Reduced Pupillary Unrest: Autonomic Nervous System Abnormality in Diabetes Mellitus

Pupillary unrest (fluctuations in pupil size) was measured by infrared television videopupillography in 80 insulin-dependent diabetic patients (age 25–43 yr, diabetes duration 0–35 yr) and 26 control subjects (age 26–39 yr). In darkness, pupillary unrest was 21% less in diabetic subjects than in controls. During prolonged and brief illumination, pupillary unrest was 35 and 37% less in diabetic subjects than in controls, respectively, and in both cases the unrest was inversely correlated to the duration of diabetes. There were inverse correlations between 1) vibratory perception threshold, long-term high blood glucose levels, and severity of retinopathy, and 2) pupillary unrest in darkness and during prolonged illumination. The fractional reduction in pupil size (relative miosis) was 19% less during prolonged illumination in diabetic subjects than in controls and was positively correlated to the pupillary unrest in both groups. For a given fractional reduction in pupil size during illumination, diabetic subjects still had a smaller unrest than controls. Pupil size in darkness was 19% smaller in diabetic subjects than in controls, and in diabetic subjects it was positively correlated to the unrest in darkness and during prolonged and brief illumination. None of the pupillary abnormalities showed correlation to biomicroscopic changes in the iris. The autonomic nervous system abnormalities reflected in the pupil in longstanding diabetes are 1) a reduction in pupillary unrest in light and in darkness, more pronounced in light, 2) a reduction in the ability to maintain miosis in continuous light, and 3) a reduction in size.