Vector analysis of astigmatic correction after small-incision lenticule extraction and femtosecond-assisted LASIK for low to moderate myopic astigmatism.

To compare astigmatic correction between femtosecond-assisted laser in situ keratomileusis (LASIK) and small-incision lenticule extraction (SMILE). A total of 111 patients were included in this prospective study. Fifty-seven eyes were treated with LASIK and 54 eyes were treated with SMILE for myopia with low to moderate (-0.25 to -4.0 D) astigmatism. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity and manifest refraction were measured preoperatively and at 1 and 3 months postoperatively. Visual and refractive outcomes were reported. Changes in refractive astigmatism were evaluated using vector analysis. Preoperative characteristics were similar between both groups. The UDVA at 1 and 3 months was better in the LASIK group compared with the SMILE group (p<0.009). Postoperative cylinder was higher in the SMILE group (p<0.001). Fewer eyes attained the attempted cylindrical correction in the SMILE group (p<0.029). Vector analysis showed no significant difference in target-induced astigmatism (p=0.091) and angle of error (p>0.596) between the two groups. Surgically induced astigmatism was significantly lower in the SMILE group (p<0.023), while the difference vector (p<0.001) and absolute angle of error (p<0.016) were significantly higher in the SMILE group. No significant difference was found in these parameters between 1 and 3 months in both groups (p>0.122). Our results showed that SMILE offered a less favourable astigmatic correction comparable to femtosecond-assisted LASIK in eyes with low to moderate myopic astigmatism. The alignment of treatment was more variable in SMILE, leading to a lower efficacy compared with LASIK by 3 months postoperatively.

Chan TC ，Ng AL ，Cheng GP ，Wang Z ，Ye C ，Woo VC ，Tham CC ，Jhanji V ... -  《-》

Vector analysis of high (≥3 diopters) astigmatism correction using small-incision lenticule extraction and laser in situ keratomileusis.

To compare the astigmatic correction in high myopic astigmatism between small-incision lenticule extraction and laser in situ keratomileusis (LASIK) using vector analysis. Hong Kong Laser Eye Center, Hong Kong. Retrospective case series. Patients who had correction of myopic astigmatism of 3.0 diopters (D) or more and had either small-incision lenticule extraction or femtosecond laser-assisted LASIK were included. Only the left eye was included for analysis. Visual and refractive results were presented and compared between groups. The study comprised 105 patients (40 eyes in the small-incision lenticule extraction group and 65 eyes in the femtosecond laser-assisted LASIK group.) The mean preoperative manifest cylinder was -3.42 D ± 0.55 (SD) in the small-incision lenticule extraction group and -3.47 ± 0.49 D in the LASIK group (P = .655). At 3 months, there was no significant between-group difference in uncorrected distance visual acuity (P = .915) and manifest spherical equivalent (P = .145). Ninety percent and 95.4% of eyes were within ± 0.5 D of the attempted cylindrical correction for the small-incision lenticule extraction and LASIK group, respectively (P = .423). Vector analysis showed comparable target-induced astigmatism (P = .709), surgically induced astigmatism vector (P = .449), difference vector (P = .335), and magnitude of error (P = .413) between groups. The absolute angle of error was 1.88 ± 2.25 degrees in the small-incision lenticule extraction group and 1.37 ± 1.58 degrees in the LASIK group (P = .217). Small-incision lenticule extraction offered astigmatic correction comparable to LASIK in eyes with high myopic astigmatism.

Chan TCY ，Wang Y ，Ng ALK ，Zhang J ，Yu MCY ，Jhanji V ，Cheng GPM ... -  《-》

Three-year outcomes of small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia and myopic astigmatism.

To compare long-term clinical outcomes following small incision lenticule extraction (SMILE) and femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) for myopia and myopic astigmatism correction. In this retrospective study, we enrolled a total of 101 patients (101 eyes) who underwent SMILE or FS-LASIK 3 years prior. Measured parameters included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction and corneal wavefront aberrations. No significant differences in patient characteristics were found between the two groups. At the 3-year follow-up, UDVA was better than or equal to 20/20 in 90% and 85% (p=0.540) of the eyes; the efficacy indexes were 1.05±0.19 and 1.01±0.21 in the SMILE and FS-LASIK groups, respectively (p=0.352). Safety indexes were 1.19±0.17 and 1.15±0.20 in the SMILE and FS-LASIK groups, respectively (p=0.307). Eighty per cent and 65% of eyes were within ±0.50 D of the attempted spherical equivalent correction after SMILE and FS-LASIK, respectively (p=0.164). Vector analysis revealed no significant differences in astigmatic correction between the two groups (p>0.05). Surgically induced spherical aberration was higher in the FS-LASIK group than in the SMILE group (p<0.001). Long-term follow-up analysis suggested that both SMILE and FS-LASIK were safe and equally effective for myopic and astigmatic correction.

Han T ，Xu Y ，Han X ，Zeng L ，Shang J ，Chen X ，Zhou X ... -  《-》

Clinical Outcomes After SMILE and Femtosecond Laser-Assisted LASIK for Myopia and Myopic Astigmatism: A Prospective Randomized Comparative Study.

Liu M ，Chen Y ，Wang D ，Zhou Y ，Zhang X ，He J ，Zhang T ，Sun Y ，Liu Q ... -  《-》

Topography-Guided LASIK Versus Small Incision Lenticule Extraction (SMILE) for Myopia and Myopic Astigmatism: A Randomized, Prospective, Contralateral Eye Study.

To compare safety and efficacy of topography-guided LASIK and contralateral eye SMILE for myopia and myopic astigmatism correction. This prospective, randomized contralateral eye study included 44 eyes of 22 patients with bilateral myopia or myopic astigmatism. Treated eyes were divided into two groups: 22 eyes were treated with topography-guided LASIK and the fellow eye of each patient was treated with SMILE. The following parameters were evaluated preoperatively and up to 3 months postoperatively: uncorrected distance vision acuity (UDVA), corrected distance vision acuity (CDVA), refractive error, corneal keratometry, contrast sensitivity, and Objective Scatter Index. At 3 months, 86.4% of the LASIK group and 68.2% of the SMILE group had UDVA of 20/20 (P < .002) and 59.1% and 31.8%, respectively, had UDVA of 20/16 (P < .002). Spherical equivalent refraction (±0.50 D) was 95.5% for the LASIK group and 77.3% for the SMILE group (P < .002). Residual refraction cylinder (≤ 0.25 D) was 81.8% for the LASIK group and 50% for the SMILE group (P < .001). Contrast sensitivity (6 cycles/degree) was 7.2 ± 1.01 in the LASIK group and 6.20 ± 1.52 in the SMILE group. Objective Scatter Index measurements at 3 months were 1.35 in the LASIK group and 1.42 in the SMILE group. Topography-guided LASIK was superior in all visual performance parameters studied, both subjective and objective. The main difference between the two techniques likely derives from the eye tracking, cyclorotation compensation, and active centration control in the LASIK technology studied in contrast to the current technology available with SMILE-like procedures. This difference appears to affect refractive and visual aberration performance outcomes. [J Refract Surg. 2017;33(5):306-312.].

Kanellopoulos AJ 《-》