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Jennifer H. Acton, Beulah A. Abraham, R. Theodore Smith, Donald C. Hood, Vivienne C. Greenstein; Photoreceptor Layer Thinning in Areas of Visual Field Defect in Early AMD. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4466.
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To evaluate the structural changes in patients with early age-related macular degeneration (AMD), associated with visual field defects, using spectral domain optical coherence tomography (SD-OCT).
Ten eyes of 10 patients with soft drusen, with or without pigmentary changes were studied. Visual acuities ranged from 20/20 to 20/30 and all eyes had foveal fixation. Nidek MP-1 10-2 visual fields were obtained and total deviation defects were generated from a previously collected normative database. Structural changes in the outer retinal layers in the central 20° were evaluated with SD-OCT volume scans (Heidelberg Spectralis HRA+OCT). The thicknesses of the outer segment (OS) and retinal pigment epithelium (RPE) layers, as well as the elevation of the RPE from Bruch’s membrane in regions with drusen, were measured with a computer-aided, manual segmentation technique. Retinal layer thicknesses at locations with visual field defects were compared to non-defect locations at equivalent eccentricities. OS and RPE thicknesses on line scans through the fovea of the patients’ eyes were compared to the results from 10 age-similar healthy subjects.
Foveal line scans showed significant thinning of the OS layer in the AMD eyes compared to healthy subjects. OCT characteristics of early AMD were observed in both normal and abnormal regions of the visual field. RPE elevations in drusen areas, and disruptions of the inner-outer segment junction, were seen in all 10 eyes with AMD. Hyper-reflective foci were seen in 8 eyes. A comparison of thicknesses of the OS and RPE layers at locations with visual field defects to those without, showed that the OS layer was thinner in locations with defects in 8 of 10 eyes and this difference (mean = 9µm) was statistically significant (p = 0.02). Although the RPE layer was thinner in 6 eyes and showed greater elevation from Bruch’s membrane in 6 eyes, in locations with defects, these differences (mean = 3µm; mean = 18µm) were not statistically significant (p = 0.25; p = 0.17).
SD-OCT changes characteristic of early AMD were observed in areas of both normal and abnormal visual field sensitivity. However, the OS layer was significantly thinner in regions with decreased visual sensitivity, consistent with previous findings of photoreceptor loss in early AMD. The results highlight the clinical utility of both SD-OCT retinal layer quantification and visual field testing for following disease progression in early AMD. 1. Hood et al.(2009)IOVS;50:2328-36; 2. Curcio et al.(1996) IOVS;37:1236-49.
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