Ultrahigh-speed handheld swept-source panretinal OCT angiography for pediatric ophthalmic imaging

Abstract

Purpose : We aimed to develop an enhanced version of the ultrahigh-speed handheld swept-source panretinal OCT angiography (OCTA) imaging system, featuring an 800 kHz VCSEL light source. This iteration achieved an exceptional 140° field of view (FOV), measured from the pupil plane, using a contact approach. This innovation enables comprehensive imaging coverage, extending to the peripheral retina for pediatric ophthalmic imaging.

Methods : We employed a 1060 nm center wavelength, 800 kHz A-scan sweep rate VCSEL (Thorlabs, Inc.) swept-source laser with 100 nm bandwidth, offering an imaging depth of 6 mm and an axial resolution of 4.94 µm in air. Customized and optimized relay lenses ensured collimated light and minimal beam wandering on both galvanometer scanner planes. The incident power on the cornea was 4.75 mW. The contact ocular lens comprised an advanced aspheric lens and a meniscus lens, all coated with a customized anti-reflection coating to enhance sample collection efficiency. Two data acquisition protocols were implemented: one for retinal structure in OCT with 800 A-scans/B-scan and 800 B-scans/volume (0.8 s), and the other for high-resolution OCTA volumes with 800 A-scans/B-scan and 2400 B-scans/Volume (2.4 s). OCT/OCTA images were acquired, processed by our GPU-accelerated software, and displayed on the imaging probe, facilitating real-time feedback for alignment and navigation.

Results : Thirty-eight pediatric patients were recruited and imaged using the advanced system in the NICU. Each imaging session, including alignment and data acquisition, was completed within 2 minutes. Figure 1 illustrates a representative en face OCT image and corresponding retinal and choroidal vasculatures with the posterior pole and peripheral retina captured in a single shot from a pediatric patient with stage 3 retinopathy of prematurity (ROP). Detailed morphologies of the retinal periphery and extraretinal neovascular proliferation were fully appreciated in the corresponding OCTA images.

Conclusions : We present an advanced iteration of the 800 kHz handheld swept-source panretinal OCTA imaging system, featuring an unprecedented single shot of 140° FOV, extending imaging capabilities to the retinal periphery. The detailed morphologies and comprehensive visualization provided by OCTA have the potential to offer quantitative assessment opportunities in diagnosing pathologies starting from the retinal periphery.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.