Abstract
Abstract: :
Purpose:To investigate the association of primary open angle glaucoma, ocular hypertension, and high cup–to–disc ratio with the progression of diabetic retinopathy. Methods:This project is a retrospective study of patients with diabetes mellitus seen at a county eye clinic and a private eye clinic. 75 patients and 150 eyes were included. Severity of retinopathy was determined by clinical examination. Glaucoma status was determined by clinical examination of cup–to–disc ratio, intraocular pressure as measured by applanation tonometry, gonioscopy, and Humphrey visual field. . Patients were categorized by glaucoma status (primary open angle glaucoma, ocular hypertension, high cup–to–disc ratio, and normal), and chi–square analysis was used to compare the stages of retinopathy for each glaucoma status. Results:The percentages of proliferative retinopathy for each glaucoma status were as follows: primary open angle glaucoma 3.1%, high cup–to–disc ratio 7.1%, ocular hypertension 37.5%, and normal 32.1%. Patients with primary open angle glaucoma (p<0.002) and patients with high cup–to–disc ratios (p<0.05) were significantly different in the severity of retinopathy than normal patients based on chi–square analysis. Normal patients were not significantly different in the severity of retinopathy than patients with ocular hypertension (p=0.79). The severity of retinopathy was significantly different between patients with primary open angle glaucoma and patients with ocular hypertension (p<0.02). There was no significant difference in the severity of retinopathy between patients with primary open angle glaucoma and patients with high cup–to–disc ratios (p=0.65). Conclusions:The results of this study suggest a suppressive effect of glaucoma on diabetic retinopathy. Since the effect did not exist in patients with only ocular hypertension, the results support the metabolic theory of reduced number ganglion cells leading to a decreased ischemic response. Surprisingly, high cup–to–disc ratio also appears to suppress the progression of retinopathy. This may suggest a beneficial effect of subclinical ganglion cell loss on the progression of retinopathy.
Keywords: diabetic retinopathy