Purchase this article with an account.
K Bailey Freund, Karen Schaal, Jeffrey D Messinger, Christine A Curcio; Outer Retinal Tubulation (ORT) in Age-Related Macular Degeneration (AMD): Optical Coherence Tomographic (OCT) Findings Correlate with Histology. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4014.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To correlate OCT and histologic findings of ORT secondary to advanced AMD in living patients and post-mortem specimens.
High-resolution OCT raster scans of 43 eyes (33 patients) manifesting ORT secondary to advanced AMD were correlated with histologic studies of post-mortem specimens. High-resolution sections through the fovea and superior perifovea of donor eyes preserved ≤4 hours of death (12 atrophic AMD and 40 neovascular AMD) were examined by light microscopy.
ORT seen on OCT correlated with the histologic finding of tubular structures comprised largely of cones lacking outer segments and, in some cases, lacking inner segments, leaving a luminal border delimited by the external limiting membrane (ELM). ORT was observed in both open and closed configurations that were typically easily distinguished from cysts and photoreceptor islands on both OCT and histologically. Histology showed that the hyper-reflective luminal material seen on OCT represents retinal pigment epithelium (RPE) and non-RPE cells trapped within the ORT structure. ORT histologic findings correlated with OCT findings in regard to composition, location, shape, and different stages in ORT formation, for ORT with luminal cross-sectional diameter ≥ 31 µm on OCT.
Histologic correlation gives a better understanding of ORT formation and composition. ORT is comprised primarily of cone and Müller cells. The defining feature of ORT on OCT is a hyper-reflective line that appears to represent the ellipsoid zone, as the outer segments and inner segment / outer segment junction are infrequently observed in these structures. The occurrence of ORT bordered solely by ELM without inner segment ellipsoids (“ELM-only-ORT”) challenges OCT interpretation in the differentiation of ORT from cysts.
This PDF is available to Subscribers Only