OCT with integrated video optotype for wide field-of-view choroidal thickness maps in response to defocused stimuli

Abstract

Purpose : The last century has seen a rapidly growing incidence of myopia. Using optical coherence tomography (OCT), others have shown that the choroid appears to have a role in the regulation of eye growth and may respond to defocus cues. The purpose of this study was to characterize the impact of myopic defocus on changes in choroidal thickness over time.

Methods : We describe a novel table-top swept-source OCT (SSOCT; 1050nm @ 200 kHz) and video optotype retinal stimulus system deemed the controlled entry pupil position choroidal optical thickness system (CEPPCOTS; Fig. 1). The optotype subsystem consisted of an OLED screen, a tunable lens for defocus control, and a pupil tracking and compensation system consisting of a 2D scanning mirror and camera. Under an IRB approved protocol, each consented subject was imaged over two sessions, occurring on separate days (±2 hour start time difference) with a randomized test condition (0D and +5D defocus) occurring in each session. In a session, dark adapted subjects watched a video (ep. 1 or 2 of BBC’s Planet Earth II) during which we acquired a radial OCT volume (180 x3 repeated B-scans; 55°retinal FOV) of the right eye (left eye patched) every 10 min for 40 min. Two independent graders segmented the internal limiting membrane (ILM), retinal pigment epithelium (RPE), and choroid-sclera boundaries to obtain retinal (ILM – RPE) and choroidal (RPE – sclera) thickness maps.

Results : We imaged 4 subjects under both 0D and +5D defocus test conditions with example choroidal thickness maps shown in Fig. 2. Choroidal thickness changed over time at a rate of -0.52, -0.45, 0.15, and 0.63 um/hr in the 0D condition and -0.31, -0.39, -0.17, and -0.93 in the +5D condition for each of the four subjects, respectively.

Conclusions : We demonstrated a wide field-of-view OCT system with integrated video optotype for investigation of choroidal thickness. This system offers the potential to investigate choroidal changes over the entire macula and under multiple stimulus conditions.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1: A) CEPPCOTS system schematic B) Solidworks rendering of combined system. C) Photograph of CEPPCOTS system

 

Figure 2: A) CEPPCOTS B-scan with ILM, RPE, and choroid-sclera segmentations B) Optotype screen as seen through the imaging system (0D defocus). C) [NDD1] Example choroidal thickness maps at the start and end of 0D and +5 defocus imaging sessions. Optic nerve head is masked.