Corticosteroid–Eluting Lid Spacers for Eyelid Retraction Surgery

Abstract

Abstract: : Purpose: Lower eyelid retraction can be effectively corrected with porous polyethylene eyelid spacers. However, an exuberant fibrovascular response surrounding the implant is a frequent cause of recurrent postoperative eyelid retraction . We investigated a corticosteroid–eluting lower eyelid spacer to prevent excessive fibrovascularization. Methods: The lower eyelid spacers, consisting of high density porous polyethylene with a 390 mm² surface area, were provided by Porex, Inc. 3 mm diameter discs and 390 mm² sheets of porous polyethylene were coated with various concentrations of superhydrolyzed polyvinyl alcohol (PVA) and triamcinolone acetonide (TA) matrix. In vitro TA release rates were determined by placing the discs and sheets in PBS and assaying the drug concentrations over time by HPLC. 3 mm diameter TA coated Porex discs were surgically inserted in the region of the right lower eyelid retractors of NZW rabbits and a 3 mm diameter uncoated Porex disc was inserted in the fellow lower eyelid. The fibrovascular and inflammatory changes in both lower eyelids were compared using histopathology and immunohistochemistry. Results: 3 mm diameter discs of 15% PVA, 50% TA maintained steady state release for 37 days, at an average release rate of 47.6 µg/day. 390 mm² sheets of 10% PVA, 30% TA released at an average rate of 330.8 µg/day for 25 days. Other 390 mm2 sheets of 15% PVA, 50% TA maintained steady state release for ≥59 days at an average release rate of 333.4 µg/day. Histopathology results showed less fibrovascular tissue and less encapsulation surrounding the TA coated implant compared with the fellow eyelid with the uncoated implant. Anti CD68 rabbit antibody stain showed a dramatic decrease in macrophage recruitment in the region of the drug–eluting implant. Conclusions: Superhydrolyzed PVA is an effective coating agent for matrix style corticosteroid release from Porex polyethylene implants. The duration and rate of steady state release increases with polymer and drug concentrations in the matrix. Corticosteroid release from coated discs in the region of the lower eyelid retractors demonstrated reduced fibrovascularization and inflammatory response compared with uncoated discs. Corticosteroid–eluting lower eyelid spacers offer much promise to reduce excessive fibrovascularization and improve success rates of lower eyelid retraction correction surgeries.

Keywords: eyelid • corticosteroids • drug toxicity/drug effects