Different determinants of neovascularization on the optic disc and on the retina in patients with severe nonproliferative diabetic retinopathy
P. Valsania, J. H. Warram, L. I. Rand and A. S. Krolewski
Epidemiology and Genetics Section, Joslin Diabetes Center, Boston, MA 02215.
Almost all patients with type I and many with type II diabetes develop
proliferative retinopathy. This entity consists of two components: new
blood vessels on the optic disc (NVD), which frequently lead to visual
loss, and new blood vessels elsewhere on the retina (NVE), which do not
pose such a serious threat to vision. This study examined determinants of
neovascularization specifically on the optic disc in eyes with severe
nonproliferative retinopathy. The study eyes were under surveillance as the
untreated control eyes of participants in the Diabetic Retinopathy Study.
During the 5-year follow-up period, NVE developed in almost all of the
eyes, whereas the cumulative incidence of NVD in these same eyes was 64%
and varied according to several factors. The risk of NVD in a study eye was
increased if the contralateral treated eye had NVD rather than NVE or
severe nonproliferative retinopathy (odds ratio [OR], 6.1; P < .0001).
It was also increased if the study eye had, at the baseline examination,
soft exudates and intraretinal microvascular abnormalities (OR, 5.7; P =
.002) or soft exudates alone (OR, 4.0; P = .04). Nephropathy and poor
glycemic control were each associated with a two-fold increase in risk but
neither was statistically significant. Eyes of individuals over 40 years of
age were protected from the development of NVD (OR, 0.5; P < .05). The
findings of this study support the hypothesis that, in patients with
diabetes, the development of NVD is determined by different factors than
the development of NVE.
