SOME PLASMA CONSTITUENTS CORRELATE WITH HUMAN CATARACT LOCATION AND NUCLEAR COLOR

Aims: To look for differences in levels of various plasma constituents between pair-matched controls and patients who had cataracts classifi ed by location and appearance of lens opacity and nuclear colour in or der to identify systemic risk factors. Methods: One thousand patients were taken from the cataract waiting list of a specialist eye hospital . For each patient, a matched control of the same sex and half-decade of age but without cataract was taken from the patient-list of the fam ily doctor of the patient; the control was the next alphabetically aft er the patient on the doctor's list. At an early morning visit to the homes of both patients and controls, fasting, a team of nurses perform ed venepunctures and collected information for a questionnaire. Eye ex aminations were performed by a team of ophthalmologists. Results: Pred ominantly nuclear cataract was significantly associated with raised pl asma alanine aminotransferase and bilirubin, posterior subcapsular cat aract with increased calcium and urea, cuneiform with reduced potassiu m, mature/hypermature with raised potassium and reduced total carbon d ioxide. The following were consistently significantly associated with all forms of cataract: diabetes and raised plasma glucose (not in non- diabetics), use of steroid medication, raised levels of cortisol (ster oid users excluded), albumin, alkaline phosphatase, gamma-glutamyl tra nspeptidase, sodium and total protein and reduced levels of cholestero l and albumin/(total protein - albumin) ratio (an approximation for th e albumin/globulin ratio). The multivariate analysis indicated that th e most important non-specific cataractogenic effects were those of inc reased total protein, diabetes and use of steroid medication. Conclusi on: This and other studies support, broadly, the conclusions that seni le or age-related cataract is not merely caused by increasing age and also that various morphological types have different risk factors. The mechanisms underlying the biochemical associations with different pat terns of lens opacification and the identification of the ultimate ris k factors remain to be elucidated.