INTRAOPERATIVE BLEB BEHAVIOR IN SUBRETINAL GENE AUGMENTATION THERAPY FOR INHERITED RETINAL DISEASES

In subretinal gene therapy for inherited retinal diseases (IRDs), blebs may not propagate predictably in the direction of the injection cannula. We evaluated factors that influenced bleb propagation among various IRDs.

Retrospective review of all subretinal gene therapy procedures performed by a single surgeon between September 2018 and March 2020 for various IRDs. Main outcome measures were directional bias of bleb propagation and intraoperative foveal detachment.

Desired injection volumes and/or foveal treatment were successfully achieved in all 70 eyes of 46 patients with IRD regardless of IRD indication. Bullous foveal detachment was associated with retinotomy closer to the fovea, posterior bleb bias, and greater bleb volumes ( P < 0.01). Blebs biased anteriorly or posteriorly based on disease indication ( P = 0.04) and age ( P < 0.001). Retinotomy location ≤ 3.7 mm (approximately two disk diameters) from the fovea favored foveal detachment ( P < 0.001). Multiple retinotomies and blebs allowed greater surface area coverage in some eyes, but intersecting blebs did not propagate further.

Bleb formation and propagation are predictable based on patient age, retinotomy location, disease indication, and how tangentially fluid is directed into the subretinal space.