Accurate Henle’s Fiber Layer Measurement by Volumetric Directional OCT

Progressive photoreceptor cell body loss could result in the thinning of the outer nuclear layer (ONL), which is an important pathological feature of retinal degenerations and a useful imaging biomarker in age-related macular degeneration. However, it is challenging to demarcate the boundary between the ONL and the adjacent Henle's fiber layer (HFL), which consists of Müller cell and obliquely oriented photoreceptor axons, by standard optical coherence tomography (OCT). We proposed a novel imaging technology, Volumetric Directional OCT (VD-OCT), a dedicated OCT system with two sets of optical scanners that can precisely control and continuously and synchronously update the imaging beam entry points during a volumetric OCT scan. A customized spoke-circular scanning pattern was also implemented to observe the appearance of HFL with sufficient optical contrast in continuous cross-sectional scans through the entire volume. The application of VD-OCT for retinal imaging provides a more reliable and efficient approach to clearly distinguish the structure between the ONL and HFL. The novel imaging technology has the potential to allow for early identification of retinal diseases.