Purpose: Different swept-source (SS) OCT scan patterns were used to image geographic atrophy (GA) to determine if they provided similar area and enlargement measurements in eyes with age-related macular degeneration (AMD). Design: Prospective, observational case series. Participants: Patients with GA secondary to nonexudative AMD. Methods: Patients were imaged using SS OCT (PLEX Elite 9000; Carl Zeiss Meditec, Dublin, CA), with follow-up imaging performed after 6 months and 1 year. Both the 6×6 mm and 12×12 mm scan patterns were obtained at each visit. Area measurements of GA were obtained from the en face images generated from a slab with boundaries extending 64 to 400 μm beneath Bruch's membrane. Main Outcome Measures: Comparison of area measurements and enlargement rates (ERs) measurements between the 6×6 mm and 12×12 mm scan patterns. Results: Thirty-two eyes of 25 patients with GA secondary to nonexudative AMD were enrolled. The mean lesion area measurements at baseline were 3.81 mm2 for the 6×6 mm scan and 3.75 mm2 for the 12×12 mm scan. At baseline and over 1 year, the lesion area measurements between the 6×6 mm and the 12×12 mm scan patterns were comparable for all eyes (0.04 mm2; P < 0.001, analysis of variance). The annual ER measurements from the 6×6 mm and 12×12 mm scan patterns were similar (Pearson r = 0.99), with an average ER using the square root transformation strategy of 0.3 mm/year. Conclusions: Both the 6×6 mm and the 12×12 mm scan patterns resulted in similar area and ER measurements for GA when visualized using the en face images. With the 12×12 mm scan pattern, which represents a 40° field of view (FOV), the measurement of GA using OCT en face imaging is no longer limited by the 6×6 mm FOV. Since macular GA can extend beyond the 6×6 mm FOV, the 12×12 mm FOV can now image all macular GA. With a FOV now similar to autofluorescence and color fundus imaging, SS OCT imaging can be used as the sole imaging method for the detection, measurement, and ER assessment of all GA associated with AMD in clinical practice and in clinical trials.
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