Influence of systemic diseases and environmental factors on age at appearance, location and type of acquired cataract.

We studied 257 patients scheduled for cataract surgery for possible correlation with systemic diseases, blood chemistry, and environmental exposure. We found that posterior subcapsular cataract appeared in patients 10 years younger on average than those with other types of cataract. Nuclear cataract patients had higher blood levels of uric acid and creatinine and lower blood levels of calcium. We suggest capsular insult as a possible pathophysiological explanation for cataract formation in young age groups (as well as diabetes) and a toxic effect of blood metabolites in patients with renal failure, resulting in earlier and more prevalent sclerosis of lens fibers. No effect of smoking or of exposure to sunlight on the distribution of various types of cataracts was noted.