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1.  Prevalence of Cataract in an Older Population in India 
Ophthalmology  2011;118(2-19):272-278.e2.
To describe the prevalence of cataract in older people in 2 areas of north and south India.
Population-based, cross-sectional study.
Randomly sampled villages were enumerated to identify people aged ≥60 years. Of 7518 enumerated people, 78% participated in a hospital-based ophthalmic examination.
The examination included visual acuity measurement, dilatation, and anterior and posterior segment examination. Digital images of the lens were taken and graded by type and severity of opacity using the Lens Opacity Classification System III (LOCS III).
Main Outcome Measures
Age- and gender-standardized prevalence of cataract and 95% confidence intervals (CIs). We defined type of cataract based on the LOCS III grade in the worse eye of: ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any unoperated cataract was based on these criteria or ungradable dense opacities. Any cataract was defined as any unoperated or operated cataract.
The prevalence of unoperated cataract in people aged ≥60 was 58% in north India (95% CI, 56–60) and 53% (95% CI, 51–55) in south India (P = 0.01). Nuclear cataract was the most common type: 48% (95% CI, 46–50) in north India and 38% (95% CI, 37–40) in south India (P<0.0001); corresponding figures for PSC were 21% (95% CI, 20–23) and 17% (95% CI, 16–19; P = 0.003), respectively, and for cortical cataract 7.6% (95% CI, 7–9) and 10.2% (95% CI, 9–11; P<0.004). Bilateral aphakia/pseudophakia was slightly higher in the south (15.5%) than in the north (13.2%; P<0.03). The prevalence of any cataracts was similar in north (73.8%) and south India (71.8%). The prevalence of unoperated cataract increased with age and was higher in women than men (odds ratio [OR], 1.8). Aphakia/pseudophakia was also more common in women, either unilateral (OR, 1.2; P<0.02) or bilateral (OR, 1.3; P<0.002).
We found high rates of unoperated cataract in older people in north and south India. Posterior subcapsular cataract was more common than in western studies. Women had higher rates of cataract, which was not explained by differential access to surgery.
Financial Disclosure(s)
The authors have no proprietary or commercial interest in any of the materials discussed in this article.
PMCID: PMC3146699  PMID: 20801514
2.  Risk factors for nuclear, cortical and posterior subcapsular cataracts in the Chinese population of Singapore: the Tanjong Pagar Survey 
The British Journal of Ophthalmology  2003;87(9):1112-1120.
Aim: To describe risk factors for nuclear, cortical, and posterior subcapsular (PSC) cataracts in Chinese Singaporeans.
Methods: A population based cross sectional study was carried out on ethnic Chinese men and women aged 40–81 years. A stratified, clustered, disproportionate (more weights to older people), random sampling procedure was used to initially select 2000 Chinese names of those aged 40–79 years from the 1996 electoral register in the Tanjong Pagar district in Singapore. Eligible subjects (n = 1717) were invited for a standardised ocular examination and interview at a centralised clinic, following which an abbreviated examination was conducted for non-respondents in their homes. Cataract was graded clinically using to the Lens Opacity Classification System (LOCS) III system. The main outcome measures were adjusted odds ratio for risk factors for specific cataract types (nuclear, cortical and PSC), any cataract and cataract surgery, examined in multiple logistic regression models.
Results: Out of the 1232 (71.8%) examined, 1206 (70.2%) provided lens data for this analysis. Increasing age was associated with all cataract types, any cataract, and cataract surgery. There was no significant sex difference in presence of any cataract, specific cataract types or cataract surgery. After controlling for age, sex, and other factors, diabetes was associated with cortical cataract (3.1; 95% CI: 1.6 to 6.1), PSC cataract (2.2; 95% CI 1.2 to 4.1), any cataract (2.0; 95% CI: 0.9 to 4.5), and cataract surgery (2.3; 95% CI: 1.3 to 4.1). Lower body mass index was associated with cortical cataract (1.8; 95% CI: 1.1 to 2.9; lowest versus highest quintile) and any cataract (2.3; 95% CI: 1.3 to 4.0). Current cigarette smoking was associated with nuclear cataract (1.7, 95% CI: 1.0 to 2.9; more than 10 cigarettes per day versus none). A non-professional occupation was associated with nuclear cataract (2.9; 95% CI: 1.5 to 5.8; for production or machine operators and 2.6; 95% CI: 1.2 to 5.5; for labourers or agricultural workers, both versus professionals). Lower education was associated with nuclear cataract (2.3; 95% CI: 1.0 to 5.2, none versus tertiary), while lower household income was associated with PSC cataract (4.7, 95% CI: 1.1 to 20.0; income S$4000).
Conclusions: Age related cataracts are associated with a variety of risk factors among Chinese people in Singapore, similar to those reported in European, Indian, and African derived populations. These data support common aetiological mechanisms for age related cataracts, irrespective of ethnic origin.
PMCID: PMC1771847  PMID: 12928278
cataracts; Chinese; Singapore
3.  Risk factors associated with incident cataracts and cataract surgery in the Age Related Eye Disease Study (AREDS). AREDS Report Number 32 
Ophthalmology  2011;118(11):2113-2119.
To investigate potential risk factors associated with incident nuclear, cortical, and posterior subcapsular (PSC) cataracts and cataract surgery in participants in the Age-Related Eye Disease Study (AREDS).
Clinic-based prospective cohort study.
Persons (N=4425), aged 60 to 80 years of age enrolled in a controlled clinical trial of antioxidant vitamins and minerals, AREDS, for age-related macular degeneration (AMD) and cataract.
Lens photographs were graded centrally for nuclear, cortical, and PSC opacities using the AREDS System for Classifying Cataracts. Type-specific incident cataracts were defined as an increase in cataract grade from none or mild at baseline to a grade of moderate at follow-up, with also a grade of at least moderate at the final visit, or cataract surgery. Cox regression analyses were used to assess baseline risk factors associated with type specific opacities and cataract surgery.
Main Outcome Measures
Moderate cataract was defined as a grade of ≥4.0 for nuclear opacity, ≥10% involvement within the full visible lens for cortical opacity, and ≥5% involvement of the central 5 mm circle of the lens for PSC opacity. These were graded on baseline and annual lens photographs.
A clinic-based cohort of 4425 persons aged 55–80 years at baseline was followed for an average of 9.8 ± 2.4 years. The following associations were found: increasing age with increased risk of all types of cataract and cataract surgery; males with increased risk of PSC and decreased risk of cortical cataracts; non-whites with increased risk of cortical cataract; hyperopia with decreased risk of PSC, nuclear cataract, and cataract surgery; Centrum use with decreased risk of nuclear cataract; diabetes with increased risk of cortical, PSC cataract, and cataract surgery; higher educational level with decreased risk of cortical cataract; and smoking with increased risk of cortical cataract and cataract surgery. Estrogen replacement therapy in female participants increased the risk of cataract surgery.
Our findings are largely consistent with the results of previous studies, providing further evidence for possible modifiable risk factors for age-related cataract.
PMCID: PMC3178670  PMID: 21684602
4.  EPHA2 Polymorphisms and Age-Related Cataract in India 
PLoS ONE  2012;7(3):e33001.
We investigated whether previously reported single nucleotide polymorphisms (SNPs) of EPHA2 in European studies are associated with cataract in India.
We carried out a population-based genetic association study. We enumerated randomly sampled villages in two areas of north and south India to identify people aged 40 and over. Participants attended a clinical examination including lens photography and provided a blood sample for genotyping. Lens images were graded by the Lens Opacification Classification System (LOCS III). Cataract was defined as a LOCS III grade of nuclear ≥4, cortical ≥3, posterior sub-capsular (PSC) ≥2, or dense opacities or aphakia/pseudophakia in either eye. We genotyped SNPs rs3754334, rs7543472 and rs11260867 on genomic DNA extracted from peripheral blood leukocytes using TaqMan assays in an ABI 7900 real-time PCR. We used logistic regression with robust standard errors to examine the association between cataract and the EPHA2 SNPs, adjusting for age, sex and location.
7418 participants had data on at least one of the SNPs investigated. Genotype frequencies of controls were in Hardy-Weinberg Equilibrium (p>0.05). There was no association of rs3754334 with cataract or type of cataract. Minor allele homozygous genotypes of rs7543472 and rs11260867 compared to the major homozygote genotype were associated with cortical cataract, Odds ratio (OR) = 1.8, 95% Confidence Interval (CI) (1.1, 3.1) p = 0.03 and 2.9 (1.2, 7.1) p = 0.01 respectively, and with PSC cataract, OR = 1.5 (1.1, 2.2) p = 0.02 and 1.8 (0.9, 3.6) p = 0.07 respectively. There was no consistent association of SNPs with nuclear cataract or a combined variable of any type of cataract including operated cataract.
Our results in the Indian population agree with previous studies of the association of EPHA2 variants with cortical cataracts. We report new findings for the association with PSC which is particularly prevalent in Indians.
PMCID: PMC3297613  PMID: 22412971
5.  Risk factors for age related cataract in a rural population of southern India: the Aravind Comprehensive Eye Study 
Aim: To determine risk factors for lens opacities and age related cataract in an older rural population of southern India.
Methods: A cross sectional population based study of 5150 people aged 40 years and above from 50 clusters from three districts in southern India. The lens was graded and classified after dilation using LOCS III system at the slit lamp for cataract. Definite cataract was defined as nuclear opalescence ⩾3.0 and/or cortical cataract ⩾3.0 and/or PSC ⩾2.0.
Results: Definite cataracts were found in 2449 (47.5%) of 5150 subjects and the prevalence of cataract increased with age. The age adjusted prevalence of cataract was significantly lower in males (p = 0.0002). Demographic risk factors—increasing age and illiteracy—were common for the three subtypes of cataract; females were more likely to have cortical cataracts and nuclear cataracts. Additionally, nuclear cataracts were associated with moderate smoking (OR:1.28, 95% CI:1.01 to 1.64), lean body mass indices (OR: 1.37, 95% CI: 1.17 to 1.59) and higher waist to hip ratios (OR: 0.67, 95% CI: 0.54 to 0.82); cortical cataracts with hypertension (OR: 1.39 95% CI:1.11 to 1.72), pseudoexfoliation (OR:1.53,95% CI:1.17 to 2.01), and moderate to heavy smoking; and posterior subcapsular cataracts with diabetes (OR:1.55, 95% CI:1.12 to 2.15), lean body mass (OR:1.32, 95% CI:1.11 to 1.57), and high waist to hip ratios (OR: 0.77, 95% CI: 0.62 to 0.94).
Conclusions: Risk factors for age related cataract in this population do not appear to be different from those reported in other populations. Further studies are required to identify the reason for the high prevalence of age related cataract and to understand better the role of each risk factor for cataractogenesis in this population.
PMCID: PMC1772282  PMID: 15258010
age related cataract; India; Aravind Comprehensive Eye Study
6.  Five year incidence of cataract surgery: the Blue Mountains Eye Study 
Aims: To assess the 5 year incidence of cataract surgery in an older population based prospective cohort.
Methods: 5 Year prospective follow up of the population based Blue Mountains Eye Study (BMES) performed in 1992. The follow up study examined 2335 survivors (75.1%) of the 3654 baseline participants. Baseline and 5 year slit lamp and retroillumination lens photographs were graded for presence of cortical, nuclear, or posterior subcapsular cataract using the Wisconsin cataract grading method and cataract surgery was documented from the history and the clinical examination.
Results: An overall cataract surgery rate of 5.7% in first or both eyes was documented. The incidence was 0.3% in people aged 49–54 years at baseline, 1.7% for ages 55–64 years, 7.9% for ages 65 to 74 years, and 17.4% in people aged 75 years or older. The rate of surgery in first or both eyes was 6.0% in women and 5.2% in men, age adjusted p = 0.66. Bilateral cataract surgery was performed during follow up on 2.7% of participants, while 43.1% of unilateral phakic cases had second eye surgery. Presence of any posterior subcapsular (PSC) cataract, either alone or in combination with other cataract types, was the most likely type of cataract at baseline to be associated with incident cataract surgery. Baseline age was the most important non-ocular variable predicting incident cataract surgery.
Conclusions: This study has documented age specific rates for 5 year incident cataract surgery in an older community. The finding of relatively similar incidence rates and ocular predictors of cataract surgery to those reported by the Beaver Dam Eye Study, Wisconsin, United States, is of interest, given previous documented similarities between these two populations.
PMCID: PMC1771515  PMID: 12543745
cataract; cataract surgery; Blue Mountains Eye Study
7.  Fruit and vegetable intake and vitamins C and E are associated with a reduced prevalence of cataract in a Spanish Mediterranean population 
BMC Ophthalmology  2013;13:52.
Cataract is among the major causes of vision impairment and blindness worldwide. Epidemiological studies support the role of antioxidants in the etiology of cataract, but the evidence for one specific antioxidant over another is inconsistent. Few studies have examined the association of cataract with fruit and vegetable intake with inconclusive results. In the present study, the relationship between cataract and fruit and vegetable intake and dietary and blood levels of carotenoids, vitamins C and E were examined in a Spanish Mediterranean population.
The present work is an analysis of data from 599 elderly ( ≥ 65 years) participants from the Spanish segment of the EUREYE study. This is a European multi-center cross-sectional population-based study. Cataract was diagnosed using a slit-lamp examination and defined as any lens opacity in either eye or evidence of its removal (cataract extraction). Energy-adjusted intake of fruit and vegetables and antioxidant vitamins was estimated using a semi-quantitative food frequency questionnaire. Plasma concentrations of vitamin C were analyzed by a colorimetric method and carotenoids and α-tocopherol by a HPLC method. The associations between cataract and quartiles of fruit and vegetable intake and plasma antioxidants were investigated using logistic regression models.
Of the 599 elderly recruited, 433 (73%) had cataract or cataract extraction, 54% were women and 46% were men. After adjustments, increasing quartiles of combined fruit and vegetable intake were associated with decreasing reduction of odds of cataract or cataract extraction, (P for trend = 0.008). Increasing quartiles of dietary intakes from 107 mg/d of vitamin C showed a significant decreasing association with prevalence of cataract or cataract extraction (P for trend = 0.047). For vitamin E, a protective association was found from intakes from 8 mg/d, but no linear trend was observed across quartiles of intake (P for trend = 0.944).
High daily intakes of fruit and vegetables and vitamins C and E were associated with a significantly decreased of the prevalence of cataract or cataract surgery. This study reinforces the WHO recommendations on the benefits of diets rich in fruit and vegetables.
PMCID: PMC3853246  PMID: 24106773
Cataract; Fruit intake; Vegetables intake; Antioxidant vitamins; WHO recommendations
8.  Lens retrodots and vacuoles and their associations with the prevalence and incidence of age-related cataract 
Eye  2011;26(4):568-575.
To assess the prevalence of retrodots and vacuoles and their associations with the prevalence and long-term incidence of age-related cataract in an older Australian cohort.
Of 3654 baseline participants of the Blue Mountains Eye Study aged 49+ years (1992–1994), 2335 and 1952 were re-examined after 5 and 10 years, respectively. Lens photographs were graded for cataract, retrodots, and vacuoles. Eye-specific data were used to assess the associations between retrodots or vacuoles at baseline and the prevalence and 10-year incidence of nuclear, cortical, and posterior subcapsular (PSC) cataract and cataract surgery.
At baseline, retrodots were present in 142 persons (4%) and vacuoles in 1333 persons (40%). Prevalence of both lens features increased with increasing age (Pfor trend <0.0001). After adjusting for age and gender, vacuoles were associated with prevalent PSC cataract at baseline (odds ratio (OR), 1.60, 95% confidence interval (CI), 1.25–2.05). After adjusting for age, gender, smoking, hypertension, diabetes, education, and use of inhaled/oral steroids, baseline retrodots were associated with an increased incidence of cataract surgery (OR 2.90, 95% CI 1.71–4.91), while 3+ vacuoles at baseline were associated with an increased risk of PSC cataract (OR 3.56, 95% CI 2.13–5.95) and cataract surgery (OR 1.84, 95% CI 1.22–2.77).
Lens retrodots and vacuoles were found to be positively associated with 10-year incidence of cataract surgery, and vacuoles associated with PSC cataract, a finding suggestive of shared risk factors or pathogenesis between these two lens features and the development of PSC cataract.
PMCID: PMC3325569  PMID: 22193877
cataract; cataract surgery; lens opacities
9.  A prospective study of dietary carotenoids, vitamins C and E, and risk of cataract in women 
Archives of ophthalmology  2008;126(1):102-109.
To examine in prospective data the relation between dietary intake of carotenoids and vitamins C and E and risk of cataract in women.
Dietary intake was assessed at baseline in 1993 among 39,876 female health professionals by use of a detailed food-frequency questionnaire. A total of 35,551 of these women provided detailed information on antioxidant nutrient intake from food and supplements and were free of a diagnosis of cataract.
Main Outcome Measure
Cataract defined as an incident, age-related lens opacity, responsible for a reduction in best-corrected visual acuity to 20/30 or worse, based on self-report confirmed by medical record review.
A total of 2,031 cases of incident cataract were confirmed during an average of 10 years of follow-up. Comparing women in extreme quintiles, the multivariate relative risk of cataract was 0.82 (95% confidence interval, 0.71-0.95; P, test for trend, 0.045) for lutein/zeaxanthin, and 0.86 (95% confidence interval, 0.74-1.00; P, test for trend, 0.03) for vitamin E from food and supplements.
In these prospective observational data from a large cohort of female health professionals, higher dietary intakes of lutein/zeaxanthin and vitamin E from food and supplements were associated with significantly decreased risks of cataract.
PMCID: PMC2396535  PMID: 18195226
10.  A Case-Control Study to Assess the Relationship between Poverty and Visual Impairment from Cataract in Kenya, the Philippines, and Bangladesh 
PLoS Medicine  2008;5(12):e244.
The link between poverty and health is central to the Millennium Development Goals (MDGs). Poverty can be both a cause and consequence of poor health, but there are few epidemiological studies exploring this complex relationship. The aim of this study was to examine the association between visual impairment from cataract and poverty in adults in Kenya, Bangladesh, and the Philippines.
Methods and Findings
A population-based case–control study was conducted in three countries during 2005–2006. Cases were persons aged 50 y or older and visually impaired due to cataract (visual acuity < 6/24 in the better eye). Controls were persons age- and sex-matched to the case participants with normal vision selected from the same cluster. Household expenditure was assessed through the collection of detailed consumption data, and asset ownership and self-rated wealth were also measured. In total, 596 cases and 535 controls were included in these analyses (Kenya 142 cases, 75 controls; Bangladesh 216 cases, 279 controls; Philippines 238 cases, 180 controls). Case participants were more likely to be in the lowest quartile of per capita expenditure (PCE) compared to controls in Kenya (odds ratio = 2.3, 95% confidence interval 0.9–5.5), Bangladesh (1.9, 1.1–3.2), and the Philippines (3.1, 1.7–5.7), and there was significant dose–response relationship across quartiles of PCE. These associations persisted after adjustment for self-rated health and social support indicators. A similar pattern was observed for the relationship between cataract visual impairment with asset ownership and self-rated wealth. There was no consistent pattern of association between PCE and level of visual impairment due to cataract, sex, or age among the three countries.
Our data show that people with visual impairment due to cataract were poorer than those with normal sight in all three low-income countries studied. The MDGs are committed to the eradication of extreme poverty and provision of health care to poor people, and this study highlights the need for increased provision of cataract surgery to poor people, as they are particularly vulnerable to visual impairment from cataract.
Hannah Kuper and colleagues report a population-based case-control study conducted in three countries that found an association between poverty and visual impairment from cataract.
Editors' Summary
Globally, about 45 million people are blind. As with many other conditions, avoidable blindness (preventable or curable blindness) is a particular problem for people in developing countries—90% of blind people live in poor regions of the world. Although various infections and disorders can cause blindness, cataract is the most common cause. In cataract, which is responsible for half of all cases of blindness in the world, the lens of the eye gradually becomes cloudy. Because the lens focuses light to produce clear, sharp images, as cataract develops, vision becomes increasingly foggy or fuzzy, colors become less intense, and the ability to see shapes against a background declines. Eventually, vision may be lost completely. Cataract can be treated with an inexpensive, simple operation in which the cloudy lens is surgically removed and an artificial lens is inserted into the eye to restore vision. In developed countries, this operation is common and easily accessible but many poor countries lack the resources to provide the operation to everyone who needs it. In addition, blind people often cannot afford to travel to the hospitals where the operation, which also may come with a fee, is done.
Why Was This Study Done?
Because blindness may reduce earning potential, many experts believe that poverty and blindness (and, more generally, poor health) are inextricably linked. People become ill more often in poor countries than in wealthy countries because they have insufficient food, live in substandard housing, and have limited access to health care, education, water, and sanitation. Once they are ill, their ability to earn money may be reduced, which increases their personal poverty and slows the economic development of the whole country. Because of this potential link between health and poverty, improvements in health are at the heart of the United Nations Millennium Development Goals, a set of eight goals established in 2000 with the primary aim of reducing world poverty. However, few studies have actually investigated the complex relationship between poverty and health. Here, the researchers investigate the association between visual impairment from cataract and poverty among adults living in three low-income countries.
What Did the Researchers Do and Find?
The researchers identified nearly 600 people aged 50 y or more with severe cataract-induced visual impairment (“cases”) primarily through a survey of the population in Kenya, Bangladesh, and the Philippines. They matched each case to a normally sighted (“control”) person of similar age and sex living nearby. They then assessed a proxy for the income level, measured as “per capita expenditure” (PCE), of all the study participants (people with cataracts and controls) by collecting information about what their households consumed. The participants' housing conditions and other assets and their self-rated wealth were also measured. In all three countries, cases were more likely to be in the lowest quarter (quartile) of the range of PCEs for that country than controls. In the Philippines, for example, people with cataract-affected vision were three times more likely than normally sighted controls to have a PCE in the lowest quartile than in the highest quartile. The risk of cataract-related visual impairment increased as PCE decreased in all three countries. Similarly, severe cataract-induced visual impairment was more common in those who owned fewer assets and those with lower self-rated wealth. However, there was no consistent association between PCE and the level of cataract-induced visual impairment.
What Do These Findings Mean?
These findings show that there is an association between visual impairment caused by cataract and poverty in Kenya, Bangladesh, and the Philippines. However, because the financial circumstances of the people in this study were assessed after cataracts had impaired their sight, this study does not prove that poverty is a cause of visual impairment. A causal connection between poverty and cataract can only be shown by determining the PCEs of normally sighted people and following them for several years to see who develops cataract. Nevertheless, by confirming an association between poverty and blindness, these findings highlight the need for increased provision of cataract surgery to poor people, particularly since cataract surgery has the potential to improve the quality of life for many people in developing countries at a relatively low cost.
Additional Information.
Please access these Web sites via the online version of this summary at
This study is further discussed in a PLoS Medicine Perspective by Susan Lewallen
The MedlinePlus encyclopedia contains a page on cataract, and MedlinePlus also provides a list of links to further information about cataract (in English and Spanish)
VISION 2020, a global initiative for the elimination of avoidable blindness launched by the World Health Organization and the International Agency for the Prevention of Blindness, provides information in several languages about many causes of blindness, including cataract. It also has an article available for download on blindness, poverty, and development
Information is available from the World Health Organization on health and the Millennium Development Goals (in English, French, and Spanish)
The International Centre for Eye Health carries out research and education activities to improve eye health and eliminate avoidable blindness with a focus on populations with low incomes
PMCID: PMC2602716  PMID: 19090614
11.  Cataract surgery and subtype in a defined, older population: the SEECAT Project 
The British Journal of Ophthalmology  2004;88(12):1512-1517.
Aim: To describe the distribution of cataract subtypes present before surgery among a defined population of older, bilaterally pseudophakic individuals.
Methods: This was a cohort study of bilaterally pseudophakic individuals participating in the Salisbury Eye Evaluation (SEE), and their locally resident siblings. Subjects underwent slit lamp and retroillumination photography and grading using the Wilmer Cataract Grading System. For all individuals determined to be bilaterally pseudophakic, an attempt was made to determine for each eye the type(s) of cataract present before surgery, based on previous SEE photographs (for SEE participants) and/or medical records obtained from the operating ophthalmologist (for both SEE participants and their siblings).
Results: The mean age of 223 participants providing data in this study was 78.7 (SD 5.2) years, 19.3% of subjects were black and 60.1% female. The most common surgically removed cataract subtype in this population was pure nuclear (43.5%), followed by nuclear combined with posterior subcapsular cataract (PSC) (20.6%), and nuclear combined with cortical (13.9%); less common types were pure cortical (4.9%), pure PSC (4.5%), and PSC combined with cortical (2.7%). Factors such as sex and source of lens data (study photograph versus clinical record) did not significantly affect the distribution of lens opacity types, while PSC was significantly (p = 0.01) more common among younger people and nuclear cataract was significantly (p = 0.001) more common among white compared to black people.
Conclusion: Epidemiological studies have suggested that the different subtypes of cataract are associated with different risk factors. As studies begin to identify new prevention strategies for cataract, it would appear likely that different strategies will be efficacious against different types of cataract. In this setting, it will be helpful to know which cataract types are most frequently associated with surgery. Among this older, majority white population, nuclear cataract showed a clear predominance among individuals having undergone surgery in both eyes. This may be contrasted with both clinic and population based studies of younger people, which have generally found PSC cataract to predominate.
PMCID: PMC1772435  PMID: 15548802
Cataract surgery; older people
12.  Cortical, but Not Posterior Subcapsular, Cataract Shows Significant Familial Aggregation in an Older Population after Adjustment for Possible Shared Environmental Factors 
Ophthalmology  2005;112(1):73-77.
To quantify the risk for age-related cortical cataract and posterior subcapsular cataract (PSC) associated with having an affected sibling after adjusting for known environmental and personal risk factors.
Sibling cohort study.
Participants in the ongoing Salisbury Eye Evaluation (SEE) study (n = 321; mean age, 78.1±4.2 years) and their locally resident siblings (n = 453; mean age, 72.6±7.4 years) were recruited at the time of Rounds 3 and 4 of the SEE study.
Intervention/Testing Methods
Retroillumination photographs of the lens were graded for the presence of cortical cataract and PSC with the Wilmer grading system. The residual correlation between siblings' cataract grades was estimated after adjustment for a number of factors (age; gender; race; lifetime exposure to ultraviolet-B light; cigarette, alcohol, estrogen, and steroid use; serum antioxidants; history of diabetes; blood pressure; and body mass index) suspected to be associated with the presence of cataract.
The average sibship size was 2.7 per family. Multivariate analysis revealed the magnitude of heritability (h2) for cortical cataract to be 24% (95% CI, 6%–42%), whereas that for PSC was not statistically significant (h2 4%; 95% CI, 0%–11%) after adjustment for the covariates. The model revealed that increasing age, female gender, a history of diabetes, and black race increased the odds of cortical cataract, whereas higher levels of provitamin A were protective. A history of diabetes and steroid use increased the odds for PSC.
This study is consistent with a significant genetic effect for age-related cortical cataract but not PSC.
PMCID: PMC3102010  PMID: 15629823
13.  Association between Lutein and Zeaxanthin Status and the Risk of Cataract: A Meta-Analysis 
Nutrients  2014;6(1):452-465.
The purpose of this meta-analysis was to evaluate the relationship between blood lutein and zeaxanthin concentration and the risk of age-related cataract (ARC). MEDLINE, EMBASE, ISI and Cochrane Library were searched to identify relevant studies up to April 2013. Meta-analysis was conducted to obtain pooled relative risks (RRs) for the highest-versus-lowest categories of blood lutein and zeaxanthin concentrations. One cohort study and seven cross-sectional studies were included in the meta-analysis. There were significant inverse associations between nuclear cataract and blood lutein and zeaxanthin concentrations, with the pooled RRs ranging from 0.63 (95% confidence interval (CI): 0.49, 0.77) for zeaxanthin to 0.73 (95% CI: 0.59, 0.87) for lutein. A stronger association between nuclear cataract and blood zeaxanthin might be noted for the studies conducted in the European Nations. Blood lutein and zeaxanthin were also noted to lead towards a decrease in the risk of cortical cataract and subcapsular cataract; however, these pooled RRs were not statistically significant, with the exception of a marginal association between lutein and subcapsular cataract. Our results suggest that high blood lutein and zeaxanthin are significantly associated with a decrease in the risk of nuclear cataract. However, no significant associations were found for ARC in other regions of the lens.
PMCID: PMC3916871  PMID: 24451312
lutein; zeaxanthin; blood; age-related cataract; meta-analysis
14.  Prevalence of visual impairment, cataract surgery and awareness of cataract and glaucoma in Bhaktapur district of Nepal: The Bhaktapur Glaucoma Study 
BMC Ophthalmology  2011;11:2.
Cataract and glaucoma are the major causes of blindness in Nepal. Bhaktapur is one of the three districts of Kathmandu valley which represents a metropolitan city with a predominantly agrarian rural periphery. This study was undertaken to determine the prevalence of visual impairment, cataract surgery and awareness of cataract and glaucoma among subjects residing in this district of Nepal.
Subjects aged 40 years and above was selected using a cluster sampling methodology and a door to door enumeration was conducted for a population based cross sectional study. During the community field work, 11499 subjects underwent a structured interview regarding awareness (heard of) and knowledge (understanding of the disease) of cataract and glaucoma. At the base hospital 4003 out of 4800 (83.39%) subjects underwent a detailed ocular examination including log MAR visual acuity, refraction, applanation tonometry, cataract grading (LOCSΙΙ), retinal examination and SITA standard perimetry when indicated.
The age-sex adjusted prevalence of blindness (best corrected <3/60) and low vision (best corrected <6/18 ≥3/60) was 0.43% (95%C.I. 0.25 - 0.68) and 3.97% (95% C.I. 3.40 - 4.60) respectively. Cataract (53.3%) was the principal cause of blindness. The leading causes of low vision were cataract (60.8%) followed by refractive error (12%). The cataract surgical coverage was 90.36% and was higher in the younger age group, females and illiterate subjects. Pseudophakia was seen in 94%. Awareness of cataract (6.7%) and glaucoma (2.4%) was very low. Among subjects who were aware, 70.4% had knowledge of cataract and 45.5% of glaucoma. Cataract was commonly known to be a 'pearl like dot' white opacity in the eye while glaucoma was known to cause blindness. Awareness remained unchanged in different age groups for cataract while for glaucoma there was an increase in awareness with age. Women were significantly less aware (odds ratio (OR): 0.63; 95%, confidence interval (CI): 0.54 - 0.74) for cataract and (OR: 0.64; 95% CI: 0.50 - 0.81) for glaucoma. Literacy was also correlated with awareness.
The low prevalence of visual impairment and the high cataract surgical coverage suggests that cataract intervention programs have been successful in Bhaktapur. Awareness and knowledge of cataract and glaucoma was very poor among this population. Eye care programs needs to be directed towards preventing visual impairment from refractive errors, screening for incurable chronic eye diseases and promoting health education in order to raise awareness on cataract and glaucoma among this population.
PMCID: PMC3036669  PMID: 21255382
15.  Comparison of age-specific cataract prevalence in two population-based surveys 6 years apart 
BMC Ophthalmology  2006;6:17.
In this study, we aimed to compare age-specific cortical, nuclear and posterior subcapsular (PSC) cataract prevalence in two surveys 6 years apart.
The Blue Mountains Eye Study examined 3654 participants (82.4% of those eligible) in cross-section I (1992–4) and 3509 participants (75.1% of survivors and 85.2% of newly eligible) in cross-section II (1997–2000, 66.5% overlap with cross-section I). Cataract was assessed from lens photographs following the Wisconsin Cataract Grading System. Cortical cataract was defined if cortical opacity comprised ≥ 5% of lens area. Nuclear cataract was defined if nuclear opacity ≥ Wisconsin standard 4. PSC was defined if any present. Any cataract was defined to include persons who had previous cataract surgery. Weighted kappa for inter-grader reliability was 0.82, 0.55 and 0.82 for cortical, nuclear and PSC cataract, respectively. We assessed age-specific prevalence using an interval of 5 years, so that participants within each age group were independent between the two surveys.
Age and gender distributions were similar between the two populations. The age-specific prevalence of cortical (23.8% in 1st, 23.7% in 2nd) and PSC cataract (6.3%, 6.0%) was similar. The prevalence of nuclear cataract increased slightly from 18.7% to 23.9%. After age standardization, the similar prevalence of cortical (23.8%, 23.5%) and PSC cataract (6.3%, 5.9%), and the increased prevalence of nuclear cataract (18.7%, 24.2%) remained.
In two surveys of two population-based samples with similar age and gender distributions, we found a relatively stable cortical and PSC cataract prevalence over a 6-year period. The increased prevalence of nuclear cataract deserves further study.
PMCID: PMC1524813  PMID: 16623958
16.  A Randomized, Placebo-Controlled, Clinical Trial of High-Dose Supplementation With Vitamins C and E and Beta Carotene for Age-Related Cataract and Vision Loss 
Archives of ophthalmology  2001;119(10):1439-1452.
Experimental and observational data suggest that micronutrients with antioxidant capabilities may retard the development of age-related cataract.
To evaluate the effect of a high-dose anti-oxidant formulation on the development and progression of age-related lens opacities and visual acuity loss.
The 11-center Age-Related Eye Disease Study (AREDS) was a double-masked clinical trial. Participants were randomly assigned to receive daily oral tablets containing either antioxidants (vitamin C, 500 mg; vitamin E, 400 IU; and beta carotene, 15 mg) or no antioxidants. Participants with more than a few small drusen were also randomly assigned to receive tablets with or without zinc (80 mg of zinc as zinc oxide) and copper (2 mg of copper as cupric oxide) as part of the age-related macular degeneration trial. Baseline and annual (starting at year 2) lens photographs were graded at a reading center for the severity of lens opacities using the AREDS cataract grading scale.
Main Outcome Measures
Primary outcomes were (1) an increase from baseline in nuclear, cortical, or posterior subcapsular opacity grades or cataract surgery, and (2) at least moderate visual acuity loss from baseline (≥15 letters). Primary analyses used repeated-measures logistic regression with a statistical significance level of P = .01. Serum level measurements, medical histories, and mortality rates were used for safety monitoring.
Of 4757 participants enrolled, 4629 who were aged from 55 to 80 years had at least 1 natural lens present and were followed up for an average of 6.3 years. No statistically significant effect of the antioxidant formulation was seen on the development or progression of age-related lens opacities (odds ratio=0.97, P=.55). There was also no statistically significant effect of treatment in reducing the risk of progression for any of the 3 lens opacity types or for cataract surgery. For the 1117 participants with no age-related macular degeneration at baseline, no statistically significant difference was noted between treatment groups for at least moderate visual acuity loss. No statistically significant serious adverse effect was associated with treatment.
Use of a high-dose formulation of vitamin C, vitamin E, and beta carotene in a relatively well-nourished older adult cohort had no apparent effect on the 7-year risk of development or progression of age-related lens opacities or visual acuity loss.
PMCID: PMC1472812  PMID: 11594943
17.  Age-Related Cataract, Cataract Surgery and Subsequent Mortality: A Systematic Review and Meta-Analysis 
PLoS ONE  2014;9(11):e112054.
Changes in lens may reflect the status of systemic health of human beings but the supporting evidences are not well summarized yet. We aimed to determine the relationship of age-related cataract, cataract surgery and long-term mortality by pooling the results of published population-based studies.
We searched PubMed and Embase from their inception till March, 2014 for population-based studies reporting the associations of any subtypes of age-related cataract, cataract surgery with all-cause mortality. We pooled the effect estimates (hazards ratios [HRs]) under a random effects model.
Totally, we identified 10 unique population-based studies including 39,659 individuals at baseline reporting the associations of any subtypes of cataract with all-cause mortality from 6 countries. The presence of any cataract including cataract surgery was significantly associated with a higher risk of death (pooled HR: 1.43, 95% CI, 1.21, 2.02; P<0.001; I2 = 64.2%). In the meta-analysis of 9 study findings, adults with nuclear cataract were at higher risks of mortality (pooled HR: 1.55, 95% CI, 1.17, 2.05; P = 0.002; I2 = 89.2%). In the meta-analysis of 8 study findings, cortical cataract was associated with higher risks of mortality (pooled HR: 1.26, 95% CI, 1.12, 1.42; P<0.001, I2 = 29.7%). In the meta-analysis of 6 study findings, PSC cataract was associated with higher risks of mortality (pooled HR: 1.37, 95% CI, 1.04, 1.80; P = 0.03; I2 = 67.3%). The association between cataract surgery and mortality was marginally non-significant by pooling 8 study findings (pooled HR: 1.27, 95% CI, 0.97, 1.66; P = 0.08; I2 = 76.6%).
All subtypes of age-related cataract were associated with an increased mortality with nuclear cataract having the strongest association among the 3 cataract subtypes. However, cataract surgery was not significantly related to mortality. These findings indicated that changes in lens may serve as markers for ageing and systemic health in general population.
PMCID: PMC4219834  PMID: 25369040
18.  Cataract, Visual Impairment and Long-Term Mortality in a Rural Cohort in India: The Andhra Pradesh Eye Disease Study 
PLoS ONE  2013;8(10):e78002.
A large-scale prevalence survey of blindness and visual impairment (The Andhra Pradesh Eye Diseases Study [APEDS1]) was conducted between 1996-2000 on 10,293 individuals of all ages in three rural and one urban clusters in Andhra Pradesh, Southern India. More than a decade later (June 2009-March 2010), APEDS1 participants in rural clusters were traced (termed APEDS2) to determine ocular risk factors for mortality in this longitudinal cohort.
Methods and Findings
Mortality hazard ratio (HR) analysis was performed for those aged >30 years at APEDS1, using Cox proportional hazard regression models to identify associations between ocular exposures and risk of mortality. Blindness and visual impairment (VI) were defined using Indian definitions. 799/4,188 (19.1%) participants had died and 308 (7.3%) had migrated. Mortality was higher in males than females (p<0.001). In multivariable analysis, after adjusting for age, gender, diabetes, hypertension, body mass index, smoking and education status the mortality HR was 1.9 (95% CI: 1.5-2.5) for blindness; 1.4 (95% CI: 1.2-1.7) for VI; 1.8 (95% CI: 1.4-2.3) for pure nuclear cataract, 1.5 (95% CI: 1.1-2.1) for pure cortical cataract; 1.96 (95% CI: 1.6-2.4) for mixed cataract, 2.0 (95% CI: 1.4-2.9) for history of cataract surgery, and 1.58 (95% CI: 1.3-1.9) for any cataract. When all these factors were included in the model, the HRs were attenuated, being 1.5 (95% CI: 1.1-2.0) for blindness and 1.2 (95% CI: 0.9-1.5) for VI. For lens type, the HRs were as follows: pure nuclear cataract, 1.6 (95% CI: 1.3-2.1); pure cortical cataract, 1.5 (95% CI: 1.1-2.1); mixed cataract, 1.8 (95% CI: 1.4-2.2), and history of previous cataract surgery, 1.8 (95% CI: 1.3-2.6).
All types of cataract, history of cataract surgery and VI had an increased risk of mortality that further suggests that these could be potential markers of ageing.
PMCID: PMC3837009  PMID: 24282482
19.  EPHA2 Is Associated with Age-Related Cortical Cataract in Mice and Humans 
PLoS Genetics  2009;5(7):e1000584.
Age-related cataract is a major cause of blindness worldwide, and cortical cataract is the second most prevalent type of age-related cataract. Although a significant fraction of age-related cataract is heritable, the genetic basis remains to be elucidated. We report that homozygous deletion of Epha2 in two independent strains of mice developed progressive cortical cataract. Retroillumination revealed development of cortical vacuoles at one month of age; visible cataract appeared around three months, which progressed to mature cataract by six months. EPHA2 protein expression in the lens is spatially and temporally regulated. It is low in anterior epithelial cells, upregulated as the cells enter differentiation at the equator, strongly expressed in the cortical fiber cells, but absent in the nuclei. Deletion of Epha2 caused a significant increase in the expression of HSP25 (murine homologue of human HSP27) before the onset of cataract. The overexpressed HSP25 was in an underphosphorylated form, indicating excessive cellular stress and protein misfolding. The orthologous human EPHA2 gene on chromosome 1p36 was tested in three independent worldwide Caucasian populations for allelic association with cortical cataract. Common variants in EPHA2 were found that showed significant association with cortical cataract, and rs6678616 was the most significant in meta-analyses. In addition, we sequenced exons of EPHA2 in linked families and identified a new missense mutation, Arg721Gln, in the protein kinase domain that significantly alters EPHA2 functions in cellular and biochemical assays. Thus, converging evidence from humans and mice suggests that EPHA2 is important in maintaining lens clarity with age.
Author Summary
Cataract is the leading cause of blindness. Cataract may form at any age, but the peak incidence is bimodal—in the perinatal period or later than 50 years of age. The early onset forms follow Mendelian inheritance patterns and are rare. Age-related cataract accounts for 18 million cases of blindness and 59 million cases of reduced vision worldwide. Among three types of age-related cataract, cortical cataract is known to be highly heritable, although few genes have been linked to its etiology. We report here that EPHA2 is associated with cortical cataract. EPHA2 is expressed in mouse and human cortical lens fiber cells, and homozygous deletion of Epha2 in two independent strains of mice led to development of cataract that progressed with age. Common and rare variants including a missense mutation in the EPHA2 gene were associated for cortical cataract in three different Caucasian populations. Our study identified EPHA2 as a gene for human age-related cataract and established Epha2 knockout mice as a model for progressive cortical cataract.
PMCID: PMC2712078  PMID: 19649315
20.  Risk of Cataract in Persons with Cytomegalovirus Retinitis and the Acquired Immune Deficiency Syndrome 
Ophthalmology  2012;119(11):2343-2350.
To evaluate cataract risk in eyes of patients with AIDS and cytomegalovirus (CMV) retinitis and to identify risk factors.
Prospective cohort study.
Patients with AIDS and CMV retinitis.
Patients 13 years of age and older were enrolled between 1998 and 2008. Demographic and clinical characteristics, slit-lamp biomicroscopy findings, and dilated ophthalmoscopy results were documented at quarterly visits. Cataract status was determined at the initial visit (prevalence) and at follow-up visits (incidence).
Main Outcome Measures
For cataract, a high grade of lens opacity by biomicroscopy to which best-corrected visual acuity worse than 20/40 was attributed. Eyes that had undergone cataract surgery before enrollment or between visits also were counted as having cataract.
Seven hundred twenty-nine eyes of 489 patients diagnosed with CMV retinitis were evaluated. Higher prevalence was observed for patients with bilateral versus unilateral CMV retinitis (adjusted odds ratio [aOR], 2.74; 95% confidence interval [CI], 1.76–4.26) and, among unilateral CMV retinitis cases, for eyes with retinitis versus without retinitis (15% vs. 1.4%; P<0.0001). The age-adjusted prevalence of cataract among CMV retinitis cases was higher than that in a population-based sample (P<0.0001). Cataract prevalence increased with age (aOR, 11.77; 95% CI, 2.28–60.65 for age ≥60 years vs. younger than 40 years) and longer duration of retinitis (aOR, 1.36; 95% CI, 1.20–1.54 per year). Among eyes with CMV retinitis initially free of cataract, the cataract incidence was 8.1%/eye-year (95% CI, 6.7%–10.0%). Prior retinal detachment was associated with higher cataract risk (if repaired with silicone oil: adjusted hazard ratio [aHR], 10.37; 95% CI, 6.51–16.52; otherwise: aHR, 2.90; 95% CI, 1.73–4.87). Large CMV retinitis lesions also were associated with higher risk of cataract (for involvement of 25–49% retinal area: aHR, 2.30; 95% CI, 1.51–3.50; for ≥50% involvement: aHR, 3.63; 95% CI, 2.18–6.04), each with respect to ≤24% involvement, as were anterior segment inflammation (aHR, 2.27; 95% CI, 1.59–3.25) and contralateral cataract (aHR, 2.52; 95% CI, 1.74–3.66).
Cytomegalovirus retinitis is associated with a high absolute and relative risk of cataract. Among several risk factors, large retinal lesion size and use of silicone oil in retinal detachment repair are potentially modifiable, albeit not in all cases. Cataract is likely to be an increasingly important cause of visual morbidity in this population.
PMCID: PMC3650486  PMID: 22853972
21.  The Association Between Refractive Errors and Cataract: The Tehran Eye Study 
To determine the association between refractive errors and different types of cataract in Tehran, Iran.
Materials and Methods:
In a cross-sectional survey with a stratified cluster sampling approach, refractive errors were tested under cycloplegia. Myopia and hyperopia were defined as a spherical equivalent refractive error <-0.5 diopters (D) and more than +0.5 D, respectively. Cataract was graded according to the Lens Opacities Classification System III classification and the association between refractive errors and cataract was assessed. Of 1434 participants over the age of 40 years who participated in the study, data from 1313 right eyes were analyzed.
The mean age of the participants was 52.7 ± 10.0 years, and 58.3% (n = 767) were female. Overall, myopia was more prevalent among those with cataract (odds ratio [OR]: 2.00, 95% confidence interval [CI]: 1.38–2.89). Based on the type of cataract and refractive errors, the odds of myopia was significantly higher with nuclear cataracts (OR: 1.81, 95% CI: 1.14–2.87). The odds of myopia was higher for cases of nuclear cataract with some degrees of posterior subcapsular cataract (PSC) (OR: 3.33, 95% CI: 1.42–7.80). Of nine participants with cortical cataract, seven participants had hyperopia (OR: 3.77, 95% CI: 0.78–18.31).
Individuals with nuclear and PSC showed a significantly higher prevalence of myopia while the prevalence of hyperopia was lower in those with cataract. High myopia was seen in higher grades of nuclear cataract. The high percentage of hyperopia was also significant in patients with cortical cataract. More studies are necessary to clarify the correlation between cortical cataract and hyperopia.
PMCID: PMC3119285  PMID: 21731327
Cataract; Population-Based Study; Refractive Errors
22.  Influence of tobacco use on cataract development 
The British Journal of Ophthalmology  2006;90(11):1374-1377.
To study the influence of tobacco use on cataract formation in a rural South Indian population.
3924 subjects from the Chennai Glaucoma Study conducted in rural south India underwent a comprehensive eye examination, including Lens Opacities Classification System II grading. Information on tobacco use, type of tobacco (smoking and smokeless), duration and quantity of use was collected.
1705 (male:female (M:F) 1106:599) people used tobacco and were significantly older (mean (standard deviation (SD)) age 55.80 (10.64) years) than non‐users (52.23 (10.51); p<0.001). 731 (M:F 730:1) people smoked, 900 (M:F 302:598) used smokeless tobacco, and 74 (M:F, 74:0) used tobacco in both forms. The unadjusted and adjusted (age and sex) odds ratio (OR) for a positive history of tobacco use and cataract was 1.72 (95% confidence interval (CI) 1.51 to 1.96) and 1.39 (95% CI 1.15 to 1.68), respectively. The unadjusted OR for smokers and smokeless tobacco users was 1.04 (95% CI 0.88 to 1.23) and 2.74 (95% CI 2.31 to 3.26), respectively. The adjusted OR was 1.19 (95% CI 0.89 to 1.59) and 1.54 (95% CI 1.22 to 1.95), respectively. No significant association was noted between smoking and any particular type of cataract. Smokeless tobacco use was found to be significantly associated with nuclear cataract even after adjusting for age and sex (OR 1.67, p = 0.067, 95% CI 1.16 to 2.39).
Tobacco use was significantly associated with cataract. Smoking was not found to be significantly associated with cataract formation; however, smokeless tobacco use was more strongly associated with cataract.
PMCID: PMC1857475  PMID: 16837540
23.  Serum antioxidant vitamins and risk of cataract. 
BMJ : British Medical Journal  1992;305(6866):1392-1394.
OBJECTIVE--To investigate serum concentrations of alpha tocopherol, beta carotene, retinol, and selenium for their prediction of end stage cataract. DESIGN--A case-control study, nested within a cohort study, based on the linkage of records of subjects aged 40-83 from a health survey with those from the national Finnish hospital discharge register. SUBJECTS--47 patients admitted to ophthalmological wards for senile cataract over 15 years and two controls per patient individually matched for sex, age, and municipality. MAIN OUTCOME MEASURE--Concentration of serum micronutrients, development of cataract according to whether operation was performed. RESULTS--Low serum concentrations of antioxidant vitamins predicted the development of senile cataract, the odds ratio between the lowest third and the two higher thirds of the distribution of serum concentrations of alpha tocopherol and beta carotene being 1.9 (95% confidence interval 0.9 to 4.1) and 1.7 (0.8 to 3.8), respectively. Patients with both alpha tocopherol and beta carotene concentrations in the lowest third had an odds ratio of 2.6 (1.0 to 6.8) of cataract compared with subjects in the top two thirds. The associations were strengthened by adjustment for potential confounding factors such as occupation, smoking, blood pressure, serum cholesterol concentration, body mass index, and diabetes. No association was found between the serum concentrations of selenium, retinol, and retinol binding protein and the risk of cataract. CONCLUSIONS--Low serum concentrations of the antioxidant vitamins alpha tocopherol and beta carotene are risk factors for end stage senile cataract. Controlled trials of the role of antioxidant vitamins in cataract prevention are therefore warranted.
PMCID: PMC1883919  PMID: 1486302
24.  The need for cataract surgery: projections based on lens opacity, visual acuity, and personal concern 
AIM—To assess the projected needs for cataract surgery by lens opacity, visual acuity, and patient concern.
METHODS—Data were collected as part of the Melbourne Visual Impairment Project, a population based study of age related eye disease in a representative sample of Melbourne residents aged 40 and over. Participants were recruited by a household census and invited to attend a local screening centre. At the study sites, the following data were collected: presenting and best corrected visual acuity, visual fields, intraocular pressure, satisfaction with current vision, personal health history and habits, and a standardised eye examination and photography of the lens and fundus. Lens photographs were graded twice and adjudicated to document lens opacities. Cataract was defined as nuclear greater than or equal to standard 2, 4/16 or greater cortical opacity, or any posterior subcapsular opacities.
RESULTS—3271 (83% response) people living in their own homes were examined. The participants ranged in age from 40 to 98 years and 1511 (46.2%) were men. Previous cataract surgery had been performed in 107 (3.4%) of the participants. The overall prevalence of any type of cataract that had not been surgically corrected was 18%. If the presence of cataract as defined was considered the sole criterion for cataract surgery with no reference to visual acuity, there would be 309 cataract operations per 1000 people aged 40 and over (96 eyes of people who were not satisfied with their vision, 210 eyes of people who were satisfied with their vision, and three previous cataract operations). At a visual acuity criterion of less than 6/12 (the vision required to legally drive a car), 48 cataract operations per 1000 would occur and people would be twice as likely to report dissatisfaction with their vision.
CONCLUSIONS—Estimates of the need for cataract surgery vary dramatically by level of lens opacity, visual acuity, and patient concern. These data should be useful for the planning of health services.

 Keywords: cataract surgery; visual acuity; patient satisfaction
PMCID: PMC1722775  PMID: 10209437
25.  A population based eye survey of older adults in Tirunelveli district of south India: blindness, cataract surgery, and visual outcomes 
Aims: To assess the prevalence of vision impairment, blindness, and cataract surgery and to evaluate visual acuity outcomes after cataract surgery in a south Indian population.
Methods: Cluster sampling was used to randomly select a cross sectional sample of people ≥50 years of age living in the Tirunelveli district of south India. Eligible subjects in 28 clusters were enumerated through a door to door household survey. Visual acuity measurements and ocular examinations were performed at a selected site within each of the clusters in early 2000. The principal cause of visual impairment was identified for eyes with presenting visual acuity <6/18. Independent replicate testing for quality assurance monitoring was performed in subjects with reduced vision and in a sample of those with normal vision for six of the study clusters.
Results: A total of 5795 people in 3986 households were enumerated and 5411 (93.37%) were examined. The prevalence of presenting and best corrected visual acuity ≥6/18 in both eyes was 59.4% and 75.7%, respectively. Presenting vision <6/60 in both eyes (the definition of blindness in India) was found in 11.0%, and in 4.6% with best correction. Presenting blindness was associated with older age, female sex, and illiteracy. Cataract was the principal cause of blindness in at least one eye in 70.6% of blind people. The prevalence of cataract surgery was 11.8%—with an estimated 56.5% of the cataract blind already operated on. Surgical coverage was inversely associated with illiteracy and with female sex in rural areas. Within the cataract operated sample, 31.7% had presenting visual acuity ≥6/18 in both eyes and 11.8% were <6/60; 40% were bilaterally operated on, with 63% pseudophakic. Presenting vision was <6/60 in 40.7% of aphakic eyes and in 5.1% of pseudophakic eyes; with best correction the percentages were 17.6% and 3.7%, respectively. Refractive error, including uncorrected aphakia, was the main cause of visual impairment in cataract operated eyes. Vision <6/18 was associated with cataract surgery in government, as opposed to that in non-governmental/private facilities. Age, sex, literacy, and area of residence were not predictors of visual outcomes.
Conclusion: Treatable blindness, particularly that associated with cataract and refractive error, remains a significant problem among older adults in south Indian populations, especially in females, the illiterate, and those living in rural areas. Further study is needed to better understand why a significant proportion of the cataract blind are not taking advantage of free of charge eye care services offered by the Aravind Eye Hospital and others in the district. While continuing to increase cataract surgical volume to reduce blindness, emphasis must also be placed on improving postoperative visual acuity outcomes.
PMCID: PMC1771133  PMID: 11973242
blindness; cataract surgery; visual acuity

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