Application of thermoreversible hydrogel (poloxamer 407) to protect the corneal endothelium during phacoemulsification in porcine and rabbit eyes.

ABSTRACT

PURPOSE: To evaluate the effectiveness of thermoreversible (poloxamer) hydrogels as a substitute for ophthalmic viscosurgical devices (OVDs) during phacoemulsification in porcine and rabbit eyes and compare their endothelial protective effect with that of hyaluronic acid-based OVDs. SETTING: Department of Ophthalmology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, South Korea. DESIGN: Experimental study. METHODS: Fluorescein-stained poloxamer hydrogels (20%, 22%, 24%, and 26% [weight/weight%]) and cohesive (sodium hyaluronate 1.0% [Provisc]) and dispersive (sodium hyaluronate 3.0%-chondroitin sulfate 4.0% [Viscoat]) OVDs were injected into the anterior chamber of porcine eyes incubated at 32°C. In the in vitro study, the retention time was measured in 3 groups of 45 porcine eyes during continuous phacoemulsification. In the in vivo study, the endothelial cell count (ECC) was measured before and 3 days after intermittent phacoemulsification in 12 rabbit eyes randomized to a poloxamer hydrogel or a dispersive OVD group. RESULTS: The optimum concentration of thermosensitive hydrogel was 26%, at which no gel-to-sol phase transition occurred in the anterior chamber, with a 21°C irrigation solution. In the in vitro study, the mean retention times were 5.53 seconds ± 1.77 (SD), 125.00 ± 29.34 seconds, and 221.53 ± 42.48 seconds in the cohesive OVD, dispersive OVD, and 26% poloxamer hydrogel groups, respectively (P < .001). Throughout the 5-minute intermittent phacoemulsification, the 26% poloxamer hydrogel remained in the anterior chamber as a semisolid gel. In the in vivo study, the mean decrease in ECC was significantly lower in the 26% poloxamer hydrogel group than in the dispersive OVD group (P = .029). CONCLUSION: Thermoreversible hydrogels might be suitable substitutes for hyaluronic acid-based OVDs for corneal endothelial protection during phacoemulsification.