sub-Bowman Keratomileusis Research Articles

Factors Predicting Loss of Best-Corrected Visual Acuity After Hyperopic Laser-Assisted In Situ Keratomileusis.

The aim of this study was to identify risk factors for the loss of corrected distance visual acuity (CDVA) after uncomplicated hyperopic laser-assisted in situ keratomileusis (LASIK). A retrospective study including hyperopic patients who underwent microkeratome-assisted LASIK between January 2000 and December 2019 at Care-Vision Laser Centers, Tel-Aviv, Israel. Loss of CDVA was defined as ≥ 2 lines (0.20 logarithm of the minimum angle of resolution [logMAR] increase). Excluded were patients who had loss of CDVA because of intraoperative or postoperative complications or developed cataract at their final visit. Overall, 1998 eyes of 1998 patients were included in the study, of which 35 eyes (1.75%) had CDVA loss at final follow-up (mean 387 days). The vision-loss group had a significantly greater spherical treatment (3.4 vs. 2.8 D, P = 0.02), ablation depth (69.4 vs. 53.8 μm, P = 0.01), a higher proportion of treatments with a smaller optic zone (6.0 mm) (31.4% vs. 13.4%, P = 0.002), treatment with the EX200 (Alcon) excimer rather than the EX500 (Alcon) (74.3% vs. 39.0%, P < 0.001), and treatment with the Moria M2-90 microkeratome rather than the Moria Sub-Bowman's keratomileusis (SBK) microkeratome (65.7% vs. 29.6%, P < 0.001). In multivariate binary logistic regression, factors that remained significant predictors of CDVA loss were a greater spherical treatment (per 1 D treatment, odds ratio = 1.42, 95% CI, 1.11-1.81, P = 0.004) and the use of the Moria M2-90 microkeratome (odds ratio = 4.66, 95% CI, 2.30-9.45, P < 0.001). In patients undergoing uncomplicated hyperopic LASIK, a greater spherical hyperopic treatment is associated with a higher risk for vision loss. Transition to a newer microkeratome model significantly reduced vision loss rate.

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.

A morphological comparison between sub-bowman keratomileusis flap and femtosecond laser-assisted flap in LASIK surgery for myopia

Abstract Purpose: Comparison between the SBK microkeratome versus femtosecond laser in flap creation during LASIK surgery for myopia. Materials and Methods: This is a prospective comparative nonrandomized interventional clinical study that included 60 eyes of 30 patients in each group. Patients were randomized to receive either the SBK microkeratome or femtosecond laser technique according to a randomization computer software. The patient’s ages ranged from 18 to 46 years in the FS200 laser group and from 20 to 44 years in the SBK group. The WaveLight FS200 femtosecond laser and the Moria SBK microkeratome were both used to generate flaps in the 60 eyes of 30 patients (Moria SA, Antony, France). About 1 month after surgery, AS-OCT was utilized to measure the thickness of five locations on each flap that was 0, 1.5 mm from the corneal vertex on the horizontal and vertical axes. Hinge size and flap diameter were measured using a caliper 1 month after surgery. Uncorrected visual acuity and best corrected visual acuity were measured at 1 day, 1 week, and 1 month postoperative in each group. Any related complications were recorded in each group. For side-cut angles, scans were done across the temporal side of the flap, and then images were transferred to Draw editor software, and measurements were recorded and analyzed 1 month after surgery using AS-OCT. Results: The mean obtained central corneal flap thickness in both eyes in the FS200 laser group was 117.4 µ ± 4.18 SD, and 84.90 µ ± 3.74 SD in the SBK group, which was statistically significant (P &lt; 0.05). The mean achieved Hinge size in both eyes in the FS200 laser group was 3.47 ± 0.26 mm, and 4.81 ± 0.63 mm (P &lt; 0.05) in the Moria SBK group. The mean achieved flap diameter in the FS200 laser group was 7.95 ± 0.43 mm, and 9.15 ± 0.21 mm in the SBK group (P &lt; 0.05). In the FS200 laser group, the average side cut angle was 126.93°9.56°, while in the SBK group, it was 37.18°6.93° (P &lt; 0.05). Conclusion: In the two study groups, there was a statistically significant difference in the side cut angles that were intended and actually achieved. In comparison to the SBK group, the FS200 laser group had better predictability of flap thickness. There were reported complications in the SBK group, while femtosecond laser technology has shown better postoperative flap uniformity with no reported complications.

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.

Changes of angle Kappa and corneal morphology changes in myopic patients after Sub-Bowman-Keratomileusis.

To investigate angle Kappa and diopter distribution in myopic patients and the changes of angle Kappa and corneal morphology after Sub-Bowman-Keratomileusis (SBK), and to analyze the effects of the surgery on corneal morphologic changes and the patients' near fixation characteristics. The clinical data of 134 myopic patients (268 eyes) undergoing SBK from August 2015 to August 2016 were retrospectively analyzed. Angle Kappa, corneal curvature in the central corneal region of 3 mm, and post-corneal Diff value were measured by Orbscan IIz Corneal Topography System before operation, 1 month and 6 months after operation. According to the values of angle Kappa before SBK, the patients were divided into 2 groups: the large K group (angle Kappa≥5°, 71 eyes) and the small K group (angle Kappa<5°, 197 eyes). Correlation analysis of the factors influencing angle Kappa at 6 months after operation was performed. In the large K group, angle Kappa was (5.67±0.65)°, spherical equivalent was (-4.84±2.32) D, and angle Kappa was decreased after operation (both P<0.05) with the increased decreasing range over time. In the small K group, angle Kappa was (3.51±1.08)°, spherical equivalent was (-5.78±2.63) D, angle Kappa was increased after operation with decreased increasing range over time, and the difference was statistically significant between 6 months after operation and before operation (P<0.05).The post-corneal Diff value of the 2 groups was increased after operation (all P<0.001), and was decreased from 1 month to 6 months after surgery. The corneal curvature in the central corneal region of 3 mm of the 2 groups 1 month after operation was decreased significantly (both P<0.001). From 1 month to 6 months after operation, the corneal curvature of the large K group tended to be stable, while the corneal curvature of the small K group tended to increase. There was no significant correlation between the changes of angle Kappa 6 months after operation and the changes of the corneal central curvature or the post-corneal Diff value (both P>0.05), but the changes of angle Kappa 6 months after operation was positively correlated with corneal cutting thickness (rlarge K group=0.398, rsmall K group=0.218, both P<0.05) and it was negatively correlated with preoperative diopter (rlarge K group=-0.283, rsmall K group=-0.233, both P<0.05). The angle Kappa is decreased in low-moderate myopia patients with large angle Kappa, while is increased in high myopia patients with small angle Kappa after SBK. Myopia patients after SBK will look for the new balance of the binocular accommodation and vergence function for improving the comfort in the near-work situations.

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.

Risk factors for early flap misalignment following microkeratome-assisted laser in situ keratomileusis: A retrospective large database analysis.

To determine factors associated with early flap misalignment following microkeratome-assisted laser in situ keratomileusis. This retrospective study included the right eyes of consecutive patients who underwent laser in situ keratomileusis procedure between 2005 and 2016 at Care-Vision Laser Centers, Tel-Aviv, Israel. Patients were divided into two groups according to whether or not they subsequently developed early flap misalignment. A total of 14,582 eyes (mean age of patients: 32.4 ± 10.3 years) were included. Post-laser in situ keratomileusis early flap misalignment developed in 158 eyes (1.1%). Misalignment was more frequent during the spring (32.3% vs 22.8%, p = 0.003) and in a higher operating room temperature (23.34 ± 1.06 vs 22.98 ± 1.26, p < 0.001). In addition, in the misalignment group, there was a higher rate with the of use of the a Moria M2 microkeratome (rather than sub-Bowman's keratomileusis microkeratome) head (55.2% vs 40.5%, respectively, p < 0.001). In a multivariable analysis adjusted for surgeon and year of surgery, high operating room temperature (odds ratio = 1.22, p = 0.006), treatment zone of 9.0 mm (as opposed to smaller treatment zones, odds ratio = 1.54, p = 0.04), and springtime (odds ratio = 1.58, p = 0.02) were associated with flap misalignment. There was a significant difference in misalignment rates between surgeons (p = 0.02). This study found that larger treatment zones, higher operating room temperature, operating during the spring, and the use of Moria M2 microkeratome were associated with increased flap misalignment rates. The association with operating room temperature and seasonal variation is of interest and merits further research.

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

Femtosecond sub-Bowmen keratomileusis at the peak of the action of Botulinum toxin A, introduced into extraocular muscles in a patient with nystagmus: A clinical case

A clinical case of excimer laser correction performed by sub-Bowman femtosecond keratomileusis at the peak of botulinum toxin A effect in a patient with high congenital anisometropic myopia and horizontal nystagmus is presented. Keratorefractive surgery improved functional visual performance and the parameters of nystagmus.

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

Evaluation of the Accuracy of Sub Bowman's Keratomileusis (SBK) Microkeratome in Flap Creation during Lasik Surgery

Evaluation of the Accuracy of Sub Bowman's Keratomileusis (SBK) Microkeratome in Flap Creation during Lasik Surgery

Clinical analysis of 1g/L bromfenac sodium eye drops in patients with high myopia astigmatism after sub-Bowman keratomileusis

Clinical analysis of 1g/L bromfenac sodium eye drops in patients with high myopia astigmatism after sub-Bowman keratomileusis

A report of traumatic cornea flap loss at two and a half years after sub-Bowman keratomileusis

A report of traumatic cornea flap loss at two and a half years after sub-Bowman keratomileusis

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.

Comparison of microkeratome assisted sub-Bowman keratomileusis with photorefractive keratectomy

PurposeTo compare the outcomes of photorefractive keratectomy (PRK) and thin-flap Laser-Assisted in Situ Keratomileusis/sub-Bowman keratomileusis (SBK) with intended flap thicknesses of 100μm using the One Use-Plus SBK microkeratome. MethodsNinety-eight eyes of 52 subjects with myopic manifest refraction spherical equivalent (MRSE) of up to −5 diopters (D), a stable refraction for 1year and a corrected distance visual acuity (CDVA) of at least 20/20 in each eye which had undergone SBK or PRK were reviewed retrospectively. Primary outcome measures were MRSE, uncorrected distance visual acuity (UDVA), CDVA, pachymetry and higher order aberrations (HOA). All patients were seen at 1 and 3days, 1week, and 1, 3, and 6months after surgery. ResultsBoth MRSE and UDVA showed a statistically significant improvement at postoperative 1, 3 and 6months from baseline in both SBK and PRK groups. At postoperative 6months, 100% of eyes were within ±0.50 D of attempted correction in both groups. However, SBK group demonstrated better outcomes with 81% of eyes within ±0.13 D, compared to 70% eyes in the PRK group. Both SBK and PRK group demonstrated similar refractive astigmatism accuracy at postoperative 6months, with 88% of eyes having cylindrical error ⩽0.25 D. None of eyes lost any lines of CDVA in the PRK, and 2% eyes lost one line of CDVA in SBK group at postoperative 6months. ConclusionThe visual and refractive outcomes after both PRK and microkeratome assisted SBK are comparable, albeit with a higher complication rate in the SBK group.

Polar Value Analysis of Low to Moderate Astigmatism with Wavefront-Guided Sub-Bowman Keratomileusis.

Purpose To evaluate the astigmatic outcomes of wavefront-guided sub-Bowman keratomileusis (WFG-SBK) for low to moderate myopic astigmatism. Methods This study enrolled 100 right eyes from 100 patients who underwent WFG-SBK for the correction of myopia and astigmatism. The polar value method was performed with anterior and posterior corneal astigmatism measured with Scheimpflug camera combined with Placido corneal topography (Sirius, CSO) and refractive astigmatism preoperatively and 1 month, 3 months, and 6 months postoperatively. Results Similar results for surgically induced astigmatism (SIA) and error of the procedure in both anterior corneal astigmatism (ACA) and total ocular astigmatism (TOA). There was a minor undercorrection of the cylinder in both ACA and TOA. Posterior corneal astigmatism (PCA) showed no significant change. Conclusions Wavefront-guided SBK could provide good astigmatic outcomes for the correction of low to moderate myopic astigmatism. The surgical effects were largely attributed to the astigmatic correction of the anterior corneal surface. Posterior corneal astigmatism remained unchanged even after WFG-SBK for myopic astigmatism. Polar value analysis can be used to guide adjustments to the treatment cylinder alongside a nomogram designed to optimize postoperative astigmatic outcomes in myopic WFG-SBK.

Femtosecond laser-assisted sub-Bowman keratomileusis versus laser-assisted subepithelial keratomileusis to correct myopic astigmatism

PurposeTo compare femtosecond laser-assisted sub-Bowman keratomileusis (FSBK) versus laser-assisted subepithelial keratomileusis (LASEK) to correct moderate to high myopic astigmatism. MethodsRetrospective, nonrandomized, interventional, comparative case series. A total of eight hundred and fifty-two eyes with myopic astigmatism of −1.5 diopters (D) or higher were included in the study. We compared 427 eyes treated with FSBK versus 425 eyes treated with LASEK with or without mitomycin C. Visual and refractive results were evaluated 1 day, 1 week, 3 and 6 months postoperatively. ResultsSix months postoperatively, the residual spherical defect was slightly but significantly higher in the LASEK group (+0.15±0.62D) than in the FSBK group (+0.09±0.35D) (P=0.05). The postoperative residual astigmatism was also slightly but significantly higher in the LASEK group (−0.38±0.52D) than in the FSBK group (−0.26±0.45D) (P=0.0005). No significant differences were found in the efficacy (0.98±0.17 versus 0.98±0.36, P=0.6) and safety indexes (1.04±0.16 versus 1.05±0.37, P=0.1) between FSBK and LASEK. The enhancement rate was significantly higher in the FSBK group (22.6%) than in the LASEK group (15.5%) (P=0.01). ConclusionsBoth FSBK and LASEK are safe and effective procedures to correct moderate to high myopic astigmatism. Slightly better visual and refractive results were observed in FSBK-treated eyes in a 6-month follow-up.

Contralateral assessment of sub-Bowman keratomileusis (SBK) microkeratome suction duration on laser-assisted in-situ keratomileusis (LASIK) flap characteristics

PurposeTo describe the effect of prolonging the standard suction duration during laser-assisted in-situ keratomileusis (LASIK) and its effect on flap thickness and hinge length using sub-Bowman keratomileusis (SBK) microkeratome. MethodsFifty-six eyes (28 patients) were included and divided into 2 groups; Group-A: eyes with flatter corneas (36 eyes, 18 patients) and mean keratometric readings ranging from 40.13 to 43.71 diopters (D). Group-B: eyes with steeper corneas (20 eyes, 10 patients) with mean keratometric readings ranging from 43.85 to 46.72 D. One-Use-Plus SBK microkeratome was used for flap creation. For right eyes, flap was created immediately once suction was built up. In left eyes, the surgeon waited for 10 s after suction was built up before flap creation. Flap hinge length and flap thickness were measured using surgical caliper and ultrasonic pachymetry, respectively. ResultsStatistically significant differences were observed in corneal flap hinge size between right eyes versus left eyes, with a mean of 3.98 ± 0.48 vs. 3.78 ± 0.55 mm (p < 0.001). Mean flap thickness in both eyes did not prove to be statistically significantly different with either surgical technique (90.2 ± 1.68 vs. 90.07 ± 1.44 μm, p = 0.8). Sub-group analysis of Group-A vs. Group-B revealed hinge sizes that were significantly larger in steeper corneas (p < 0.01 and p < 0.05, respectively). However, flap thickness in both groups was unaffected by surgical procedure (p = 0.5). ConclusionsIncreasing suction duration increases flap hinge length and stabilizes the flap, especially in steeper corneas.

Comparison of visual acuity of the patients on the first day after sub-Bowman keratomileusis or laser in situ keratomileusis.

To compare recovery of the visual acuity in patients one day after sub-Bowman keratomileusis (SBK) or laser in situ keratomileusis (LASIK). Data from 5923 eyes in 2968 patients that received LASIK (2755 eyes) or SBK (3168 eyes) were retrospectively analyzed. The eyes were divided into 4 groups according to preoperative spherical equivalent: between -12.00 to -9.00 D, extremely high myopia (n=396, including 192 and 204 in SBK and LASIK groups, respectively); -9.00 to -6.00 D, high myopia (n=1822, including 991 and 831 in SBK and LASIK groups, respectively), -6.00 to -3.00 D, moderate myopia (n=3071, including 1658 and 1413 in SBK and LASIK groups, respectively), and -3.00 to 0.00 D, low myopia (n=634, including 327 and 307 in SBK and LASIK groups, respectively). Uncorrected logMAR visual acuity values of patients were assessed under standard natural light. Analysis of variance was used for comparisons among different groups. Uncorrected visual acuity values were 0.0115±0.1051 and 0.0466±0.1477 at day 1 after operation for patients receiving SBK and LASIK, respectively (P<0.01); visual acuity values of 0.1854±0.1842, 0.0615±0.1326, -0.0033±0.0978, and -0.0164±0.0972 were obtained for patients in the extremely high, high, moderate, and low myopia groups, respectively (P<0.01). In addition, significant differences in visual acuity at day 1 after operation were found between patients receiving SBK and LASIK in each myopia subgroup. Compared with LASIK, SBK is safer and more effective, with faster recovery. Therefore, SBK is more likely to be accepted by patients than LASIK for better uncorrected visual acuity the day following operation.

Sécurité du microkératome automatisé pour le Kératomileusis sous-Bowman sur la cornée plate

Use of the One Use-Plus SBK (Sub-Bowman's Keratomileusis) automated microkeratome (Moria, Antony, France) has been shown to be safe, predictable and comfortable for the creation of thin corneal flaps with a smooth and regular stromal bed. To evaluate the use of the Moria One Use-Plus SBK (Moria, Antony, France) automated microkeratome on corneas with 180°-keratometry under 40 diopters (D). We retrospectively studied cases that underwent SBK whose 180°-keratometry was under 40 D. We separated the cases between 39 and 40 D and those less than 39 D. The preoperative data, the procedure and the postoperative outcomes were analyzed. The Moria One Use-Plus SBK microkeratome with the 90-micron head was used for all cases. Among the 2883 eyes that underwent SBK LASIK over the past six years, 80 eyes (2.77%) had a preoperative topographical 180°-keratometry of less than 40 D: 63 eyes (2.19%) between 39 and 40 D and 17 eyes (0.59%) between 38 and 39 D (38.13-38.97 D). The spherical equivalent was between -3.50 D (-2.25 sph -2.50 cyl. at 175°) and+6.00 D (+5.50 sph +1.00 cyl. at 85°). Fifty-eight eyes (72.5%) had hyperopia and/or hyperopic astigmatism; 18 eyes (22.5%) had mixed astigmatism; and 4 eyes (5%) had myopia and/or myopic astigmatism. Twenty-six eyes (32%) had a history of strabismus. Thirteen patients (27.66%) had a history of amblyopia. The "-1" ring was used in all cases, with a 7.5 stop (14%) or 8 stop (86%). The procedure went uneventfully in all cases with a stable vacuum between 117 and 123 mm Hg. The nasal hinge and the stromal bed were normal in size in all cases and sufficient to perform the photoablation laser safely with an optical zone between 6.00 and 7.00 millimeters. There were no intraoperative nor immediate postoperative complications: free cap 0%; incomplete flap 0%; button hole 0%; epithelial erosion 0%; bleeding 0%; irregular stromal bed 0%. Postoperative complications: flap displacement 0%; punctate keratitis: 8%; LASIK retreatments: 12%; safety: 100% (no loss of lines of visual acuity). Corneas with a topographical 180°-keratometry under 40 D are a very small percentage of the total eyes that undergo LASIK (SBK). Those with a 180°-keratometry under 39 D are even more infrequent. Due to the characteristics of the flat cornea, the percentage of hyperopia is much larger in than in the general LASIK group. In addition, the percentage with a history of strabismus and amblyopia is higher. The Moria One Use-Plus SBK microkeratome is an excellent device that allows the easy creation of thin corneal flaps and regular and smooth corneal beds, safely and predictably even in extremely flat corneas without complications. The safety, efficacy and predictability are quite comparable to the general LASIK group.