Four-Dimensional Microscope-Integrated Optical Coherence Tomography Guidance in a Model Eye Subretinal Surgery

Purpose: Subretinal delivery of stem cells and gene therapy vectors hold great promise in clinical care. Delivery techniques are evolving. We investigate the utility of 4-dimensional (volumes over time) microscope-integrated optical coherence tomography (4D-MIOCT) to guide such maneuvers. Methods: This investigational 4D-MIOCT system displayed heads-up cross-sectional and stereoscopic volumetric views through the microscope oculars at 3.3–10 volumes/second. In enucleated porcine eyes, we evaluated novel information available to the surgeon during subretinal: 1) injection of fluid and cell suspensions, 2) retinotomy creation, 3) insertion of membranes with a retinal pigment epithelium (RPE) cell monolayer and 4) subretinal instrument maneuvers, all in postmortem porcine eyes. Results: Interactions between tools, membranes, retina and RPE were often not detectable on the conventional microscope view but were obvious with 4D-MIOCT. 4D-MIOCT visualization was essential to: monitor the extent of induced retinal detachment, guide the cannula tip and instrument maneuvers in the subretinal space, and identify efflux of cells into the vitreous cavity. This allowed adjustment by the surgeon to avoid complications—e.g. scissors scraping RPE. Conclusions: 4D-MIOCT is useful for continuous monitoring of model subretinal surgery and may help avoid technique-related complications. 4D-MIOCT can contribute to the advancement of subretinal delivery of therapies under development.