Corneal topographic analysis after excimer photorefractive keratectomy

Objective To evaluate the corneal surface changes and visual quality after excimer photorefractive keratectomy (PRK) for myopia. Methods Corneal topographic analysis was performed on 23 patients (38 eyes) with myopia after PRK at the 1 , 3 , 6 month postoperative follow up visits. Results The corneal sphericity was changed after excimer PRK. As time went on, the mean surface regularity index (SRI) and the surface asymmetry index (SAI) decreased gradually, and the corneal surface became more smooth; mean simulated keratoscope readings (SimK) showed a gradual restoration. At the 6 month postoperative examination, corneal topography showed four main patterns of ablation: round or oblong (50%), collar button (23.68%), semicircular (18.42%) and central island (7.9%). Patterns of ablation were correlated with visual acuity. Conclusion The quantitative analysis of coneal topography is essential for evaluating corneal surface changes after PRK and helpful in the surgical design of PRK and in predicting the refractive outcome with greater precision.