The Association Between Ocular Residual Astigmatism and the Efficacy of Astigmatism Correction Via Small Incision Lenticule Extraction (SMILE)

• Published in: Ophthalmology and therapy 2023-10, Vol.12 (5), p.2631-2640
• Main Authors: Chao, Chen-Cheng, Lin, Meng-Yin, Chang, Chao-Kai
• Format: Article
• Language: English
• Subjects: Corneal astigmatism; Internal Medicine; Medicine; Medicine & Public Health; NCT; NCT05604872; Ocular residual astigmatism; Ophthalmology; Original Research; Refractive surgery; Small-incision lenticule extraction
• ISSN: 2193-8245; 2193-6528
• DOI: 10.1007/s40123-023-00766-1

Introduction Astigmatism correction after small-incision lenticule extraction (SMILE) surgery is affected by several factors, including ocular residual astigmatism (ORA), which accounts for the vector difference between refractive and corneal astigmatism. Previous studies revealed the relationship between ORA and astigmatism correction after laser-assisted in situ keratomileusis (LASIK). However, in SMILE surgery, no comprehensive study exploring the link between these two variables has been performed. We have therefore assessed the association between ORA and astigmatism correction after SMILE. Methods This was a retrospective, single-centered study. Patients with myopia or myopic astigmatism who underwent SMILE surgery using the 500-kHz Visumax laser platform and were followed up for at least 3 months were included. Patients’ demographic and clinical characteristics, such as visual acuity, refractive status and corneal tomography, were recorded. ORA was calculated using Alpins Statistical System for Ophthalmic Refractive Surgery Techniques (ASSORT) Ocular Residual Astigmatism calculator. Results A total of 888 eyes (408 eyes from males and 480 eyes from females) from 444 patients (mean age [standard deviation] 32.4 ± 7.1 years) were included in our study. Mean (± SD) preoperative sphere and cylinder were − 5.45 ± 1.98 (range − 10.00–0.00) diopter (D) and − 0.89 ± 0.70 (range − 4.00–0.00) D, respectively. Calculated mean ORA was 0.68 ± 0.35 (range 0.07–3.53) D. Postoperative logMAR uncorrected visual acuity was 0.03 ± 0.31. Mean postoperative sphere and cylinder were − 0.10 ± 0.56 (range − 1.5 to 1.0) D and − 0.51 ± 0.37 (− 1.5 to 0.0) D, respectively. The Pearson correlation test revealed preoperative sphere, steep keratometry (steep-K) and ORA were statistically correlated with the amplitude of astigmatism correction ( P