.001 and p <0.05, respectively). However, there were no significant differences in VA, and DR severity increased in both groups by week 16.

Conclusion

SCPP benefits individuals with DR, enhancing their confidence and ability to perform, monitor, and manage self-care behaviors. These strategies contribute to improved diabetes management, enhanced quality of life, and reduced DR-related blindness. Integrating SCPP into routine DR management is recommended, with nurses playing a pivotal role in overseeing and driving this integration, highlighting the critical role of nurses in managing this widespread global disease.

Trial Registry Number

Thai Clinical Trials Registration (TCTR20230302002).

Prevalence and causes of visual impairment and blindness in Lao People's Democratic Republic: the Vientiane Eye Study

AIMS

To determine the prevalence and causes of visual impairment and blindness in Vientiane Province, the Lao People's Democratic Republic (Lao PDR).

METHODS

We conducted a population-based, cross-sectional study of 1264 participants aged 40 years and older from urban and rural areas of Vientiane Province. The ophthalmic examination included presenting and pinhole Snellen visual acuity (VA) with an illiterate E chart, slit-lamp examination of the anterior segment and dilated stereoscopic fundus examination. Visual impairment and blindness were defined by both presenting and pinhole VA based on the better eye according to WHO criteria: VA worse than 6/12 to 6/18 for mild impairment, VA worse than 6/18 to 6/60 for moderate impairment, VA worse than 6/60 to 3/60 for severe impairment and VA worse than 3/60 for blindness.

RESULTS

Comprehensive ophthalmic examinations were performed on 1264 participants (77.8% participation rate). Population-weighted prevalence of presenting bilateral blindness was 1.4% (95% CI 0.8 to 2.0) and bilateral visual impairment was 22.4% (95% CI 14.7 to 30.1). After pinhole correction, the corresponding prevalence of blindness was 1.3% (95% CI 0.8 to 2.0) and that of visual impairment was 12.6% (95% CI 8.2 to 16.9). Cataract was the leading cause of presenting bilateral blindness (52.9%), whereas uncorrected refractive error was the predominant cause of presenting visual impairment (40.3%).

CONCLUSIONS

Visual impairment and blindness remain major public health problems in Lao PDR. There is an ongoing need to fund ophthalmic care resources and community education programmes to improve access to healthcare in this region.

Prevalence of Refractive Error in Vientiane Province, Lao People's Democratic Republic

PURPOSE

To determine the prevalence of adult refractive error and associated risk factors in the Vientiane Province of the Lao People's Democratic Republic.

METHODS

Population-based, cross-sectional ophthalmic survey of individuals ≥ 40 years of age in Vientiane Province. Suitable refractive data was available in 1058 individuals. Demographic data, which included age and gender, was obtained from all participants. Smoking status, presence of diabetes and hypertension was also recorded. The ophthalmic examination included autorefraction, grading of cataract, applanation tonometry and ultrasound pachymetry for ocular biometry, including axial length.

RESULTS

Mean refractive error measured -0.36 diopters (D) (standard deviation [SD], 1.41) and mean cylindrical error measured -0.33 D (SD 0.95). Myopia ≤ -0.5 D and ≤ -5.0 D occurred in 53.2% (95% confidence interval [CI]: 43.7 to 62.6) and 2.0% (95% CI: 0.4 to 3.6) of participants, respectively. There was a correlation between myopia and both age and higher grading of nuclear cataract (p < .001). Hyperopia ≥ +0.5 D was present in 26.4% of participants and was associated with increasing age (p < .001). Astigmatism was present in 55.8% (95% CI: 51.5 to 60.2) of the population and was associated with increased nuclear cataract (p < .001). Urban participants had a reduced prevalence of myopia compared with rural participants.

CONCLUSION

Myopia was associated with younger age and a higher grade of nuclear cataract. The prevalence of myopia in the adult population of Vientiane Province was higher than that reported in neighbouring Asian regions and contributed to low vision.

Inclusion of diabetic retinopathy screening strategies in national-level diabetes care planning in low- and middle-income countries: a scoping review

BACKGROUND

Diabetes is a major public health concern, with approximately 80% of the burden falling on low- and middle-income countries (LMICs). Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes, and early detection through diabetic eye screening programmes is essential to prevent visual impairment and blindness. Careful planning at a national level is crucial for effective implementation of such programmes.

METHODS

A scoping review was conducted, and the protocol was published previously to explain the methods in detail. Data were collected from databases and searches, including grey literature. Furthermore, consultations were conducted with key informants from LMICs.

RESULTS

Lower-middle-income countries (29/50, 58%) and upper-middle-income countries (27/59, 45.8%) are making more progress than low-income countries (4/29, 13.8%) in terms of DR policy planning. However, no identified data for published policies have actually implemented national DR policies. Compared to low-income and lower-middle-income countries, upper-middle-income countries are making the most progress in implementing national diabetic eye screening programmes; however, their progress is still slow, with only 5/59 (8.5%) having such programmes.

CONCLUSION

There are significant gaps in the literature, with no data reported for 78/138 (56.5%) LMICs. Further research is clearly needed to support and document DR policy development in LMICs.

Prevalence and Factors Associated with Suicidal Ideation Among Older People with Visual Impairments Attending an Eye Center During the COVID-19 Pandemic: A Hospital-Based Cross-Sectional Study

Purpose

To evaluate the prevalence of suicidal ideation and associated factors among older people with visual impairments attending an eye center during the COVID-19 pandemic.

Patients and Methods

A total of 314 older people aged 60 and above with visual impairments who attended an eye center were included in this study. This was a hospital-based cross-sectional study conducted from February to July, 2022. Data were collected in person. Suicidal ideation was measured using the Columbia-Suicide Severity Rating Scale (C-SSRS). Multivariable logistic regression analysis was used to explore associations between related factors and suicidal ideation.

Results

Of 314 older people with visual impairments, the prevalence of suicidal ideation was 32.5%. Suicidal ideation was independently associated with diabetic retinopathy (adjusted odds ratio (AOR)=2.4, 95% confidence interval (CI): 1.0-5.8; p=0.038) and depression (AOR=6.3, 95% CI: 3.5-11.2; p<0.001).

Conclusion

This study found a relatively high prevalence of suicidal ideation among older people with visual impairments. There was also a significant association between depression and suicidal ideation among these individuals. Visual impairments can lead to negative émotions. This underscores the importance of addressing the mental health needs of older individuals with visual impairments, including suicide prevention efforts tailored to their needs. Ophthalmologists should be equipped with the skills necessary to identify the early signs of suicidal ideation and refer patients to mental healthcare specialists for appropriate treatment.

Blindness and visual impairment and their causes in India: Results of a nationally representative survey

Introduction

Avoidable blindness is a significant public health problem in India. Nationally representative RAAB surveys (Rapid Assessment of Avoidable Blindness) are being conducted periodically in the country to know the current status of blindness in the country. The current study describes the findings from the RAAB survey conducted during 2015–19 in India.

Methodology

A cross-sectional, population-based survey was conducted across the entire country among persons aged 50 years and above using RAAB version 6 methodology. Presenting and pinhole visual acuity was recorded followed by lens examination using a torchlight. In order to estimate the prevalence of blindness and visual impairment in overall population in India, district weights were assigned to each of the 31 surveyed districts and the prevalence was standardized using the RAAB software.

Results

The overall weighted, age-gender standardized, prevalence of blindness (presenting visual acuity <3/60 in better eye) in population aged ≥50 years was 1.99% (95% CI 1.94%, 2.13%) and of visual impairment (VI) (presenting visual acuity <6/12 in better eye) was 26.68% (95% CI 26.57–27.17%). On multivariate analysis, adjusted odds ratio showed that blindness was associated with age ≥ 80 years (OR = 20.3, 95% CI: 15.6–26.4) and being illiterate (OR = 5.6, 95% CI: 3.6–8.9). Blindness was not found to be significantly associated with either gender or locality.

Conclusion

The results of the survey demonstrate that currently more than one fourth of persons aged 50 years and above are visually impaired (PVA<6/12 in better eye) in India. The prevalence of blindness among them is 1.99%, and older age and illiteracy are significantly associated with blindness. Major causes of blindness included cataract (66.2%), corneal opacity (CO) (8.2%), cataract surgical complications (7.2%), posterior segment disorders (5.9%) and glaucoma (5.5%). The proportion of blindness and visual impairment that is due to avoidable causes include 92.9% and 97.4% respectively.

Survey of blindness in Saki East, Oyo State, Nigeria

Background:

Aim and Objectives:

Materials and Methods:

Results:

Conclusion:

Corneal Blindness in Asia: A Systematic Review and Meta-Analysis to Identify Challenges and Opportunities

PURPOSE

To describe the causes and prevalence of moderate-to-severe visual impairment (MSVI) and blindness from corneal diseases, as well as corneal transplantation across Asia.

METHODS

A meta-analysis of the published literature to identify population-based surveys conducted from 2008 to 2019 in 22 Asian countries regarding the prevalence and causes of MSVI and blindness from corneal disease, and a review of national corneal transplant data and eye bank statistics.

RESULTS

A total of 5307 records were screened to identify 57 reports that were used to estimate a prevalence of MSVI and blindness caused by corneal diseases in Asia of 0.38% (95% confidence interval, 0.29%-0.48%). The most frequent corneal diseases were infectious keratitis, trauma, and pseudophakic bullous keratopathy. As expected, these represented the most common indications for corneal transplantation, although the percentages in each country differed based on the level of economic development, with pseudophakic bullous keratopathy being the most common indication in countries with higher gross national income per capita. Despite this, endothelial keratoplasty is not the most commonly performed form of corneal transplantation in any Asian country and represents only a small percentage of keratoplasty procedures performed in most countries.

CONCLUSIONS

The prevalence of MSVI and blindness from corneal disease in Asia is approximately 0.4%, with a nearly 20-fold difference in the national prevalence across the region. The indications for keratoplasty, reflective of the causes of corneal dysfunction, also vary, more so according to the gross national income than to geographic location, and only a few Asian countries have rates of corneal transplantation above international means.

Prevalence of glaucoma in the Lao People's Democratic Republic: the Vientiane Eye Study

AIMS

To determine the prevalence and subtypes of glaucoma in Vientiane Province.

METHODS

We conducted a population-based study of 1264 participants aged ≥40 years of age from urban and rural areas of Vientiane Province. Data collection included Snellen visual acuity, slip lamp examination, tonometry, gonioscopy, dilated stereoscopic disc examination and perimetry. Glaucoma was categorised by clinical subtype.

RESULTS

The mean age of the 1264 participants was 57.6 years; 91.9% of eyes had a gradable disc. The prevalence of glaucoma of any category in at least one eye was 1.54% (95% CI 0.66% to 3.59%). The overall prevalence of primary open-angle glaucoma, primary angle-closure glaucoma and secondary glaucoma was 0.62% (95% CI 0.19% to 1.98%), 0.55% (95% CI 0.12% to 2.54%) and 0.37% (95% CI 0.07% to 1.86%); 12 (66.7%) of participants with glaucoma were at least unilaterally blinded by WHO definition.

CONCLUSIONS

The prevalence of glaucoma in the Vientiane Eye Study is relatively low compared with the prevalence reported in other studies from Asian regions; however, the median age in this study was low, reflecting the age group of the population and the rapid urbanisation occurring in the Lao People's Democratic Republic. Nevertheless, glaucoma remains a blinding disease in this population.

Diagnostic Accuracy of Rapid Assessment of Avoidable Blindness: A Population-based Assessment

OBJECTIVES

To evaluate the diagnostic accuracy of rapid assessment of avoidable blindness (RAAB).

DESIGN

Population-based diagnostic accuracy study.

METHODS

A total of 2145 (95.3%, 2145/2250) subjects aged 50 years and older who participated in the RAAB survey were included. All the recruited participants underwent ophthalmic examination according to the RAAB protocol and then were reexamined with instruments in a mobile eye clinic set up in a village center on the same day. Examination in the mobile clinic included standardized visual acuity (VA) tests using logMAR charts, refraction, slit-lamp biomicroscopy, and dilated fundal examination with a binocular indirect ophthalmoscope. Blindness and economic blindness were defined as VA in the better-seeing eye <3/60 and <6/60, respectively. Visual impairment (VI) was defined as VA <6/18 in the better eye. The primary cause of blindness and VI was defined according to the cause of VI in the participant's better eye.

MAIN OUTCOME MEASURES

The sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and area under the curve (AUC) of receiver operating characteristics of RAAB for detection of blindness and the principal causes of VI.

RESULTS

A total of 1816 subjects (84.7%), including 686 men (37.8%) and 1130 women (62.2%), underwent ophthalmic examination in the mobile eye clinic. The mean (±standard deviation) age was 64.4 ± 9.6 years. The sensitivities, specificities, AUC, PLR, and NLR of RAAB were 90.3%, 99.3%, 0.948, 124.0, and 0.10, respectively, for detection of blindness (presenting visual acuity, PVA <3/60); 89.5%, 98.7%, 0.940, 69.2, and 0.11, respectively, for detection of economic blindness (PVA <6/60); and 90.3%, 97.7%, 0.940, 38.7, and 0.10, respectively, for detection of VI (PVA <6/18). The sensitivities, specificities, AUC, PLR, and NLR were 90.5%, 98.1%, 0.943, 48.1, and 0.10; and 60.4%, 98.7%, 0.796, 46.4, and 0.40 for detection of VI (PVA <6/18) owing to cataract and refractive error, respectively.

CONCLUSION

The diagnostic performances of RAAB were high for detecting the prevalence of blindness, VI, and VI owing to cataract.

Capacity building for universal eye health coverage in South East Asia beyond 2020

BACKGROUND

The World Report on Vision suggests that universal eye health coverage (UEHC) can be achieved through an integrated people-centered eye care (IPCEC) delivery. This study provides an estimation of capacity building of facilities and workforce to attain UEHC through IPCEC in South East Asia (SEA) beyond 2020.

METHODS

The data sources on the magnitude of blindness and visual impairment in the SEA region included reports of the Vision Loss Expert Group, most recent population-based studies from the member states and unpublished data from the study teams. The model is based on the estimated or projected population of the member states in 2020 and 2030.

RESULTS

Data from the ten member states of the World Health Organization (WHO) SEA show that the magnitude of blindness and moderate to severe visual impairment (MSVI) has decreased between 1990 and 2015, but still higher than global average. Cataract and uncorrected refractive errors were the common causes of blindness and MSVI, respectively. The estimated WHO SEA region share of world population is likely to increase from 38.39% in 2020 to 44.32% in 2030, and so also will be the visually impaired people. By adopting the IPCEC the WHO SEA countries would require at least 429,802 community workers, 164,784 allied ophthalmic personnel and 10,744 ophthalmologists in the public facilities in 2030.

CONCLUSION

In order to attain UEHC and use the IPCEC model, each country in the region should invest substantially more in structured eye care delivery and workforce.

Association Between a Centrally Reimbursed Fee Schedule Policy and Access to Cataract Surgery in the Universal Coverage Scheme in Thailand

Importance

Uptake of cataract surgery in developing countries is much lower than that in developed countries. Cataract unawareness and financial barriers have been cited as the main causes. Under the Universal Coverage Scheme (UCS), Thailand introduced a central reimbursement (CR) system for cataract surgery. It is unknown if this financial arrangement could incentivize service provision (private or public) in areas that are hard to reach.

Objective

To examine the association between the CR policy and access to cataract surgery in Thailand.

Design, Setting, and Participants

Using time series analysis, hospitalization data during 2005 to 2015 for UCS members were analyzed for time trends and subnational variations in the cataract surgery rate (CSR) before and after the CR implementation.

Main Outcomes and Measures

The annual growth in access was estimated using segmented regression. The CSR gap across regions was determined by the slope index of inequality (SII). Unequal access across districts was represented by the gap between the top and bottom quintiles.

Results

During 2005 to 2015, a total of 0.98 million UCS members (mean [SD] age, 67.4 [11.2] years; 58.7% female) received cataract surgery. The number of cases increased from 77 897 in 2005 to 192 290 in 2015. At the national level, the CSR per 100 000 population increased from 352.0 to 378.7 cases in 2005 to 2008, to 716.3 cases in 2013, and then to 765.3 cases in 2015. With the use of mobile services through an exclusive CR, 3 private hospitals took the lead in service growth, sharing 79.2% of cases in the private sector in 2009. From 2010, the number of cases in public hospitals grew yearly by 12.6% to 13.6% until 2012, rose 21.7% in 2013, and then the rate of increase declined to that of 8.2% to 8.3% in 2014-2015. During the periods of an increase in overall access, the CSR gap across regions widened as indicated by the SII of 755.4 cases per 100 000 population in 2010 because of rapid uptake in areas with mobile services. When the national CSR became adequately large and mobile services were discouraged in 2013, the gap in 2014-2015 narrowed.

Conclusions and Relevance

This study found that the appropriate payment and service designs helped reduce the cataract surgery backlog. With an adequately high CSR, Thailand is on track to reach the VISION 2020 goal, aiming for blindness elimination by the year 2020, which has been achieved by most developed countries.

Changing trends of blindness, visual impairment and cataract surgery in Bhutan: 2009-2018

Purpose

To obtain new rapid assessment of avoidable blindness (RAAB) data on the prevalence, causes and trends of blindness, visual impairment and cataract surgery; and compare the new 2018 data with the older RAAB 2009 data.

Methodology

The second nationwide RAAB used android based mRAAB technique and technology for data collection. Using the compact segment sampling probability proportionate to size, 5,050 participants from 101 clusters of 50 people aged 50 years and older were enrolled through house-to-house visits. Eligible participants received ophthalmic examination and interview by the ophthalmologist-led emuneration team as per the RAAB protocol.

Results

The age-sex adjusted magnitude of bilateral blindness in Bhutan was 1.0% (95% Confidence Interval, CI 0.5–1.4) with relatively higher prevalence in rural population (Odds Ratio, OR 1.5, p = 0.13) and women (OR 1.6, p = 0.06). Untreated cataract accounted for the most of blindness (53.8%), severe vision impairment (57.1%), and moderate visual impairment (65.3%); uncorrected refractive error was the main cause of early visual impairment (46.7%). Cataract Surgical Coverage was 86.1% with relatively better coverage in men (76.7% men; 73.1% female) and urban population (79.2% urban; 70.2% rural). Good cataract surgical outcome was achieved in 67.3% and leading cause of poor outcome was ocular comorbidity (43.6%). Accessibility was a significant barrier to the uptake of cataract surgical services.

Conclusion

There is a 33% reduction in blindness from 1.5% to 1.0%, since the first RAAB survey in 2009. In order to further reduce blindness and visual impairment, Bhutan should continue to implement long-term strategic action plan for eye health focused on strengthening primary eye care and comprehensive eye care service.

Deep learning versus human graders for classifying diabetic retinopathy severity in a nationwide screening program

Deep learning algorithms have been used to detect diabetic retinopathy (DR) with specialist-level accuracy. This study aims to validate one such algorithm on a large-scale clinical population, and compare the algorithm performance with that of human graders. A total of 25,326 gradable retinal images of patients with diabetes from the community-based, nationwide screening program of DR in Thailand were analyzed for DR severity and referable diabetic macular edema (DME). Grades adjudicated by a panel of international retinal specialists served as the reference standard. Relative to human graders, for detecting referable DR (moderate NPDR or worse), the deep learning algorithm had significantly higher sensitivity (0.97 vs. 0.74, p < 0.001), and a slightly lower specificity (0.96 vs. 0.98, p < 0.001). Higher sensitivity of the algorithm was also observed for each of the categories of severe or worse NPDR, PDR, and DME (p < 0.001 for all comparisons). The quadratic-weighted kappa for determination of DR severity levels by the algorithm and human graders was 0.85 and 0.78 respectively (p < 0.001 for the difference). Across different severity levels of DR for determining referable disease, deep learning significantly reduced the false negative rate (by 23%) at the cost of slightly higher false positive rates (2%). Deep learning algorithms may serve as a valuable tool for DR screening.

First Rapid Assessment of Avoidable Blindness Survey in the Maldives: Prevalence and Causes of Blindness and Cataract Surgery

PURPOSE

A nationwide rapid assessment of avoidable blindness survey was undertaken in the Maldives among people aged 50 years or more to assess the prevalence and causes of blindness and visual impairment, cataract surgical coverage, cataract surgery outcome, and barriers to uptake of cataract surgical services.

DESIGN

Prospective population-based study.

METHODS

In the cluster sampling probability proportionate to size method, 3100 participants in 62 clusters across all 20 atolls were enrolled through house-to-house visits. They were examined in clusters by an ophthalmologist-led team. Data was recorded in mRAAB version 1.25 software on a smartphone.

RESULTS

The age-sex standardized prevalence of blindness was 2.0% [95% confidence interval (CI), 1.5-2.6]. Cataract was the leading cause of blindness (51.4%) and uncorrected refractive error was the leading cause of visual impairment (50.9%). Blindness was more prevalent in higher age groups and women (16.3%). Cataract surgical coverage was 86% in cataract blind eyes and 93.5% in cataract blind persons. Good visual outcome in cataract operated eyes was 67.9% (presenting) and 76.6% (best corrected visual acuity). In this study, 48.1% of people had received cataract surgery in neighboring countries. Important barriers for not using the services were "did not feel the need" (29.7%) and "treatment deferred" (33.3%).

CONCLUSIONS

Cataract surgical coverage is good, though nearly half the people received surgery outside the Maldives. Cataract surgery outcomes are below World Health Organization standards. Some barriers could be overcome with additional human resources and training to improve cataract surgical outcomes, which could encourage greater uptake of services within the country.

Blindness and Visual Impairment Profile and Rapid Assessment of Avoidable Blindness in South East Asia: Analysis of New Data. 2017 APAO Holmes Lecture

PURPOSE

The International Agency for Prevention of Blindness (IAPB) South East Asia region (SEAR) that consists of 11 countries contains 26% of the world's population (1,761,000,000). In this region 12 million are blind and 78.5 million are visually impaired. This amounts to 30% of global blindness and 32% of global visual impairment.

DESIGN

Rapid assessment of avoidable blindness (RAAB) survey analysis.

METHODS

RAAB, either a repeat or a first time survey, was completed in 8 countries in this decade (2010 onwards). These include Bangladesh, Bhutan, India, Indonesia, Maldives, Sri Lanka, Thailand, and Timor Leste.

RESULTS

Cataract is the principal cause of blindness and severe visual impairment in all countries. Refractive error is the principal cause of moderate visual impairment in 4 countries: Bangladesh, India, Maldives, and Sri Lanka; cataract continues to be the principal cause of moderate visual impairment in 4 other countries: Bhutan, Indonesia, Thailand, and Timor Leste. Outcome of cataract surgery is suboptimal in the Maldives and Timor Leste.

CONCLUSIONS

Rigorous focus is necessary to improve cataract surgery outcomes and correction of refractive error without neglecting the quality of care. At the same time allowances must be made for care of the emerging causes of visual impairment and blindness such as glaucoma and posterior segment disorders, particularly diabetic retinopathy.

Association between visual status and mental health status in Thai rural elderly: a community-based study

AIM

To evaluate the association between visual impairment (VI) and mental health or social engagement in older adults living in rural Thailand.

METHODS

Data for this cross-sectional study were drawn from a community survey conducted in 2015 in Saraburi Province, Thailand. Participants were 327 adults aged ≥50y. VI was assessed using presenting distance visual acuity. Mental health and social engagement were evaluated in face-to-face interviews using validated questionnaires. After determining the prevalence of VI and relevant sociodemographic characteristics, multivariate regression analysis was used to evaluate the impact of VI on mental health and social engagement.

RESULTS

The prevalence of VI was 18.3%. Major causes were refractive error (58.3%) and cataract (35%). Factors associated with VI in the crude analysis were: older age [odds ratio (OR) 8.08], unemployment (OR 2.72), widowhood (OR 2.47), being divorced/separated (OR 3.27), smoking (OR 2.09) and disability in activities of daily living (OR 2.35). Protective factors were undergoing eye screening at least once a year (P=0.029) and obesity (P=0.005). VI was significantly associated with low social engagement (adjusted OR 4.13) but not with poor mental health (P>0.05).

CONCLUSION

Although VI older adults reported less participation in social activities, there is no significant association between VI and poor mental health. Annual eye examinations may prevent VI in older adults. Information about employment and anti-smoking should be targeted to older adults with VI.

Global prevalence and causes of visual impairment with special reference to the general population of Saudi Arabia

Objective:

This review was undertaken to highlight the worldwide prevalence and causes of visual impairment (VI), on the basis of a wide range of recent and clearly defined data and in comparison with published articles from the Kingdom of Saudi Arabia.

Methods:

These data are mainly based on PubMed indexed journal articles. Some representative surveys from each of the six WHO regions across the globe were included in this review with special reference to Saudi Arabian studies.

Results:

Published literature show that the prevalence and causes of VI varies markedly in different parts of the world and from region to region within the same country. Cataract, uncorrected refractive errors and glaucoma were shown to be the leading causes of VI worldwide and in Saudi Arabia. Diabetic retinopathy was found to have more contribution in Saudi Arabia due the higher prevalence of diabetes mellitus in this country.

Conclusion:

Epidemiological surveys about the prevalence and causes of VI are crucial for the formulation of preventive and curative measures. Data about VI are still scarce with a need to make wider population based surveys, worldwide and in Saudi Arabia for in-depth evaluation of the problem and better strategies to reduce the burden of VI.

Rapid assessment of avoidable blindness in Papua New Guinea: a nationwide survey

Objective

To estimate the prevalence and main causes of blindness and vision impairment in people aged 50 years and older in Papua New Guinea (PNG).

Design

National cross-sectional population-based survey in National Capital District (NCD), Highlands, Coastal and Islands regions.

Methods

Adults aged 50 years and above were recruited from 100 randomly selected clusters. Each participant underwent monocular presenting and pinhole visual acuity (VA) assessment and lens examination. Those with pinhole VA<6/12 in either eye had a dilated fundus examination to determine the primary cause of reduced vision. Those with obvious lens opacity were interviewed on barriers to cataract surgery.

Results

A total of 4818 adults were examined. The age-adjusted and sex-adjusted prevalence of blindness (VA <3/60), severe vision impairment (SVI, VA <6/60 but ≥3/60), moderate vision impairment (MVI, VA <6/18 but ≥6/60) and early vision impairment (EVI, VA <6/12 but ≥6/18) was 5.6% (95% CI 4.9% to 6.3%), 2.9% (95% CI 2.5% to 3.4%), 10.9% (95% CI 9.9% to 11.9%) and 7.3% (95% CI 6.6% to 8.0%), respectively. The main cause of blindness, SVI and MVI was cataract, while uncorrected refractive error was the main cause of EVI. A significantly higher prevalence of blindness, SVI and MVI occurred in the Highlands compared with NCD. Across all regions, women had lower cataract surgical coverage and spectacle coverage than men.

Conclusions

PNG has one of the highest reported prevalence of blindness globally. Cataract and uncorrected refractive error are the main causes, suggesting a need for increased accessible services with improved resources and advocacy for enhancing eye health literacy.

Feasibility of the rapid assessment of avoidable blindness with diabetic retinopathy module (RAAB+DR) in industrialised countries: challenges and lessons learned in Hungary

PURPOSE

To present experiences gained during the planning, implementation, and practical performance of the rapid assessment of avoidable blindness with diabetic retinopathy module (RAAB+DR) in an established market economy.

METHODS

A total of 3523 people aged 50 years or older were examined at their homes in 105 randomly selected clusters in Hungary. During the 4-month-long field work, five teams visited the clusters. Each team was composed of a senior ophthalmic resident or eye specialist, a nurse, an assistant, a driver, and a local guide. The local guides were found through local mayors of the towns or villages or other local leaders.

RESULTS

Of all 105 clusters, 41% were completed in 1 day and 59% required a longer stay. The shortest daily examination time was 3.5 hours and the longest was 10 hours. Altogether, 7.6% of the enumeration areas needed revisit, mainly due to insufficient preparatory work and absence of the subjects. The best local guides were the local government workers, health visitors, and general practitioner (GP) nurses. Refusal of pupillary dilatation was relatively high and varied greatly among the study groups (7.7-43.8%).

CONCLUSION

The performance of a RAAB+DR study in a well-industrialised country is difficult, but may be successful. The most critical factor for success is an excellent local guide who is able to achieve participation of the people. The results of the RAAB are a solid basis for the development of a national programme for universal eye health and to prepare active media campaigns.

The Prevalence and Causes of Vision Loss in Indigenous and Non-Indigenous Australians: The National Eye Health Survey

PURPOSE

To conduct a nationwide survey on the prevalence and causes of vision loss in Indigenous and non-Indigenous Australians.

DESIGN

Nationwide, cross-sectional, population-based survey.

PARTICIPANTS

Indigenous Australians aged 40 years or older and non-Indigenous Australians aged 50 years and older.

METHODS

Multistage random-cluster sampling was used to select 3098 non-Indigenous Australians and 1738 Indigenous Australians from 30 sites across 5 remoteness strata (response rate of 71.5%). Sociodemographic and health data were collected using an interviewer-administered questionnaire. Trained examiners conducted standardized eye examinations, including visual acuity, perimetry, slit-lamp examination, intraocular pressure, and fundus photography. The prevalence and main causes of bilateral presenting vision loss (visual acuity <6/12 in the better eye) were determined, and risk factors were identified.

MAIN OUTCOME MEASURES

Prevalence and main causes of vision loss.

RESULTS

The overall prevalence of vision loss in Australia was 6.6% (95% confidence interval [CI], 5.4-7.8). The prevalence of vision loss was 11.2% (95% CI, 9.5-13.1) in Indigenous Australians and 6.5% (95% CI, 5.3-7.9) in non-Indigenous Australians. Vision loss was 2.8 times more prevalent in Indigenous Australians than in non-Indigenous Australians after age and gender adjustment (17.7%, 95% CI, 14.5-21.0 vs. 6.4%, 95% CI, 5.2-7.6, P < 0.001). In non-Indigenous Australians, the leading causes of vision loss were uncorrected refractive error (61.3%), cataract (13.2%), and age-related macular degeneration (10.3%). In Indigenous Australians, the leading causes of vision loss were uncorrected refractive error (60.8%), cataract (20.1%), and diabetic retinopathy (5.2%). In non-Indigenous Australians, increasing age (odds ratio [OR], 1.72 per decade) and having not had an eye examination within the past year (OR, 1.61) were risk factors for vision loss. Risk factors in Indigenous Australians included older age (OR, 1.61 per decade), remoteness (OR, 2.02), gender (OR, 0.60 for men), and diabetes in combination with never having had an eye examination (OR, 14.47).

CONCLUSIONS

Vision loss is more prevalent in Indigenous Australians than in non-Indigenous Australians, highlighting that improvements in eye healthcare in Indigenous communities are required. The leading causes of vision loss were uncorrected refractive error and cataract, which are readily treatable. Other countries with Indigenous communities may benefit from conducting similar surveys of Indigenous and non-Indigenous populations.

Rapid Assessment of Avoidable Blindness and Diabetic Retinopathy in Gilan Province, Iran

PURPOSE

To conduct an assessment of avoidable blindness and diabetic retinopathy (DR) in Gilan, 2014.

METHODS

A cross-sectional population-based survey was performed on a representative sample of urban and rural individuals aged ≥50 years of the province. Blindness was defined as presenting visual acuity (PVA) <3/60 in the better eye. Moderate visual impairment (MVI) and severe visual impairment (SVI) were defined as 6/60 ≤ PVA <6/18 and 3/60 ≤ PVA <6/60 in the better eye, respectively. Diabetes mellitus (DM) was determined based on random blood sugar (RBS) levels ≥200 mg/dL or a previous diagnosis. We used the Scottish grading system to grade DR.

RESULTS

We invited 2975 individuals from 85 clusters. Age- and sex-adjusted prevalence and 95% confidence interval (CI) of blindness, SVI, MVI, and DM in 2587 participants (response rate: 86.9%) were 1.5% (95% CI: 1.1-2.0), 1.5% (95% CI: 0.9-2.0), 11.3% (95% CI: 9.9-12.7) and 21.4% (95% CI: 19.2-23.7), respectively. The leading causes of blindness were cataract (47.1%), age-related macular degeneration (14.7%) and DR (8.8%). Cataract surgery (CS) coverage was 69.3%. The main challenges for CS were cost and unawareness. The outcome of CS was good in 66.9% of operated eyes. Any DR and/or maculopathy were observed in 25.3% (95% CI: 21.0-29.5) of subjects including 12.6% (95% CI: 9.7-15.6) sight-threatening DR. In previously known DM cases, 215 (41.7%) had never undergone an eye examination for DR.

CONCLUSION

The proportion of avoidable blindness and DR is considerable in Gilan Province.