Comparative analysis of outcomes of Surface Ablation for myopic astigmatism in patients After PKP and DALK
Sadra Ashrafi1 , Kiana Hassanpour2 , Farid Karimian2 *
- Ophthalmic Research Center, Research Institute for Ophthalmology and Vision Science, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of Ophthalmology, Labbafinejad Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Abstract: Corneal transplantation, Penetrating Keratoplasty (PKP) and Deep Anterior Lamellar Keratoplasty (DALK), are the final surgical procedures in management of Keratoconus (KCN). One major drawback of these procedures is the induction of post-operative refractive errors, particularly high astigmatism and myopia. Surface Ablation (SA) has been proposed as a corrective intervention for these refractive errors. This study aims to compare the outcomes of SA in patients who have previously undergone DALK and PKP.
Methods: This retrospective study, conducted at Negah Hospital between 2015 and 2019, evaluated the outcomes of SA in KCN patients who had previously undergone DALK or PKP and at least 6 months has passed after complete suture removal. A total of 36 eyes (20 eyes post-DALK and 16 eyes post-PKP) were enrolled. Data collected included demographic information (age, gender, and affected eye) and clinical characteristics (refractive error, corrected and uncorrected distance visual acuity (CDVA and UDVA), central corneal thickness, keratometry, surgical procedure specifics, ablation depth, duration of mitomycin application, and post-surgical complications). The primary outcomes assessed were final refractive error, CDVA, UDVA and any postoperative complication.
Results: No significant demographic or clinical differences were observed between the PKP and DALK groups who underwent SA. Comparing SA outcomes in both groups revealed no significant differences in safety index (1.14 vs. 1.12, P = 0.69), efficacy index (0.94 vs. 0.84, P = 0.27), logMAR CDVA (0.23 vs. 0.18, P = 0.336), logMAR UDVA (0.34 vs. 0.30, P = 0.52), or post-op Spherical Equivalent (SEQ) (-2.18 vs. -1.36, P = 0.19). There was no significant complication and corneal haziness in both groups. However, a notable and major finding was the greater stability of SEQ over 48 months in the DALK group compared to the PKP group.
Conclusion: SA surgery post-corneal transplantation (DALK and PKP) effectively manages refractive errors with minimal complications. While outcomes were generally comparable between the two groups, DALK patients exhibited a trend towards greater long-term SEQ stability.
