Clinical research on topography-guided transepithelial photorefractive keratectomy in the treatment of astigmatism after penetrating keratoplasty

Abstract

Objective To evaluate the safety and efficacy of topography-guided transepithelial photorefractive keratectomy (T-PRK) in the treatment of high and irregular astigmatism after penetrating keratoplasty (PKP).Methods In this non-randomized retrospective study,18 patients (20 eyes) with high or irregular astigmatism after PKP were treated with topography-guided T-PRK.Uncorrected distance visual acuity (UDVA),corrected distance visual acuity (CDVA),refraction,corneal topography,and subjective evaluation of visual symptoms were recorded and analyzed both preoperatively and at the last follow-up visit during this study.A Wilcoxon signed-rank test was used for the statistical analysis of UDVA,CDVA,refraction and corneal topography.Results At a mean follow-up time of 12.15±2.06 months postoperatively,mean UDVA and CDVA improved from 1.36± 0.42 to 0.65±0.40 (Z=-3.727,P＜0.01),and from 0.34±0.22 to 0.17±0.14 (Z=-3.607,P＜0.01),respectively,with 10 eyes gaining two or more lines of CDVA.Moreover,mean sphere decreased from 1.48±3.14 D to-0.19±2.11 D (Z=-2.373,P＜0.05); mean cylinder was reduced from-7.81± 3.43 D to-3.06±1.99 D (Z=-3.792,P＜0.01); the mean postoperative spherical equivalent (SE)refraction adjusted by intended SE was-1.72±2.55 D.Of all eyes,3 eyes were within ±0.50 D of the intended refraction,9 eyes were within ±1.00 D of the intended refraction.The mean corneal irregularity index (IRI) and orthogonal curvature asymmetry decreased from 66.33±22.03 μm to 59.11±14.66 pm (Z=-0.831,P＞0.05),and from 8.96±4.36 D to 7.44±3.56 D (Z=-2.576,P＜0.05)respectively.All patients reported visual symptoms had improved or remained unchanged.Conclusion Topography-guided T-PRK appears to be a safe and effective treatment for post-PKP high and irregular astigmatism. Key words: Photorefractive keratectomy; Corneal topography; Irregular astigmatism; Keratoplasty, penetrating