400 kHz handheld OCTA system designed for rapid imaging of supine and non-compliant subjects

Abstract

Purpose : Retinopathy of prematurity and many other pediatric retinal diseases have a vascular etiology. However, most commercial OCT angiography (OCTA) systems are large table systems that cannot be used to image pediatric or other non-cooperative subjects. Even if they could be brought to the bed side, OCTA image acquisition with these systems takes tens of seconds as they use relatively slow 100 kHz engines. To address this need we have previously reported a 200 kHz handheld OCTA (HH-OCTA) system, allowing for capture of OCTA images from infants at the bedside in 3 to 6 seconds. This work describes the continued development of the HH-OCTA system via the integration of 400 kHz OCT engine

Methods : We developed a 400 kHz OCT engine based on a 400 kHz VCSEL laser (Thorlabs inc.) and used our previously reported HH-OCTA scanner that has an ergonomic grip optimized for supine imaging, ±10D refractive error correction, and a 30x30° degree field of view. OCT and OCTA images were taken from consented, healthy volunteers lying in a supine position. OCT images were taken over an ~10x10 mm field of view using a 950 A-scan/B-scan, 128 B-scan/volume scan protocol (0.374s), and a 950 A-scan/B-scan and 4x averaged 128 B-scan protocol (1.495s). OCTA images were acquired over an ~6x3mm field of with 500 Ascans/ B-scan, 250 lateral locations sampled with 4 repeated B-scans (1.8s). OCTA images were generated in post processing using speckle variance and graph cut based segmentation was used to create projections of the vasculature. Optical power was set in accordance with the ANSI Z80.36 standard Light Hazard Protection for Ophthalmic Instruments and all human subjects research was performed under protocols approved by the Duke University institutional review board in accordance with the Declaration of Helsinki.

Results : Representative HH-OCT and OCTA images from normal subjects are shown in fig. 1.

Conclusions : We demonstrated a 400 kHz HH-OCT probe capable of acquisition of OCTA images from supine subjects in 1.8s. We believe that the increase in speed for both structural OCT and OCTA images will facilitate bedside imaging in infants.

This is a 2021 ARVO Annual Meeting abstract.

 

Fig. 1: a) Unaveraged B-scan of the fovea and optic nerve of a normal volunteer. b) 4x averaged B-scan (the unaveraged scan in (a) is one of the 4 scans in the averaged scan to allow for direct comparison). c) 400 kHz OCT system and scanner mounted on a cart. d) OCTA image from a normal subject