Abstract
Purpose :
Subretinal injection is a commonly used method to deliver retinal gene therapy. Recording and evaluating parameters of the surgical procedure including the site of the injection(s), bleb locations, duration of injection and other parameters could compliment the understanding of treatment efficacy and safety. The goal of this study is to use our surgical experience with post FDA-approval voretigene neparvovec gene therapy to develop a grading procedure of the surgical steps using surgical videos and intra-operative optical coherence tomography (iOCT) that may be applied by the Casey Reading Center (CRC).
Methods :
12 eyes of six patients underwent pars plana vitrectomy with subretinal injection of voretigene neparvovec-rzyl (Luxturna®) in patients diagnosed with RPE65 mutation-associated retinopathy. The grading procedure was developed by reviewing intra-operative images and iOCT surgical videos. The following sequential steps of the surgery were carefully reviewed and analyzed: core vitrectomy, pre-bleb placement, vector injection, post-injection posterior pole exam and air-fluid exchange. A surgery evaluation grading form was developed in collaboration with vitreoretinal surgeons and utilized by an experienced grader for each surgical procedure.
Results :
Video interpretation was useful in delineating bleb location, number of injections and total bleb injection time. Critical features of the procedure and dynamic intraoperative events could be identified and catalogued using the surgical videos (Table 1). Figure 1 shows representative still images captured from iOCT videos.
Conclusions :
This standardized analysis of the surgical procedure with intraoperative video and iOCT is useful to study and understand the variability associated with subretinal surgery. This pilot study demonstrated that pre-blebs and blebs were visualized in all cases without apparent loss in volume, that a wide range of subretinal injection times could be accurately measured, and that foveal detachment could be confirmed in 64% of cases. Implementation of the CRC intraoperative surgical grading procedures may contribute to an improved understanding of efficacy and safety of other subretinal delivery of gene and cell-based therapies.
This is a 2021 ARVO Annual Meeting abstract.