Risk factors for nuclear opacities - The longitudinal study of cataract

Purpose. To evaluate risk factors for increases of nuclear opacification of the lens in a longitudinal study. Methods. The Longitudinal Study of Cataract followed 764 participants in a case-control study of lens opacities, which provided baseline data on personal, nutritional, medical, biochemical, and other risk factors. Follow-up visits were completed at yearly intervals from 1989 to 1993. Ophthalmologic and other data were collected at baseline and follow-up, as well as lens photographs, which were graded using the Lens Opacities Classification System III protocol. Analyses evaluated which risk factors collected at baseline were related to increases in nuclear opacification at follow-up. The MULCOX2 approach, which is based on the Cox regression model for multiple failure times, was used to estimate the effects of the risk factors. This model accounted for the correlation between fellow eyes. Results. Of the 744 participants with lens status classification of nuclear opalescence at baseline, 47% had nuclear opacities (score ≥2.0 in either eye) and 53% had no nuclear opacities (score<2.0 in both eyes). Risk factors (P<0.05) for the incidence of new nuclear opacities were age (RR=1.1) and baseline PSC cataract (RR=5.3). Factors associated (P<0.05) with the progression of nuclear opacities in persons with pre-existing opacities were white race (RR=2.3), and use of gout medications (RR=2.0). In addition, factors associated with the development or worsening of nuclear opacities were lower education (RR=1.6), current smoking status (RR=1.6), family history of cataract (RR= 1.4), and use of eyeglasses by age 20 years, an indicator of myopia (RR=1.6). Conclusions. Nuclear opacities were associated with potentially modifiable factors, such as current smoking and use of gout medications. Most risk factors identified by this longitudinal study confirm those found by the original case-control study.