The 25-Year Incidence of Visual Impairment in Type 1 Diabetes Mellitus: The Wisconsin Epidemiologic Study of Diabetic Retinopathy
Received 16 February 2009; received in revised form 1 May 2009; accepted 22 June 2009. published online 02 November 2009.
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.
Available online: October 31, 2009.
1Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
2Departments of Population Health Sciences and of Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
Correspondence: Ronald Klein, MD, MPH, Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, 610 North Walnut Street, 417 WARF, Madison, WI 53726-2336
Manuscript no. 2009-220.
Financial Disclosure(s): The author(s) have made the following disclosure(s):
Ronald Klein - Consultant - Astra-Zeneca, Lilly, and Pfizer.
The other authors do not have any financial disclosures.
Supported by the National Institutes of Health, Bethesda, Maryland (grant nos.: EY03083 and EY016379 [RK, BEK]); and, in part, by Research to Prevent Blindness, Inc., New York, New York (RK and BEKK, Senior Scientific Investigator Awards). The National Eye Institute provided funding for the entire study, including collection and analyses and of data; Research to Prevent Blindness provided further additional support for data analyses.
ABSTRACT