Tunable Poly(acrylamide- co -HEMA) Hydrogel Intraocular Lenses for Canine Ophthalmic Applications

A soft hydrogel intraocular lens (IOL) based on poly(acrylamide-co-2-hydroxyethyl methacrylate) (poly(AAm-co-HEMA)) was developed as a tunable material platform for canine ophthalmic applications, addressing the limited exploration of hydrogel-based IOL materials in veterinary use. By systematically varying the AAm:HEMA composition, the hydration, surface, mechanical, optical, and cytocompatibility properties were evaluated to identify a formulation with a favorable overall balance of material characteristics. The selected hydrogel formulation, consisting of 18% (w/v) total monomer content with an AAm:HEMA ratio of 90:10, exhibited high visible-light transmittance (99.31 ± 0.05%), favorable wettability (16.69 ± 1.03°), a swelling ratio of 31.71 ± 2.06%, an elastic modulus of 45.96 ± 10.55 kPa, and high cytocompatibility (97.23 ± 8.40% cell viability). Functional imaging using a USAF 1951 resolution target further showed spatial resolution and image contrast comparable to a commercial IOL under the tested conditions. At the investigated lens geometry, the selected 90:10 formulation exhibited an optical power of 29.16 ± 0.54 D. Preliminary injector-assisted delivery also demonstrated folding and recovery of the overall IOL configuration without visible structural damage. Although the measured optical power was below the typical 35–40 D range for canine IOLs, adjustment of optic curvature and thickness provides a route toward the required optical power, while accounting for hydration-dependent dimensional and optical changes. Overall, the developed composition–geometry platform enables material properties and lens geometry to be considered as complementary design parameters, providing a foundation for further canine-specific geometric, biological, ex vivo, and in vivo evaluation.