Assessing the Natural Course of Diabetic Retinopathy: A Population-Based Study in Kinmen, Taiwan

Abstract

Purpose: To explore the natural course of diabetic retinopathy among type 2 diabetics using the indirect ophthalmoscope and single-field fundus photographs in Kinmen, Taiwan. Methods: A screening program for diabetic retinopathy was carried out by a panel of ophthalmologists, who employed the ophthalmoscope and 45-degree retinal color photographs to examine the fundus after pupil dilation. Screening, which was conducted between 1999 and 2002, involved 971 patients diagnosed with type 2 diabetes. A multi-state Markov model was used to assess the natural course of diabetic retinopathy among type 2 diabetics. Results: Among the 725 diabetes patients who attended at least two ophthalmological fundus check-ups and were screened, the overall response rate was about 75%. The mean duration of the disease states mild nonproliferative diabetic retinopathy, moderate nonproliferative diabetic retinopathy, severe nonproliferative diabetic retinopathy, and proliferative diabetic retinopathy were 4.05 [95% confidence interval (CI): 3.28–5.32], 4.18 (95% CI: 3.18–6.06), 2.52 (95% CI: 1.78–4.27), and 4.22 (95% CI: 2.88–7.81) years, respectively. Compared to controls, the incidence of blindness reduction for annual, biennial, 3-year, 4-year, and 5-year screenings of diabetic retinopathy were approximately 94.4% (95% CI: 91.6%–96.3%), 83.9% (95% CI: 83.6%–84.2%), 70.2% (95% CI: 69.8%–70.7%), 57.2% (95% CI: 56.7%–57.7%), and 45.6% (95% CI: 45.0%–46.1%), respectively. Conclusions: In conclusion, the average time for the development of diabetic retinopathy from nonexistence to blindness was approximately 26.5 years. The present recommendation for annual screening in type 2 diabetics with nonproliferative diabetic retinopathy should be retained only for the mild form, not for the moderate or severe forms.