Three–Dimensional Ultrahigh Resolution Optical Coherence Tomography (3D UHR OCT): A Video Presentation

Abstract

Abstract: : Purpose:To highlight the state–of–the–art background and the spectrum of clinical applications of three–dimensional (3D) ultrahigh resolution (UHR) optical coherence tomography (OCT). Methods:More than 140 eyes with a distinct pathology of each of the posterior pole compartments – including the vitreoretinal interface, the retinal vasculature, the neurosensory retina, the retinal pigment epithelium and the choriocapillary layer – were imaged using 3D UHR OCT. Three–dimensional retinal imaging was performed with high axial resolution of 3 µm employing a compact, commercially available ultrabroad bandwidth (160 nm) Titanium: sapphire laser at video–rate with up to 25 B–scans/second, each tomogram consisting of 1024x1024 pixels, resulting in 25 Megavoxels/second. Results:3D UHR OCT offers a high–precision detection of pathologies in their three–dimensional extension at all the structural levels, which is best appreciated by video imaging. The UHR modality allows to identify the contour of the hyaloid membrane, epiretinal membranes and the inner limiting membrane. The 3D quality images the topography of tractive forces from the retinal surface down to the level of the photoreceptor segments. The pattern of the retinal vasculature is distinctly recognized by the hyperreflectivity of the vascular walls and the resulting reflectance shadow exhibiting a three–dimensional angiographic image of the entire vascular net without the use of fluorescent markers. Intraretinal pathologies are demarcated within the specific layer of the neurosensory ultrastructure. Photoreceptor inner and outer segments are clearly delineated in configuration and size in micrometer with a characteristic peak in the subfoveal area. In RPE disease, 3D UHR OCT recognizes prominent areas of RPE elevation (+ phenomenon) as well as patterns of RPE loss with increased reflectance transmission towards the choroid (– phenomenon). Classic and occult components of choroidal neovascularization and related leakage can be identified and their volume may be quantified. Conclusions:High–speed UHR OCT is the first tool which offers a realistic three–dimensional imaging of pathologies at all epi–, intra– and subretinal levels. Ultrastructural changes are identified and displayed using a dynamic video technique.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • imaging/image analysis: clinical