Development Of Nuclear Cataract Research Articles

Function of mitochondrial cytochromec oxidase is enhanced in human lens epithelial cells at high temperatures.

Enhancement of density via human lens epithelium (HLE) cell proliferation is the underlying cause of nuclear cataracts. Moreover, our previous epidemiological study demonstrated that the risk of nuclear cataract development is significantly higher under elevated environmental temperatures compared with under lower temperatures. The present study investigated the relationship between temperature and cell proliferation in terms of mitochondrial function, which is a nuclear cataract‑inducing risk factor, using two different HLE cell lines, SRA01/04 and immortalized human lens epithelial cells NY2 (iHLEC‑NY2). Cell proliferation was significantly enhanced under the high‑temperature condition (37.5˚C) in both cell lines. The cell growth levels of SRA01/04 and iHLEC‑NY2 cells cultured at 37.5˚C were 1.20‑and1.16‑fold those in the low‑temperature cultures (35.0˚C), respectively. Moreover, the levels of cytochromec oxidase mRNA (mitochondrial genome, cytochromec oxidase‑1‑3) and its activity in SRA01/04 and iHLEC‑NY2 cells cultured at 37.5˚C were higher compared with those in cells cultured at 35.0˚C. In addition, adenosine‑5'‑triphosphate (ATP) levels in SRA01/04 and iHLEC‑NY2 cells were also significantly higher at 37.5˚C compared with those at 35.0˚C. By contrast, no significant differences in Na+/K+‑ATPase or Ca2+‑ATPase activities were observed between HLE cells cultured at 35.0and 37.5˚C. These results suggested that expression of the mitochondrial genome was enhanced in high‑temperature culture, resulting in a sufficient ATP content and cell proliferation for lens opacity. Therefore, elevated environmental temperatures may increase the risk of nuclear cataracts caused by HLE cell proliferation via mitochondrial activation.

Risk of cataract of different morphological types in Urals population chronically exposed at low doses

ObjectiveTo assess the risk of lens opacity depending on the dose in the population exposed to external and internal radiation for a long time, based on a long-term clinical follow-up of the cohorts of people exposed to radiation as a result of two radiation accidents in the South Urals. MethodsA layer-by-layer morphological study of the lens of 1,377 exposed individuals was conducted according to a special program in the Clinical Department of the Urals Research Center for Radiation Medicine (URCRM) 68 years after the onset of exposure. Lens changes were classified in accordance with the lens opacities classification (LOCS) III and included images of lens. To calculate the doses to lens, the data were taken into account, including the person's residence history in the radioactively contaminated territory, age and sex that affected their lifestyle and diet, radionuclide distribution in organs and tissues. Individualized lens doses were calculated using Techa River Dosimetry System (TRDS)-2016. Case-control method was used for statistical analysis. ResultsIndividual values of absorbed dose to lens ranged from 0 to 600 ​mGy. A dose-dependent increased risk of posterior subcapsular cataract (PSC) (OR ​1.54, 95%CI: 1.04–2.27) and nuclear cataract (OR ​1.84, 95%CI: 1.14–2.95) was found among chronically exposed individuals by a case-control method. No evidence of dose effect was found for cortical cataracts. ConclusionsThe results showed that population exposed to long-term chronic low-dose radiation was subjected to an increased risk of PSC and nuclear cataract development.

Effect of Body Temperature on ATP Production in the Human Lens and its Involvement in the Development of Nuclear Cataract

Effect of Body Temperature on ATP Production in the Human Lens and its Involvement in the Development of Nuclear Cataract

Non-Modifiable Risk Factors for Cataract Genesis

The review reflects the current data on unmodified risk factors for cataract development; most prominent are genetic factors and age. Research shows that about half of nuclear and two-thirds of cortical cataracts can be hereditary. Congenital cataracts are hereditary in 25 % of cases, of which 75 % are autosomal dominant. From 30 % to 50 % of congenital cataracts are caused by mutations in genes encoding proteins in the structure of the lens. To date, 115 genes have been identified associated with syndromic and non-syndromic cataracts. Proof of the genetic theory is the development of nuclear cataract in Stickler syndrome (SS), a relatively rare multisystem connective tissue disease inherited in an autosomal dominant manner. The syndrome is characterized by structural abnormalities in collagens of types 2, 9 and 11 and manifests itself in various clinical signs, including the development of facial skeleton anomalies, damage to the vision organ, the musculoskeletal system and the auditory system. Ophthalmic complications of SS are represented by a combination of pathological myopia, retinal detachment, ocular hypertension, early vitreous liquefaction and premature cataract development. Age is the main unmodified risk factor for developing cataracts. The most common form of cataract is age-related nuclear cataract, which in developing countries accounts for 50 % to 90 % of the total number of cases (> 70 versus ≤ 65 years, OR = 12.7). The pathogenesis of age-related nuclear cataract is associated with oxidative damage to proteins under certain conditions: a decrease in the concentration of glutathione (GSH) and vitamin C in the lens nucleus. When examining the frequency of cortical cataract, there was also a relationship with an increase in the age of patients (> 70 years versus ≤ 65 years, OR = 5.96). With age, a barrier is created for the advancement of GSH from the site of its synthesis and regeneration in the cortical layer of the lens towards the nucleus. Numerous experimental and morphological studies confirm the accommodative theory of the development of age-related cortical cataract. Lens deformations caused by accommodation forces lead to heterogeneity of the lens density at the border of the nucleus and cortical layers, an increase in light scattering and damage to the lens fibers. Genetic predisposition and age are interactions of many complex factors that can contribute to the development of cataracts.

Effect of a Lens Protein in Low-Temperature Culture of Novel Immortalized Human Lens Epithelial Cells (iHLEC-NY2).

The prevalence of nuclear cataracts was observed to be significantly higher among residents of tropical and subtropical regions compared to those of temperate and subarctic regions. We hypothesized that elevated environmental temperatures may pose a risk of nuclear cataract development. The results of our in silico simulation revealed that in temperate and tropical regions, the human lens temperature ranges from 35.0 °C to 37.5 °C depending on the environmental temperature. The medium temperature changes during the replacement regularly in the cell culture experiment were carefully monitored using a sensor connected to a thermometer and showed a decrease of 1.9 °C, 3.0 °C, 1.7 °C, and 0.1 °C, after 5 min when setting the temperature of the heat plate device at 35.0 °C, 37.5 °C, 40.0 °C, and 42.5 °C, respectively. In the newly created immortalized human lens epithelial cell line clone NY2 (iHLEC-NY2), the amounts of RNA synthesis of αA crystallin, protein expression, and amyloid β (Aβ)1-40 secreted into the medium were increased at the culture temperature of 37.5 °C compared to 35.0 °C. In short-term culture experiments, the secretion of Aβ1-40 observed in cataracts was increased at 37.5 °C compared to 35.0 °C, suggesting that the long-term exposure to a high-temperature environment may increase the risk of cataracts.

Association between ultraviolet radiation exposure dose and cataract in Han people living in China and Taiwan: A cross-sectional study.

PurposeWe investigated associations between ocular ultraviolet (UV) radiation exposure dose and cataract opacities among Han people living in China and Taiwan, to assess the effects of UV exposure intensity.MethodsThis cross-sectional study included Han people aged ≥40 years (1,801 individuals, 450 in Sanya, 636 in Taiyuan, and 715 in Taichung) as subjects who completed a questionnaire including items about diabetes, smoking, steroid use, work history, and time spent outdoors, and underwent an ophthalmic examination. Right eye axial length was measured using A-mode ultrasonography or IOLMaster. Slit-lamp imaging under maximum mydriasis was used to classify cataracts into three major types [cortical (COR), nuclear (NUC), and posterior subcapsular cataracts (PSC)] and two subtypes [retrodots (RD) and waterclefts (WC)] by one ophthalmologist. COR was divided into opacity presence (CEN+) or absence (CEN-) in the central 3-mm diameter area of the pupil. COR was also subdivided into three groups according to opacity shape: axle-shaped opacity concomitant with WC, wedge-shaped opacity around the pupil to the eye center, and ring-shaped opacity in the lens equator along the pupillary margin. The cumulative ocular UV exposure (COUV) was calculated. A logistic regression analysis was used for multivariate analysis.ResultsCataract odds ratios in high COUV eyes were 5.35 for NUC, 1.87 for PSC, and 1.35 for RD. In eyes with WC, risk of COR ring-shaped opacity significantly increased but that of wedge-shaped opacity (CEN+) significantly decreased. In eyes without WC, risk of COR axle-shaped opacity (CEN–) and ring-shaped opacity significantly increased but that of wedge-shaped opacity (CEN+) significantly decreased.ConclusionsIncreased COUV level among Han people may be a risk factor for the development of nuclear cataracts, PSC, retrodots and ring-shaped cortical cataract. Risk of ocular UV exposure for cortical cataract may differ by opacity shape.

Quantitative metabolomic analysis of changes in the lens and aqueous humor under development of age-related nuclear cataract.

Metabolites are essential for the proper functioning of the eye lens, they either enter the lens from the aqueous humor (AH), or are synthesized in the lens epithelium. Antioxidants, osmolytes and UV filters are especially important for the lens protection, and their lack may cause the development of ophthalmic diseases. Comparison of the metabolomic compositions of lenses and AH taken from cataract patients with that taken from human cadavers without cataract can shed light onto molecular mechanisms underlying onset of age-related nuclear cataract. Combined use of 1H nuclear magnetic resonance and high performance liquid chromatography with optical and high-resolution mass spectrometric detection for the identification and quantification of metabolites in the lens and AH extracts. The concentrations of 86 metabolites were determined for four groups of samples, including lenses and AH from cataract patients and from human cadavers. In cataractous lens the most abundant metabolites are (in descending order): myo-inositol, lactate, acetate, glutamate, glutathione; in AH-lactate, glucose, glutamine, alanine, valine. The concentrations of the majority of metabolites in normal post-mortem samples of both lens and AH are higher than that in samples from the cataract patients. Comparison of metabolite concentrations in lens and corresponding AH reveal that the most important for the lens protection metabolites are synthesized in the lens epithelial cells. The reduced levels of antioxidants, UV filters, and osmolytes were found in the cataractous lenses what cannot be explained by post-mortem changes in normal lens; that indicates that the age-related nuclear cataract development may originate from the dysfunction of the lens epithelial cells.

Serum 25-hydroxyvitamin D and Age-Related Cataract

ABSTRACTPurpose: Cataract and insufficient vitamin D intake are both increasing worldwide concerns, yet little is known about the relationship between serum 25-hydroxyvitamin D (25(OH)D) levels and age-related cataract. We performed this study to determine the association between serum 25(OH)D levels and age-related cataract in adults.Methods: Study participants comprised 16,086 adults aged 40 years or older who had never been diagnosed with or undergone surgery for cataract using Korean National Health and Nutrition Examination Survey data from 2008 to 2012. Participants were assessed to have cataract when diagnosed with cortical, nuclear, anterior subcapsular, posterior subcapsular, or mixed cataract. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to evaluate the magnitude and significance of the association between serum 25(OH)D levels and cataract in multivariable logistic regression models.Results: The OR for nuclear cataract with the highest quintile of serum 25(OH)D levels was 0.86 (95% CI 0.75–0.99) compared to the lowest quintile. A linear trend across quintiles was significant. Natural log-transformed serum 25(OH)D levels were also significantly associated with nuclear cataract (OR 0.84, 95% CI 0.75–0.95). The opulation-attributable fraction of nuclear cataract due to serum 25(OH)D insufficiency (<30 ng/mL) was 8.8% (p = 0.048).Conclusions: Serum 25(OH)D levels were inversely associated with the risk of nuclear cataract. Prospective studies investigating the effects of serum 25(OH)D levels on the development of nuclear cataract are needed to confirm our findings.

Vitreous Humor Changes Expression of Iron-Handling Proteins in Lens Epithelial Cells.

PurposeIn humans, vitrectomy is associated with development of nuclear cataracts. Iron catalyzes free radical formation causing oxidative damage, which is implicated in cataract formation. This study was designed to determine if vitreous humor, which can initiate differentiation of lens epithelial cells, would have an effect on iron-handling proteins.MethodsCultured canine lens epithelial cells were treated with collected canine vitreous humor. Lysates of treated and control cells were separated by SDS-PAGE. Ferritin H- and L-chains, transferrin receptor 1, and aquaporin 0 were immunodetected and quantitated with specific antibodies. Morphologic changes in treated cells were assessed.ResultsTreatment of lens epithelial cells with a 33% (vol/vol) solution of vitreous humor changed the morphology of lens cells and induced expression of aquaporin 0, a marker of fiber cell differentiation that was undetectable in control cells. Treatment did not modify the size of iron-handling proteins but significantly increased content of ferritin from 2.9- to 8.8-fold over control and decreased levels of transferrin receptor by 37% to 59%.ConclusionsVitreous humor may significantly limit iron uptake by transferrin/transferrin receptor pathway, and by increasing ferritin levels could profoundly increase the iron-storage capacity of ferritin in lens cells. Vitreous humor may play a significant protective role against iron-catalyzed oxidative damage of lens epithelial cells and therefore in the formation of cataracts.

CRYβA3/A1-Crystallin Knockout Develops Nuclear Cataract and Causes Impaired Lysosomal Cargo Clearance and Calpain Activation.

βA3/A1-crystallin is an abundant structural protein of the lens that is very critical for lens function. Many different genetic mutations have been shown to associate with different types of cataracts in humans and in animal models. βA3/A1-crystallin has four Greek key-motifs that organize into two crystallin domains. It shown to bind calcium with moderate affinity and has putative calcium-binding site. Other than in the lens, βA3/A1 is also expressed in retinal astrocytes, retinal pigment epithelial (RPE) cells, and retinal ganglion cells. The function of βA3/A1-crystallin in the retinal cell types is well studied; however, a clear understanding of the function of this protein in the lens has not yet been established. In the current study, we generated the βA3/A1-crystallin knockout (KO) mouse and explored the function of βA3/A1-crystallin in lens development. Our results showed that βA3-KO mice develop congenital nuclear cataract and exhibit persistent fetal vasculature condition. At the cellular level KO lenses show defective lysosomal clearance and accumulation of nuclei, mitochondria, and autophagic cargo in the outer cortical region of the lens. In addition, the calcium level and the expression and activity of calpain-3 were increased in KO lenses. Taken together, these results suggest the lack of βA3-crystallin function in lenses, alters calcium homeostasis which in turn causes lysosomal defects and calpain activation. These defects are responsible for the development of nuclear cataract in KO lenses.

Longitudinal Study of Age-Related Cataract Using Dynamic Light Scattering: Loss of α-Crystallin Leads to Nuclear Cataract Development

To conduct a longitudinal study on age-related nuclear cataracts using dynamic light scattering (DLS) to determine if cataract progression is associated with loss of the unbound form of the lens molecular chaperone protein, α-crystallin. Natural history and cohort study. Patients 30 years of age or older of either gender seeking treatment at the Wilmer Eye Institute Cornea-Cataract Department. All patients underwent a comprehensive dilated eye examination every 6 months, including slit-lamp grading of their lenses using the Age-Related Eye Disease Study (AREDS) clinical lens grading system and obtaining an estimate of unbound α-crystallin level in the nucleus, the α-crystallin index (ACI), using the National Aeronautics and Space Administration-National Eye Institute DLS device. We used a random effects statistical model to examine the relationship of lens opacity changes over time with ACI changes. α-Crystallin Index (ACI) and AREDS nuclear cataract grade. Forty-five patients (66 eyes) 34 to 79 years of age with AREDS nuclear lens grades of 0 to 3.0 were followed up every 6 months for a mean of 19 months (range, 6-36 months). We found that lenses with the lowest baseline levels of ACI had the most rapid progression of cataracts, whereas lenses with higher ACI at baseline had no or slower cataract progression. Lenses that lost α-crystallin at the highest rates during the study also had faster progression of nuclear cataracts than lenses with a slower rate of ACI loss. Kaplan-Meier survival curves showed that lenses with the lowest initial ACI had the highest risk of undergoing cataract surgery. This longitudinal study corroborates our previous cross-sectional study finding that higher levels of unbound α-crystallin as assessed by ACI are associated with lower risk of cataract formation and that loss of ACI over time is associated with cataract formation and progression. This study suggested that assessment of ACI with the DLS device could be used as a surrogate for lens opacity risk in clinical studies, and for assessing nuclear cataract events in studies where cataract development may be a side effect of a drug or device.

Oxygen-induced changes in mitochondrial DNA and DNA repair enzymes in aging rat lens

The treatment of patients with hyperbaric oxygen (HBO), vitrectomy and loss of vitreous gel during aging is associated with a high risk of subsequent development of nuclear cataract. Many studies proved that oxidation is the key reason of nuclear cataract. Reactive oxygen species (ROS) are formed in mitochondria as a by-product of normal metabolism and as a consequence of exposure to environmental compounds. Therefore, mitochondrial DNA (mtDNA) is at particularly high risk of ROS-induced damage. Oxidative damage to mtDNA has been implicated as a causative factor in a wide variety of degenerative diseases and aging. However, the effect of mtDNA damage to the lens has not been studied. The goals of the study were to identify if there was increased mtDNA damage in lens when the eye were exposed to hyperoxic or hypoxic conditions and also to evaluate the changes in gene expression of mtDNA base excision repair (mtBER) enzymes. Our data have shown that the damage of mtDNA, the expression of mtBER enzymes and the level of 8-OHdG in lens increased after inspired hyperoxia, which is likely associated with oxidative stress. However, there was no effect to mtDNA and mtBER enzymes in lens after inspired hypoxia. Nuclear cataract appeared rapidly at 14 month old rats in hyperoxia group, and lens kept transparency in other groups.

Use of Inhaled and Oral Corticosteroids and the Long-term Risk of Cataract

Longitudinal associations between inhaled and oral corticosteroid use and 10-year incident cataract were examined. Population-based cohort study. The Blue Mountains Eye Study examined 3654 Australians aged 49 years or older (1992-1994); 2335 were re-examined after 5 years and 1952 were re-examined after 10 years (75.1%, 75.6% of survivors, respectively). Questionnaires were used to assess inhaled and oral corticosteroid use at baseline. Past users were participants who had used these medications for at least 1 month in the past but were not using them at baseline. Current users were those who were using these medications at baseline and had been doing so for at least 1 month. Ever users combined past and current users. Lens photographs were obtained at each examination and graded for nuclear, cortical, and posterior subcapsular (PSC) cataracts following the Wisconsin Cataract Grading System. Participants without a specific subtype of cataract in either eye at baseline were considered to be at risk of that type of cataract developing over the 10-year follow-up. Incidence of each cataract subtype in this report refers to person-specific, first-eye incidence. At baseline, 103 participants were current and 120 past users of inhaled corticosteroids, and 31 were current and 147 were past users of oral corticosteroids. Current users had a greater risk of developing PSC cataract after adjustment for age and gender (inhaled: odds ratio [OR] 2.50, 95% confidence interval [CI] 1.33-4.69; oral: OR 4.11; 95% CI 1.67-10.08) and nuclear cataract (inhaled: OR 2.04, 95% CI 1.21-3.43; oral: OR 3.45, 95% CI 1.26-9.43) but not cortical cataract. Interaction between inhaled and oral corticosteroid use was significant for PSC (P = 0.01) and nuclear (P = 0.02) cataract incidence. In subgroup analyses, only individuals who used both inhaled and oral steroids were at increased risk of PSC cataract (after adjusting for age, sex, smoking, hypertension, diabetes, and education levels; OR 4.76, 95% CI 2.59-8.74), comparing ever users of both with users of neither. High long-term risks of PSC and nuclear cataract development were found for users of combined inhaled and oral corticosteroids.

Antioxidant nutrient intake and the long-term incidence of age-related cataract: the Blue Mountains Eye Study

BackgroundOxidative stress has been implicated in cataractogenesis. Long-term intake of antioxidants may offer protection against cataract. ObjectiveWe investigated relations between antioxidant nutrient intakes measured at baseline and the 10-y incidence of age-related cataract. DesignDuring 1992–1994, 3654 persons aged ≥49 y attended baseline examinations of the Blue Mountains Eye Study (82.4% response). Of these persons, 2464 (67.4%) participants were followed ≥1 time after the baseline examinations (at either 5 or 10 y). At each examination, lens photography was performed and questionnaires were administered, including a 145-item semiquantitative food-frequency questionnaire. Antioxidants, including β-carotene, zinc, and vitamins A, C, and E, were assessed. Cataract was assessed at each examination from lens photographs with the use of the Wisconsin Cataract Grading System. Nuclear cataract was defined for opacity greater than standard 3. Cortical cataract was defined as cortical opacity ≥ 5% of the total lens area, and posterior subcapsular (PSC) cataract was defined as the presence of any such opacity. ResultsParticipants with the highest quintile of total intake (diet + supplements) of vitamin C had a reduced risk of incident nuclear cataract [adjusted odds ratio (OR): 0.55; 95% CI: 0.36, 0.86]. An above-median intake of combined antioxidants (vitamins C and E, β-carotene, and zinc) was associated with a reduced risk of incident nuclear cataract (OR: 0.51; 95% CI: 0.34, 0.76). Antioxidant intake was not associated with incident cortical or PSC cataract. ConclusionHigher intakes of vitamin C or the combined intake of antioxidants had long-term protective associations against development of nuclear cataract in this older population.

Smoking and the Long-Term Incidence of Cataract: The Blue Mountains Eye Study

Purpose: To assess the association between smoking and the long-term incidence of cataract and cataract surgery. Methods: In a population-based cohort of Australians aged 49 years and over, 3654 participants were seen at baseline (1992–94) and 2406 were seen after 5- and/or 10-years and had photographs taken to assess incident cataract. Smoking status was recorded at interview. History, physical examination and fasting blood samples provided data on possible risk factors. Cataract incidence was calculated using the Kaplan-Meier survival approach. Discrete linear logistic models were used to assess risk of incident cataract. Results: After controlling for age, sex and other factors, ever smokers had an increased risk of developing nuclear cataract compared to never smokers (relative risk (RR) 1.41; 95% confidence interval (CI) 1.09–1.83; RR 1.37, CI 1.04–1.81 for past smoking and RR 1.57, CI 1.06–2.31 for current smoking). The effect of smoking was strongest in ever smokers reporting 36 + pack-years of smoking compared to never smokers (RR 1.46; CI, 1.02–2.08). Current smokers also developed nuclear cataract slightly younger than non-smokers (mean age 65.2 versus 67.5 years, p = 0.049). No statistically significant associations were found between smoking status and the incidence of cortical or posterior subcapsular cataract, or cataract surgery. Conclusions: These epidemiological data confirm smoking as a modest risk factor for the development of nuclear cataract.

Post-Translational Modifications in the Nuclear Region of Young, Aged, and Cataract Human Lenses

The urea-soluble proteins from the nucleus of two young, two aged, and two early-stage nuclear cataract lenses were subjected to tryptic digestion and analysis by 2D LC-MS/MS. Several novel post-translational modifications were identified. Deamidation was, by far, the most common modification. A number of differences were found in cataract compared to normal lenses, most notably an increase in the number of oxidized tryptophan residues. Semiquantitative analysis revealed that there appeared to be a trend toward increased levels of deamidation with age; however, there was no apparent increase upon the onset of nuclear cataract. This is in contrast to Trp oxidation, where an increase in the extent of modification was apparent in cataract lenses when compared to aged normal lenses. These findings suggest Trp oxidation may be involved in nuclear cataract development.

Nuclear Cataract

JAMA Statin Use and Incident Nuclear Cataract Context: Statins are widely prescribed for their lipid-lowering effects but also have putative antioxidant properties. Oxidative stress is believed to play a role in the development of nuclear cataract, but little is known regarding the relationship of statin use and cataract incidence. Objective: To evaluate the relationship of use of statins and incident cataract in adults in a midwestern community in the United States. Design, Setting, and Participants: The Beaver Dam Eye Study, an observational, longitudinal, population-based study of age-related eye disease in Beaver Dam, Wis. There were 1299 persons who were seen at the third examination in 1998-2000, had gradable photographs in both eyes, and were deemed to be at risk of developing nuclear cataract within 5 years. Main Outcome Measure: Five-year incidence of cataract with respect to statin use. Cataracts were graded from photographs taken through the participant's dilated pupil. Results: A total of 210 persons developed incident nuclear cataract in the interval from 1998-2000 to 2003-2005. Five-year incidence of nuclear cataract was 12.2% in statin users compared with 17.2% in nonusers (odds ratio [OR], 0.55; 95% confidence interval [CI], 0.36-0.84), controlling for age. When only never smokers without diabetes were assessed, the age-, lipid level–, and sex-adjusted OR was 0.40 (95% CI, 0.18-0.90). Five-year incidence of cortical cataract was 9.9% in statin users and 7.5% in nonusers (OR, 1.28; 95% CI, 0.79-2.08); posterior subcapsular cataract occurred in 3.0% of statin users and 3.4% of nonusers (OR, 0.82; 95% CI, 0.39-1.71). Conclusion: Statin use in a general population appears to be associated with lower risk of nuclear cataract, the most common type of age-related cataract.

Statin Use and Incident Nuclear Cataract

Statins are widely prescribed for their lipid-lowering effects but also have putative antioxidant properties. Oxidative stress is believed to play a role in the development of nuclear cataract, but little is known regarding the relationship of statin use and cataract incidence. To evaluate the relationship of use of statins and incident cataract in adults in a midwestern community in the United States. The Beaver Dam Eye Study, an observational, longitudinal, population-based study of age-related eye disease in Beaver Dam, Wis. There were 1299 persons who were seen at the third examination in 1998-2000, had gradable photographs in both eyes, and were deemed to be at risk of developing nuclear cataract within 5 years. Five-year incidence of cataract with respect to statin use. Cataracts were graded from photographs taken through the participant's dilated pupil. A total of 210 persons developed incident nuclear cataract in the interval from 1998-2000 to 2003-2005. Five-year incidence of nuclear cataract was 12.2% in statin users compared with 17.2% in nonusers (odds ratio [OR], 0.55; 95% confidence interval [CI], 0.36-0.84), controlling for age. When only never smokers without diabetes were assessed, the age-, lipid level-, and sex-adjusted OR was 0.40 (95% CI, 0.18-0.90). Five-year incidence of cortical cataract was 9.9% in statin users and 7.5% in nonusers (OR, 1.28; 95% CI, 0.79-2.08); posterior subcapsular cataract occurred in 3.0% of statin users and 3.4% of nonusers (OR, 0.82; 95% CI, 0.39-1.71). Statin use in a general population appears to be associated with lower risk of nuclear cataract, the most common type of age-related cataract.

Development of Cataract and Associated Risk Factors

To evaluate risk factors for the development of cataract in Australian residents. A total of 3721 participants from 9 randomly selected urban districts within Victoria were recruited and invited to attend comprehensive standardized interviews and ophthalmic examinations at baseline and then 5-year follow-up. Lens opacities were graded clinically and on photographs according to the Wilmer cataract grading system. The development of cortical, nuclear, and posterior subcapsular cataract were assessed separately for associated risk factors. Risk exposure at baseline was used as the predictor for cataract development, which included various sociodemographic, dietary, familial, medical, and ocular characteristics of the participants. Risk factor analyses were performed by univariate and multivariate logistic regression. Increased age was a risk factor for development of all types of cataract with an increasing risk trend throughout life for nuclear cataract. Female sex, a laborer's occupation, and myopia were independent risk factors for development of cortical cataract. For development of nuclear cataract, the independent risk factors were having a birthplace outside Australia and New Zealand, current cigarette smoking, and having a history of arthritis. Diabetes mellitus and having taken calcium channel blockers for longer than 5 years were independent risk factors for posterior subcapsular cataract. The trend of increasing incidence of cataract with increased age is a major public health concern with an aging population in Australia and the world. Among the risk factors identified, cigarette smoking is a factor that is readily modifiable and preventable. The other risk factors identified require further support or clarification of underlying mechanisms to find modifiable features.

Smoking and cataract: Review of causal association

Several risk factors for the development of cataract have been identified. This review evaluates epidemiologic literature that has examined tobacco smoking as a risk factor for cataract formation using established causality criteria. Twenty-seven studies were included in this review. Evidence suggests that smoking has a 3-fold increase on the risk for incident nuclear cataract development. There was also evidence of dose response, temporal relationship, and reversibility of effect. There was limited evidence of an association between smoking and posterior subcapsular cataract, but little or no association with cortical cataract. Thus, the literature review indicated a strong association between smoking and the development of cataract, particularly nuclear cataract. The association fulfills the established criteria for causality. The association between smoking and other types of cataract is less distinct and requires further evaluation.