Investigation of Photoreceptor Layer Impairment in Macular Pathologies using Ultrahigh Resolution Ophthalmic Optical Coherence Tomography

Abstract

Abstract: : Purpose: To demonstrate the clinical feasibility of ultrahigh resolution ophthalmic optical coherence tomography (OCT) for investigating the impairment of the photoreceptor layer in different macular pathologies. Methods: A compact, new generation ultrahigh resolution ophthalmic optical coherence tomography (OCT) system has been developed and used in a clinical setting for the first time. In vivo ultrahigh resolution ophthalmic OCT has been performed in more than 300 eyes of 160 patients, demonstrating unprecedented visualization of intraretinal morphology, especially the photoreceptor layer in several retinal pathologies. Results: Ultrahigh resolution OCT enables unprecedneted identification of delicate retinal sublayers in vivo. This provides a foundation to analyze unprecedented details revealed in in vivo ultrahigh resolution OCT retinal tomograms from normal and diseased human maculas. In particular differentiation of distal retinal sublayers - outer nuclear layer (ONL), external limiting membrane (ELM) and inner/outer segments (IS/OS) has been achieved in normals as well as different macular pathologies. In patients with Stargardt dystrophy the ONL, ELM and IS/OS appear completely degenerated, whereas in different stages of macular hole the IS/OS as well as the ELM seem to be affected according to macula hole stage. A displacement of the IS/OS as well as the ELM can be seen in acute CSC and partially in chronic CSC, whereas in AMD with minimal CNV the IS/OS layer and the ELM are affected mainly in the foveal center. In patients with AMD and vitelliform lesion, despite retinal detachment, the IS/OS layer, the ELM and the ONL appear normal, in accordance with the preservation of visual acuity of these patients. Conclusions: Ultrahigh resolution ophthalmic OCT has the potential to enhance sensitivity and specificity for early ophthalmic diagnosis, to monitor the efficacy of therapy as well as to contribute to a better under standing of ocular pathogenesis.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • retina: distal(photoreceptors, horizontal cell • retina