Real time ultrahigh speed and widefield handheld swept source OCTA pediatric retinal imaging

Abstract

Purpose : Developing a robust handheld OCT system, with ultrahigh speed, widefield, and real-time in vivo OCT/OCTA visualization for clinical imaging of pediatric retina.

Methods : We optimized the optical design for the handheld OCT/OCTA system that achieved a 55-degree field of view and a 1.3 mm beam size on the entrance pupil with low system optical aberrations (Fig. 1). A 11-element lens group was used to relay the imaging beam, and the fast and slow axis of the galvanometer scanner were separated and both conjugated to the pupil plane to reduce the vignetting artifacts. We used a 1060 nm, 400-kHz VCSEL (Thorlabs, Inc.) swept source laser with 100 nm bandwidth that provides an imaging depth of 6 mm and an axial resolution of 4.96 µm in air. A 4-coupler interferometer with an optimum coupling ratio delivered 1.8-mw incident power on the cornea. A 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. Our GPU accelerated OCT acquisition software displayed en face and cross-sectional view of the retina on the imaging probe which enabled direct real-time feedback and facilitated alignment process and navigation. A high-speed alignment mode (10Hz volume rate) and a high-resolution OCTA scanning mode (500 × 1500 A-scans, 3 B-scans per BM-scan, 5ms interscan time, and 1.875 seconds) were available for the operator to toggle between them.

Results : 3 healthy adult volunteers, 16 awake neonates in neonatal intensive care unit and 7 pediatric patients under general anesthesia in operating room prior to retinal surgery were successfully imaged, all the imaging sessions were completed within 5 minutes. Representative retinal OCT/OCTA images from a patient with X-linked retinoschisis and a patient with retinopathy of prematurity were shown in Fig 2. Vascular network and pathologies were clearly visualized in these images without pronounced motion artifacts.

Conclusions : We have demonstrated a 400-kHz and 55-degree field of view handheld OCT/OCTA system that has overcome many technical challenges in ultrahigh speed OCTA imaging as well as in pediatric retinal imaging in general. The advantages of the system have the potential to improve the diagnosis of retinal diseases and clinical validation.

This is a 2021 ARVO Annual Meeting abstract.