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1.  The Association of Outdoor Activity and Age-Related Cataract in a Rural Population of Taizhou Eye Study: Phase 1 Report 
PLoS ONE  2015;10(8):e0135870.
To study the relationship between outdoor activity and risk of age-related cataract (ARC) in a rural population of Taizhou Eye Study (phrase 1 report).
A population-based, cross-sectional study of 2006 eligible rural adults (≥45 years old) from Taizhou Eye Study was conducted from Jul. to Sep. 2012. Participants underwent detailed ophthalmologic examinations including uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), intraocular pressure (IOP), slit lamp and fundus examinations as well as questionnaires about previous outdoor activity and sunlight protection methods. ARC was recorded by LOCSⅢ classification system. The prevalence of cortical, nuclear and posterior subcapsular cataract were assessed separately for the risk factors and its association with outdoor activity.
Of all 2006 eligible participants, 883 (44.0%) adults were diagnosed with ARC. The prevalence rates of cortical, nuclear and posterior subcapsular cataract per person were 41.4%, 30.4% and 1.5%, respectively. Women had a higher tendency of nuclear and cortical cataract than men (OR = 1.559, 95% CI 1.204–2.019 and OR = 1.862, 95% CI 1.456–2.380, respectively). Adults with high myopia had a higher prevalence of nuclear cataract than adults without that (OR = 2.528, 95% CI 1.055–6.062). Multivariable logistic regression revealed that age was risk factor of nuclear (OR = 1.190, 95% CI 1.167–1.213) and cortical (OR = 1.203, 95% CI 1.181–1.226) cataract; eyes with fundus diseases was risk factor of posterior subcapsular cataract (OR = 6.529, 95% CI 2.512–16.970). Outdoor activity was an independent risk factor of cortical cataract (OR = 1.043, 95% CI 1.004–1.083). The risk of cortical cataract increased 4.3% (95% CI 0.4%-8.3%) when outdoor activity time increased every one hour. Furthermore, the risk of cortical cataract increased 1.1% (95% CI 0.1%-2.0%) when cumulative UV-B exposure time increased every one year.
Outdoor activity was an independent risk factor for cortical cataract, but was not risk factor for nuclear and posterior subcapsular cataract. The risk of cortical cataract increased 4.3% when outdoor activity time increased every one hour. In addition, the risk of cortical cataract increased 1.1% (95% CI 0.1%-2.0%) when cumulative UV-B exposure time increased every one year.
PMCID: PMC4540437  PMID: 26284359
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.  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
4.  Risk Factors Associated with Age-Related Nuclear and Cortical Cataract 
Ophthalmology  2001;108(8):1400-1408.
Objective: To investigate possible risk factors for age-related nuclear and cortical cataracts in participants in the Age-Related Eye Disease Study (AREDS).
Design: Case-control study.
Participants: Of the 4757 persons enrolled in AREDS, 4477 age 60 to 80 years are included in the study.
Main Outcome Measures: Slit-lamp lens photographs were used to classify participants into one of three nuclear opacity groups (moderate nuclear, mild nuclear, and controls), ignoring cortical opacities. Retroillumination lens photographs were used to classify participants into one of three cortical opacity groups (moderate cortical, mild cortical, and controls), ignoring nuclear opacities.
Results: Persons with moderate nuclear opacities were more likely to be female, nonwhite, and smokers and to have large drusen. Moderate nuclear opacities were less common in persons with higher educational status, a history of diabetes, and among those taking nonsteroidal antiinflammatory drugs. Moderate cortical opacities were associated with dark iris color, large drusen, weight change, and, at a borderline level of significance, higher levels of sunlight exposure and use of thyroid hormones. Moderate cortical opacities were less common in persons with higher educational status.
Conclusion: Consistent findings have now been reported across many studies for gender, educational status, sunlight exposure, and smoking. Our findings that use of nonsteroidal antiinflammatory drugs is inversely associated with nuclear cataract and that dark iris color and use of thyroid hormones may increase cortical cataract risk are less well substantiated and require further investigation. Ophthalmology 2001;108:1400-1408
PMCID: PMC1473213  PMID: 11470690
5.  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
6.  Inverse Association of Vitamin C with Cataract in Older People in India 
Ophthalmology  2011;118(10):1958-1965.e2.
To examine the association between vitamin C and cataract in the Indian setting.
Population-based cross-sectional analytic study.
A total of 5638 people aged ≥60 years.
Enumeration of randomly sampled villages in 2 areas of north and south India to identify people aged ≥60 years. Participants were interviewed for socioeconomic and lifestyle factors (tobacco, alcohol, household cooking fuel, work, and diet); attended a clinical examination, including lens photography; and provided a blood sample for antioxidant analysis. Plasma vitamin C was measured using an enzyme-based assay in plasma stabilized with metaphosphoric acid, and other antioxidants were measured by reverse-phase high-pressure liquid chromatography.
Main Outcome Measures
Cataract and type of cataract were graded from digital lens images using the Lens Opacity Classification System III (LOCS III), and cataract was classified from the grade in the worse eye of ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any cataract was defined as any unoperated or operated cataract.
Of 7518 enumerated people, 5638 (75%) provided data on vitamin C, antioxidants, and potential confounders. Vitamin C was inversely associated with cataract (adjusted odds ratio [OR] for highest to lowest quartile = 0.61; 95% confidence interval (CI), 0.51–0.74; P=1.1×10−6). Inclusion of other antioxidants in the model (lutein, zeaxanthin, retinol, β-carotene, and α-tocopherol) made only a small attenuation to the result (OR 0.68; 95% CI, 0.57–0.82; P < 0.0001). Similar results were seen with vitamin C by type of cataract: nuclear cataract (adjusted OR 0.66; CI, 0.54–0.80; P < 0.0001), cortical cataract (adjusted OR 0.70; CI, 0.54–0.90; P < 0.002), and PSC (adjusted OR 0.58; CI, 0.45–0.74; P < 0.00003). Lutein, zeaxanthin, and retinol were significantly inversely associated with cataract, but the associations were weaker and not consistently observed by type of cataract. Inverse associations were also observed for dietary vitamin C and cataract.
We found a strong association with vitamin C and cataract in a vitamin C–depleted population.
Financial Disclosure(s)
The author(s) have no proprietary or commercial interest in any materials discussed in this article.
PMCID: PMC3185206  PMID: 21705085
7.  Relation between time spent outdoors and exfoliation glaucoma or exfoliation glaucoma suspect 
American journal of ophthalmology  2014;158(3):605-614.e1.
To evaluate the relation between time spent outdoors at various life periods and risk of exfoliation glaucoma or exfoliation glaucoma suspect.
Retrospective cohort study in the United States.
Participants (49,033 women in the Nurses Health Study and 20,066 men in the Health Professionals Follow-up Study) were 60+ years old, free of glaucoma and cataract, reported eye exams and completed questions about time spent outdoors in direct sunlight at mid-day at 3 life periods: high school to age 24 years, age 25-35 years, and age 36-59 years (asked in 2006 in women and 2008 in men). Participants were followed biennially with mailed questionnaires from 1980 (women) / 1986 (men) to 2010. Incident cases (223 women and 38 men) were confirmed with medical records. Cohort-specific multivariable-adjusted rate ratios from Cox proportional hazards models were estimated and pooled with meta-analysis.
Although no association was observed with greater time spent outdoors in the ages of 25-35 or ages 36-59 years, the pooled multivariable-adjusted rate ratios for ≥11 hours per week spent outdoors in high school to age 24 years compared with ≤5 hours per week was 2.00 (95% confidence interval=1.30, 3.08; p for linear trend=0.001). In women, this association was stronger in those who resided in the southern geographic tier in young adulthood (p for interaction = 0.07).
Greater time spent outdoors in young adulthood was associated with risk of exfoliation glaucoma or exfoliation glaucoma suspect, supporting an etiologic role of early exposures to climatic factors.
PMCID: PMC4138242  PMID: 24857689
8.  Biomass Stoves and Lens Opacity and Cataract in Nepalese Women 
Cataract is the most prevalent cause of blindness in Nepal. Several epidemiologic studies have associated cataracts with use of biomass cookstoves. These studies, however, have had limitations, including potential control selection bias and limited adjustment for possible confounding. This study, in Pokhara city, in an area of Nepal where biomass cookstoves are widely used without direct venting of the smoke to the outdoors, focuses on pre-clinical measures of opacity, while avoiding selection bias and taking into account comprehensive data on potential confounding factors
Using a cross-sectional study design, severity of lenticular damage, judged on the LOCS III scales, was investigated in females (n=143), aged 20-65 years, without previously diagnosed cataract. Linear and logistic regression analyses were used to examine the relationships with stove type and length of use. Clinically significant cataract, used in the logistic regression models, was defined as a LOCS III score > 2.
Using gas cookstoves as the reference group, logistic regression analysis for nuclear cataract showed the evidence of relationships with stove type: for biomass stoves, the odds ratio (OR) was 2.58 (95% confidence interval [CI]: 1.22-5.46) and, for kerosene stoves, the OR was 5.18 (95% CI: 0.88-30.38). Similar results were found for nuclear color (LOCS III score > 2), but no association was found with cortical cataracts. Supporting a relationship between biomass stoves and nuclear cataract was a trend with years of exposure to biomass cookstoves (p=0.01). Linear regression analyses did not show clear evidence of an association between lenticular damage and stove types. Biomass fuel used for heating was not associated with any form of opacity.
This study provides support for associations of biomass and kerosene cookstoves with nuclear opacity and change in nuclear color. The novel associations with kerosene cookstove use deserve further investigation.
PMCID: PMC4349399  PMID: 23400024
cookstove; heating stove; cross-sectional study; indoor air pollution; kerosene; LOCS III scale
9.  Use of traditional cooking fuels and the risk of young adult cataract in rural Bangladesh: a hospital-based case-control study 
BMC Ophthalmology  2011;11:16.
This study aimed to investigate the independent relationship between the use of various traditional biomass cooking fuels and the occurrence of cataract in young adults in rural Bangladesh.
A hospital-based age- and sex-matched case-control study incorporating two control groups was conducted. Cases were cataract patients aged 18 and 49 years diagnosed on the basis of any opacity of the crystalline lens or its capsule and visual acuity poorer than 6/18 on the Log Mar Visual Acuity Chart in either eye, or who had a pseudophakic lens as a result of cataract surgery within the previous 5 years. Non-eye-disease (NE) controls were selected from patients from ENT or Orthopaedics departments and non-cataract eye-disease (NC) controls from the Ophthalmology department. Data pertaining to history of exposure to various cooking fuels and to established risk factors for cataract were obtained by face-to-face interview and analyzed using conditional logistic regression.
Clean fuels were used by only 4% of subjects. A majority of males (64-80% depending on group) had never cooked, while the rest had used biomass cooking fuels, mainly wood/dry leaves, with only 6 having used rice straw and/or cow dung. All females of each group had used wood/dry leaves for cooking. Close to half had also used rice straw and/or cow dung. Among females, after controlling for family history of cataract and education and combining the two control groups, case status was shown to be significantly related to lifetime exposure to rice straw, fitted as a trend variable coded as never, ≤ median of all exposed, > median of all exposed (OR = 1.52, 95%CI 1.04-2.22), but not to lifetime exposure to wood/dry leaves. Case status among females showed an inverse association with ever use of cow dung as a cooking fuel (OR 0.43, 95%CI 0.22-0.81).
In this population, where cooking is almost exclusively done using biomass fuels, cases of young adult cataract among females were more likely to have had an increased lifetime exposure to cooking with rice straw fuel and not to have cooked using cow dung fuel. There is a possibility that these apparent associations could have been the result of uncontrolled founding, for instance by wealth. The nature of the associations, therefore, needs to be further investigated.
PMCID: PMC3148558  PMID: 21679452
Young adult cataract; risk factor; traditional cooking fuels; Bangladesh
10.  Prevalence of Visually Significant Cataract and Factors Associated with Unmet Need for Cataract Surgery: Los Angeles Latino Eye Study 
Ophthalmology  2009;116(12):2327-2335.
To estimate in a United States (U.S.) Latino population the prevalence of visually significant cataract, and to report predisposing, enabling, need, and health behavior characteristics associated with the unmet need for cataract surgery (UNCS).
Population-based, cross-sectional study.
6142 Latinos 40 years and older from 6 census tracts in Los Angeles County, California.
Participants completed an in-home interview and a comprehensive eye examination which included assessment of lens opacification, using the slit lamp-based Lens Opacities Classification System II (LOCS II), and best-corrected visual acuity (BCVA). Visually significant cataract was defined by: any LOCS II grading ≥2, BCVA <20/40, cataract as the primary cause of vision impairment, and self-reported vision of fair or worse. Because cataract surgery is not needed in all persons, participants with a visually significant cataract or prior cataract surgery in at least one eye composed the at-risk cohort needing cataract surgery. UNCS was defined as any person in the at-risk cohort who had at least one eye with a visually significant cataract. Univariate and stepwise logistic regression analyses were used to identify predisposing, enabling, need, and health behavior characteristics associated with UNCS.
Main Outcome Measure
Prevalence of visually significant cataract, and odds ratios for factors associated with UNCS.
Of 6142 participants who completed the interview and clinical examination, 118 (1.92%) had visually significant cataract in at least one eye. Of the 344 participants who have needed cataract surgery, 118 (29.9%) had UNCS. Independent factors associated with UNCS included health behavior - having last eye exam ≥5 years ago compared to <1 year ago (odds ratio; 95% confidence interval [OR], 3.76; 1.71-8.25)- and enabling factors - being uninsured (OR, 2.79; 1.30- 5.19), income less than $20,000 (OR, 2.60; 1.40-5.56), and self-reported barriers to eye care (OR 2.41; 1.14-5.13).
Latinos in our study had a substantial unmet need for cataract surgery. As Latinos with specific health behavior and enabling characteristics were more likely to have UNCS, interventions aimed at modifying these characteristics may be beneficial in reducing the unmet need and thus reducing the burden of visual impairment related to cataract in the U.S.
PMCID: PMC2787839  PMID: 19815276
11.  Intraocular Lenses for the Treatment of Age-Related Cataracts 
Executive Summary
The objective of the report is to examine the comparative effectiveness and cost-effectiveness of various intraocular lenses (IOLs) for the treatment of age-related cataracts.
Clinical Need: Target Population and Condition
A cataract is a hardening and clouding of the normally transparent crystalline lens that may result in a progressive loss of vision depending on its size, location and density. The condition is typically bilateral, seriously compromises visual acuity and contrast sensitivity and increases glare. Cataracts can also affect people at any age, however, they usually occur as a part of the natural aging process. The occurrence of cataracts increases with age from about 12% at age 50 years, to 60% at age 70. In general, approximately 50% of people 65 year of age or older have cataracts. Mild cataracts can be treated with a change in prescription glasses, while more serious symptoms are treated by surgical removal of the cataract and implantation of an IOL.
In Ontario, the estimated prevalence of cataracts increased from 697,000 in 1992 to 947,000 in 2004 (35.9% increase, 2.4% annual increase). The number of cataract surgeries per 1,000 individuals at risk of cataract increased from 64.6 in 1992 to 140.4 in 1997 (61.9% increase, 10.1% annual increase) and continued to steadily increase to 115.7 in 2004 (10.7% increase, 5.2% increase per year).
Description of Technology/Therapy
IOLs are classified either as monofocal, multifocal, or accommodative. Traditionally, monofocal (i.e.. fixed focusing power) IOLs are available as replacement lenses but their implantation can cause a loss of the eye’s accommodative capability (which allows variable focusing). Patients thus usually require eyeglasses after surgery for reading and near vision tasks. Multifocal IOLs aim to improve near and distant vision and obviate the need for glasses. Potential disadvantages include reduced contrast sensitivity, halos around lights and glare. Accommodating IOLs are designed to move with ciliary body contraction during accommodation and, therefore, offer a continuous range of vision (i.e. near, intermediate and distant vision) without the need for glasses. Purported advantages over multifocal IOLs include the avoidance of haloes and no reduction in contrast sensitivity.
Polymethyl methacrylate (PMMA) was the first material used in the fabrication of IOLs and has inherent ultraviolet blocking abilities. PMMA IOLs are inflexible, however, and require a larger incision for implantation compared with newer foldable silicone (hydrophobic) and acrylic (hydrophobic or hydrophilic) lenses. IOLs can be further sub-classified as being either aspheric or spheric, blue/violet filtered or non-filtered or 1- or 3-piece.
Methods of Evidence-Based Analysis
A literature search was conducted from January 2003 to January 2009 that included OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), The Cochrane Library, and the International Agency for Health Technology Assessment/Centre for Review and Dissemination.
adult patients with age-related cataracts
systematic reviews, randomized controlled trials (RCTs)
primary outcomes: distance visual acuity (best corrected distance visual acuity), near visual acuity (best distance corrected near visual acuity)
secondary outcomes: contrast sensitivity, depth of field, glare, quality of life, visual function, spectacle dependence, posterior capsule opacification.
studies with fewer than 20 eyes
IOLs for non-age related cataracts
IOLs for presbyopia
studies with a mean follow-up <6months
studies reporting insufficient data for analysis
Comparisons of Interest
The primary comparison of interest was accommodative vs. multifocal vs. monofocal lenses.
Secondary comparisons of interest included:
tinted vs. non-tinted lenses
aspheric vs. spheric lenses
multipiece vs. single piece lenses
biomaterial A (e.g. acrylic) vs. biomaterial B (e.g. silicone) lenses
sharp vs. round edged lenses
The quality of the studies was examined according to the GRADE Working Group criteria for grading quality of evidence for interventional procedures.
Summary of Findings
The conclusions of the systematic review of IOLs for age-related cataracts are summarized in Executive Summary Table 1.
Considerations for the Ontario Health System
Procedures for crystalline lens removal and IOL insertion are insured and listed in the Ontario Schedule of Benefits.
If a particular lens is determined to be medically necessary for a patient, the cost of the lens is covered by the hospital budget. If the patient chooses a lens that has enhanced features, then the hospital may choose to charge an additional amount above the cost of the usual lens offered.
An IOL manufacturer stated that monofocal lenses comprise approximately 95% of IOL sales in Ontario and premium lenses (e.g., multifocal/accomodative) consist of about 5% of IOL sales.
A medical consultant stated that all types of lenses are currently being used in Ontario (e.g., multifocal, monofocal, accommodative, tinted, nontinted, spheric, and aspheric). Nonfoldable lenses, rarely used in routine cases, are primarily used for complicated cataract implantation situations.
Conclusions for the Systematic Review of IOLs for Age-Related Cataracts
BCDVA refers to best corrected distance visual acuity; BDCUNVA, best distance corrected unaided near visual acuity; HRQL, health related quality of life; PCO, posterior capsule opacification; VA, visual acuity.
PMCID: PMC3377510  PMID: 23074519
12.  Case–Control Studies and Risk Factors for Cataract in Two Population Studies in Nigeria 
The aim of this study was to determine and investigate the risks associated with cataract in South Western and North Central Nigeria.
Materials and Methods:
A hospital-based, case–control study was conducted in Lagos (Lagos group), South Western Nigeria, and Kano (Kano group), North Central Nigeria. In this study, 530 subjects with visually impairing cataracts (study group) and 530 age- and sex-matched controls (control group) were recruited from patients aged 40 to 89 years attending the ophthalmology clinics at the same hospital. All subjects were examined for the presence/absence of cataract and interviewed about their educational achievements, diarrhea/dehydration crises, urban/rural residence, and ophthalmological conditions. A standardized questionnaire was administered to all subjects. Logistic regression analysis with age adjustment, literacy, outdoor work, body mass index, crowding, regular vegetable intake, heavy alcohol, and cigarette intake was performed. P < 0.05 was considered statistically significant.
Using multivariate regression analysis, after adjustment for age and other demographics factors, low education and no education [adjusted odds ratios (OR) = 2.42 for the Lagos group and 4.10 for Kano group] and a positive history of diarrhea or dehydration crises (adjusted OR = 1.31 for the Lagos group and 2.12 for Kano group) were associated with an increased risk for cataract. Senile cataracts were more common among the Fulani ethnic group (adjusted OR = 2.21) of North Central Nigeria. However, rural or urban residence did not reveal any positive risk for cataract.
The risk of cataract in North Central Nigeria is similar to that in South Western Nigeria. Cataracts were strongly associated with increasing age, with peak age of 55 years and were more common in those with lower education, severe diarrhea and among the members of Fulani in North Central Nigeria.
PMCID: PMC2991446  PMID: 21180429
Case–Control Studies; Cataract; Fulani; Nigeria; Risk Factors; Severe Diarrhea
13.  Sunlight exposure, antioxidant status, and cataract in Hong Kong fishermen. 
STUDY OBJECTIVES--The aim was to test whether cataract is associated with higher lifetime exposure to sunlight, and whether antioxidants protect against cataract. DESIGN--This was a cross sectional survey of eye disease, with assessment of antioxidant status in a subgroup. SETTING--Hong Kong fishing communities in 1989. PARTICIPANTS--685 men and women aged 55 to 74 years old were included in the study, of whom 367 (54%) attended hospital for detailed examination. MEASUREMENTS AND MAIN RESULTS--At a mobile clinic visual acuity and lens opacities were assessed, and using a questionnaire, occupational history and lifetime exposure to sunlight. At hospital ophthalmic measurements were repeated and blood was taken for measurement of plasma vitamin C, vitamin E, and total carotenoids, and red cell activities of glucose-6-phosphate dehydrogenase, glutathione peroxidase, superoxide dismutase, and catalase. Higher grades of cataract (particularly nuclear cataract) tended to be more common in subjects with the most sun exposure, although not to the point of statistical significance. In contrast to earlier studies, no association was found with antioxidant status. CONCLUSIONS--The findings give some support to the hypothesis that sunlight causes cataract. The absence of a relation to antioxidant status may be because blood levels of antioxidants at one point in time do not adequately reflect a subject's past metabolic state, and particularly the past activity of antioxidants in the lens.
PMCID: PMC1059710  PMID: 8436894
14.  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
15.  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
16.  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
17.  Selected Sun-Sensitizing Medications and Incident Cataract 
Archives of ophthalmology  2010;128(8):959-963.
Sunlight exposure has been found to be associated with the development of age-related cataract. Use of some medications has been related to the development of sensitization to sun exposure.
To examine the relationship of use of sun-sensitizing medication on cumulative incidence of age-related cataract.
Population-based longitudinal cohort study.
Adults in the Midwestern community of Beaver Dam, Wisconsin, who were seen at baseline and three follow-up visits each five years apart.
Sun exposure was estimated from residential history that permitted calculation of Wisconsin sun years (WISY) at the baseline examination. Medication history was reported at each examination. Cataract presence was determined by standardized lens photographs that were taken at each examination and graded according to standard protocols.
Main Outcome Measure
Cumulative incidence of age-related cataract.
There were no significant effects of WISY exposure or use of sun-sensitizing medications on cumulative incidence of any type of age-related cataract while controlling for age and gender. However, there was a significant interaction term combining WISY and use of any sun-sensitizing medication on cortical cataract (P=.04) such that risk of cataract is significantly higher for persons in both risk groups: taking sun-sensitizing medication and higher sun exposure. Further controlling for diabetes status, history of heavy drinking and hat or sunglasses use did not alter the relationships.
These data suggest that use of sun-sensitizing medications interacts with sun exposure to influence the risk of cortical cataract, a common age-related cataract. If confirmed, this finding may have important implications for medication use.
PMCID: PMC2919611  PMID: 20547934
18.  Nuclear Cataract Shows Significant Familial Aggregation in an Older Population after Adjustment for Possible Shared Environmental Factors 
To quantify the association between siblings in age-related nuclear cataract, after adjusting for known environmental and personal risk factors.
All participants (probands) in the Salisbury Eye Evaluation (SEE) project and their locally resident siblings underwent digital slit lamp photography and were administered a questionnaire to assess risk factors for cataract including: age, gender, lifetime sun exposure, smoking and diabetes history, and use of alcohol and medications such as estrogens and steroids. In addition, blood pressure, body mass index, and serum antioxidants were measured in all participants. Lens photographs were graded by trained observers masked to the subjects' identity, using the Wilmer Cataract Grading System. The odds ratio for siblings for affectedness with nuclear cataract and the sibling correlation of nuclear cataract grade, after adjusting for covariates, were estimated with generalized estimating equations.
Among 307 probands (mean age, 77.6 ± 4.5 years) and 434 full siblings (mean age, 72.4 ± 7.4 years), the average sibship size was 2.7 per family. After adjustment for covariates, the probability of development of nuclear cataract was significantly increased (odds ratio [OR] = 2.07, 95% confidence interval [CI], 1.30–3.30) among individuals with a sibling with nuclear cataract (nuclear grade ≥ 3.0). The final fitted model indicated a magnitude of heritability for nuclear cataract of 35.6% (95% CI: 21.0%–50.3%) after adjustment for the covariates.
Findings in this study are consistent with a genetic effect for age-related nuclear cataract, a common and clinically significant form of lens opacity.
PMCID: PMC3092733  PMID: 15223793
19.  The Association of Dietary Lutein/Zeaxanthin and B Vitamins with Cataracts in the Age- Related Eye Disease Study AREDS Report No. 37 
Ophthalmology  2015;122(7):1471-1479.
To evaluate whether dietary intake of lutein/zeaxanthin and B vitamins is associated with cataract prevalence and incidence.
Clinic-based, baseline cross-sectional and prospective cohort study designs.
3115 (6129 eyes) persons enrolled in the Age-Related Eye Disease Study, aged 55 to 80 years, followed for mean of 9.6 years.
Participants completed baseline food frequency questionnaires. Baseline and annual lens photographs were graded centrally. Multivariable models controlling for previously identified risk factors for cataracts were used to measure the association of cataracts with reported dietary intake, using the lowest quintile as reference.
Main Outcome Measures
Cataract surgery, cataract status (type and severity) at baseline, development of cataracts.
At baseline, increased dietary riboflavin and B12 were inversely associated with nuclear and cortical lens opacities. In comparisons of persons with and without cataract, persons with the highest riboflavin intake vs. those with the lowest intake had the following associations: odds ratio (OR): 0.78, 95% confidence interval (CI): 0.63–0.97 for mild nuclear, OR: 0.62, 95% CI: 0.43–0.90 for moderate nuclear, and OR: 0.80, 95% CI: 0.65–0.99 for mild cortical cataracts. For B12, the results were: OR: 0.78, 95% CI: 0.63–0.96 for mild nuclear, OR: 0.62, 95% CI: 0.43–0.88 for moderate nuclear, and OR: 0.77, 95% CI: 0.63–0.95 for mild cortical cataracts. Highest dietary B6 intake was associated with a decreased risk of developing moderate nuclear lens opacity compared with the lowest quintile, OR: 0.67, 95% CI: 0.45–0.99. Highest dietary intake levels of niacin and B12 were associated with a decreased risk of development of mild nuclear or mild cortical cataracts in participants not taking Centrum® multivitamin. For participants taking Centrum® during the study, highest intake of dietary folate was associated with an increased risk of development of mild posterior subcapsular lens opacity. No statistically significant associations were found between lutein/zeaxanthin intake and presence at baseline or development of nuclear or cortical lens opacity outcomes.
Findings from our study are consistent with earlier studies suggesting that dietary intake of B vitamins may affect the occurrence of age-related lens opacities. Further investigations are warranted.
PMCID: PMC4485544  PMID: 25972257
20.  Increased mortality in women with cataract: a population based follow up of the North London Eye Study 
Background/aims: In diabetics, cataract is associated with higher risk of death. In non-diabetics the data are conflicting, but some indicate an association between one type of cataract (nuclear) and increased mortality. The aim of this study was to estimate and compare age and sex specific mortality for elderly people with and without cataract in a population based cohort.
Methods: A random sample drawn from a defined population of elderly people (age 65 and older) registered with 17 general practice groups in north London formed the study cohort and were followed up for 4 years. The age and sex specific mortality from various causes was estimated and compared in those with and without cataract.
Results: In non-diabetics (n=1318), cataract (lens opacity at baseline) was significantly associated with higher mortality in women. The age standardised death rate per 1000 was 39.8 and 24.8 in women with and without cataract, respectively (age adjusted hazard ratio 1.7, confidence limits 1.1 to 2.7, p=0.032). This was not the case in non-diabetic men (hazard ratio 0.9, confidence limits 0.6 to 1.5, p=0.782). The excess mortality in women with cataract was consistent for cardiovascular, respiratory, and other non-cancer causes of death. There was no association between cataract and mortality from cancer.
Conclusions: This study has shown, for the first time, that cataract is associated with higher mortality in women but not in men, among the non-diabetic population. This sex effect suggests that women may be exposed to risk factors that increase both the risk of cataract and mortality, and that men may have little or no exposure to these “sex specific” factors. Possible risk factors that warrant further investigation may be those associated with some pregnancy and childbearing experience.
PMCID: PMC1771079  PMID: 11914212
mortality; women; cataract; London
21.  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
22.  Risk of Cataract among Subjects with the Acquired Immune Deficiency Syndrome Free of Ocular Opportunistic Infections 
Ophthalmology  2014;121(12):2317-2324.
To evaluate the risk of cataract in the setting of AIDS.
Prospective cohort study.
Subjects with AIDS free of ocular opportunistic infections throughout catamnesis.
During 1998–2008 inclusive, subjects ≥13 years of age were enrolled. Demographic characteristics and clinical characteristics were documented at enrollment and semiannually.
Main Outcome Measures
Cataract was defined as high-grade lens opacity observed by biomicroscopy and judged to be the cause of a best-corrected visual acuity worse than 20/40. Eyes that underwent cataract surgery during follow-up were considered to have developed cataract prior to the first visit when pseudophakia or aphakia was observed.
Among 1,606 participants (3,212 eyes), at enrollment 1.9% (95% confidence interval (CI): 1.3%−2.7%) were observed to have cataract or prior cataract surgery. Among the 2,812 eyes initially free of cataract, and followed longitudinally (median follow-up=4.6 years), the incidence of cataract was 0.37%/eye-year (95% CI: 0.26%– 0.53%). In addition to age, significant cataract risk factors included prior cataract in the contralateral eye (adjusted hazard ratio (aHR)=21.6, 95% CI: 10.4–44.8), anterior segment inflammation (aHR=4.40, 95% CI: 1.64–11.9), prior retinal detachment (aHR=4.94, 95% CI: 2.21–11.0), and vitreous inflammation (aHR=7.12, 95% CI: 2.02– 25.0), each studied as a time-updated characteristic. Detectable HIV RNA in peripheral blood was associated with lower risk of cataract at enrollment (adjusted odds ratio=0.32, 95% CI: 0.12–0.80) but not of incident cataract (aHR=1.58, 95% CI: 0.90–2.76). After adjustment for other factors, neither the then current absolute CD4+ T cell count nor antiretroviral therapy status showed consistent association with cataract risk, nor did an additive diagnosis of other other co-morbidities. Compared to the available population-based studies that used similar definitions of cataract, the age-specific prevalence of cataract in our cohort was higher than in one of two such studies, and the age-specific incidence of cataract surgery was higher.
Our results suggest cataract may occur earlier among patients with AIDS free of ocular opportunistic infections than in the general population. Cataract risk was associated most strongly with age and with other ocular morbidity in this population. With improved survival, the burden of cataract likely will increase for persons with HIV/AIDS.
PMCID: PMC4252252  PMID: 25109932
23.  Ultraviolet radiation and the eye: an epidemiologic study. 
Circumstantial evidence from biochemical, animal, and epidemiologic studies suggests an association between exposure to UV-B radiation (290 nm to 320 nm) and cataract. Such an association had not been proven because it had not been possible to quantify ocular UV-B exposure of individuals or to reliably grade the type and severity of cataract in field studies. We undertook an epidemiologic survey of cataract among 838 watermen who work on the Chesapeake Bay. Their individual ocular UV-B exposure was quantified for each year of life over the age of 16, on the basis of a detailed occupational history combined with laboratory and field measurements of ocular UV-B exposure. Cataracts were graded by both type and severity through clinical and photographic means. SMD changes were ascertained by fundal photography. A general medical history was taken to discover potentially confounding factors. This study showed that people with cortical lens opacities had a 21% higher UV-B exposure at each year of life than people without these opacities. A doubling in lifetime UV-B exposure led to a 60% increase in the risk of cortical cataract, and those with a high annual UV-B exposure increased their risk of cortical cataract over threefold. Corneal changes, namely pterygium and CDK, were also strongly associated with high UV-B exposure. No association was found between nuclear lens opacities or macular degeneration and UV-B exposure. This study also indicated several simple, practical measures, such as wearing spectacles or a hat, that effectively protect the eye from UV-B exposure. Thus it is easily within the power of individuals to protect their eyes from excessive UV-B exposure and reduce their risk of cortical cataract. A program of public education in this area could be a cost-effective means of reducing this important disease.
PMCID: PMC1298564  PMID: 2562534
24.  Role of Mediterranean diet, tropical vegetables rich in antioxidants, and sunlight exposure in blindness, cataract and glaucoma among African type 2 diabetics 
To assess whether regular Mediterranean diet and regular intake of vegetables may reduce the risk of blindness, cataract, and glaucoma in these type 2 diabetics.
A cross-sectional design was carried out among known black diabetics admitted at the diabetic clinics of Kinshasa, between October 2008 and March 2009. The Mediterranean-style dietary score (MSDPS) was used to characterize a Mediterranean-style dietary pattern in the study population using the Harvard semi quantitative FFQ adapted for Africa.
Five hundred Type 2 diabetic patients were included in this study (48% of males; 40% aged ≥60 years). There was a significant association between blindness, cataract and aging; between blindness (P<0.05), cataract (P<0.05), glaucoma (P<0.05), and physical inactivity; between blindness (P<0.05), cataract (P<0.0001), glaucoma (P<0.01) and high SES, and a very significant association between blindness (P<0.0001), cataract (P<0.0001), glaucoma (P<0.0001) and exposure to sunlight. There was also a significant association between blindness, glaucoma, and male sex. Regular intake of Mediterranean diet, Brassica Rapa, beans, Abelmoschus, Musa acuminata reduced significantly the risk of blindness, cataract and glaucoma.
Regular intake of Mediterranean diet, Brassica Rapa, beans, Abelmoschus, and Musa acuminata may significantly reduce the risk of blindness or its major causes among type 2 diabetes mellitus in Africa.
PMCID: PMC3359045  PMID: 22762057
type 2 diabetes mellitus; Mediterranean diet; blindness; cataract; Africa
25.  Exposure to Sunlight Reduces the Risk of Myopia in Rhesus Monkeys 
PLoS ONE  2015;10(6):e0127863.
Exposure to sunlight has recently been postulated as responsible for the effect that more time spent outdoors protects children from myopia, while early life exposure to natural light was reported to be possibly related to onset of myopia during childhood. In this study, we had two aims: to determine whether increasing natural light exposure has a protective effect on hyperopic defocus-induced myopia, and to observe whether early postnatal exposure to natural light causes increased risk of refractive error in adolescence. Eight rhesus monkeys (aged 20-30 days) were treated monocularly with hyperopic-defocus (-3.0D lens) and divided randomly into two groups: AL group (n=4), reared under Artificial (indoor) Lighting (08:00-20:00); and NL group (n=4), exposed to Natural (outdoor) Light for 3 hours per day (11:00-14:00), and to indoor lighting for the rest of the light phase. After being reared with lenses for ca. 190 days, all monkeys were returned to unrestricted vision until the age of 3 years. Another eight age-matched monkeys, reared with unrestricted vision under artificial lighting since birth, were employed as controls. The ocular refraction, corneal curvature and axial dimensions were measured before lens-wearing (at 23±3 days of age), monthly during the light phase, and at the age of puberty (at 1185+3 days of age). During the lens-wearing treatment, infant monkeys in the NL group were more hyperopic than those in the AL group (F=5.726, P=0.032). Furthermore, the two eyes of most NL monkeys remained isometropic, whereas 3 of 4 AL monkeys developed myopic anisometropia more than -2.0D. At adolescence, eyes of AL monkeys showed significant myopic anisometropia compared with eyes of NL monkeys (AL vs NL: -1.66±0.87D vs -0.22±0.44D; P=0.002) and controls (AL vs Control: -1.66±0.87D vs -0.05±0.85D; P<0.0001). All differences in refraction were associated with parallel changes in axial dimensions. Our results suggest that exposure to natural outdoor light might have an effect to reduced hyperopic defocus-induced myopia. Also, the data imply that early life exposure to sunlight may help to maintain normal development of emmetropization later in life, and thus lower the risk of myopic anisometropia in adolescent monkey.
PMCID: PMC4451516  PMID: 26030845

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