Subretinal Therapy Delivery Technique Guided by Intraoperative 4-Dimensional Microscope-Integrated Optical Coherence Tomography

Abstract

Purpose : Atrophic age-related macular degeneration is common, untreatable cause of vision loss; investigational treatments include stem cell-based therapies delivered into subretinal (SR) space with various surgical techniques. Treatment success is dependent on accurate SR therapy delivery and intraoperative tissue depth assessment is challenging. To address this challenge, we propose the use of a prototype, swept-source, 4-dimensional microscope-integrated optical coherence tomography (4D-MIOCT) device with near-real time OCT volumetric images for guidance of SR therapy delivery.

Methods : A prototype 4D-MIOCT device was used to monitor and direct SR delivery of biodegradable retinal pigment epithelium cell scaffold in ex-vivo, porcine eyes with a novel delivery instrument (designed by AM, JA, KB). The 4D-MIOCT scanner allowed live OCT imaging of surgical maneuvers, and the surgeon controlled the en face images, B-scans, and near real-time volumes displayed within surgical oculars and on a high-resolution monitor with a joystick foot pedal.

Results : High-quality 4D-MIOCT en face images, B-scans, and volumes were successfully acquired live during all steps of SR therapy delivery. Advantages of the 4D-MIOCT guided delivery were: enhancement of all surgical steps, exact SR bleb and retinotomy creation and precise and careful delivery of scaffold without damage to it or damage to surrounding tissues such as Bruch’s membrane or choroid (Figure 1 & 2). With traditional microscope visualization, it is challenging to assess the depth of delivery instrument and scaffold location in the SR space.

Conclusions : 4D-MIOCT provided high-resolution, cross-sectional visualization and volumetric data to guide SR therapy delivery technique and to monitor and confirm appropriate scaffold positioning in the SR space. Such near real-time visualization may enhance various SR delivery techniques for stem-cell therapies by guiding the precise delivery location and implant positioning and by decreasing the chances of known complications such as Bruch’s membrane rupture.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Figure 1 & 2: 4D-MIOCT guided scaffold (PLGA membrane; blue arrowhead) insertion with novel instrument (green arrow) into SR space. Conventional microscope views (A) with simultaneous 4D-MIOCT volumes (B) and B-scans (C) displayed within surgical oculars. (red asterisk): retinal surface; (red arrow): retinotomy.