sub-Bowman Keratomileusis Group Research Articles

Sub-Bowman keratomileusis versus femtosecond laser in situ keratomileusis on the long-term visual recovery: A comparative study.

To explore the long-term visual quality of the same subjects after sub-Bowman keratomileusis (SBK) or femtosecond laser in situ keratomileusis (FS-LASIK). This prospective study included patients screened for corneal refractive surgery at the Refractive Surgery Center of our Hospital between November 2017 and March 2018. One eye underwent SBK, while the other eye underwent FS-LASIK. Total higher-order aberrations, coma aberrations, and clover aberrations were evaluated before and at 1 month and 3 years after the procedure. The visual satisfaction of both eyes was investigated, respectively. The participants completed a surgical satisfaction questionnaire. Thirty-three patients were included. There were no significant differences in total higher-order aberrations, coma aberrations, and clover aberrations between the two procedures before and 1 month and 3 years after surgery (all P > 0.05), except for the total coma aberrations in FS-LASIK were significantly higher compared with the SBK group at 1 month after surgery [0.51 (0.18, 0.93) vs. 0.77 (0.40, 1.22), P = 0.019]. The surgical satisfaction questionnaire scores of the SBK group and the FS-LASIK group were 9.8 ± 0.8 and 9.8 ± 0.8, respectively, at 1 month, and 9.7 ± 0.9 and 9.7 ± 1.0, respectively, at 3 years (all P > 0.05). There were no differences in corneal aberrations and satisfaction between SBK and FS-LASIK procedures at 1 month and 3 years.

Lipidomics Analysis of the Tears in the Patients Receiving LASIK, FS-LASIK, or SBK Surgery.

Purpose: Tear film lipid layer (TFLL) plays a vital role in maintaining the tear film stability and, thus, the lipid composition of the tears could greatly affect the physiological function and biophysical integrity of the tear film. The objective of this study is to assess the tear lipid composition of the patients receiving laser-assisted in situ keratomileusis (LASIK), femtosecond LASIK (FS-LASIK), or sub-Bowman's keratomileusis (SBK) surgery preoperatively and postoperatively.Methods: Tear samples were collected from the left eye of the patient who receiving LASIK (n = 10), FS-LASIK (n = 10), or SBK (n = 10) surgery in week 0, week 1, week 4, and week 52. A rapid direct injection shotgun lipidomics workflow, MS/MSALL (<2 min/sample), was applied to examine the tear lipidome.Results: In week 52, the SBK group demonstrated a similar lipidome profile compared to week 0, while the FS-LASIK and LASIK groups shifted away from week 0. Two lipids, ganglioside (GD3) 27:4 and triacylglycerol (TAG) 59:3, were found to be associated with the lipidome changes preoperatively and postoperatively. No statistical significance was found in the overall lipid classes from the FS-LASIK group. The LASIK group showed significant alteration in the phospholipid and sphingolipid over time, while the SBK group demonstrated a significant difference in the (O-acyl)-ω-hydroxy fatty acid (OAHFA) and phospholipid.Conclusion: LASIK showed the greatest impact on the tear lipidome changes over time, while SBK demonstrated minimal impact among the three types of refractive surgeries after 1 year.

Flap thickness and side-cut angle using sub-Bowman keratomileusis microkeratome, 200-kHz femtosecond laser system, and Moria M2 microkeratome

Purpose The aim of this study was to compare the thickness and side-cut angle of corneal flap in candidates undergoing laser-assisted in situ keratomileusis using sub-Bowman keratomileusis (SBK) microkeratome, femtosecond (FS) laser, or Moria M2 microkeratome (MK). Patients and methods This prospective clinical study included 60 eyes of 30 patients. They were divided into three groups (20 eyes in each group). The study was conducted from January 2019 till December 2019. Corneal flaps were created using Moria SBK microkeratome, Alcon Wavelight FS-200 FS laser, or Moria MK. Heidelberg anterior segment optical coherence tomography was done 1 month postoperatively to assess the central flap thickness and side-cut angle. Results The mean error cut angle was −39.00±19.00, 24.75±12.56, and −25.65±10.31° in the SBK, FS, and MK groups, respectively (P Conclusion There was a statistically significant difference between the intended and achieved side-cut angle in the three groups. Flap thickness was more predictable in the SBK and FS group, with an insignificant difference between the intended and achieved flap thickness, whereas in the MK group, the difference was statistically significant.

Comparision on the effects of ocular surface tear system between two novel corneal refractive surgery

Objective To investigate the different effects of small incision lenticule extraction(SMILE) and sub-Bowman keratomileusis (SBK) on ocular surface tear system. Methods A prospective study. Total of 63 eyes of 63 cases were selected randomly in this study. There were 33 eyes who underwent SMILE and 30 eyes who underwent SBK. Corneal fluorescein(FL) staining, tear break-up time (BUT), Schirmer I test (SIT), central corneal sensitivity and ocular surface disease index (OSDI) score were estimated periodically before and 3 months after surgery. Results The FL scores in SMILE group were lower than those in SBK group at 1 week postoperatively (Z=2.455, P=0.014). The BUT of SMILE group were larger than those of SBK group at 1 (t=2.432, P=0.018) at 3 months postoperatively (t=2.150, P=0.036). The central corneal sensitivity was observed in SMILE group at any visit postoperatively were higher than that in SBK group (P 0.05). Conclusion The effect of SMILE surgery on ocular surface tear system is smaller than that of SBK. And the former recovers with less time. Key words: Small incision lenticule extraction; Sub-Bowman keratomileusis; Ocular surface; Tear

Early changes in posterior corneal elevation and related factors after femtosecond laser assisted LASIK and SBK

Objective To compare the early change of posterior corneal elevation with femtosecond laser assisted laser in situ keratomileusis (FS-LASIK) and sub-Bowman keratomileusis (SBK) by Oculyzer and analyze the related factors after FS-LASIK. Methods A longitudinal observational study was designed.Ninety-one eyes of 46 patients with myopia or myopic astigmatism in the First Affiliated Hospital of Anhui Medical University from January to April in 2016 were divided into FS-LASIK group (53 eyes of 27 patients), SBK group (38 eyes of 19 patients) according to the patients' wishes and each part of corneal elevation change values were explored after FS-LASIK and SBK surgeries.The posterior corneal elevation was measured at twenty-seven measuring points along the central, paracentral, midperipheral and peripheral zone (vertex and 1, 2 and 3 mm radius) using Oculyzer preoperatively, l day, 7 days and 1 month postoperatively, respectively.Written informed consent was obtained from each patient before the surgery. Results In the FS-LASIK group, the posterior corneal elevation difference values in the central zone were (-0.924±1.859), (-1.151±1.586) and (-0.940±1.994)μm 1 day, 7 days and 1 month postoperatively, respectively.In the periphery zone, the elevation difference values were (1.046±1.667), (1.172±1.566) and (1.023±1.622)μm.In the paracentral and midperipheral zone, the cornea displayed slightly backward or forward shift.In SBK group, the posterior corneal elevation difference values of the vertex were (-0.684±1.454), (-1.053±1.723) and (-0.553±1.572)μm 1 day, 7 days and 1 month after operation, respectively.In the paracentral and midperipheral zone displayed the same trend with FS-LASIK group, and in the periphery, the values were (1.207±1.317), (1.327±1.529) and (1.208±1.415)μm.There were no statistically significant differences in posterior corneal elevation between the two surgery modes among the three time points (all at P>0.05). At 1 month postoperatively, only two independent variables, which were spherical equivalent (SE) and ablation depth (AD) entered the regression in the central and paracentral zones.Independent variables, such as central thinnest corneal thickness (TCT), SE, AD, residual bed thickness (RBT) and the ratio of AD and TCT (AD/TCT) did not enter the regression in other two areas. Conclusions The posterior corneal elevation in the central 6 mm area shows tiny change in the early stage and the variation is larger 7 days after operation in the two groups, but it does not result in keratectasia.With the increase of SE and AD, the posterior corneal elevation is more likely to be affected. Key words: Myopia; Femtosecond laser assisted laser in situ keratomileusis; Sub-Bowman keratomileusis; Posterior corneal elevation; Oculyzer

Impact of Treatment Decentration on Higher-Order Aberrations after SMILE

Purpose. To evaluate decentration following femtosecond laser small incision lenticule extraction (SMILE) and sub-Bowman keratomileusis (SBK) and its impact on higher-order aberrations (HOAs). Methods. Prospective, nonrandom, and comparison study. There were 96 eyes of 52 patients who received SMILE and 96 eyes of 49 patients who received SBK in this study. Decentration was calculated 6 months after surgery with Pentacam. HOAs and visual acuity after the surgery were examined for patients in both groups before and 6 months after surgery. Results. The mean decentration displacement in SMILE group was significantly less than SBK group (P = 0.020). 89 eyes were decentered within 0.50 mm after SMILE and SBK. The association between vertical decentration and the induced spherical aberration was insignificant in SMILE group (P = 0.035). There was an association between decentration and safety index, efficacy index, vertical coma, spherical aberration, and HOAs in root mean square (RMS, μm) after SBK (all P < 0.05). No difference was found in uncorrected and corrected distance visual acuity, safety index, efficacy index, and wavefront aberrations between the two subgroups at any delimited value after SMILE (all P > 0.05). Decentration exceeding 0.37 mm affected vertical coma and RMSh of SBK eyes (P = 0.002, 0.005). Conclusion. SMILE surgery achieved more accurate centration than SBK surgery. Vertical decentration is associated with the induced spherical aberration in SMILE.

Clinical comparation of femtosecond small incision lenticule extraction and sub-Bowman keratomileusis for the correction of myopia

Objective To compare the clinical results of small incision lenticule extraction (SMILE) and sub-Bowman keratomileusis (SBK) for correction of myopia. Methods Total of 1080 eyes of 544 cases were enrolled in this prospective case-control study. In the groups, 510 eyes of 258 cases were treated with small incision lenticule extraction as the SMILE group, and 570 eyes of 286 cases were treated with sub-Bowman keratomileusis as the SBK group. The uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), corneal posterior surface's vertex altitude, high order aberrations(HOA), tear film break-up time(BUT) and Schirmer Ⅰtest were obtained and compared between preoperation and 1and 3 months after surgery.Data were analyzed using chi-square test, ANOVA and independent t test. Results UCVA: There were not satistically significant differences between two groups at each time. Corneal posterior surface's vertex altitude(μm): There were not satistically significant differences between two groups at 1 week, 1 and 3 months after operation. Surgically induced HOA(μm): For the total HOA、coma、trefoil、spherical aberration of the anterior surface, there were not satistically significant differences between two groups at each time. BUT(s): at 1 month after operation, the BUT was (7.22±2.43) s and (5.87±1.33) s in SMILE and SBK group respectively, and there were satistically significant differences between two groups. At 3 month after operation, there were not satistically significant differences between two groups. SchirmerⅠtest(mm): at 1 month after operation, the value was (8.71±2.56) mm and (8.24±2.48) mm in SMILE and SBK group respectively, and there were satistically significant differences between two groups. At 3 month after operation, there were not satistically significant differences between two groups. Conclusion SMILE and SBK have equal safety and efficacy for myopia correction. SMILE has a better stability for tear film in early period of postoperation. Key words: Surgery, refractive, laser; Correction, myopia; Small incision lenticule extraction, femtosecond laser; Sub-Bowman Keratomileusis, laser in situ

Longitudinal Comparison of Outcomes After Sub-Bowman Keratomileusis and Laser in Situ Keratomileusis: Randomized, Double-Masked Study

To compare the outcomes of sub-Bowman keratomileusis (100-μm flap) and laser in situ keratomileusis (LASIK) (120-μm flap) using 150-kHz femtosecond laser. Randomized, double-masked, contralateral clinical trial. One hundred patients (200 eyes) with myopia or myopic astigmatism were included. Postoperative examinations were performed at week 1 and months 1, 3, 6, and 12. Main outcome measures included postoperative uncorrected (UCVA) and best-corrected distance visual acuity (BCVA); manifest refraction spherical equivalent; efficacy and safety indices; corneal thickness; and complications. The mean age of patients was 33.9 ± 7.9 years. Overall, the preoperative UCVA, BCVA, and manifest refraction spherical equivalent were 1.349 ± 0.332, -0.022 ± 0.033, and -5.81 ± 1.61 diopters, respectively. No significant difference was observed in preoperative (P ≥ .226) or intraoperative parameters (P ≥ .452) between both groups, except residual stromal thickness (P < .001). The UCVA, manifest refraction spherical equivalent, and central corneal thickness stabilized by 1 week, while the thinnest corneal thickness stabilized by 3 months postoperatively. There was no significant difference between both groups for any parameter during all follow-up visits (P ≥ .132) except the 3-month safety index, which was better in the sub-Bowman keratomileusis group (P = .007). Soft opaque bubble layer was noted intraoperatively in 12 cases (7, 100-μm group; 5, 120-μm group; P = .577). No postoperative complications were observed. Our study did not find any differences in the visual and refractive outcomes between femtosecond-assisted sub-Bowman keratomileusis and LASIK. Both surgeries resulted in quick visual recovery as early as 1 week postoperatively.

Comparisons of morphologic characteristics between thin-flap LASIK and SBK.

To compare the morphologic characteristics between thin-flap laser in situ keratomileusis (LASIK) and Sub-Bowman keratomileusis (SBK), and to evaluate the uniformity of flap and to explore the correlative factors of corneal flap thickness. A prospective, randomized, comparative clinical study was performed in Department of Ophthalmology, West Hospital of China, Chengdu, Sichuan Province, China. Totally 59 patients 114 eyes underwent LASIK or SBK to correct myopia, 29 patients 57 eyes underwent SBK, 30 patients 57 eyes underwent LASIK. Anterior optical coherence tomography(OCT) was used to measure corneal flap thickness in all the patients 1 week after surgeries, 16 positions were set to be measured in each eye. Comparisons of flap thickness in each group and between 2 groups were evaluated. Correlative factors of flap thickness were evaluated. Coefficient of variation (CV, s/×%) in SBK group were lesser than that in LASIK group, t test showed there was significant statistical difference between 2 groups(P=0.000). Comparisons of the difference of 2 paired positions(temporal-nasal; superior-inferior) showed there were no significant differences in each group, but between 2 groups, there were statistical significance of value of difference (D-value) of superior and inferior positions between SBK and LASIK group(P=0.036). Linear regression analysis of correlative factors of flap thickness showed there were no statistic significances related to central corneal thickness(CCT)(P=0.060, t=1.921) and corneal curvature(P=0.083, t=1.766). SBK is better than LASIK in creating much uniform corneal flap. There was no evidence showing correlations between flap thickness and CCT or corneal curvature.

Thin-flap (sub-Bowman keratomileusis) versus thick-flap laser in situ keratomileusis for moderate to high myopia: Case-control analysis

To compare the refractive and visual outcomes of sub-Bowman keratomileusis (SBK) and thick-flap laser in situ keratomileusis (LASIK) for moderate to high myopia and evaluate the effect of corneal flap thickness on outcomes. Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, USA. Two studies were performed. In the first study, the refractive and visual outcomes in 33 eyes that had SBK (flap thickness 82 to 120 microm) and 62 eyes that had thick-flap LASIK (flap thickness >or=160) were retrospectively analyzed. Inclusion criteria were spherical equivalent -4.0 to -10.0 diopters (D), astigmatism 3.0 D or less, and follow-up 3 months or more. In the second study, the influence of flap thickness was evaluated. A case-control matched study (21 pairs) that controlled for residual stromal bed (RSB) thickness was performed. The mean flap thickness was 110.2 microm+/-9.2 (SD) in the SBK group and 179.2+/-19.5 microm in the thick-flap LASIK group. There were no significant differences in visual outcomes. In the second study with equivalent RSB thickness, case-control matched comparisons between SBK (mean 108.6+/-8.0 microm) and thick-flap LASIK (mean 165.7+/-12.6 microm) showed no differences in preoperative and postoperative refractive and visual outcomes. Comparison of the intended versus achieved correction showed no significant differences between the 2 groups. Retrospective analyses showed that the safety, efficacy, and predictability of SBK were similar to those of conventional thick-flap LASIK in corneas with equivalent RSB thickness.