Assessing the natural course of diabetic retinopathy: a population-based study in Kinmen, Taiwan.
OBJECTIVE
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.
Tung
Tao-Hsin
TH
Community Medicine Research Center and Institute of Public Health, National Yang-Ming University, Taipei, Taiwan.
Chen
Shih-Jen
SJ
Shih
Hui-Chuan
HC
Chou
Pesus
P
Li
An-Fei
AF
Shyong
Mong-Ping
MP
Lee
Feng-Li
FL
Liu
Jorn-Hon
JH
D000368:Aged; D003153:Community Health Services; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000175:diagnosis* / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D008297:Male; D008390:Markov Chains; D008875:Middle Aged; D009887:Ophthalmoscopy; D015203:Reproducibility of Results; D013624:Taiwan / Q000453:epidemiology