Diabetic retinopathy. Screening and prevention of blindness. A doctoral thesis

Diabetic eye disease is a major cause of blindness in the Western World and remains one of the most serious complications of diabetes mellitus. Retinopathy is the ocular complication of diabetes that most often leads to impaired vision. In recent years laser treatment has been introduced that can significantly decrease the likelihood of blindness in diabetic patients, if the eyes are treated at the appropriate stage of the disease. It remains a public health problem to make sure that each patient is treated at the optimal time in the development of the eye disease. Several types of screening programs have been designed throughout the world to meet this problem. We now report on our active screening program for diabetic eye disease and describe the sight and eye condition of the diabetic patients who have been involved in this program. In 1980, regular eye screening for diabetic retinopathy was initiated at Department of Ophthalmology, Landakot Hospital. The number of diabetic patients seen regularly has increased considerably since then, with 70-80% of type 1 diabetic patients in the country participating in the program in 1990, increasing to over 90% in 1994. About a fifth of type 2 diabetics in the country participated in the program in 1990. The patients have undergone annual eye examinations and fundus photography. Laser treatment is administered for proliferative retinopathy and diabetic macular edema according to the Diabetic Retinopathy Study and Early Treatment Diabetic Retinopathy Study criteria. In 1990, we embarked on a cross-sectional study to evaluate the prevalence of retinopathy and visual impairment of the type 1 and type 2 patients participating in our program. At the time of study, 205 insulin-taking patients, with age at diagnosis of less than 30 years, participated in our screening program. Out of those, retinopathy was present in 106 (52%), patients proliferative retinopathy in 26 (13%) and macular edema in 19 (9%). Visual acuity of 196 patients (96%) was equal or better than 6/12 in their better eye, 6 patients (3%) had 6/18-6/36 in their better eye, and 2 patients (1%) had equal or worse than 6/60 in their better eye, or legally blind. We concluded that the prevalence of retinopathy and visual impairment in type 1 diabetic patients in the country was low compared with other countries. In 1990, out of 245 diabetic patients with Type 2 diabetes, retinopathy was present in 100 patients (41%), proliferative retinopathy had been present in 17 (7%) and 24 (10%) had diabetic macular edema. A total of 224 patients (91%) had visual acuity equal or better than 6/12 in their better eye, 17 patients (7%) with 6/18-6/36 in their better eye, and 4 patients (1.6%) equal or worse than 6/60 in their better eye, or legally blind. We concluded that the prevalence of visual impairment of those type 2 diabetic patients participating in our screening program at the time of study was low compared with population-based studies from other countries. In 1992 we examined ways to make the screening program more efficient by identifying subgroups at low risk for developing eye disease that required treatment and therefore needed less frequent screening. We studied whether diabetic eye disease screening programs could be trimmed by excluding children and examining diabetic patients without retinopathy every other year. We examined all children under the age of 15 at the time of study and went through the files of all patients under age 15 examined from 1980 to 1992 at our diabetic eye screening program. We also followed for two years the type 1 and type 2 diabetic patients found to have no retinopathy in 1990, establishing their retinopathy stage two years later. Our results indicated that diabetic children under the age of 12 do not need regular screening for eye disease. Biannual examinations seemed to suffice in type 1 and 2 diabetic patients without retinopathy. (ABSTRACT TRUNCATED)