Iris transluminance in type 2 diabetes.

OBJECTIVE

Cross-sectional analysis of iris transluminance in type 2 diabetic patients compared with control subjects, all followed in a cohort study.

METHODS

A cohort consisting of a well-characterized group of 82 type 2 diabetic patients were followed for 10 years after diagnosis, as were 125 control subjects. The prevalence of iris transluminance was determined by transscleral transillumination and by grading of black-and-white positive prints at the 10-year examination. The frequency of diabetic retinopathy was prospectively determined by grading of fundus photographs at baseline and after five and 10 years.

RESULTS

Iris transluminance was found in 27% of diabetic patients and 8.0% of control subjects (P = 0.001). The diabetic patients with more severe and short-term retinopathy more commonly had abnormal iris transluminance than those with no or only mild retinopathy (P < 0.05). Iris transluminance was not associated with intraocular pressure or glycemic control.

CONCLUSIONS

In type 2 diabetic patients, abnormal iris transluminance tended to associate with more severe and short-term retinopathy. Therefore we assume that hypoxia is responsible for the defects in the pigment layer of the iris. Thus, abnormal iris transluminance may serve as a marker for rapidly progressive retinopathy.