Methodological Approach to Improving Surgical Outcomes of Subretinal Implantation by Minimizing IOP instability

Abstract

Purpose : The purpose of this study was to address complications following full-thickness incision through the sclera and choroid during subretinal implantation surgery in a domestic pig model.

Methods : Human fibrin hydrogels were implanted into the subretinal space of thirty-three pig eyes. The surgery required an incision of 3.6mm that penetrated the sclera and choroid approximately 3.5 mm posterior to the limbus. The first 23 received surgeries that managed choroidal bleeding following incision, yet often resulted in excessive choroidal bleeding with hemorrhagic retinal detachment. To address these issues an ex-vivo experiment using ten cadaver pig eyes was conducted to monitor the intraocular pressure (IOP) fluctuation during the surgery. Various prototype devices were tested to stabilize the IOP during the surgery. Using these data we altered our surgery to include pre-cauterization of the choroid and pre-placement of scleral sutures at the site of the incision in the second set of 10 in-vivo surgeries. Those in-vivo surgeries were compared by the success rate of implantation and the prevalence of complications.

Results : In the ex-vivo experiments, mean IOP dropped from 30.2±3.0 to 5.0±2.1mmHg after the 3.6mm scleral/choroidal incision. The IOP was further lowered to 3.2±1.8 mmHg when the standard inserter was introduced. Two different prototype IOP stabilizer plugs attached to the inserter maintained a significantly higher IOP than the inserter alone (rigid type plug; 12.7±5.7 p=0.004, soft type plug; 17.1±7.8 p<0.0001, standard inserter; 3.2±1.8 mmHg). In the second set of in-vivo surgeries using the modified protocol and controlling IOP, retinal detachments were significantly reduced vs the initial group (n=11 in 23 vs. n=1 in 10, p=0.03). The cases of bleeding from the retinotomy site were also reduced in the latter group (9 of 23 vs. 0 of 10, p=0.005). Overall, the successful implantation rate improved from 73% in the former group to 90% in the latter group.

Conclusions : The modified procedures for the subretinal implantation successfully reduced the complications by minimizing the time of transplantation. The IOP stabilizer would be helpful for the maintenance of IOP during the transplantation surgery.

This is a 2020 ARVO Annual Meeting abstract.