Abstract
Purpose: :
To evaluate the influence of ischemia in the peripheral retina as a risk factor in the development of macular edema.
Methods: :
A retrospective case series was performed. Forty patients with clinical evidence of macular edema of any etiology who underwent diagnostic ultra wide field fluorescein angiogram (UWFA) (Optos) and spectral domain optical coherence tomography (SD-OCT) were included. Evidence of peripheral vascular leakage, capillary non-perfusion and/or neovascularization were quantified in the UWFA. The ischemic index (ISI) was calculated for each eye using Adobe Photoshop CS3 software, dividing the total area of capillary non-perfusion by the total image area. Central macular thickness (CMT) and intraretinal cysts (IRC) were graded on the SD-OCT images. The ISI was then correlated with macular edema features on OCT and UWFA.
Results: :
The mean ISI was 26% (range from 10-45). Neovascularization was present in 15 eyes with a mean ISI of 40%. Mean central macular thickness was 395 microns, and evidence of intraretinal cysts was found in 95% of cases. Visual acuity varied from 20/30 to 20/400 (mean 20/70). A higher ISI was associated with more extensive areas of capillary non-perfusion and perivascular leakage. The correlation of higher ISI with macular edema was evidenced by a directly proportional relationship.
Conclusions: :
The potential involvement of peripheral non-perfusion in the development of macular edema has not been completely elucidated. A causative effect has not been proven, but a strong correlation exists and an upregulation of VEGF due to hypoxia has been proposed as the promoting factor. Prospective studies are needed to elucidate the predictive value of the ISI in these patients.
Keywords: macula/fovea • ischemia