Prevalence of blindness and low vision: a study in the rural Heilongjiang Province of China

What do eye care workers do when their patients go blind?

Sometimes even with the best efforts by the eye care worker (ECW), patients cannot be stopped from losing vision even in the best of centers anywhere in the world. However, in developing countries, most vision loss happens in rural and suburban areas away from where ECWs are majorly located due to poor facilities, adverse living conditions, and poverty. Once irreversible blindness happens, rehabilitation should follow. However, the numbers of those who are not referred for rehabilitation by far outstrips those who are, for various reasons. To find out why this is so, 150 ECWs with 1:2 M:F ratio were contacted through Google links sent through WhatsApp groups. Glaucoma was statistically the commonest cause of irreversible blindness (χ2 = 66.17, p-value < .0001) mostly from late presentation ( n = 146 of 150 responses, 97.7%). When patients go blind, most ( n = 132, 87.4%) of the ECW advise them to go to a blind school (81.2%). Only about a quarter of the respondents properly ensure that they go. A third admitted ( n = 78, 39%) that knowing the patients personally improved their willingness to refer. Many do not think the government is doing enough to help the blind ( n = 118, 78.7%). Even though many ECWs have given sensitization talks on blindness (124 of 164 responses), very few focus on what happens after blindness occurs (42.4% of respondents). A third of the ECW admitted to not doing enough for the blind in their practice ( n = 51, 34%). Majority have, however, heard about The Lens Eye Clinic (TLEC) rehab center, one of the foremost rehabilitation centers for the blind in Nigeria ( n = 103, 68.7%). ECW should ensure those who live in rural areas have poor socioeconomic background, less educated, female, elderly, or born blind should have regular screening and awareness programs in the areas of practice to catch the condition on time with provision made for early counseling and support services.

Prevalence, causes, and impact of self-reported vision impairment among older people in China: Findings from the China health and retirement longitudinal study

This article investigated the prevalence, causes, and impact of self-reported vision impairment among older people in China. A total of 12,910 participants aged ⩾50 years were included in this study from China Health and Retirement Longitudinal Study (CHARLS) over the periods of 2011, 2013, and 2015. All data were reported by participants via a self-reported questionnaire. Distance vision was assessed by asking if they could see the face of a person on the other side of the street. Near vision was assessed by asking if they could read ordinary newspaper. Depressive symptoms were evaluated by 10-item Center for Epidemiological Studies Depression Scale. The analysis method included the χ2 – square distribution test and multiple regression analysis. This article first found that prevalence of self-reported vision impairment was much higher in rural than in urban areas; in urban areas, females had a greater chance of being affected than males, and for both sexes, it increases with increasing age. Second, some factors found are significantly associated with increased vision impairment rates, include increasing age, female gender, rural residents, elementary-level education, unmarried individuals, and non-agricultural occupations. Third, the leading cause of vision impairment was a refractive error and the most common causes of vision impairment include cataracts and glaucoma. Fourth, vision impairment was significantly associated with falls and depressive symptoms and has a negative effect on the quality of life of older Chinese. The article concluded that older people with self-reported vision impairment were relatively low and it is majorly caused by refractive error. Older people with distance vision impairment and near vision impairment were more likely to report falls and depressive symptoms in the future. In line with these findings, a couple of policy recommendations for further research were made.

Prevalence of Pediatric Cataract in Asia: A Systematic Review and Meta-Analysis

Purpose

To conduct a systematic review and meta-analysis for estimating the prevalence of pediatric cataracts across Asia.

Methods

A detailed literature search of PubMed, Embase, Web of Science, Cochrane Library, and Google Scholar databases, from 1990 to July 2021, was performed to include all studies reporting the prevalence of cataracts among children. Two researchers performed the literature search and screening of articles independently, and a third researcher critically reviewed the overall search and screening process to ensure the consistency. The JBI Critical Appraisal Checklist for studies reporting prevalence data was used to assess the methodological quality of the included studies.

Results

Of the 496 identified articles, 35 studies with a sample size of 1,168,814 from 12 Asian countries were included in this analysis. The estimated pooled prevalence of pediatric cataracts in Asian children is 3.78 (95% confidence interval: 2.54-5.26)/10,000 individuals with high heterogeneity (I[2] = 89.5%). The pooled prevalence by each country per 10,000 was 0.60 in Indonesia, 0.92 in Bangladesh, 1.47 in Iran, 2.01 in Bhutan, 3.45 in Laos, 3.68 in China, 4.27 in Thailand, 4.47 in India, 5.33 in Malaysia, 5.42 in Nepal, 9.34 in Vietnam, and 10.86 in Cambodia.

Conclusions

This study utilizes existing literature to identify the prevalence of cataracts in Asian children. Moreover, it highlights the need for more epidemiological studies with large sample sizes from other countries in Asia to accurately estimate the burden of disease.

Short-wavelength blue light contributes to the pyroptosis of human lens epithelial cells (hLECs)

PURPOSE

The purpose of this study is to examine the effect of short-wavelength blue light (SWBL) on cultured human lens epithelial cells (hLECs). The pathogenesis of cataracts after SWBL exposure is discussed.

METHODS

HLE-B3 hLECs were randomly divided into 3 groups: the NC group, which was grown in a dark incubator; the acetyl (Ac)-Tyr-Val-Ala-Asp-chloromethyl ketone (AC-YVAD-CMK) treatment group; and the SWBL exposure group. After SWBL (2500 lux) irradiation (for 8, 16, 24, and 32 h), caspase-1 and gasdermin D (GSDMD) expression levels in HLE-B3 hLECs were examined using ELISA, immunofluorescence staining, and Western blotting analyses. Double-positive staining of hLECs for activated and inhibited caspase-1 was used to determine pyroptosis in HLE-B3 hLECs.

RESULTS

SWBL led to hLEC death, but a caspase-1 inhibitor suppressed cell death. The flow cytometry results also confirmed the dose-dependent effect of SWBL irradiation on the pyroptotic death of hLECs. Caspase-1 and GSDMD expression levels in all hLEC groups changed with blue light exposure times (8, 16, 24, and 32 h) and were higher in the AC-YVAD-CMK and SWBL exposure groups than in the NC group. The immunofluorescence results revealed higher GSDMD-N expression in the cell membrane of both the AC-YVAD-CMK and SWBL exposure groups than in the NC group.

CONCLUSIONS

Based on the data, SWBL induces pyroptotic programmed cell death by activating the GSDMD signalling axis in HLE-B3 hLECs. These results provide new insights into the exploitation of new candidates for the prevention of cataracts.

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 visual impairment among older Chinese population: A systematic review and meta-analysis

Background

To evaluate the prevalence of visual impairment (VI) among elderly Chinese population.

Methods

All population-based studies on VI prevalence among elderly Chinese populations were searched and only studies with clear definitions of diagnosis were selected. Meta-analysis methods were used to estimate the pooled prevalence and its 95% confidence interval (95%CI) of moderate and severe visual impairment (MSVI) and blindness both by presenting visual acuity (PVA) and best corrected visual acuity (BCVA). Subgroup analysis of gender, district, geographical location, age, education level and examined year were also conducted.

Results

72 studies with 465 039 individuals were included and analyzed. Using PVA, the pooled prevalence of MSVI is 10.9% (95% CI = 9.4%-12.6%) and blindness is 2.2% (95% CI = 1.8%-2.8%), while prevalence of MSVI and blindness by BCVA was 5.4% (95% CI = 4.6%-6.2%) and 2.2% (95% CI = 1.9%-2.5%), respectively. Females, rural residents, older age and lower educational level were risk factors for MSVI and blindness.

Conclusions

VI causes a great health burden among Chinese populations, particularly affecting female subjects, subjects dwelling in rural area, older subjects and subjects with lower educational level.

Prevalence and causes of bilateral visual impairment in rural areas of Tianjin, China - The Tianjin Eye Study

PURPOSE

To estimate the prevalence, causes and risk factors of bilateral visual impairment in rural areas of Tianjin, China.

METHODS

A large population-based, cross-sectional study. A stratified random cluster sampling method was used to investigate 12 233 participants in all age groups living in rural Tianjin. Participants completed questionnaires and received professional ophthalmology examinations.

RESULTS

According to World Health Organization best-corrected visual acuity (BCVA) criteria, the crude prevalence of bilateral visual impairment (BCVA < 20/63), bilateral low vision (BCVA < 20/63 to ≥20/400) and bilateral blindness (BCVA < 20/400) was 2.53%, 2.40% and 0.14% (age- and gender-standardized prevalence was 1.86%, 1.76% and 0.11%). The prevalence increased with age and was higher in women than men. The most common causes of bilateral visual impairment in the total population were cataract (48.39%), refractive error/amblyopia (17.74%), age-related macular degeneration (AMD) (10.00%), diabetic retinopathy (5.81%) and glaucoma (3.87%). For participants younger than 50 years, refractive error/amblyopia was the leading cause of low vision and blindness, while cataract was the major cause in the participants over 50. Female gender, older age and self-reported diabetes were associated with increased risks of visual impairment.

CONCLUSION

The age- and gender-standardized prevalence of low vision, especially in the older group (50+), was higher in this study compared with previous studies in China. Refractive error/amblyopia was the leading cause of bilateral visual impairment in younger group, while cataract was the primary cause in the older group. These findings will provide useful information for planning comprehensive eye healthcare programmes in China.

Retinal vascular abnormalities and their associations with cardiovascular and cerebrovascular diseases: a Study in rural southwestern Harbin, China

Background

Limited data is available on retinal vessel morphology in the north China. The study aimed to evaluate the prevalence of retinal vascular abnormalities (RVAs) and investigate their associations with the self-reported diagnosis of cardiovascular and cerebrovascsular diseases (CCVds) in a rural adult population of northeast China.

Methods

A population-based, cross-sectional study was conducted, using the cluster random sampling method. One eye of each participant was photographed with a non-mydriatic fundus camera. RVAs including focal and general arteriolar narrowing (FAN and GAN), arteriovenous nicking (AVN), arteriolar sheathing (AS), and retinopathy were evaluated. Data on self-reported diagnosis of cardiovascular and cerebrovascular diseases and status of smoking and alcohol drinking were obtained from questionnaires.

Results

Among the 6267 participants with an age ≥ 50 years, photographs were obtained of 99.2%, with quality sufficient to perform retinal evaluations in 82.5%. The prevalence of FAN, AVN, AS, retinopathy and GAN were 9.1, 8.9, 5.0, 6.6 and 6.2%, respectively. All the retinal lesions were associated with hypertension (all P < 0.01). After adjusting for age, gender, and left/right eyes, hypertension, hyperlipidaemia, diabetes mellitus, habits of past or current smoking and alcohol consumption, AVN was strongly associated with the self-reported diagnosis histories of coronary heart diseases(CHD) (OR, 1.44; 95% CI, 1.09, 1.89) and retinopathy was significantly associated with a self-reported diagnosis of stroke (OR, 2.05; 95% CI, 1.18, 3.57).

Conclusions

The overall prevalence of retinal microvascular abnormalities in this population was relatively higher than that reported in other regions of the world. Retinopathy is associated with the self-reported diagnosis of stroke while AVN was associated with the self-reported diagnosis of CHD, but the remaining retinal lesions were not consistently associated with CCVds. Thus, an examination of retinal microvascular characteristics may offer clues to CCVds and could be a potentially novel biomarkers for CCVds risk.

Visual acuity of young men in China: Results from 3 national cross-sectional surveys from 1974 to 2012

The prevalence of low vision has increased in China especially among youth population, which is an important public health issue. The trend on the prevalence of subnormal visual acuity and updated information is essential to quantify health effects and to prompt decision makers to prioritize action and assess the effectiveness of measures. Therefore, the study aimed to analyze the prevalence and geographical distribution of visual acuity level among young men in China based on 3 national cross-sectional surveys from 1974 to 2012.The data on visual acuity of young men were collected from 3 national surveys among military recruit youth conducted in 1974, 2001, and 2012 by using a stratified cluster sampling method in China. The prevalence of visual acuity among military recruit youth during this period was analyzed by region, year, age, and economic level.A total of 139,929, 72,894, and 58,106 young men were included, covering all 31 provinces of mainland of China, from the 3 national surveys respectively. The prevalence of subnormal visual acuity had geographic diversity and increased significantly from 1974 to 2012 (P < .05). The visual acuity level was negatively correlated with the age (17-23 years) in 2012 (P < .05). Furthermore, the prevalence of subnormal visual acuity was positively correlated with the gross domestic product in 31 provinces of China (P ≤ .001).The prevalence of subnormal visual acuity increased with economic development among young men from 1974 to 2012, with distinct variation among geographic areas in China. Furthermore, subnormal visual acuity was increasingly prevalent with age and warrant public health attention.

Prevalence of Vision Impairment in Older Adults in Rural China in 2014 and Comparisons With the 2006 China Nine-Province Survey

PURPOSE

To estimate the prevalence of vision impairment and blindness in 2014 among older adults in rural China with comparisons with the 2006 Nine-Province Survey.

DESIGN

Population-based, cross-sectional study.

METHODS

Geographical cluster sampling was used in randomly selecting residents from a rural county or semi-rural district within 9 provinces: Beijing, Jiangsu, Guangdong, Heilongjiang, Jiangxi, Hebei, Ningxia, Chongqing, and Yunnan. Persons 50 years of age or older were enumerated through household visits and invited to examination sites for visual acuity testing and examination. Vision impairment and blindness in 2014 was compared with data from the 2006 survey.

RESULTS

Among 51 310 examined persons, the prevalence of presenting vision impairment (<20/63 to ≥20/400) in the better-seeing eye ranged from 6.05% to 15.3% across the 9 study sites, with presenting blindness (<20/400) ranging from 0.66% to 5.35%. With best-corrected visual acuity, the prevalence of vision impairment ranged from 1.96% to 8.74%, and blindness from 0.47% to 5.01%. Vision impairment was associated with older age, female sex, and little or no education. The overall prevalence of presenting vision impairment and blindness decreased during the 2006-2014 interval by 6.31% and 29.0%, respectively; and by 16.1% and 38.0%, respectively, after standardization of 2006 prevalence rates to the 2014 population.

CONCLUSIONS

Substantial progress has been made in the reduction of vision impairment in rural China. Nevertheless, vision impairment remains an important public health problem with substantial geographic disparities and with older age, female sex, and illiteracy as risk factors.

Population-based survey of prevalence, causes, and risk factors for blindness and visual impairment in an aging Chinese metropolitan population

AIM

To assess the prevalence, causes, and risk factors for blindness and visual impairment among elderly (≥60 years of age) Chinese people in a metropolitan area of Shanghai, China.

METHODS

Random cluster sampling was conducted to identify participants among residents ≥60 years of age living in the Xietu Block, Xuhui District, Shanghai, China. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were checked by the Early Treatment Diabetic Retinopathy Study (ETDRS) visual chart. All eligible participants underwent a comprehensive eye examination. Blindness and visual impairment were defined according to World Health Organization (WHO) criteria.

RESULTS

A total of 4190 persons (1688 men and 2502 women) participated in the study, and the response rate was 91.1%. Based on PVA, the prevalence of blindness was 1.1% and that of visual impairment was 7.6%. Based on BCVA, the prevalence of blindness and visual impairment decreased to 0.9% and 3.9%, respectively. Older (≥80 years of age) women, with low educational levels and smoking habits, exhibited a significantly greater chance for blindness and visual impairment than did those with high educational levels and no smoking habits (P<0.05). Based on PVA and BCVA, the main causes of blindness were cataract, myopic maculopathy, and age-related macular degeneration (AMD).

CONCLUSION

Our findings help to identify the population in need of intervention, to highlight the need for additional eye healthcare services in urban China.

Prevalence and causes of low vision and blindness in Baotou: A cross-sectional study

The aim of this study was to investigate the prevalence and causes of low vision and blindness in Baotou, Inner Mongolia.A cross-sectional study was carried out. Multistage sampling was used to select samples. The visual acuity was estimated using LogMAR and corrected by pinhole as best-corrected visual acuity.There were 7000 samples selected and 5770 subjects included in this investigation. The overall bilateral prevalence rates of low vision and blindness were 3.66% (95% CI: 3.17-4.14) and 0.99% (95% CI: 0.73-1.24), respectively. The prevalence of bilateral low vision, blindness, and visual impairment increased with age and decreased with education level. The main leading cause of low vision and blindness was cataract. Diabetic retinopathy and age-related macular degeneration were found to be the second leading causes of blindness in Baotou.The low vision and blindness were more prevalent in elderly people and subjects with low education level in Baotou. Cataract was the main cause for visual impairment and more attention should be paid to fundus diseases. In order to prevent blindness, much more eye care programs should be established.

Prevalence and Causes of Visual Impairment in a Chinese Adult Population: The Taizhou Eye Study

PURPOSE

To study the current prevalence and causes of low vision and blindness in an adult Chinese population.

DESIGN

Population-based, cross-sectional study.

PARTICIPANTS

We used a random cluster sampling method and evaluated 10 234 eligible subjects ≥45 years old (response rate, 78.1%) in the Taizhou Eye Study.

METHODS

Examinations were performed from July 2012 through December 2013. Participants underwent a detailed examination, including uncorrected visual acuity, best-corrected visual acuity (BCVA), intraocular pressure, axial length, slit-lamp, and fundus examinations to evaluate the prevalence and primary causes of visual impairment (VI).

MAIN OUTCOME MEASURES

We defined low vision and blindness according to the World Health Organization (WHO) criteria (low vision: BCVA, <20/63-≥20/400; blindness: BCVA, <20/400 in the better eye) and United States criteria (low vision: BCVA, <20/40-≥20/200; blindness: BCVA, <20/200 in the better eye).

RESULTS

Using the WHO BCVA criteria, the standardized prevalence of bilateral low vision and blindness were 5.1% and 1.0%, respectively. Using the United States BCVA criteria, the standardized prevalence were 12.8% and 1.5%, respectively. Using the WHO criteria, the primary causes of bilateral low vision and blindness were cataract (59.1% and 48.5%, respectively), myopic macular degeneration (17.6% and 17.2%, respectively), and age-related macular degeneration (11.6% and 10.1%, respectively). The primary causes of monocular low vision were cataract (55.6%), age-related macular degeneration (12.6%), and myopic macular degeneration (8.9%), whereas those of monocular blindness were cataract (46.8%), atrophy of eyeball or prosthetic eye (10.2%), and cornea opacity (7.3%). A further analysis revealed that in adults 45-59 years old, myopic macular degeneration (59.6% and 27.2%, respectively) and cataract (13.8% and 23.4%, respectively) were the leading causes of bilateral and monocular VI. In adults ≥60 years old, cataract (66.8% and 61.2%, respectively) and age-related macular degeneration (12.6% and 11.8%, respectively) were the primary causes of bilateral and monocular VI.

CONCLUSIONS

The prevalence of low vision and blindness in Chinese adults remains a severe public health problem. In the Taizhou Eye Study, cataract was the leading cause of low vision and blindness. Myopic macular degeneration and cataract were the primary causes of VI in adults 45-59 years and ≥60 years old, respectively.

Prevalence of and risk factors for pterygia in a rural Northern Chinese population

PURPOSE

To determine the prevalence of and associated risk factors for pterygia development in a high-latitude-dwelling Northern Chinese population.

METHODS

A prospective population-based survey was conducted between November 2008 and July 2009. A stratified, clustered, randomized sampling procedure was used to select 8445 subjects, aged ≥18 years, all with diagnosed, graded pterygia. Risk factors associated with the occurrence of pterygia were evaluated according to logistic regression models.

RESULTS

A total of 8445 residents (aged 18-94 years) from the Heilongjiang Province, China, participated in the study. Of these, 208 (2.5%) had at least one diagnosed pterygium. The prevalence of bilateral pterygia was 1.2% (95% confidence interval, CI, 1.0-1.4%). According to multivariable analysis, pterygia were significantly more likely to occur in persons aged 70-94 years than in those aged 18-39 years (odds ratio, OR, 29.0, 95% CI 13.6-61.6, p < 0.01). Pterygia were significantly associated with male sex (OR 1.9, 95% CI 1.4-2.6, p < 0.01) and outdoor work (OR 1.8, 95% CI 1.2-2.6, p < 0.01). Multivariable analysis indicated that pterygia were not associated with smoking status (OR 1.0, 95% CI 0.8-1.4) or alcohol intake (OR 1.0, 95% CI 0.7-1.4, p > 0.05).

CONCLUSIONS

This study details the occurrence of and risk factors for pterygia in a Chinese population residing in a rural, high-latitude, cold-climate area of Northern China. The primary risk factors for pterygia were age, male sex, and outdoor work.

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

BACKGROUND

The prevalence of refractive error in the north of China is unknown. The study aimed to estimate the prevalence and associated factors of refractive error in school-aged children in a rural area of northern China.

DESIGN

Cross-sectional study.

PARTICIPANTS OR SAMPLES

The cluster random sampling method was used to select the sample.

METHODS

A total of 1700 subjects of 5 to 18 years of age were examined. All participants underwent ophthalmic evaluation. Refraction was performed under cycloplegia. Association of refractive errors with age, sex, and education was analysed.

MAIN OUTCOME MEASURES

The main outcome measure was prevalence rates of refractive error among school-aged children.

RESULTS

Of the 1700 responders, 1675 were eligible. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye was 6.3%, 3.0% and 1.2%, respectively. The prevalence of myopia was 5.0% (84/1675, 95% CI, 4.8%-5.4%) and of hyperopia was 1.6% (27/1675, 95% CI, 1.0%-2.2%). Astigmatism was evident in 2.0% of the subjects. Myopia increased with increasing age, whereas hyperopia and astigmatism were associated with younger age. Myopia, hyperopia and astigmatism were more common in females. We also found that prevalence of refractive error were associated with education. Myopia and astigmatism were more common in those with higher degrees of education.

CONCLUSION

This report has provided details of the refractive status in a rural school-aged population. Although the prevalence of refractive errors is lower in the population, the unmet need for spectacle correction remains a significant challenge for refractive eye-care services.