Diabetic retinopathy in Mexico: prevalence and clinical characteristics

ABSTRACT

We present the result of a population based study designed to estimate the prevalence of diabetic retinopathy in a series of 284 type 2 diabetics residing in low income areas of Mexico city. These patients were identified in a survey performed between february 1990 and october 1992 (The Mexico City Diabetes study). We located 214 (75.35 per cent) of the original 284 patients and invited them to attend a clinic where they were interviewed and had a complete opthalmologic examination. All participant had, in addition to the retinal examination by a certified opthalmologist, seven fields stereo fundus photographs taken with a Topcon 50X retinal camera. Photos were taken using ASA 100 Kodak film and processed in their laboratory. All photographs were read and graded for quality and level of diabetic retinopathy (DR) in the Reading Center of the Department of Ophthalmology of the University of Winsconsin. A total of 37 (43.5 per cent) men and 69 (53.5 per cent) women had no evidence of DR. In 16 (18.8 per cent) men and 21 (16.3 per cent) women there was background DR. In 25 (29.4 per cent) men and 30 (23.3 per cent) women there was preproliferative DR. In 5 (5.9 per cent) men and in 7 (5.4 per cent) women there was proliferative DR. Macular edema was diagnosed in 7(8.2 per cent) men and 6 (4.7 per cent) women, of these in 3 (3.5 per cent) men and in 5 (3.9 per cent) women the macular edema was central. There was an association of duration of DM, level of fasting hyuperglycemia and microalbuminuria with the presence of DR. In 5 (7.5 per cent) men and in 7 (10.5 per cent) women with sight threatening DR, the microvascular complication had been previously undiagnosed and untreated. We conclude that DR is very common in Mexican diabetic. This complication is associated with duration of diabetes, chronic poor metabolic control and microalbuminuria. A very significant proportion of cases with sight threatening DR remains undiagnosed and untreated. Consequently there is a significant number of cases developing into blindness that could have been prevented