Non-contact cell-detail real-time full-field OCT: capabilities and potential clinical applications of the novel anterior eye imaging tool

Abstract

Purpose : We developed an improved time-domain full-field optical coherence tomography (FFOCT) system that can reliably in real-time acquire non-contact cellular resolution en face images of anterior human eye. We demonstrate instrument’s abilities to image not only the central corneal region, but also peripheral and limbal corneal zones, limbus with palisades of Vogt and vasculature. Potential applications of the new device are discussed.

Methods : A customized combined FFOCT/Spectral-domain OCT (SDOCT) system was developed. In real-time it tracks the axial position of the eye and performs defocus correction, which results in instruments ability to consistently acquire and display FFOCT images in real-time. Even single FFOCT images in this new device show high signal-to-noise ratio, therefore eliminating the need for the post-processing steps, of image registration and image averaging. Fast acquisition speed (275 en face frames/sec.) was sufficient to acquire images clear from eye movements artifacts and visualize the blood flow propagation in the limbal region of the anterior eye.

Results : Real-time FFOCT revealed structures in central, peripheral cornea and limbus. In cornea tear-film, superficial epithelial cells with nuclei, sub-basal nerve plexus, stromal keratocytes and nerves, endothelium with nuclei were visible. Images of limbus showed palisades of Vogt and blood vessels. Blood flow was directly visible and measured (0.3 mm/sec.). All the images had high lateral and axial resolutions (1.7 µm and 7.7 µm, respectively), had relatively large field-of-view of 1.25 mm² and were acquired and displayed in real-time. Imaging procedure was non-contact and did not require introduction of medication into the eye.

Conclusions : FFOCT can display in real-time images from corneal and limbal parts of the anterior eye. Blood flow in limbus and conjunctiva can be directly viewed and quantified. Contactless operation presents advantages over confocal microscopy in terms of comfort for the patient. Larger field of view, comparing to confocal microscopy, allows to perform more precise measurements of nerve and cell-densities, which may lead to more precise diagnosis and monitoring of the diseases, such as diabetes (linked to nerves density) and endothelial dystrophy (linked to endothelial cell density).

This abstract was presented at the 2019 ARVO Imaging in the Eye Conference, held in Vancouver, Canada, April 26-27, 2019.

 

In vivo human corneal and limbus images, captured with real-time FFOCT.