Nutritional factors and risk of nuclear opacities - The longitudinal study of cataract

Purpose. The importance of age-related cataract as a cause of worldwide blindness has led to many efforts to identify risk factors, particularly ones that are potentially modifiable. We report on the association between nutritional factors and progression of nuclear opacification of the lens in a longitudinal study. Methods. The Longitudinal Study of Cataract followed 764 participants from a case-control study of lens opacities. Data collection of nutritional status at baseline included a dietary intake assessment through a food frequency questionnaire, use of nutritional supplements, and vitamin E determinations in frozen plasma samples. 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. The MULCOX2 approach, based on the Cox regression model for multiple failure times, was used to estimate the effects of the nutritional factors. This model accounted for the correlation between fellow eyes. Results. Data on nuclear changes were available on 744 participants. At baseline, 47% had nuclear opacities (score ≥2.0 in either eye) and 53% had no nuclear opacities (score <2.0 in both eyes). Median age was 65 years and 45% were men. When all participants were evaluated, the intake of multivitamin supplements was associated with a decreased risk of nuclear opacities (RR=0.63; 95% CI: 0.43-3.93). In the subset of patients with nuclear opacities at baseline, regular use of multivitamins (RR=0.65; 95% CI: 0.42-0.98) and higher plasma levels of vitamin E (RR=0.53; 95% CI: 0.29-0.94) were associated with a lower progression of nuclear opacities. Conclusions. The study confirmed results found in the original case-control study, where the use of nutritional supplements and higher levels of plasma vitamin E decreased the risk of nuclear opacities. These findings offer the possibility of cataract prevention, which needs to be confirmed in controlled clinical trials.