The 25-year incidence of visual impairment in type 1 diabetes mellitus the wisconsin epidemiologic study of diabetic retinopathy.

OBJECTIVE: To examine the 25-year cumulative incidence of visual impairment (VI) and its relation to various risk factors.
DESIGN: Population-based study. PARTICIPANTS: Nine hundred fifty-five insulin-taking persons living in an 11-county area in southern Wisconsin with type 1 diabetes diagnosed before age 30 years who participated in a baseline (1980-1982) and at least 1 of 4 follow-up (4-, 10-, 14-, and 25-year) examinations or who died before the first follow-up examination (n = 64).
METHODS: Best-corrected visual acuity (VA) was measured using a modification of the Early Treatment Diabetic Retinopathy Study protocol. Visual impairment and severe VI were defined as best-corrected VA in the better eye of 20/40 or worse and 20/200 or worse, respectively. MAIN OUTCOME MEASURES: Incidence of VI.
RESULTS: The 25-year cumulative incidences of any VI and severe VI (accounting for competing risk of death) were 13% and 3%, respectively. Multivariate models showed increased risk of VI was associated (hazard ratio, 95% confidence interval, and P value) with more severe baseline retinopathy (1.14 per 1-step increase in retinopathy level; 1.03-1.27; P = 0.01), presence of cataract (2.49 versus absence; 1.53-4.04; P<0.001), higher glycosylated hemoglobin (1.28 per 1%; 1.16-1.42; P<0.001), presence of hypertension (1.72 versus absence; 1.05-2.83; P = 0.03), and currently smoking (vs. never smoked, 1.63; 1.01-2.61; P = 0.04), but not proteinuria.
CONCLUSIONS: These data show that the 25-year cumulative incidence of VI is related to modifiable risk factors and, therefore, that VI may be reduced by better glycemic and blood pressure control and avoidance of smoking. FINANCIAL DISCLOSURE(S): Proprietary or commercial disclosure may be found after the references. Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.