Trachoma and poverty: unnecessary blindness further disadvantages the poorest people in the poorest countries

Trachoma is the leading cause of infectious blindness worldwide. Many populations living in poverty are affected by trachoma. The infectious organism is provided with an ideal milieu for transmission, where markers of poverty are present. These include overcrowding, lack of adequate water resources, limited use of water for personal hygiene, inadequate waste disposal and other conditions that encourage the proliferation of flies. This review summarises treatment strategies that have been effectively instituted in many countries to reduce the prevalence of trachoma. The review promotes partnerships working towards achieving the Millennium Development Goals developed by the United Nations to address issues associated with poverty. These goals are in keeping with many of the strategies to reduce the burden of potentially blinding trachoma that afflicts some of the world's poorest citizens.     

Prevalence and causes of blindness in the rural population of the Chennai Glaucoma Study

AIM: To study the prevalence and causes of blindness in a rural south Indian population. METHODS: 3924/4800 enumerated (81.75%) subjects, aged 40 years or more from rural Tamil Nadu, underwent comprehensive ophthalmic examination-visual acuity, refraction, intraocular pressure, gonioscopy, cataract grading (LOCS II), retinal examination, and SITA Standard where indicated. Blindness was defined using WHO criteria as best corrected visual acuity of less than 3/60 and/or visual field of less than 10 degrees in the better eye. The influence of age, sex, literacy, and occupation was assessed using multiple logistic regression. RESULTS: 753 subjects (19.2%; 321 males, 432 females) presented with a visual acuity of <3/60; 132 subjects (3.36%, 95% CI: 2.80 to 3.93) were diagnosed to be blind. Cataract was responsible in 74.62% of eyes; glaucoma, cystoid macular oedema, optic atrophy, and corneal scars accounted for 3.79% each. Bilateral causes of blindness were cataract (78.63%), glaucoma (4.29%), optic atrophy (3.42%), cystoid macular oedema, and corneal scars (2.56% each). In 19 eyes (7.2%) the blindness was probably related to cataract surgery. Blindness was positively associated with increasing age (p<0.0001). CONCLUSION: 3.36% of the studied rural population was bilaterally blind, with cataract being the single most important cause.     

The burden of trachoma in the rural Nile Delta of Egypt: a survey of Menofiya governorate

BACKGROUND: Evidence of widespread distribution of trachoma in Egypt had not been clarified as previous surveys were limited to individual communities which may not have been representative of the general population. The Nile Delta of Egypt presents a unique environment for trachoma to persist. Economic improvements in the past decade have affected even the poorest rural environments; availability of electricity is now found in many rural communities. Availability of water in Nile Delta has always been good but poor hygienic conditions have been the primary factor in trachoma transmission. A survey of trachoma was undertaken in Menofiya governorate to determine if Egypt should be identified as trachoma endemic and targeted for trachoma control efforts. METHODS: A multistage random cluster study design was used with the target population defined as adults aged 50 and over and children aged 2-6 years from throughout the governorate. Among preschool children only trachoma was graded while among adults presenting visual acuity and cause of vision loss or blindness were also recorded. Adults were interviewed regarding past trichiasis surgery; those currently with trichiasis or a history of trichiasis surgery were also interviewed regarding outcome of surgery. RESULTS: A total of 3272 children aged 2-6 and 3322 adults age 50+ were enumerated. Among the children 81.3% were examined and among the adults 73.0% were examined. Active trachoma (follicles (TF) and/or intense inflammation (TI)) was found among 36.5% (95% confidence interval (CI) 34.7-38.3%) of the children. TI was 1.89 (95% CI 1.22-2.94) times more common in rural children compared to urban children. The prevalence of trichiasis (TT) in adults was 6.5%; women had an age adjusted odds of trichiasis of 1.68 (95% CI 1.18-2.39) compared to men. Trichiasis was 2.11 times (95% CI 1.33-3.37) more common in rural Menofiya compared to urban Menofiya. TT accounts for blindness (presenting vision <3/60) in 8% of patients and accounts for 13.2% of visual impairment. Overall, trichiasis surgical coverage was 34.4%, slightly higher among men than women. The outcome of trichiasis surgery was poor in 44.4% of cases. CONCLUSION: Trachoma is a serious public health problem in Menofiya governorate and a significant contributor to vision loss. These findings would suggest that continued poor hygienic conditions in rural Egypt have limited the reduction of active trachoma even in the face of significant improvements in socioeconomic status. Furthermore, the high proportion of trichiasis surgery cases with a poor outcome would indicate a need to reassess current surgical practices in Egypt and improve training and monitoring.     

Prevalence of blindness and low vision in a rural population in northern china: preliminary results from a population-based survey

Purpose: To investigate the prevalence of visual impairment in a rural northern Chinese population. Methods: A cross-sectional, population-based survey was conducted in 2010 in Ci County, Hebei Province in northern China. Residents aged 7 years and older in Lucunying Town, located within Ci County, underwent presenting visual acuity (VA) testing at home; those with presenting VA <20/60 were invited to participate in further examination at the local hospital. Population-weighted prevalences of blindness and low vision were determined according to World Health Organization definitions. Results: Among the 24,539 residents aged older than 7 years, 20,298 (82.7%) participated in the study, and 20,072 (98.9%) of these had valid VA data. The population-weighted prevalence rates of presenting bilateral blindness and bilateral low vision were 0.3% and 2.4% for the entire population, 0% and 0.5% for residents 7-39 years of age, and 0.8% and 6.4% for residents 40 years and older, respectively. Based on best-corrected VA, the corresponding prevalence rates of bilateral blindness and bilateral low vision were 0.2% and 1.4% for the entire population, 0% and 0.1% for residents 7-39 years, and 0.6% and 4.0% for residents 40 years and older, respectively. Prevalence rates of blindness and low vision were generally higher among women than men. Blindness and low vision increased with age among residents 40 years and older. Conclusion: Our findings highlight the need for eye healthcare services for visual impairment in rural China.     

Corneal blindness in a southern Indian population: need for health promotion strategies

AIM: To assess the distribution and causes of corneal blindness in a population in southern India. METHODS: A total of 11 786 people of all ages from 94 clusters representative of the population of the Indian state of Andhra Pradesh were sampled using a stratified, random, cluster, systematic sampling strategy. These participants underwent a detailed interview and eye examination including measurement of visual acuity with logMAR charts, refraction, slit lamp biomicroscopy, applanation tonometry, gonioscopy, and stereoscopic dilated fundus evaluation. An eye was considered to have corneal blindness if the visual acuity was <20/200 due to a corneal disease. RESULTS: Of those sampled, 10 293 (87.3%) people participated in the study. Corneal blindness in at least one eye was present in 86 participants, an age, sex, and urban-rural distribution adjusted prevalence of 0.66% (95% confidence interval 0.49 to 0.86), which included 0.10% prevalence of corneal blindness in both eyes and 0.56% in one eye. The most frequent causes of corneal blindness in at least one eye included keratitis during childhood (36.7%), trauma (28.6%), and keratitis during adulthood (17.7%). Nearly 95% of all corneal blindness was avoidable. Multivariate analysis showed that the prevalence of corneal blindness was significantly higher with decreasing socioeconomic status and with increasing age. Of the 99 eyes with corneal blindness, 51 (51.5%) had visual acuity of inaccurate projection of light or no perception of light. CONCLUSIONS: There is a significant burden of corneal blindness in this population, the majority of which is avoidable. Eye health promotion strategies are warranted to raise awareness about the causes and prevention of corneal blindness.     

Visual impairment and blindness in rural central India: the Central India Eye and Medical Study

Purpose: The aim of the study was to investigate prevalence of visual impairment in rural central India. Methods: The population‐based Central India Eye and Medical Study included 4711 subjects with an age of 30+ years. Presenting visual acuity (PRVA) and best‐corrected visual acuity (BCVA) were recorded. Visual impairment and blindness were defined using the World Health Organization (WHO) standard and United States (US) standard. Results: On the basis of PRVA and using WHO and US standards, 1049 [22%; 95% confidence interval (CI): 21.1, 23.5] subjects and 1290 (27%; 95% CI: 26.1, 28.7) subjects, respectively, were visually impaired, and 35 (0.7%; 95% CI: 0.5, 1.0) subjects and 116 (2.5%; 95% CI: 2.0, 2.9) subjects, respectively, were blind. The corresponding age‐standardized prevalence figures were 17%, 21%, 0.5% and 2%, respectively. Using best‐correcting glasses could eliminate PRVA‐visual impairment/blindness in 729 subjects (67% of all subjects with visual impairment/blindness). On the basis of BCVA and using WHO and US standards, 333 (7%; 95% CI: 6.3, 7.8) subjects and 473 (10%; 95% CI: 9.2, 10.9) subjects, respectively, had visual impairment, and 22 (0.5%; 95% CI: 0.3, 0.7) and 31 (0.7%; 95% CI: 0.4, 0.9) subjects, respectively, were blind. Corresponding age‐standardized prevalence figures were 5%, 8%, 0.4% and 0.5%, respectively. Causes for BCVA‐visual impairment/blindness were cataract (75%), postoperative posterior capsular opacification (4%), surgical complications (2%), corneal opacifications (2%), age‐related macular degeneration (2%), other macular diseases (1%), and glaucoma (1%). Conclusions: Age‐standardized prevalence of PRVA‐visual impairment/blindness (WHO definition) in the adult population of rural central India was 17%. Most frequent cause was undercorrected refractive error. Supply of correct glasses is the most efficient way to improve vision in the rural central India.     

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

Background: The prevalence of blind individuals in the north of China is unknown. The study aimed to investigate the prevalence and causes of blindness and low vision in rural areas in Heilongjiang province of China in 2008–2009. Design: Cross‐sectional study. Participants or Samples: A cluster random sampling method was used to recruit participants of all ages in rural areas of Heilongjiang. Methods: Trained professionals performed interviews and clinical examinations to measure visual acuity. The relationships between blindness or low vision and age, gender and education level were analysed. Main Outcome Measures: The main outcome measure was prevalence rates of bilateral blindness and bilateral low vision. Results: Of the 11 787 subjects, 10 384 (88.1%) were surveyed. The overall age‐adjusted prevalence rates were 0.7% (95% confidence interval: 0.5–0.8%) for bilateral blindness and 1.7% (95% confidence interval: 1.4–1.9%) for bilateral low vision. The prevalence rates of blindness and low vision were higher in the elderly and uneducated population (P < 0.05). The main causes for blindness and low vision were cataracts (44.1 and 46.0%, respectively) and refractive errors (17.7 and 42.5%, respectively). Conclusion: Blindness and low vision are highly prevalent among people with cataracts and refractive errors. Eye care planning must focus on treating the avoidable and curable forms of blindness.     

Population screening for glaucoma in UK: current recommendations and future directions

Effective population screening for glaucoma would enable earlier diagnosis and prevention of irreversible vision loss. The UK National Screening Committee (NSC) recently published a review that examined the viability, effectiveness and appropriateness of a population-based screening programme for primary open-angle glaucoma (POAG). In our article, we summarise the results of the review and discuss some future directions that may enable effective population screening for glaucoma in the future. Two key questions were addressed by the UK NSC review; is there a valid, accurate screening test for POAG, and does evidence exist that screening reduces morbidity from POAG compared with standard care. Six new studies were identified since the previous 2015 review. The review concluded that screening for glaucoma in adults is not recommended because there is no clear evidence for a sufficiently accurate screening test or for better outcomes with screening compared to current care. The next UK NSC review is due to be conducted in 2023. One challenge for POAG screening is that the relatively low disease prevalence results in too many false-positive referrals, even with an accurate test. In the future, targeted screening of a population subset with a higher prevalence of glaucoma may be effective. Recent developments in POAG polygenic risk prediction and deep learning image analysis offer potential avenues to identifying glaucoma-enriched sub-populations. Until such time, opportunistic case finding through General Ophthalmic Services remains the primary route for identification of glaucoma in the UK and greater public awareness of the service would be of benefit.Subject terms: Optic nerve diseases, Predictive markers     

3.8 million blinded by cataract each year: projections from the first epidemiological study of incidence of cataract blindness in India.

Data from a population based longitudinal study of randomly selected communities in Central India have for the first time provided direct estimates of age specific incidence of blindness from cataract. Person-time denominators have been used to compute age specific incidence rates (risk) of blindness from cataract for populations aged 35 and older. These age specific incidence measures have been applied to the 'population at risk' in each 5-year age class in order to estimate the total number of new cases of cataract blindness that occur in the country each year. The findings indicate that an estimated 3.8 million persons become blind from cataract each year in India (approximate 95% confidence limits: 3 to 4.5 million). The reasons why the estimates are considered as minima, and their implications concerning future national planning of ophthalmic services, are briefly discussed.