Purpose To assess the contribution of corneal myofibroblasts to optical changes induced by photorefractive keratectomy (PRK) in a cat model. Methods First, we tested the transforming growth factor β (TGFβ)-dependence of feline corneal keratocyte differentiation into α-smooth muscle actin (αSMA)-positive myofibroblasts in vitro. Twenty-nine eyes from 16 cats were then treated with −10D PRK in vivo and divided into two post-operative treatment groups: (1) eyes that received 100μg anti-TGFβ antibody for 7 days, followed by 50μg Dexamethasone for another 7 days to inhibit myofibroblast differentiation; (2) eyes that received vehicle solution for 14 days (controls). Corneal thickness and reflectivity were measured by optical coherence tomography. Wavefront sensing was performed in the awake-behaving state pre-operatively and 2, 4, 8 and 12 weeks post-operatively. Wound healing was monitored using in vivo confocal imaging and postmortem αSMA immunohistochemistry. Results In culture, TGFβ caused cat corneal keratocytes to differentiate into αSMA-positive myofibroblasts, an effect that was blocked by co-incubation with anti-TGFβ antibody. In vivo, anti-TGFβ treatment post-PRK resulted in less αSMA immunoreactivity in the sub-ablation stroma, lower corneal reflectivity, less stromal re-growth and lower non-spherical, higher order aberration (HOA) induction than controls. However, there were no inter-group differences in epithelial regeneration or lower order aberration changes. Conclusions Anti-TGFβ treatment reduced feline myofibroblast differentiation in vitro and following PRK. It also decreased corneal haze and fine-grained irregularities in ocular wavefront after PRK, suggesting that attenuation of the differentiation of keratocytes into myofibroblasts can significantly enhance optical quality after refractive surface ablations.

Modeling decentration with real WFE changes showed irregularities of decentration effects for rotationally symmetric treatments. The main aberrations induced by decentration were defocus, astigmatism, and coma. Treatments that induced more spherical aberration were less tolerant of decentration.