Ultra-widefield Imaging of the Peripheral Retinal Vasculature in Normal Subjects

Purpose: To establish the extent of the peripheral retinal vasculature in normal eyes using ultra-widefield (UWF) fluorescein angiography. Design: Prospective, observational study. Participants: Fifty-nine eyes of 31 normal subjects, stratified by age, with no evidence of ocular disease in either eye by history and ophthalmoscopic examination. Methods: Ultra-widefield fluorescein angiographic images were captured centrally and with peripheral steering using the Optos 200Tx (Optos, Dunfermline, United Kingdom). Images obtained at different gaze angles were montaged and corrected for peripheral distortion using a stereographic projection method to provide a single image for grading of the peripheral edge of the visible vasculature. The border of the vascularized retina was expressed as a radial surface distance from the center of the optic disc. The vascularized area was calculated based on this mean peripheral border position for each quadrant. Main Outcome Measures: Mean distance (mm) from the center of optic disc to the peripheral vascular border. Results: In normal eyes, the mean radial surface distance from the center of the optic disc to the peripheral edge of the visible vasculature was 20.3 +/- 1.4 mm and the mean area of normal perfused retina was 977.0 mm(2). There was no significant difference between right and left eyes or between male and female participants. However, the distance to the periphery differed depending on the quadrant, with temporal (22.5 +/- 0.9 mm) being larger than inferior (20.4 +/- 1.7 mm) being larger than superior (19.2 +/- 1.5 mm) being larger than nasal (17.4 +/- 0.9 mm; P < 0.001) for all interquadrant comparisons. Interestingly, the distances to the perfused vascular border were significantly shorter in older individuals (>= 60 years) than in younger subjects. Conclusions: Ultra-widefield fluorescein angiography is an important tool for studying the extent of peripheral retinal vasculature. With the increasing use of UWF imaging to evaluate and manage patients with retinal vascular disease, the normative data from this study may provide a useful reference when assessing the pathologic significance of findings in the setting of disease. (C) 2016 by the American Academy of Ophthalmology.