Distribution and location of neovascularization at onset of proliferative diabetic retinopathy
Purpose: To determine if a correlation exists between the initial development of proliferative neovascularization (NVE) and retinal location. Methods: A sample population was selected from an on-going clinical trial database at the Vanderbilt Fundus Photo Reading Center. Over a six month period of time, patients showing NVE in their annual photographs were selected for further analysis. A total of 217 patient eyes met the criteria. Previous annual photographs of these patients were evaluated to find the first instance of neovascularization. The specific site of initial NVE was analyzed. The distance from the site of NVE to the edge of the optic disk was measured and the quadrant distribution (superior nasal [SN], superior temporal [ST], inferior nasal [IN], and inferior temporal [IT]) was noted. Results: NVE originated in ST field at 35.5%, IT at 23.5%, SN at 12.9%, and IN at 28.1%. When compared to an equal distribution among the four quadrants, the observed distributions constitute a statistically significant difference under chi-square analysis. Mean distance to the optic disk in ST field was calculated at 5511 microns, IT at 5141 microns. SN at 4250 microns, and IN at 4883 microns. Conclusions: Spatial distribution favored the superior temporal field. While the mechanisms for this distribution are unclear, distribution information may prove helpful in directing laser photocoagulation therapy and photographic monitoring protocols.
Feman, SS; Semchyshyn, TM; Leonard-Martin, TC
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