Abstract
Purpose :
Oculomotor nerve palsies are a rare but severe cause of strabismus and amblyopia, typically resulting in vision loss at the level of legal blindness. Current treatment options are limited, consisting mainly of transposition procedures that limit the range of ocular rotation necessary for peripheral gaze. This study proposes the use of synthetic hydrogels as extraocular muscle (EOM) substitutes to treat oculomotor nerve palsy. This innovative material aims to realign the eyes while preserving movement and expanding the field of single binocular vision.
Methods :
A hierarchically structured polyvinyl alcohol (PVA) hydrogel was fabricated to mimic the stress-strain curve and mechanical properties of human EOM. The hydrogel implant was synthesized using a directional freezing-assisted salting-out method and chemically crosslinked with glutaraldehyde (GA) to mimic the mechanical behavior of native EOM. In-vitro experiments cultured stimulated orbital fibroblast cells onto the hydrogel surface to assess the fibrotic response induced by GA and the mechanical properties of the hydrogel in the presence of fibroblast cells. Following sterilization, the hydrogel was implanted into a rabbit orbit between the orbital wall and the lateral rectus insertion, functioning as an abducting force after lateral rectus (LR) extirpation.
Results :
Preliminary findings indicate that such a PVA hydrogel can well replicate the human EOM master curve of mechanical behaviors. Confocal microscopic images revealed minimal fibroblast growth and proliferation in the presence of GA in vitro. Tensile stress testing of the hydrogels demonstrated preserved mechanical properties, and the sterilization procedure ensured the absence of bacterial growth. Following LR extirpation, hydrogel implantation between the orbital wall and LR insertion improved ocular alignment from esotropia to exotropia while preserving some adduction.
Conclusions :
This hierarchically structured hydrogel emulates the mechanical properties of human extraocular muscle tissue, demonstrating high strength, fatigue resistance, and elasticity. In vitro studies demonstrated minimal fibrotic response, and in vivo implantation improved ocular alignment while maintaining contralateral movement. This synthetic hydrogel presents a promising substitute for denervated extraocular muscles, proposing a groundbreaking treatment approach for oculomotor nerve palsy.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.