Retinal microaneurysm counts and 10-year progression of diabetic retinopathy
R. Klein, S. M. Meuer, S. E. Moss and B. E. Klein
Department of Ophthalmology and Visual Sciences, University of Wisconsin Medical School, Madison, USA.
OBJECTIVE: To determine the relationship of change in the number of retinal
microaneurysms to the 10-year progression to significant retinopathy,
proliferative retinopathy, and clinically significant macular edema.
DESIGN: Population-based study of persons with younger- and older-onset
diabetes with 10 years of follow-up. SETTING AND PATIENTS: Eleven-county
area in southern Wisconsin, where 189 patients with diabetes who had only
retinal microaneurysms in photographs at baseline participated in 4- and
10-year follow-up examinations. OUTCOME MEASURES: Ten-year incidence of
moderate nonproliferative diabetic retinopathy or worse, proliferative
retinopathy, or clinically significant macular edema as determined by
masked grading of stereoscopic color fundus photographs of seven standard
fields. RESULTS: The increase in the number of retinal microaneurysms and
the ratio of the number of retinal microaneurysms at the 4-year follow-up
to the number at baseline were positively associated with incidence of
proliferative retinopathy or clinically significant macular edema at the
10-year follow-up. Proliferative retinopathy was approximately 4.6 times
and clinically significant macular edema was approximately 9.1 times more
likely to develop at 10-year follow-up in eyes in which the number of
microaneurysms increased by 16 or more from baseline to the 4-year
follow-up than in eyes with no increase. Proliferative retinopathy was 3.4
times and clinically significant macular edema was 6.7 times more likely to
develop at 10-year follow-up in eyes that had ratios of 3 or greater of the
number of retinal microaneurysms at the 4-year follow-up to the number at
baseline than in eyes in which the ratios were smaller. These relationships
remained after controlling for the level of glycosylated hemoglobin and
type of diabetes. CONCLUSIONS: Microaneurysm counts using stereoscopic
color fundus photographs are an early important measure of progression of
retinopathy and may serve as a surrogate end point for severe change in
some clinical trials.
