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Renata Portella Nunes, Zohar Yehoshua, Andrew Moshfeghi, Giovanni Gregori, Paul Stetson, William Feuer, Philip Rosenfeld; Progression of Geographic Atrophy Predicted by SD-OCT En Face Imaging of the Outer Retina. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6297.
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Spectral domain optical coherence tomography (SD-OCT) imaging was used to measure the growth of geographic atrophy (GA) and identify anatomic changes associated with disease progression in eyes with dry age-related macular degeneration (AMD).
Patients with non-exudative AMD were enrolled in a prospective SD-OCT study. All eyes with GA were imaged using the 200X200 and the 512X128 A-scan raster patterns (Cirrus HD-OCT, Carl Zeiss Meditec Inc.). Outer retinal anatomy was visualized using en face imaging of a slab encompassing the inner segment/outer segment (IS/OS) boundary. This 20 µm thick outer retinal slab was created using an outer segmentation line located 20 µm above the retinal pigment epithelium and an inner segmentation line positioned 20 µm above the outer segmentation line.
Initially, 30 patients were enrolled and 49 eyes with GA were imaged. At 6 and 12 months, the growth rates of GA correlated with the magnitude of the low luminance visual acuity deficits (LLDs) measured at baseline. Lesions with faster growth rates had larger LLDs (p=0.007 and p=0.003 at 6 and 12 months, respectively). This correlation in eyes with visual acuity of 20/63 or better suggested a deficit in photoreceptor (PR) function within the central macula where the GA had not yet progressed. Outer retinal assessment using en face imaging revealed extensive areas of outer PR disruption extending beyond the borders of GA in most eyes, with a bilaterally symmetrical pattern evident in some patients. In some cases, these areas of outer PR disruption accurately predicted the progression of GA over 1 year. In other cases, the area of PR disruption was much larger than the area of progression. Eyes with reticular pseudodrusen displayed a speckled pattern that appeared diagnostic for this condition.
En face imaging of the IS/OS boundary can predict the growth of GA. Due to the bilateral symmetry of these findings, this imaging strategy may prove useful in identifying a genetic subset of patients in which PR loss precedes the appearance and progression of GA. Identification of these areas with PR disruption should be monitored in clinical trials designed to test treatments for non-exudative AMD.
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