In-vivo imaging of the healthy and pathological human limbus with 250 kHz, axicon lens-based, 1-µm axial resolution SD-OCT

Abstract

Purpose : To image the structure and vasculature of the healthy and pathological human limbus in-vivo at cellular resolution and without tissue contact, by utilizing a novel high speed (250 kHz), 1.2 µm axial resolution SD-OCT with an extended depth of focus.

Methods : The SD-OCT system utilizes a femtolaser and a combination of an axicon lens and 10x infrared corrected microscope objective to achieve 1.2 µm axial and ~ 2 µm lateral resolution in biological tissue over ~100 µm depth of focus. The system uses a 250 kHz, tall pixel, linear array camera. Because the axicon lens generates significant artefacts in the OCT images, we are currently developing image processing algorithms that can reduce their effect and compensate for the optical aberrations. So far, the novel SD-OCT system has been tested on 11 healthy controls and 4 subjects with limbal stem cell dysfunction (LSCD). A larger clinical LSCD study is scheduled to begin in January 2018.

Results : Figures A and B show cross-sectional and enface limbal images respectively, acquired from a healthy subject with highly pigmented palisades of Vogt (POV). Figures C, D and E show a closer look at the cellular structure of the limbal crypts in healthy subjects with high (C) and low (D) concentration of melanocytes in the limbus and from an LSCD subject with dystrophic POV (E). Figure F shows a cross-sectional image from another subject with LSCD.

Conclusions : The novel SD-OCT system is able to image the cellular structure and vasculature of the healthy and pathological limbus without contact with tissue. The system can assist ophthalmologists with the diagnostics and treatment of LSCD.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.