Is renal impairment a predictor of the incidence of cataract or cataract surgery? Findings from a population-based study

Purpose: To explore the relationship between creatinine clearance, an estimate of glomerular filtration rate, and 5-year incidence of cataract and cataract surgery. Design: Population-based cohort study. Participants: Of the 3654 participants (aged 49 years or older) of the Blue Mountains Eye Study (BMES I) baseline examination (during 1992 to 1994), 2334 (75%) were reexamined after 5 years from 1997 to 1999 (BMES II). Method. Risk factor data were collected for all participants at baseline (BMES I). Assessment of renal function was based on estimated creatinine clearance (C-Cr) calculated with the Cockcroft-Gault formula, adjusted for body surface area, and expressed in ml/minute/1.73 m(2). Cataract incidence was determined from graded photographs. The association between renal function and incidence of cataract and cataract surgery was analyzed by logistic regression. Main Outcome Measures: Incidence of nuclear, cortical, and posterior subcapsular cataract, and cataract surgery. Results: Mean C-Cr +/- standard deviation was 60 +/- 13 ml/minute/1.73 m(2). The overall 5-year incidence of nuclear, cortical, and posterior subcapsular cataract was 35.7% (417 of 1167 participants at risk), 16.7% (274 of 1641), and 4.3% (77 of 1790), respectively. Cataract surgery was performed in 6.8% (144 of 2123) of participants. There were no significant associations of renal function with incident nuclear (odds ratio [OR], 1.0; 95% confidence interval [Cl], 0.99-1.02), cortical (OR, 1.0; Cl, 0.98-1.01), and posterior subcapsular cataract (OR, 1.0; Cl, 0.99-1.04) after adjusting for multiple risk factors. After adjusting for age, gender, and dark brown iris color, moderate or worse renal impairment (C-Cr < 60 ml/minute/1.73 m(2)) compared with normal or mildly impaired function (C-Cr greater than or equal to 60 ml/minute/1.73 m(2)) was significantly associated with incident cataract surgery (P < 0.05), but the effect depended on age. Participants younger than 60 years of age with moderate to severe renal impairment had increased odds of incident cataract surgery (OR, 2.75; Cl, 1.06-7.14), but this OR decreased with age. In participants 80 years old or older, the OR was 0.34 (Cl, 0.11-1.10). Conclusions: There were no significant effects of renal function on the incidence of cataract of any type. The effect of moderate or worse renal impairment on incident cataract surgery depended on age. However, the interpretation of this effect is uncertain because of additional factors that may be involved in patients having surgery.