Femtosecond Laser-assisted LASIK Group Research Articles

Comparison of the visual quality at 1 year following femtosecond laser-assisted LASIK, wavefront-guided femtosecond LASIK and small incision lenticule extraction for myopia and astigmatism

Objective: To investigate mesopic contrast sensitivity (CS) and high-order aberrations after femtosecond laser-assisted LASIK (FS-LASIK), wavefront-guided femtosecond LASIK (WF-LASIK) and small incision lenticule extraction (SMILE) for myopia and astigmatism. Methods: In this case-control study, 212 eyes of 108 patients with myopia and astigmatism from September 2014 to September 2016 were treated by refractive surgery. There were 34 males (66 eyes) and 74 females (146 = eyes), aged 27 (24, 32) years. They were divided into 3 groups, with 37 patients (71 eyes), 35 patients (69 eyes) and 36 patients (72 eyes) treated by FS-LASIK, WF-LASIK and SMILE, respectively. Refraction diopters, corneal tomography, wavefront aberrations and contrast sensitivity were evaluated before and at 12 months after surgery. The results of different groups were compared by rank sum test. Results: At 12 = months of follow-up, 69 eyes (97.18%) treated by FS-LASIK, 67 eyes (97.10%) by WF-LASIK and 69 eyes (95.83%) by SMILE had the uncorrected distance visual acuity of 20/20 or better. Fifty-nine eyes (83.10%) treated by FS-LASIK, 60 eyes (86.96%) by WF-LASIK and 61 eyes (84.72%) by SMILE had better postoperative uncorrected distance visual acuity than preoperative corrected distance visual acuity. Surface regularity index of the WF-LASIK group decreased from 0.11 (0.07, 0.28) to 0.07 (0.06, 0.20) (Z=-2.662, P=0.008), which was less than that of the FS-LASIK and SMILE groups (Z=-3.236, -3.118, P=0.001, 0.000). Surface asymmetry index of the WF-LASIK group increased from 0.34 (0.25, 0.43) to 0.38 (0.30, 0.52) (Z=-2.140, P=0.032), which was less than that of the FS-LASIK and SMILE groups (Z=-2.910, -3.779, P=0.004, 0.000). The root mean square of high-order of the FS-LASIK group increased from 0.32 (0.27, 0.41) to 0.53 (0.40, 0.65) (Z=-6.228, P=0.000), which was more than that of the WF-LASIK and SMILE groups (Z=-3.595, -4.806, P=0.000, 0.000). Coma of the WF-LASIK group increased from 0.16 (0.11, 0.24) to 0.26 (0.15, 0.37) (Z=-3.816, P=0.000), which was less than that of the FS-LASIK group (Z=-3.528, P=0.000). Spherical aberration of the FS-LASIK and WF-LASIK groups increased from 0.10 (0.05, 0.21) and 0.08 (0.04, 0.12) to 0.24 (0.13, 0.34) and 0.15 (0.09, 0.26), respectively (Z=-5.141, -4.864, P=0.000, 0.000), which were more than that of the SMILE group (Z=-2.549, -4.682, P=0.011, 0.000). CS of the WF-LASIK group at 12 cycles per degree (c/d) increased from 1.34 (1.18, 1.48) to 1.48 (1.34, 1.63) (Z=-2.985, P=0.003), which was more than that of the FS-LASIK and SMILE groups (Z=-3.194, -2.977, P=0.001, 0.003). CS with glare of the WF-LASIK group at 12.0 c/d increased from 1.26 (1.18, 1.34) to 1.34 (1.34, 1.63) (Z=-3.608, P=0.000), which was more than that of the FS-LASIK and SMILE groups (Z=-4.033, -2.913, P=0.000, 0.004). Conclusions: FS-LASIK, WF-LASIK and SMILE achieved ideal visual outcomes at 12 months postoperatively. WF-LASIK treated eyes showed the best corneal symmetry, the least increase of high-order aberrations and the best visual quality among three kinds of surgeries. (Chin J Ophthalmol, 2020, 56: 118-125).

Femtosecond laser–assisted laser in situ keratomileusis versus photorefractive keratectomy: Effect on ocular surface condition

To compare ocular surface characteristics in eyes after femtosecond laser-assisted laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK). Centro de Oftalmologia Barraquer, Barcelona, Spain. Prospective comparative observational study. Patients with myopia who had femtosecond laser-assistedLASIK or PRK were included. Tear osmolarity, the Ocular Surface Disease Index questionnaire, Schirmer I, corneal sensitivity, tear breakup time (TBUT), and corneal fluorescein staining were evaluated preoperatively and 3, 6, and 12months postoperatively. The Wilcoxon signed-rank test was used for temporal intragroup analysis, and the Mann-Whitney U test was used for intergroup comparisons. The study comprised 44 patients (44 eyes) with myopia. Comparison of the parameters between the femtosecond laser-assisted LASIK group (22 eyes) and the PRK group (22 eyes) showed a similar temporal progression postoperatively. Compared with the preoperative evaluation, corneal sensitivity decreased after 3months (P=.002 and P=.02, respectively) and 6months (P=.03 and P=.04, respectively). The TBUT reached the highest mean value after 12months (P=.01 and P=.04, respectively), and tear osmolarity was slightly increased after 1year, although the mean values remained within the normal range (P=.01 and P=.04, respectively). The only difference between the 2 groups was lower corneal sensitivity in the femtosecond laser-assisted LASIKgroup after 3months (P=.02). The ocular surface condition could be considered clinically unaltered after 1year in both groups. Femtosecond laser-assisted LASIK and PRK techniques seemed to be safe for the ocular surface condition and to have a similar effect on it.

Dry Eye after Small Incision Lenticule Extraction (SMILE) versus Femtosecond Laser-Assisted in Situ Keratomileusis (FS-LASIK) for Myopia: A Meta-Analysis.

PurposeTo compare dry eye after small incision lenticule extraction (SMILE) and femtosecond laser-assisted LASIK (FS-LASIK) for correcting myopia.MethodsCENTRAL, Embase and PubMed were searched in November 2016. All randomized controlled trials (RCTs) and prospective cohorts that compared dry eye after SMILE with FS-LASIK were selected.ResultsFive cohorts and one RCT were identified for comparing dry eye after SMILE (291 eyes) and FS-LASIK (277 eyes). The pooled results revealed that the SMILE and FS-LASIK groups did not differ significantly in terms of Schirmer’s I test (SIT) and tear film osmolarity (TFO) at any postoperative visits. By contrast, tear break up time (TBUT; p = 0.04 for one month, p < 0.001 for three months, and p = 0.02 for six months) and ocular surface disease index (OSDI; p < 0.001 for one month and three months, and p = 0.006 for six months) were significantly worse in the FS-LASIK group than in the SMILE group at follow-up. At six months postoperatively, TBUT and TFO values in both the SMILE and FS-LASIK groups and OSDI scores in the SMILE group returned to preoperative levels, but SIT values in both groups (p = 0.02 for the SMILE group and p < 0.001 for the FS-LASIK group) and OSDI in the FS-LASIK group (p < 0.001) were still statistically impaired.ConclusionDry eye after both SMILE and FS-LASIK usually occurs transiently. SMILE does not show obvious superiority over FS-LASIK by exhibiting similar and acceptable objective parameters, and SMILE may have milder subjective symptoms.

Evaluation of Changes in Human Corneas After Femtosecond Laser-Assisted LASIK and Small-Incision Lenticule Extraction (SMILE) Using Non-Contact Tonometry and Ultra-High-Speed Camera (Corvis ST)

ABSTRACT Purpose: To evaluate theoretical biomechanical advantages of human corneas treated with small incision lenticule extraction (SMILE) compared with femtosecond laser-assisted LASIK (FS-LASIK) Patients and methods: In a prospective, comparative, non-randomized, consecutive case series patients with moderate to high myopia and/or astigmatism underwent corneal refractive surgery. Patients either received standard FS-LASIK or SMILE. Preoperatively and up to 3 months postoperatively data were analyzed including tomography with Pentacam HR, Goldmann tonometry, non-contact tonometry, and deformability of the cornea using an ultra-high-speed camera (Corvis ST). Data were analyzed and p < 0.05 was considered as statistically significant (t-test). Results: Seventy-three patients (128 eyes) were treated. Forty-eight eyes of 29 patients underwent FS-LASIK and 80 eyes of 44 patients underwent SMILE. Preoperative spherical equivalent (SE) was −3.23 ± 1.64 D (FS-LASIK group) and −4.83 ± 1.63 D (SMILE group) (p < 0.0001). Almost all parameters obtained by Corvis ST between preoperative and postoperative measurements showed significant changes after refractive surgery. Significant changes were seen between both groups postoperatively. However, matched pair subgroup analysis (n = 69; 26 eyes FS-LASIK; 43 eyes SMILE) of eyes with initially equal pachymetry, intraocular pressure, SE, and difference of pre- to postoperative pachymetry (p>0.05), showed no significant changes in parameters measured with Corvis ST (p>0.05). Conclusions: Corneal biomechanical parameters measured preoperatively with Corvis ST showed significant differences postoperatively in total and in both groups. In subgroup analysis with homogenous groups, FS-LASIK showed no significant changes in biomechanical data measured with Corvis ST compared with SMILE.

Comparison of the efficacy of femtosecond laser small incision lenticule extraction and femtosecond laser assisted LASIK

Objective To compare the efficacy of femtosecond laser small incision lenticule extraction(SMILE) and femtosecond laser assisted LASIK(FS-LASIK). Methods This is a prospective nonrandom cohort study. There were 200 eyes of 200 cases in both SMILE group and FS-LASIK group respectively. Uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA) and residual refraction (spherical equivalent, SE) were measured before surgery and 3 months after surgery. Vertex altitude of corneal posterior surface and corneal wavefront aberrations were measured by pentacam. Data were compared between two groups and between preoperation and postoperation in same group. Results Difference was not statistically significant in visual acuities, SE, safety, effectiveness and predictability between two groups (P>0.05). Pre-operative and postoperative vertex altitude of corneal posterior surface in SMILE group were(1.96±2.15) μm, and(2.08±1.87)μm, whereas those in FS-LASIK group were(1.96±2.15) μm, and(2.08±1.87)μm, and there were no statistically significant differences between preoperative and postoperative results in both groups (P>0.05). There was no statistically significant difference in postoperative outcome between two groups(t=2.527, P=0.16). Compared with pre-operative results, the corneal aberrations increased after surgeries, including root mean square of total (RMS TOTAL), root mean square of lower-order abberation (RMS LOA), root mean square of higher-order abberation (RMS HOA) and root mean square of spherical abberation (RMS Z4, 0) (P=0.000). Although corneal aberrations in SMILE group were bigger than those in FS-LASIK group, but there were no statistically significant differences between two groups (P>0.05). Conclusion Both SMILE group and FS-LASIK group have good safety, effectiveness and predictability, and corneal posterior surfaces of two groups all keep stable after surgery. Small incision without corneal flap is the most significant advantage of SMILE which can avoid potential risks, such as striation, shift and losing of corneal flap. Key words: Keratomileusis, laser in situ, femtosecond laser assisted(FS-LASIK); Small incision lenticule extraction (SMILE)

Comparison of keratocyte density after femtosecond laser vs mechanical microkeratome from 3 months up to 5 years after LASIK

To compare keratocyte density after mechanical microkeratome LASIK (MK-LASIK) and femtosecond-laser assisted LASIK (FS-LASIK). We performed a prospective study of myopic patients that underwent MK-LASIK or FS-LASIK. We measured keratocyte density 3 and 15 months, and 3-5 years after the surgery using confocal microscopy, and compared them with healthy, non-operated corneas. Thirty-one eyes were included in the FS-LASIK group, 30 in the MK-LASIK group and 28 in the control group. Three months postoperatively, there was an increase in the keratocyte population of the whole cornea, mainly due to the mid and posterior stromal layers, in both treatment groups. It was also increased in the stromal bed after MK-LASIK, but not after FS-LASIK. In both groups, this was followed by a normalisation and stabilisation of cell density in those deeper layers 15 months after the surgery. Keratocyte density in the flap and stromal bed was decreased 15 months after FS- and MK-LASIK compared to 3 months postoperatively and compared to controls. It seemed to remain stable thereafter. In spite of this decrease, the average cell density throughout the cornea was not decreased compared to controls at any time point. We found a reorganization of keratocytes density after LASIK, with an initial increase, followed by a decrease in the stromal flap and stromal bed 15 months postoperatively, and stable from then onwards, but still maintaining normal average densities in the total cornea. There were no differences between MK- and FS-LASIK.