Purpose : To assess the safety, efficacy and predictability of photorefractive keratectomy (PRK) [Tissue-saving (TS) versus Plano-scan (PS) ablation algorithms] of Technolas 217z excimer laser for correction of myopic astigmatism
Methods : In this retrospective study one hundred and seventy eyes of 85 patients (107 eyes (62.9%) with PS and 63 eyes (37.1%) with TS algorithm) were included. TS algorithm was applied for those with central corneal thickness less than 500 µm or estimated residual stromal thickness less than 420 µm. Mitomycin C (MMC) was applied for 120 eyes (70.6%) in case of an ablation depth more than 60 μm and/or astigmatic correction more than one diopter (D). Mean sphere, cylinder, spherical equivalent (SE) refraction, uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) were measured preoperatively, and 4 weeks,12 weeks and 24 weeks postoperatively.
Results : One, three and six months postoperatively, 60%, 92.9%, 97.5% of eyes had UCVA of 20/20 or better, respectively. Mean preoperative and 1, 3, 6 months postoperative SE were -3.48±1.28 D (-1.00 to -8.75), -0.08±0.62D, -0.02±0.57 and -0.004± 0.29, respectively. And also, 87.6%, 94.1% and 100% were within ±1.0 D of emmetropia and 68.2, 75.3, 95% were within ±0.5 of emmetropia. The safety and efficacy indices were 0.99 and 0.99 at 12 weeks and 1.009 and 0.99 at 24 weeks, respectively. There was no clinically or statistically significant differences between the outcomes of PS or TS algorithms or between those with or without MMC in either group in terms of safety, efficacy, predictability or stability. Dividing the eyes with subjective SE≤4 D and SE ≥4 D postoperatively, there was no significant difference between the predictability of the two groups. There was no intra- or postoperative complication.
Conclusion : Outcomes of PRK for correction of myopic astigmatism showed great promise with both PS and TS algorithms.
Iranian Journal of Ophthalmology 201325(3):227-237 © 2013 by the Iranian Society of Ophthalmology