Diabetes Can Alter the Interpretation of Visual Dysfunction in Ocular Hypertension

Abstract

The authors examined the influences of diabetes on the results of visual function testing in patients with ocular hypertension (OHT). Color vision (desaturated D-15), contrast sensitivity together with both transient and steady-state pattern electroretinogram (PERG) findings from patients with documented OHT were examined in a historic cohort study. All patients were examined at least four times (mean, 7.8 examinations) during a follow-up period that ranged from 1.5 to 4 years. Only individuals who maintained normal visual fields throughout the follow-up period were included in this analysis. The sample included 158 patients with OHT. Of these patients, 32 were African-American and 23 had a history of noninsulin-dependent diabetes with no evidence of retinopathy (by ophthalmoscopy). Normative data were obtained from a control group that included 65 white subjects with normal vision who did not have diabetes and who were similar in age to the patients in the OHT group. Color vision, contrast sensitivity, and PERG results were reduced significantly in patients with diabetes and OHT relative to control subjects. Patients with OHT who did not have diabetes did not have similar abnormalities. Color vision and PERG results also were reduced significantly in patients with diabetes and OHT relative to those with OHT who did not have diabetes. Only the steady-state PERG was reduced in African-American patients with OHT (relative to both control subjects and white patients with OHT). Patients with diabetes and OHT have significantly greater color vision, contrast sensitivity and PERG abnormalities than patients with OHT without diabetes. Race factors do not play a major role in these differences. Screening for diabetes is recommended before drawing conclusions from the results of these types of functional tests in patients with OHT.