Optical coherence tomography of enucleated human eye specimens with histological correlation: Origin of the outer "red line"

• PURPOSE: To further define the origin of the "outer red line" (ORL) present in retinal optical coherence tomograms. • DESIGN: Laboratory investigation. • METHODS: Eleven formalin-fixed caps of seven human eyes previously enucleated for choroidal melanoma at the Wilmer Eye Institute were studied. The ORL evaluation consisted of sequential, surgical elimination of the retinal pigment epithelium, Bruch's membrane (BM), and choroid in separate, but adjacent, areas. Optical coherence tomography (OCT) images through each of these areas were correlated with corresponding histologic sections. The relative contribution of the retinal pigment epithelium, BM, and choroid to the ORL in retinal OCT3 images was evaluated. • RESULTS: In the specimens examined, the ORL correlated anatomically with a highly reflective optical surface at the level of the outer retina, and did not appear to represent a specific anatomic layer. The reflecting layers appeared to be composed of the retinal pigment epithelium, BM, and inner choroid. The relative contribution of BM together with the inner choroid to the ORL appeared greater than that of the retinal pigment epithelium. • CONCLUSIONS: This study suggests that the ORL present in retinal OCT3 images and generally associated with the retinal pigment epithelium/BM/inner choroidal complex appears to indicate a highly reflective optical surface which, when eye layers are normally configured, represents this complex of anatomic structures with a predominant contribution from BM and inner choroid. The findings of this study suggest a potential role for OCT in the eye pathology laboratory.