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Jedediah McClintic, Peter K Kaiser, Sunil K Srivastava, Rishi P Singh, Justis P Ehlers; Measurement of Peripheral Non-perfusion in Ultra wide-field fluorescein angiography. Invest. Ophthalmol. Vis. Sci. 2014;55(13):270.
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Ultra-widefield fluorescein angiography has allowed the evaluation of peripheral non perfusion in retinal vascular disease such as diabetic retinopathy and retinal vein occlusions. The purpose of this study was to compare measurements of peripheral retinal ischemia using ischemic index on standard images and stereographic corrected projection images created with Optos Optomap ® software and to compare these measurements to the Optomap area measurement tool in patients with branch retinal vein occlusions
Retrospective chart review of patients with branch retinal vein occlusions who received ultra-widefield angiography in the preceding 1 year. Quantitative analysis of ischemic burden was performed using Image J software. Areas of ischemia were identified and measured against the total area to compute an ischemic index as described by Schwartz et al. Images were then processed using Optos Optomap software that adjusts image presentation to a best-fit 24 mm globe and projects a flat map which preserves peripheral aspect ratios. Ischemic index was calculated again using these images. Direct measurement of ischemic retinal area was performed using the Optos area measurement tool.
Ultra-widefield fluorescein angiography from 8 eyes of eight patients diagnosed with BRVO who had not been treated with laser photocoagulation were analyzed in both standard and Optos Optomap ® projections. Total area of peripheral nonperfusion measured using Image J software was, on average, 72% larger on standard images than Optomap stereoscopic projections (P = 0.015). However, the ischemic index of visualized retina trended larger (7.6%) using Optomap projections than standard images (P = 0.08).
Ultra-widefield fluorescein angiography has allowed for the assessment of peripheral non perfusion in various disease states. Image distortion can be variable and introduces significant error when interpreting the dimension of ischemia. Current ultra-widefield imaging typically over-represents peripheral retina. Stereoscopic map projections of the retina allow for more accurate analyses of non perfusion and will promote specificity in characterizing the impact of ischemia on clinical endpoints such as macular edema and neovascularization.
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