Purpose:
To assess and quantify the vascular and peripheral angiographic findings of patients with Age Related Macular Degeneration (AMD).
Methods:
Analysis was performed on 170 subjects: 80 with wet AMD, 60 with dry AMD and 30 controls who had undergone imaging with ultra-widefield fluorescein angiography (Optos plc). Angiographic gamma normalization and luminance analysis was numerically quantified to determine differences in the study population.
Results:
Quantitative Image Analysis was performed on the images of 170 patients to assess changes, vascular patterns and luminance. In order to clinically grade the amount of peripheral vascular changes calculations were made based on fixed area luminance quantification. Each image was normalized for luminance gamma and the maximum first order vessel luminance was calculated to give a baseline measurement. The area of evaluation was determined using a circular grid and the maximum luminance value was determined within that region. Color segmentation was created based on pixel luminance, this enabled an analysis of extrapolated Quant Value for the region. We were then able to clinically grade Peripheral Fluorescence with 0 representing no hyperfluorescence, grade 1 representing 0-500, grade 2 representing 500-1000, grade 3 representing 1000-1500 and grade 4 as 1500 and above.
Conclusions:
The quantification of peripheral perfusion and ischemia is possible using ultra-widefield fluorescein angiography and may be a useful adjunct in the determining the efficacy of anti-VEGF therapy in controlling macular edema in these patients. Dynamic widefield imaging may allow for eyes with wet AMD to be treated more effectively than previously indicated due to its ability to image and quantify vascular findings in the peripheral retina. A statistically powered prospective trial is planned to further examine the utility of quantifying peripheral angiographic hyperfluorescence in wet AMD.
Keywords: age-related macular degeneration • imaging/image analysis: clinical • clinical (human) or epidemiologic studies: prevalence/incidence