En Face Imaging of Geographic Atrophy Using Different Swept-Source OCT Scan Patterns

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 6x6 mm and 12x12 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 400m beneath Bruch's membrane. Main outcome measures: Comparison of area measurements and enlargement rates (ERs) measurements between the 6x6 mm and 12x12 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 mm(2) for the 6x6 mm scan and 3.75 mm(2) for the 12x12 mm scan. At baseline and over 1 year, the lesion area measurements between the 6x6 mm and the 12x12 mm scan patterns were comparable for all eyes (0.04 mm(2); P < 0.001, analysis of variance). The annual ER measurements from the 6x6 mm and 12x12 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 6x6 mm and the 12x12 mm scan patterns resulted in similar area and ER measurements for GA when visualized using the en face images. With the 12x12 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 6x6 mm FOV. Since macular GA can extend beyond the 6x6 mm FOV, the 12x12 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. (C) 2018 by the American Academy of Ophthalmology