Abstract
Abstract: :
Purpose: Conventional 50° digital fluorescein angiography is typically centered at the disc or macula, hence pathology outside of these fields is not imaged unless additional fields are obtained. Ultra wide–angle fluorescein angiography (200°) thus carries an advantage over traditional angiography for the detection of potentially relevant retinal pathology. We compared the detection of retinal ischemia and neovascularization using two separate methods: 7–field angiography and ultra wide field angiography. Methods: Eleven eyes of eleven patients with presumed pre proliferative diabetic retinopathy underwent fluorescein angiography using both the Topcon TRC50 50 degree fundus camera and the Optos Panoramic 200A. Each angiogram was performed on a separate visit using a single dye injection. With the Topcon camera, seven standard fields were taken by experienced photographers during angiography. A montage was created manually from the fields. For the Panoramic200A, the best quality arteriovenous phase image for each patient was selected. The images in each case were "overlain" by a digitally rendered grid which was divided into 12 concentric circles centered at the fovea, and further divided radially into eight 45° sectors. The radii of the rings was equal to one to twelve disc diameters (DD), and the grid size was adjusted accounting for variability in disc size. The peripheral limit of the retina image was measured in each sector, and the number of segments containing retinal neovascularization and/or ischemia were determined by a masked retinal specialist and tabulated. Results: For the 7–field fluorescein image montage, the mean extent of the outermost edge of the imaged field was 6.843 ± 0.71 DD while for the Optos Panoramic 200A images the mean was 9.56 ± 0.93 DD. The mean number of sectors containing retinal ischemia was 14.6 ± 10.4 sectors and 22.7 ± 14.9 sectors respectively for the montage and P200A. The number of sectors containing retinal neovascularization had mean values of 1.19 ± 1.87 for the 7–field technique versus 3.18 ± 2.52 (Panoramic 200A). The differences between these three sets of values were each statistically significant (p < 0.05). Conclusions: Significantly more diabetic pathology was identified on Optos Panoramic 200A angiography, compared to conventional 7–field imaging after a single dye injection. The ability to better visualize areas of peripheral non–perfusion will likely lead to earlier identification of eyes at higher risk of disease progression.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • diabetic retinopathy • clinical (human) or epidemiologic studies: systems/equipment/techniques