Small incision lenticule extraction and femtosecond-assisted laser in situ keratomileusis in patients with deep corneal opacity:case series

AIM:To report the safety,efficacy,and accuracy of small-incision lenticule extraction(SMILE)or femtosecondassisted laser in situ keratomileusis(FS-LASIK)for the correction of myopia or myopic astigmatism in patients with deep corneal opacity denoted by anterior segment optical coherence tomography(AS-OCT).METHODS:Four patients with monocular corneal opacity(3 due to mechanical injury,1 due to a firecracker wound)were recruited and treated with refractive surgery(3 for SMILE,1 for FS-LASIK combined with limbal relaxing incision(LRI).Preoperative ocular manifestations,surgical details,postoperative visual outcomes,corneal opacity parameters,and corneal topography were analyzed.RESULTS:Preoperatively,spherical diopter ranged from-3.0 D to-4.75 D with cylinder ranging from-0.75 to-5.0 D,and corrected distance visual acuity(CDVA)ranging from 20/25 to 20/20.One eye’s corneal opacity was located in the central zone and three were in the mid-peripheral optical zone.Three patients underwent uneventful SMILE in both eyes,whilst one patient underwent FS-LASIK for high astigmatism in both eyes and LRI in the right eye.CDVA of the eye with corneal opacity ranged from 20/22to 20/20 one to six weeks postoperatively.Two patients achieved better CDVA and no patients lost Snellen lines.The postoperative diopter was within±0.75 D for all eyes.Significant edema existed above the corneal opacity in one eye and dissipated soon.No eccentric corneal topography or morphological anomaly of the corneal cap or flap was observed.CONCLUSION:The cases demonstrate that SMILE or FS-LASIK is safe and effective to treat myopic astigmatism combined with deep corneal opacity lesions after comprehensive preoperative evaluation and appropriate candidate selection.FS-LASIK combined with LRI is also sufficient for correcting high astigmatism due to corneal scarring.

Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism

AIM： To compare and calculate the 3-year refractive results, higher-order aberrations （HOAs）, contrast sensitivity （CS） and dry eye parameters after small incision lenticule extraction （SMILE） and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis （FS-LASIK） for correction of high myopia and myopic astigmatism. METHODS： In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent （SE） of -8.11±1.09 diopters （D） received a SMILE surgery, and 65 eyes with SE of -8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the VisuMax femtosecond laser （Carl Zeiss Meditec, Jena, Germany） for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index （OSDI） and tear break-up time （TBUT） were evaluated during a 3-year follow-up. RESULTS： The difference of uncorrected distance visual acuity （UDVA） postoperatively was achieved at lmo and at 3mo, whereas the difference of the mean UDVA between two groups at 3y were not statistically significant （t=-1.59, P=-0.13）. The postoperative change of SE was 0.89 D in the FS-LASIK group （t=5.76, P=0.00）, and 0.14 D in the SMILE group （t=-0.54, P=0.59） from lmo to 3y after surgery. At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group （P=0.00）, but the coma root mean square （RMS） was higher in the SMILE group （0.59±0.26） than in the FS-LASIK group （0.29±0.14, P=0.00）. The mesopic CS values between two groups were not statistically significant at 3y postoperatively. Compared with the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at Imo and 3mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3y after surgery. CONCLUSION： Both SMILE and wavefront-guided FS- LASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive outcome and better control of early postoperative dry eye as compared to FS-LASIK.

Corneal flap morphological analysis using anterior segment optical coherence tomography in laser in situ keratomileusis with femtosecond lasers versus mechanical microkeratome

AIM: To assess and compare the flap morphology using anterior segment optical coherence tomography (AS-OCT) in laser in situ keratomileusis (LASIK) with Femto LDV femtosecond lasers versus Hansatome mechanical Microkeratome. METHODS: AS-OCT (Visante) was used to compare 1 month postoperatively the morphology of the flaps created with Femto LDV femtosecond lasers or Hansatome Microkeratome. The intendedfiap thickness was 110 mu m and 160 mu m respectively. The thickness of twenty-five points across each flap, which were 0mm, 1.5mm, 2.5mm, and 3.5mm to the corneal vertex on the horizontal, vertical, 45 degrees and 135 degrees meridian respectively, was evaluated. RESULTS: One month postoperative, the central flap thickness in the Femto LDV group was 107.43 +/- 4.70 mu m, while 125.90 +/- 17.50 mu m in the Hansatome group. The difference between the actual and the expectedfiap thickness was 5.61 +/- 3.84 mu m and 31.52 +/- 12.27 mu m, respectively. The Hansatome group had presented a statistically significant result (P<0.001). Flap morphology showed a more regular planar shape in the Femto LDV group and a meniscus shape in the Hansatome group. CONCLUSION: AS-OCT is a direct and fast procedure to assess the flap morphology. The morphology by AS-OCT showed that the flaps created with Femto LDV femtosecond laser were more accurate and regular than the flaps created with Hansatome microkeratome.

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

AIM：To compare recovery of the visual acuity in patients one day after sub-Bowman keratomileusis（SBK）or laser in situ keratomileusis（LASIK）.· METHODS：Data from 5923 eyes in 2968 patients that received LASIK（2755 eyes） or SBK（3168 eyes） were retrospectively analyzed.The eyes were divided into 4groups 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.· RESULTS：Uncorrected visual acuity values were0.0115±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.· CONCLUSION：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.

Influence of transient intraocular pressure elevation during laser in situ keratomileusis on rabbit retina thickness

AIMTo utilize tissue micro measurement to study the effect of transient high intraocular pressure (IOP) induced by different durations of suction during laser in situ keratomileusis (LASIK) on rabbit retina thickness.METHODSSixty healthy New Zealand white rabbits were randomly divided into a control group, and 3 negative-pressure suction groups (20s group, 45s group, and 3min group) and each group was comprised of 15 rabbits (30 eyes); the latter 3 groups were the transient high IOP models. The retinal tissue around the papilledema was separated. Hematoxylin and eosin (HE) staining was carried out to generate slices for light microscopy. The changes in the retina thickness values of each layer were measured for all animals in each group at different postoperative recovery periods and compared with the values recorded for the animals in the control group. The thickness of the retinal tissue showed a normal distribution. The ANOVA was performed by using SPSS13.0 statistic software.RESULTSIn the comparison between the 20s and 45s negative-pressure suction groups and the control group, no significant differences were observed, except at 14d. Significant difference was observed between the 3min negative-pressure suction group and the control group, and the retina thickness value of each layer reached a peak at 14d after repair.CONCLUSIONConventional negative suction during LASIK may not lead to significant changes in retinal tissue thickness; however, if the suction duration is increased to 3min, it will cause significant changes in retinal tissue thickness.

Using LaserSight Astrapro Planner 2.2 Z software in corneal topography-guided laser in situ keratomileusis for myopia with asymmetric corneal shape

AIM:To determine the clinical outcomes of laser insitu keratomileusis(LASIK)treatments using LaserSight AstraPro Planner 2.2 Z software for myopia with asymmetric corneal shape.METHODS:Four hundred and eighty-five eyes[243patients;spherical equivalent(SE),-5.93±1.88 diopters(D)]were treated with asymmetric ablations using LaserSight SLX laser(version 5.3,300Hz)were retrospectively analyzed and LaserSight AstraPro Planner2.2 Z software.Preoperative and postoperative uncorrected visual acuities(UCVA),spherical equivalent(SE)refraction,pachymetry,and corneal asphericity(Q value)and decentration were evaluated.RESULTS:At 12mo postoperatively,the decimal UCVA was 1.0 or better in 449(92.6%)eyes.Two eyes(0.4%)lost 1 line of the decimal best spectacle-corrected visual acuity(BCVA),316(65.2%)did not change,149(30.7%)gained 1 line,and 18(3.7%)gained 2 lines or more after surgery.Three hundred and thirty-two eyes(68.5%)were within 0.5 D in SE.The mean tissue saving ablation depth was 4.28±2.86(0-16)μm(median,4μm).The mean attempted remaining central corneal thickness was435.79±29.56μm,the mean postoperative pachymetry was 444.94±28.93μm.The mean preoperative Q value was-0.19±0.18,the postoperative was 0.30±0.48(P=0.000).The mean postoperative decentration was 0.39±0.19 mm.CONCLUSION:Topography-guidedLASIKwithAstraPro Planner 2.2 Z custom ablation planning software in an asymmetric ablation mode was an effective,safe,predictable,and stable refractive procedure for the myopia with asymmetric corneal topography.

Laser in situ keratomileusis in adult patients with anisometropic amblyopia

AIM: To evaluate the increase in corrected distance visual acuity (CDVA) after laser in situ keratomileusis (LASIK) in adults with anisometropic amblyopia. · METHODS: The medical records of consecutive patients diagnosed with anisometropic amblyopia at the time of refractive evaluation who underwent LASIK were retrospectively reviewed. Patients with at least a two-line difference of visual acuity (VA) between the eyes with a spherical refractive error difference of at least 3.00 diopters (D) or an astigmatic difference of at least 2.00D were included. Patients with any other possible reason for amblyopia other than anisometropia or those who had undergone previous amblyopia treatment were excluded. Amblyopic eyes with myopia or myopic astigmatism were considered as group 1, hypermetropia or hypermetropic astigmatism constituted group 2, and mixed astigmatism patients comprised group 3. Uncorrected distance visual acuity (UDVA), subjective manifest refraction, and CDVA were analyzed at 1 week and 1 month, 3, and 6 months. ·RESULTS: The study included 57 eyes of 57 patients. There were 33 eyes in group 1, 12 eyes in group 2, and 12 eyes in group 3. The preoperative mean values for spherical equivalent of subjective manifest refraction (SE) in groups 1, 2, and 3 were (-4.66±1.97)D, (4.40±1.00)D, and (0.15±1.05)D, respectively. Mean CDVA improved 0.1 log units (1 line LogMAR) at 6 months (P 【0.05). Sixteen eyes (28%) exhibited an improvement in CDVA in week 1. Fourteen eyes (25% ) experienced two or more lines of CDVA improvement at month 6. There were no statistically significant differences among the groups in terms of CDVA (P 】0.05). Moreover, age, the amount ofpreoperative refractive error, and the levels of preoperative corrected and UDVA had no effect on postoperative CDVA improvement (P 】0.05). · CONCLUSION: Correction of refractive errors with LASIK produced significant CDVA improvement in adult patients with anisometropic amblyopia and no previous amblyopia treatment.

Comparison of optical quality after implantable collamer lens implantation and wavefront-guided laser in situ keratomileusis

AIM： To compare the optical quality after implantation of implantable collamer lens（ICL） and wavefront-guided laser in situ keratomileusis（WG-LASIK）.METHODS： The study included 40 eyes of 22 patients with myopia who accepted ICL implantation and 40 eyes of 20 patients with myopia who received WG-LASIK. Before surgery and three months after surgery, the objective scattering index（OSI）, the values of modulation transfer function（MTF） cutoff frequency, Strehl ratio, and the Optical Quality Analysis System（OQAS） values（OVs） were accessed. The higher order aberrations（HOAs） data including coma, trefoil, spherical, 2^（nd） astigmatism and tetrafoil were also obtained. For patients with pupil size 〈6 mm, HOAs data were analyzed for 4 mm-pupil diameter. For patients with pupil size ≥6 mm, HOAs data were calculated for 6 mm-pupil diameter. Visual acuity, refraction, pupil size and intraocular pressures were also recorded.RESULTS： In both ICL and WG-LASIK group, significant improvements in visual acuities were found postoperatively, with a significant reduction in spherical equivalent（P〈 0.001）. After the ICL implantation, the OSI decreasedslightly from 2.34±1.92 to 2.24±1.18 with no statistical significance（P=0.62）. While in WG-LASIK group, the OSI significantly increased from 0.68±0.43 preoperatively to 0.91±0.53 postoperatively（Wilcoxon signed ranks test, P=0.000）. None of the mean MTF cutoff frequency, Strehl ratio, OVs showed statistically significant changes in both ICL and WG-LASIK groups. In the ICL group, there were no statistical differences in the total HOAs for either 4 mmpupil or 6 mm-pupil. In the WG-LASIK group, the HOA parameters increased significantly at 4 mm-pupil. The total ocular HOAs, coma, spherical and 2^（nd） astigmatism were 0.12±0.06, 0.06±0.03, 0.00±0.03, 0.02±0.01, respectively. After the operation, these values were increased into 0.16±0.07, 0.08±0.05,-0.04±0.04, 0.03±0.01 respectively（Wilcoxon signed ranks test, all P〈0.05）. At 6 mm-pupil, the induction of total HOAs was not statistically significant in the WG-LASIK group. CONCLUSION： ICL implantation has a less disturbance to optical quality than WG-LASIK. The OQAS is a valuable complementary measurement to the wavefront aberrometers in evaluating the optical quality.

Optical and visual quality comparison of implantable collamer lens and femtosecond laser assisted laser in situ keratomileusis for high myopia correction

AIM:To compare clinical outcomes and refractive stability of implantable collamer lens(ICL)implantation and femtosecond laser assisted laser in situ keratomileusis(FSLASIK)for high myopia correction.METHODS:The Optical Quality Analysis System(OQAS)was used to evaluate clinical outcomes objectively after operation for high myopia correction.We compared the two procedures in terms of 1-year changes in uncorrected distance visual acuity(UDVA),corrected distance visual acuity(CDVA),safety index,efficacy index,spherical equivalent,modulation transfer function(MTF)cutoff frequency,strehl ratio(SR)and objective scatter index(OSI).RESULTS:At 1 y postoperatively,the safety indices were 1.33±0.27 in ICL group,and 1.17±0.24 in FS-LASIK group.39.58%in the ICL group and 27.59%in the FS-LASIK group gained CDVA in 2 lines or better than that in preoperative CDVA.The efficacy indices were 1.28±0.22 in ICL group,and 1.13±0.26 in FS-LASIK group.The changes of spherical equivalent from 1 wk to 1 y postoperatively was-0.12±0.37 D in ICL group,and-0.79±0.58 D in FS-LASIK group(P<0.05).Spherical equivalent within±0.50 D was achieved in 97.92%in ICL group and 68.97%in FS-LASIK group.MTF cutoff frequency were higher with ICL as compared to FSLASIK(P<0.05)at each postoperative follow-up stage;for postoperative 1 mo later,SR was statistically significant difference between two groups(P<0.05);with no statistically significant difference in OSI between two groups(P>0.05)in postoperative 3 mo later.CONCLUSION:ICL implantation and FS-LASIK procedures both provide good safety and predictability in high myopia correction.ICL implantation provides better clinical outcomes and refractive stability than FS-LASIK.

Comparison of Intraocular Pressures at Different Points in Human's Cornea before and after Laser in situ Keratomileusis with Tono-Pen Tonometer

In order to explore the difference of intraocular pressure（IOP） at different points of cornea before and after laser in situ keratomileusis（LASIK）,IOP was measured by Tono-Pen Tonometer at central cornea,pericentral cornea and limbus respectively and analyzed statistically.After LASIK,IOP was dropped significantly at central cornea and pericentral cornea（P〈0.05）,while no statistically significant change occurred at limbus（P〉0.05）.There was no statistically significant difference in IOP at different points before LASIK（F=0.110,P=0.896）,but statistically significant difference was found after LASIK（F=7.375,P=0.001）.It was suggested that reliable IOP after LASIK could be obtained from the limbus by Tono-Pen tonometer.

Effect of Laser in situ Keratomileusis on Accommodation

The accommodative function before and after laser in situ keratomileusis （LASIK） was observed, and the effect of LASIK on accommodation was investigated. In a prospective clinical trial, 48 myopic patients （96 eyes） subject to bilateral LASIK in Refractive Surgery Center, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology （China） from March 2006 to June 2006 were selected and studied. Refractions, accommodative range, amplitude of accommodative response and high frequency component （HFC） of accommodative microfluctuations were measured with NEDIK-730A before and one week and 30 days after operation. Dominant and non-dominant eyes were determined by hole-in-card method. It was found that all of the operative eyes showed an uncorrected visual acuity of 0.8 or better one week postoperatively, and 1.0 or better 30 days postoperatively. Compared with those preoperatively, accommodative range and HFC had no significant difference at first week and 30th day after operation in both dominant eyes and non-dominant eyes （P〉0.05）, but there was a significant difference in the amplitude of accommodative response/accommodative stimulus ratio （A/S） after operation （P〈0.01）, and no significant difference was found in accommodation between one week and 30 days postoperation. No ocular dominance＇s change was noted. There was no significant difference in accommodative function between dominant eyes and non-dominant eyes. It was suggested that LASIK produced no significant effect on accommodation.

Posner-Schlossman syndrome induced laser in situ keratomileusis keratectasia–a case report

Iam Dr. Xiu Wang, from Tianjin Medical University Eye Hospital, Tianjin, China. I write to present one case report of Posner-Schlossman syndrome （PSS） induced laser in situ keratomileusis （LASIK） keratectasia.

ONE YEAR RESULTS OF LASER IN SITU KERATOMILEUSIS FOR CORRECTION OF HYPEROPIA

Objective: To evaluate the effectiveness, predictability and city of laser in situ keratomileusis (LASIK) for correction of hyperopia. Methods 54 eyes of 35 patients with hyperopia ranging from+1.00 to + 6. 00 diopter(D) received a one-pass, multizone scanning excimer laser ablations using the Chiron Technolas Keracor 11 7C excimer laser and System ALK automated corneal shaper H-230.Data on uncorrected and hot corrected visual acuity, predictability, stability of refraction, and complications were analyzed. The average follow-up was 12 months. Results At 12 months, the average residual refraction was(+ 0. 29 ±0. 78)D. 45 eyes (83.3% ) were in the range of ±1. OD and 33 eyes(61. 1% ) were within the range of ± 0. 5D. 50 eyes (92. 6% ) had uncorrected visual acuity of 20/40 or better and 34 eyes (63. 0% ) had 20/20 or better. 1 eyes (1. 9% ) lost 2 line of the best-corrected visual acuity and 2 eyes (3. 7% ) gained 2 lines or more. 2 eyes (3. 7%) had complaint of halos and 1 eyes (1. 9% ) had glare at 12 months. Conclusion LASIK can he used to treat hyperopia from + 1. 0D to + 6. 0D with good predictability and city. Primary and second hyperopia should he treated with different nomogram. some modification of the surgical algorithms and laser nomogram will help to improve predictability and stability of outcome.

Long-term efficacy of excimer laser in situ keratomileusis in the management of children with high anisometropic amblyopia

Background Children with anisometropic amblyopia are often noncompliant with traditional treatment including spectacules and contact lenses. This study was to evaluate the long-term efficacy of excimer laser in situ keratomileusis （LASIK） for children with high anisometropic amblyopia. Methods A retrospective analysis of 24 children with high unilateral anisometropic amblyopia, who underwent LASIK during the period between August 2000 and September 2005 in our hospital, was conducted. The mean age of these children was （7.4±1.9） years （range 5-14 years） and the mean follow-up period was （33.3±14.2） months （range 18.5-74.2 months）. After LASIK, visual acuity, refraction and far or near stereoacuity were analyzed. Near stereoacuity was measured by the random-dot butterfly stereogram and the pre-school random-dot stereogram, while far stereoacuity was measured by the synoptophore with Yan＇s random-dot stereogram. Results Mean preoperative uncorrected visual acuity was 0.06±0.05, while mean postoperative uncorrected visual acuity was elevated to 0.43±0.33. Mean preoperative best-corrected visual acuity was 0.26±0.22, while mean postoperative best-corrected visual acuity was elevated to 0.67±0.40. For patients with myopic anisometropia, preoperative mean spherical equivalent refraction was （-8.01±2.70） D while postoperative value significantly reduced to （-1.32±2.47） D. For patients with hyperopic anisometropia, preoperative mean spherical equivalent refraction was （ 7.35±1.55） D while postoperative value significantly reduced to （3.30±0.86） D. These results demonstrated that there was statistical difference in these parameters between preoperative and postoperative tests. At the last follow-up, 20 patients had near stereoacuity, and the mean near stereoacuities measured by the random-dot butterfly stereogram and the preschool random-dot stereogram were （149.00±152.93）＂ and （201.05±235.94）＂, respectively. In contrast, 11 patients had far stereoacuity, and the mean far stereoacuity measured by the synoptophore was （210.91±217.51）. Three cases of patients developed mild corneal complications. Conclusion LASIK for the correction of high anisometropia in children with monocular amblyopia may be safe and effective, and this can help effectively conduct postoperative amblyopia training and improve the cure rate.

A clinical trial of premedication for unscheduled laser in situ keratomileusis surgeries and a related bacteriological analysis of conjunctival sacs

Laser in situ keratomileusis （LASIK） is a quick and effective approach for treating ametropia. It is used to treat relatively healthy corneas, and patients usually have high expectations and requirements for postoperative visual results. Therefore, the prevention of severe postoperative complications, such as corneal infections, is important.~ In China, some individuals require a rapid improvement in uncorrected visual acuity through surgery. There are also individuals from other cities seeking better medical services. Because of time limitations, the preoperative preparation time may be too short to complete a 3-day eye drop treatment with antibiotics. In this case study, we compared the bacterial eliminating effects and adverse reactions of levofloxacin eye drops （Santen Corp., Japan） and 0.5% Povidone-iodine （PVI, Nanda Pharmaceutical Corp., China） irrigation, for different time periods before unscheduled LASIK surgery.

Bilateral nontuberculous mycobacterial keratitis after laser in situ keratomileusis

Laser in situ keratomileusis （LASIK） is currently the most popular keratorefractive procedure performed worldwide with generally excellent outcomes. However, infectious keratitis after LASIK is a devastating, vision-threatening complication. The common pathogens were bacteria and fungi. Nontuberculous mycobacterium （NTM） accounted for a substantial proportion of these pathogens. Most NTM infections （86% of cases） were involved in unilateral cornea. In this study, we report six patients with bilateral NTM keratitis following LASIK.

Analysis of Macular and Retinal Nerve Fiber Layer Thickness in Children with Refractory Amblyopia after Femtosecond Laser-assisted Laser In situ Keratomileusis：A Retrospective Study

Background：Localized macular edema and retinal nerve fiber layer （RNFL） thinning have been reported shortly after laser in situ keratomileusis （LASIK） in adults.However,it is still unclear how LASIK affects the retina of children.This study aimed to investigate the macular retina and RNFL thickness in children with refractive amblyopia who underwent femtosecond laser-assisted LASIK （FS-LASIK）.Methods：In this study,we included 56 eyes of 32 patients with refractive amblyopia who underwent FS-LASIK in our hospital from January 2012 to December 2016.Foveal （foveal center retinal,parafoveal retinal,and perifoveal）,macular inner retinal （superior and inferior）,and peripapillary RNFL thicknesses （superior,inferior,temporal,and nasal） were measured using Fourier-domain optical coherence tomography before surgery and l day,3 days,and 1 week after surgery.We divided these patients into three groups based on their refractive error：High myopic group with 22 eyes （equivalent sphere,〉6.00 D）,mild myopic group with 19 eyes （equivalent sphere,0-6.00 D）,and hyperopic group with 15 eyes （equivalent sphere,〉＋0.50 D）.We compared the macular retina and RNFL thickness before and after LASIK.A paired simple t-test was used for data analysis.Results：One week after surgery,the visual acuity for all 56 eyes of the 32 patients reached their preoperative best-corrected vision.Visual acuity improved two lines or better for 31% of the patients.The residual refractive errors in 89% of the patients were within ±0.5 D.In the high myopic group,the foveal center retinal and parafoveal retinal thicknesses were thicker 1 day and 3 days after surgery than before surgery （t =2.689,P =0.012;t =2.383,P =0.018,respectively）;no significant difference was found 1 week after surgery （P 〉 0.05）.The foveal center retinal and parafoveal retinal thicknesses were greater 1 day after surgery than they were before surgery （P =0.000 and P =0.005,respectively） in the mild myopic and hyperopic groups.No significant difference was found 3 days or 1 week after surgery （P 〉 0.05）.In all three groups,no significant difference was found in the macular inner retinal or peripapillary RNFL thickness 1 day,3 days,or 1 week after surgery （P 〉 0.05）.Conclusions：The foveal center retinal edema after FS-LASIK is mild and reversible in children,that mostly occurred in the high myopic group with no effect on the visual acuity,and is always relieved within 1 week.

STREPTOCOCCUS PNEUMONIAE KERATITIS FOLLOWING LASER IN SITU KERATOMILEUSIS

A 22-year-old man underwent bilateral laser in situ keratomileusis and developed Streptococcus pneumoniae keratitis after surgery.This complication occurred one day after the procedure in both eyes.Topical and systemic antibiotics were promptly administered.Bacterial culture was performed following corneal flap lift and scraping of the lesions.Afterwards,the therapeutic regimen was readjusted according to the culture results.Streptococcus pneumoniae was identified from the culture.Three months after the surgery,corrected distance visual acuity achieved 20/20 in both eyes.Streptococcus pneumoniae can affect the cornea following LASIK.As prompt treatment is crucial,we recommend,for acute and subacute cases,systemic and topical application of vancomycin or moxifloxacin before the culture results come out.

Above-average defocus curves in photopic and mesopic vision with multifocal intraocular lenses after laser assisted in situ keratomileusis

I am Dr. David P Pifiero from the Department of Optics, Pharmacology and Anatomy of the University of Alicante and from the Department of Ophthalmology of Vithas Medimar （Oftalmar） and Vithas Virgen del Carmen （Qvision） hospitals in Spain.

Clinical outcomes of small incision lenticule extraction versus femtosecond laser-assisted LASIK for myopia: a Meta-analysis

AIM：To evaluate the possible differences in visual quality between small incision lenticule extraction（SMILE）and femtosecond laser in situ keratomileusis（FS-LASIK）for myopia.METHODS：A Meta-analysis was performed.Patients were from previously reported comparative studies treated with SMILE versus FS-LASIK.The Pub Med,EMBASE,Cochrane,Web of Science and Chinese databases（i.e.WANFANG and CNKI）were searched in Nov.of 2016 using Rev Man 5.1 version software.The differences in visual acuity,aberration and biomechanical effects within six months postoperatively were showed.Twenty-seven studies including 4223 eyes were included.RESULTS：No significant differences were observed between SMILE and FS-LASIK in terms of the proportion of eyes that lost one or more lines of corrected distance visual acuity after surgery（P=0.14）,the proportion of eyes achieving an uncorrected distance visual acuity of 20/20or better（P=0.43）,the final refractive spherical equivalent（P=0.89）,the refractive spherical equivalent within±1.00diopter of the target values（P=0.80）,vertical coma（P=0.45）and horizontal coma（P=0.06）.Compared with the FSLASIK group,total higher-order aberration（P〈0.001）and spherical aberration（P〈0.001）were higher and the decrease in corneal hysteresis（P=0.0005）and corneal resistance factor（P=0.02）were lower in the SMILE group.CONCLUSION：SMILE and FS-LASIK are comparable in efficacy,safety and predictability for correcting myopia.However,the aberration in the SMILE group is superior to that in the FS-LASIK group,and the loss of biomechanical effects may occur less frequently after SMILE than after FS-LASIK.