Intraoperative optical coherence tomography (OCT) allows surgeons to visualize retinal anatomy and provides the surgeon with real-time feedback on instrument-tissue interaction.
Intraoperative microscope-integrated OCT can serve as confirmation for the surgeon that gene therapy injections have reached the subretinal space rather than the suprachoroidal space, said Ninel Z. Gergori, MD, of the Bascom Palmer Eye Institute (BPEI) in Miami.
Finally, the use of intraoperative OCT can be helpful to monitor for possible complications, including an impending macular hole.
Gene therapy can be delivered via intravitreal injection or subretinal delivery, with the latter being more common (AAV and lentivirus vectors). However, these vectors do not penetrate the retina well and the vectors must be delivered subretinally if photoreceptor or retinal pigment epithelial (RPE) cells are targeted.
"These gene therapy products must transduce the photoreceptor or RPE cells," she said.
Dr. Gregori and Janet Davis, MD, (also at BPEI) have performed 31 subretinal gene therapy surgeries since 2016. These have included phase I/II and phase III choroideremia trials (sponsored by Nightstar) and a phase I/II achromatopsia trial (sponsored by AGTC).
Dr. Gregori has no financial disclosures related to her comments.
1. Gregori NZ, Lam BL, Davis JL. Intraoperative use of microscope-integrated optical coherence tomography for subretinal gene therapy delivery. Retina. 2017;April 19. doi: 10.1097/IAE.0000000000001646