Henle fiber layer mapping with directional optical coherence tomography

Abstract

Purpose: To perform a macular volumetric and topographic analysis of Henle fiber layer (HFL) from retinal scans acquired by directional optical coherence tomography. Methods: Thirty healthy eyes of 17 subjects were imaged using the Heidelberg spectral-domain optical coherence tomography (Spectralis, Heidelberg Engineering, Heidelberg, Germany) with varied horizontal and vertical pupil entry. Manual segmentation of HFL was performed from retinal sections of horizontally and vertically tilted optical coherence tomography images acquired within macular 20 x 20 degrees area. Total HFL volume, mean HFL thickness, and HFL coverage area within Early Treatment for Diabetic Retinopathy Study grid were calculated from mapped images. Results: Henle fiber layer of 30 eyes were imaged, segmented and mapped. The mean total HFL volume was 0.74 +/- 0.08 mm(3) with 0.16 +/- 0.02 mm(3), 0.18 +/- 0.03 mm(3), 0.17 +/- 0.02 mm(3), and 0.19 +/- 0.03 mm(3) for superior, temporal, inferior, and nasal quadrants, respectively. The mean HFL thickness was 26.5 +/- 2.9 mu m. Central 1-mm macular zone had the highest mean HFL thickness with 51.0 +/- 7.6 mu m. The HFL coverage that have thickness equal or above to the mean value had a mean 10.771 +/- 0.574 mm(2) of surface area. Conclusion: Henle fiber layer mapping is a promising tool for structural analysis of HFL. Identifying a normative data of HFL morphology will allow further studies to investigate HFL involvement in various ocular and systemic disorders.