Handheld ultra-widefield optical coherence tomography

Abstract

Purpose : Developing a flexible handheld ultra-widefield (UWF) OCT system with two interchangeable lens combinations, a non-contact approach with 105° FOV and a contact approach with 140° FOV, for pediatric peripheral retina imaging.

Methods : We demonstrated a flexible handheld probe for UWF OCT system with non-contact 105° FOV and contact 140° FOV for peripheral retina imaging. The novel optical designs [Figs. 1(a)-1(b)] were compatible with our previously established 55° FOV handheld OCT/OCTA system and shared the same mechanical parts, except for the telescope design after the slow axis of the galvanometer scanner [Fig. 1(c)]. The OCT engine employed a 400-kHz VCSEL (Thorlabs, Inc.) with a center wavelength of 1060 nm and 100 nm bandwidth that provides an imaging depth of 6 mm and an axial resolution of 4.96 µm in air. The working distance for the non-contact system was ~5 mm. The incident power on the cornea was 1.68 mW. A programmed motorized reference arm and an electrically tunable lens were rapidly adjusted during the imaging session to match the imaging subject’s axial eye length and fine tune focus. OCT images were acquired and processed by our GPU accelerated software which enabled direct real-time feedback and facilitated alignment process and navigation. A high-speed alignment mode (10Hz volume rate) and an OCT scanning mode (800 × 780 A-scans/Volume and 1.56 seconds) were available for the operator to toggle between them.

Results : 3 healthy adult volunteers (24-34 years old) and 57 pediatric patients were successfully imaged, all the imaging sessions were completed within 5 minutes. Two representative en face OCT images with posterior pole and peripheral retina obtained via non-contact 105° FOV and contact 140° FOV respectively from two neonates with retinopathy of prematurity (ROP) were shown in Fig 2. Peripheral pathologies were fully appreciated in these images without pronounced motion artifacts.

Conclusions : We have demonstrated a flexible 400-kHz handheld UWF OCT system that has two interchangeable eyepieces, a non-contact approach with 105° FOV and a contact approach with 140° FOV, which could acquire images from the posterior pole to peripheral retina in a single shot. The implementation of UWF OCT imaging technology has the potential to facilitate the diagnosis and treatment of retinal diseases such as ROP.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.