Effect of topical immunomodulatory interleukin 1 receptor antagonist therapy on corneal healing in New Zealand white rabbits (Oryctolagus cunniculus) after photorefractive keratectomy.

To compare topical interleukin 1 receptor antagonist (IL-1ra) to steroid treatment following photorefractive keratectomy (PRK) in rabbit eyes. Our study is a randomized, investigator-masked study that was approved by the Institutional Animal Care and Use Committee. Following standard PRK, 48 eyes of 24 rabbits were divided into 5 arms: 4 treatment arms and 1 control arm. The right eye of each rabbit served as the treatment eye, and the left eye served as a control. Eyes in treatment arms were randomized to receive either fluorometholone, 0.1%, 4 times a day (Falcon, Fort Worth, Texas), or 2.5, 1.25, or 0.25 mg of IL-1ra 4 times a day. Control eyes received only moxifloxacin hydrochloride, 0.5% (Vigamox; Alcon, Fort Worth, Texas), and a solution of polyethylene glycol 400, 0.4%, and propylene glycol, 0.3% (Systane; Alcon), 4 times a day. Primary outcome measures included weekly evaluation of subjective haze formation and time to corneal reepithelization with clinic examinations, objective haze formation using Pentacam technology (Oculus, Lynnwood, Washington), as well as histological examination for haze thickness 7 weeks after PRK. There was no difference among treatment groups in time to reepithelization. The IL-1ra treatment groups showed a statistically significant reduction in haze formation (P < .001, determined by repeated-measures analysis of variance) on corneal evaluation using the Pentacam 3 weeks after PRK compared with the control group. This effect was comparable to that in the steroid treatment group. There was also a statistically significant effect of the treatment on subjective haze evaluation at weeks 4 and 5 (P < .05, determined by repeated-measures analysis of variance), but this effect lost statistical significance when the steroid group was excluded from the evaluation. In addition, there was no statistically significant difference in histologic evaluation of haze thickness among treatment groups (P = .997). Further studies are needed to determine the efficacy and adverse effect profile of topical IL-1ra in human eyes. IL-1ra therapy may be an alternative to steroid treatment following PRK.