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Avni Badami, Nisha Warrier, Kate McConnell, Steven Ness; Ischemic index as a predictor of response to antivegf therapy.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):2092.
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© 2017 Association for Research in Vision and Ophthalmology.
Ultra-widefield fluorescein angiography (UWFA) allows examiners to view up to 200 degrees of the retina in a single photograph. In diabetic retinopathy, ischemia promotes the production of vascular endothelial growth factor (VEGF) which can lead to a breakdown of the blood-retinal barrier and cause diabetic macular edema through increased vessel permeability. We aim to determine the relationship of retinal ischemia and responsiveness to antivegf treatment in patients with diabetic macular edema. We hypothesize that patients found to have a higher ischemic index will have a poorer response or smaller decrease in central macular thickness after a single treatment with antivegf therapy.
With IRB approval, a retrospective review of 12 eyes from 9 patients with diabetic macular edema who underwent UWFA testing and subsequent antivegf treatment were selected. Excluded patients included those with prior panretinal laser photocoagulation, antivegf treatment within 6 months prior to UWFA, and patients with any coexisting ophthalmologic diseases. Areas of ischemia (in pixels) were graded using ImageJ software and divided by the total area of the image in pixels to determine an ischemic index. Central macular thicknesses (CMT) from each patient prior and post antivegf treatment were determined from optical coherence tomography. The primary outcome evaluated was the determination of a correlation between ischemic index and change in CMT pre and post antivegf treatment.
Of the included subjects, 12 of 12 eyes (100%) exhibited at least one area of retinal ischemia on UWFA. The mean ischemic index was 28.8% (range 12.3-57.8%, SD 14.4%). Central macular thickness decreased by a mean of 58.8 micrometers (range decrease of 261-increase of 141 micrometers, SD 114.2 micrometers) following a single intravitreal antiVEGF injection. Using a linear regression model, no significant correlation was found between ischemic index and change in central macular thickness post antiVEGF injection (r=0, p>0.05, n=12).
While the results of this retrospective review do not support our hypothesis that patients with a higher ischemic index would have a smaller decrease in CMT post antivegf treatment, further studies are needed to determine whether larger areas of retinal ischemia correlate with a poorer response to antivegf treatment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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