Anterior chamber gas bubble formation during femtosecond laser flap creation for LASIK

PURPOSE: To report anterior chamber gas bubble formation during corneal flap creation in a myopic patient who underwent LASIK using a femtosecond laser (IntraLase). METHODS: A 30-year-old man underwent customized wavefront-guided LASIK for myopia. The IntraLase FS15 was used to create the corneal flap. RESULTS: During flap creation, gas bubble formation was noted in the anterior chamber, in addition to cavitation bubbles under the flap. Flap creation was successful and myopic ablation was uneventful. One day postoperatively, the flap was well apposed, and no air bubbles were present in the anterior chamber. CONCLUSIONS: Gas bubbles in the anterior chamber can be an infrequent occurrence during the use of femtosecond laser for corneal flap creation. Although gas bubbles do not hinder flap creation, their presence may interfere with eye-tracking mechanisms.     

Characterization of submicrojoule femtosecond laser corneal tissue dissection

PURPOSE: To document the acute morphologic features of laser of situ keratomileusis (LASIK) flaps created using an IntraLase femtosecond laser (IntraLase, Inc.) with a 60 kHz engine. SETTING: Laser suite in a clinical practice. METHODS: A LASIK flap was created in 4 human eye-bank eyes using the 60 kHz IntraLase femtosecond laser with the following settings: 110 microm flap thickness, 9.0 mm flap diameter, 60-degree hinge length, 65-degree side cut, 0.4 muJ or 0.7 muJ raster energy, 7 microm x 7 microm or 9 microm x 9 microm spot/line separation, and 1 muJ side-cut energy. Immediately after the laser pass and without the flap being lifted, the globes were placed in fixative and subsequently processed for light and transmission electron microscopy. RESULTS: All 4 procedures were completed without complications or the appearance of an opaque bubble layer. The flaps were of uniform thickness and equaled the attempted thickness. Some areas had a complete dissection; other areas had scattered, incomplete tissue bridges. The adjacent corneal stroma and keratocytes were uninjured. When the epithelium was removed, the stromal component of the flap was measured as the attempted thickness; when the epithelium was present, the total flap thickness approximated the attempted flap thickness. CONCLUSIONS: Laser in situ keratomileusis flaps were safely created using raster energies and laser spot separations below those being used clinically. This technique may allow creation of flaps that are reproducibly thinner than those currently being performed and thus confer the benefits of surface ablation and LASIK.     

Measurement of corneal curvature change after mechanical laser in situ keratomileusis flap creation and femtosecond laser flap creation

PURPOSE: To compare the change in corneal curvature from the predicted surgical radius (sculpted in the corneal stroma) and the measured postoperative radius of the first surface of the cornea after laser in situ keratomileusis (LASIK) for myopia correction using 2 methods of flap creation: mechanical microkeratome and femtosecond laser. SETTING: Vissum-Instituto Oftalmológico de Alicante, Alicante, Spain. METHODS: This retrospective consecutive nonrandomized comparative interventional case series included 85 eyes with myopia or myopic astigmatism treated using the Esiris excimer laser (Schwind). Patients were divided into 2 groups. One group had LASIK with an M2 microkeratome (Moria) (mechanical LASIK group) and the other, with a femtosecond laser (IntraLase FS, IntraLase Corp.) (femtosecond LASIK group). The relationship between the postsurgical corneal radius and the predicted sculpted radius as well as the mean value of the percentage change in the curvature radius were analyzed to obtain the effect on the refractive defect in each group. RESULTS: There were 44 eyes in the mechanical LASIK group and 41 eyes in the femtosecond LASIK group. A high correlation was found between the final corneal radius and the predicted sculpted radius in both groups (r(2) = 0.85). The mean percentage change in the curvature radius was -3.6% in the mechanical LASIK group and -1.6% in the femtosecond LASIK group (P<.001). The mean estimated refractive change was 1.2 diopters (D) and 0.8 D, respectively. CONCLUSIONS: The refractive change in corneal curvature, which related to the biomechanical response of the corneal surface after the flap cut and repositioning, was lower after femtosecond laser LASIK than after LASIK performed using a mechanical microkeratome. Estimations of refractive change induced by this response should be taken into account in surgery design.     

Flap thickness reproducibility in laser in situ keratomileusis with a femtosecond laser: optical coherence tomography measurement

PURPOSE: To compare ultrasound (US) pachymetry, Orbscan, and optical coherence tomography (OCT) measurements of the central corneal thickness (CCT) before laser in situ keratomileusis (LASIK) and evaluate the reproducibility of flaps created with the IntraLase femtosecond laser (IntraLase, Inc.) using OCT. SETTING: Department of Ophthalmology, IIsan Paik Hospital, Goyang, Korea. METHODS: Central corneal thickness was measured using OCT, US pachymetry, and Orbscan in 59 eyes of 30 patients before femtosecond laser LASIK. The postoperative corneal flap thickness, measured using OCT, was compared with the preoperative intended thickness. RESULTS: Optical coherence tomography, US pachymetry, and Orbscan measurements provided similar CCT values (P>.05). Corneal thickness values obtained using US or Orbscan correlated well with those obtained by OCT, with the correlation coefficient ranging from 0.804 to 0.889 (P<.05). The OCT measurements showed no significant difference between the postoperative flap thickness and the intended flap thickness (P>.05). CONCLUSIONS: Optical coherence tomography was comparable to US pachymetry and Orbscan in cornea thickness measurement. Optical coherence tomography was easy and relatively accurate to use preoperatively and in the early postoperative period. The femtosecond laser created highly reproducible flaps that corresponded with the preoperative intended thickness.     

如何引领角膜屈光手术的发展

准分子激光角膜屈光手术是目前矫正屈光不正最常见的手术方式.本文分析了我国准分子激光角膜屈光手术的发展状况,实施角膜表层切削还是LASIK术的依据以及如何解决两者间的矛盾,LASIK术中不同的角膜瓣制作方式对角膜生物力学稳定性和术后视觉质量的影响.讨论了角膜地形图引导的个体化切削、波前像差引导的个体化切削、Q值调整的个体...     

Very high-frequency digital ultrasound measurement of the LASIK flap thickness profile using the IntraLase femtosecond laser and M2 and Carriazo-Pendular microkeratomes

PURPOSE: To evaluate the corneal aberrometric outcomes and corneal flap thickness profile after LASIK using three different devices for lamellar keratotomy: Moria M2 microkeratome, SCHWIND Carriazo-Pendular microkeratome, and IntraLase femtosecond laser. METHODS: Sixty-six myopic eyes of 33 patients who underwent LASIK with the SCHWIND ESIRIS excimer laser were enrolled in this study. Lamellar keratotomy was performed using three different devices that were assigned randomly to each patient: the Moria M2 microkeratome, SCHWIND Carriazo-Pendular microkeratome, and IntraLase femtosecond laser. The intended flap depth was 110 microm in all cases. Flap thickness profile, corneal aberrations, contrast sensitivity, and refractive outcomes were evaluated. RESULTS: Mean central flap thickness was 117.50 +/- 7.80, 118.08 +/- 8.34, and 115.95 +/- 6.22 microm for the M2, Carriazo-Pendular, and IntraLase systems, respectively. No significant differences were found among the groups. Nasal thicknesses were significantly larger for the M2 flaps compared to IntraLase (P < .05) and Carriazo-Pendular flaps (P = .046 only at 3-mm position). Temporal thicknesses were larger for the M2 flaps, although only differences between M2 and Carriazo-Pendular flaps reached statistical significance. Larger superior and inferior thicknesses were also observed for M2 flaps, although no statistically significant differences were found. Regarding corneal aberrometry, no statistically significant differences were observed in coma-like (P = .138) and spherical-like root-mean-square (P = .300). CONCLUSIONS: The M2, Carriazo-Pendular, and IntraLase systems create flaps of predictable thickness during lamellar keratotomy in LASIK. Additionally, the Carriazo-Pendular and IntraLase devices create flaps with a planar profile.     

Subconjunctival gas bubble Formation during LASIK flap creation using femtosecond laser

PURPOSE: To report a patient who developed subconjunctival gas bubble formation during creation of a LASIK corneal flap with the IntraLase femtosecond laser. METHODS: Case report of a 19-year-old-man with compound myopic astigmatism and a normal preoperative evaluation who underwent bilateral simultaneous LASIK. RESULTS: The IntraLase FS15 was used to create an 8.8-mm diameter superior flap. Laser settings were 110-microm depth, 1.70-mJ bed and side-cut energy, 12-microm spot separation, 10-microm line separation, 70 degrees side-cut angle, 240-microm pocket start width, and 200-microm pocket start depth. The procedure was uneventful in the right eye whereas subconjunctival air bubbles were observed along the corneal limbus in the left eye (no bubbles were seen in the peripheral cornea). The patient was examined 30 minutes later, and the subconjunctival bubbles could still be observed. By the next day, the bubbles had disappeared completely. Postoperative uncorrected visual acuity was 20/20 in both eyes. CONCLUSIONS: Subconjuctival bubbles can be found after LASIK flap creation with a femtosecond laser.     

Advances in refractive surgery: microkeratome and femtosecond laser flap creation in relation to safety, efficacy, predictability, and biomechanical stability

PURPOSE OF REVIEW: Methods of flap creation have changed over the years from the evolution of the mechanical microkeratome to the introduction of the IntraLase femtosecond laser keratome, both of which have different mechanisms of action to create corneal resections. Previous studies report the advantages and disadvantages of the mechanical microkeratome and the IntraLase femtosecond laser. The critical components in laser in-situ keratomileusis surgery remain the same, however: safety, efficiency, predictability, and biomechanical stability. RECENT FINDINGS: Keratoectasia and flap efficiency remain a constant safety concern in laser in-situ keratomileusis surgery. Unexpectedly thick flaps as well as variable thickness continue to be a concern with safety in relation to microkeratome technology. Epithelial preservation, flap complications, and newer issues such as Transient Light Sensitivity Syndrome are safety concerns of flap creation. Improved outcomes with regards to vision, induced astigmatism, induced higher-order aberrations, and enhancement rates are seen to favor predictability of femtosecond technologies over the microkeratome. Recent biomechanical studies show improved healing with femtosecond laser flap creation compared with blade-assisted flap creation. SUMMARY: The aim of this review is to summarize the key components for both the microkeratome and the femtosecond laser and to update on the recent advances reported on these topics.     

Randomized prospective clinical study comparing induced aberrations with IntraLase and Hansatome flap creation in fellow eyes: potential impact on wavefront-guided laser in situ keratomileusis

PURPOSE: To measure and compare the changes in objective wavefront aberration and subjective manifest refraction after laser in situ keratomileusis (LASIK) flap creation with a mechanical microkeratome and a femtosecond laser. SETTING: Private practice refractive surgery center, Irvine, California, USA. METHODS: This randomized prospective study comprised 9 patients (18 eyes) treated with a 2-step LASIK procedure: lamellar keratectomy with a Hansatome microkeratome (Bausch & Lomb) or the IntraLase femtosecond laser in fellow eyes followed by non-wavefront-guided (standard) excimer laser treatment with the Technolas 217A (Bausch & Lomb) excimer laser 10 weeks later. Fellow eyes were matched to within 0.75 diopter (D) sphere and 0.50 D cylinder. Patients were followed for 3 months after excimer laser treatment. Preoperative and post-flap creation wavefront aberrometry using a Hartmann-Shack aberrometer and manifest refraction were compared between the 2 groups. The same tests were performed 3 months after excimer laser ablation. RESULTS: Statistically significant changes were seen in defocus wavefront aberrations after Hansatome (P=.004) and IntraLase (P=.008) flap creation. A hyperopic shift in manifest refraction was noted in the Hansatome group after the creation of the corneal flap (P=.04); no statistically significant changes in manifest refraction were seen in the IntraLase group. Statistically significant changes in total higher-order aberrations (HOAs) (trefoil and quadrafoil Zernike terms) were seen after flap creation in the Hansatome group (P=.02). No significant changes in HOAs were noted after flap creation in the IntraLase group. After the flap was relifted and standard excimer laser ablation was performed, a statistically significant increase in coma occurred in the Hansatome group (P=.008). Standard refractive outcomes in the 2 groups were similar. CONCLUSIONS: The creation of the LASIK flap alone can modify the eye's optical characteristics in low-order aberrations and HOAs. A significant increase in HOAs was seen in the Hansatome group but not in the IntraLase group. This may have significant clinical implications in wavefront-guided LASIK treatments, which are based on measurements made before flap creation.     

Effect of femtosecond and microkeratome flaps creation on the cornea biomechanics during laser in situ keratomileusis: one year follow-up

AIM: To compare the corneal biomechanical outcomes at one year after laser in situ keratomileusis (LASIK) with the flaps created by Ziemer and Moria M2 microkeratome with 110 head and -20 blade. METHODS: Totally 100 eyes of 50 consecutive patients were enrolled in this prospective study and divided into two groups for corneal flaps created by ZiemerFemto LDV and Moria M2 microkeratome with 110 head and -20 blade. Corneal biomechanical properties including cornea resistance factor (CRF) and cornea hysteresis (CH) were measured before and 1, 3, 6, 12mo after surgery by ocular response analyzer. Central cornea thickness and corneal flap thickness were measured by optical coherence tomography. RESULTS: The ablation depth (P=0.693), residual corneal thickness (P=0.453), and postoperative corneal curvature (P=0.264) were not significant different between Ziemer group and Moria 110-20 group after surgery. The residual stromal bed thickness, corneal flap thickness, CH and CRF at 12mo after surgery were significant different between Ziemer group and Moria 110-20 group (P<0.01);Ziemer group gained better corneal biomechanical results. The CRF and CH increased gradually from 1 to 12mo after surgery in Ziemer group, increased from 1 to 6mo but decreased from 6 to 12mo in Moria 110-20 group. Both CRF and CH at one year after surgery increased with the increasing of residual cornea thickness; pre-LASIK CRF, CRF also increased with residual stromal bed thickness, while CH decreased with the increasing of pre-LASIK intraocular pressure and cornea flap thickness (P<0.01). CONCLUSION: In one year follow-up, femtosecond laser can provide better cornea flaps with stable cornea biomechanics than mechanical microkeratome.     

Unexpected flap thickness in laser in situ keratomileusis

We report a case of an unexpected thick flap during laser in situ keratomileusis (LASIK) that led to abandonment of surgery. This report illustrates the importance of stromal bed measurements after flap creation in LASIK. A thicker-than-expected flap can lead to a thinner-than-anticipated residual cornea and subsequent ectasia or even perforation during laser ablation. It is possible that reports of ectasia in normal thickness corneas reflect thicker-than-anticipated flaps.     

One thousand consecutive IntraLase laser in situ keratomileusis flaps

PURPOSE: To measure laser in situ keratomileusis (LASIK) flap dimensions created with the IntraLase FS (IL) laser (Intralase Corporation). SETTING: Private practice, San Diego, California, USA. METHODS: Consecutive LASIK flaps created with the IL were measured with subtraction ultrasound at primary and enhancement surgeries. Data were stored in Outcomes Analysis Software and analyzed using MS Excel (Microsoft Corporation) and SSPS software. RESULTS: The mean achieved flap thickness exceeded the attempted by 9.4 to 34.3 mum. The standard deviation varied from +/-10.2 to +/-21.7 mum. Preoperative corneal thickness and power did not affect achieved flap thickness. Seventy-three percent of mate eye flaps were within +/-15 mum of each other for the 90 mum attempted. The same flaps measured at enhancement were thicker than the primarily measured flaps (n = 58). Diffuse lamellar keratitis and slipped flaps were eliminated with experience. There were no decentered or irregular flaps, epithelial defects, or flap perforations. CONCLUSIONS: Compared with published results of mechanical microkeratomes, the IL reduced the standard deviation of flap thickness as well as the achieved range. It eliminated physical complications associated with mechanical flap creation, and the impact of preoperative pachymetry and corneal power, thereby permitting more myopia to be corrected without risking deep ablations.     

飞秒激光制瓣LASIK术中发生前房气泡51眼临床分析

目的 探讨飞秒激光制作角膜瓣导致前房气泡的原因.方法 回顾性病例对照研究.2009年7月至2010年6月接受飞秒激光制瓣的准分子激光原位角膜磨镶术(LASIK)患者1034例(2058眼),其中发生前房气泡的共48例(51眼)设为观察组,未发生前房气泡的2007眼为对照组,分析前房气泡发生的原因统计学处理采用成组t检验 结果 所有患者手术顺利,术后裸眼视力达到或超过术前矫正视力;观察组角膜直径较对照组小,差异有统计学意义(t=-9.21,P＜0.05);观察组角膜厚度、角膜曲率和Kappa角与对照组比较差异无统计学意义。结论 在瞳孔较大及精确的眼球眼踪系统下,飞秒激光制瓣时产生的前房气泡并不会对患者的术后视力产生影响;对于角膜直径较小的患者,应适当缩小角膜瓣直径,以避免前房气泡的发生.     

Biomechanical effects of femtosecond and microkeratome-based flap creation: prospective contralateral examination of two patients

PURPOSE: To examine flap morphology, corneal topography, and aberrometry after flap creation with a femtosecond laser in one eye and a mechanical microkeratome in the fellow eye. Comparative outcomes after subsequent refractive laser correction were also investigated. METHODS: Two patients (4 eyes) were enrolled in a clinical study in which LASIK flaps were created using the IntraLase laser set at 90 or 100 microm in one eye and the Moria M2 microkeratome with a 90-microm head in the fellow eye. Pre- and postoperative flap data at 1 day, 1 week, and 1 month were collected before lifting the flap to perform a customized laser ablation (Alcon LADARVision4000 CustomCornea System). Postoperative laser data were collected at 1 week, 1 month, 3 and 6 months, and 1 year. Visual acuity, pachymetry, high-frequency flap ultrasound profilometry (Artemis Ultralink), topography, aberrometry (LADARWave), and refraction were examined and compared between eyes. RESULTS: Postoperative flap comparisons showed a hyperopic refractive shift in all four eyes with a shift of up to 1.00 diopter (D) in the microkeratome eyes and < 0.50 D in the IntraLase eyes. Corneal topography difference maps showed peripheral steepening that was more pronounced in the microkeratome versus IntraLase eyes (2.00 D vs 0.50 to 1.00 D, respectively). Spherical aberration by wavefront variably increased by 50% to 100% in the microkeratome eyes and remained virtually unchanged in the IntraLase eyes. At 3-month postoperative laser treatment, visual acuity was 20/15 for both eyes in patient 1 and 20/15 in the right eye (IntraLase) and 20/25 in the left eye (microkeratome) in patient 2. Aberrometry revealed a two-fold greater level of higher order aberrations in microkeratome eyes than in IntraLase eyes throughout the postoperative laser period. CONCLUSIONS: Femtosecond laser and mechanical methods of flap creation lead to subtle biomechanically induced aberrations, which appear more prominent with the mechanical Moria M2 microkeratome in this small case study. Further study with a larger patient population is warranted to determine whether these differences are statistically significant.     

Corneal sensation after laser in situ keratomileusis

PURPOSE: To report the time course for the return of corneal sensation following laser in situ keratomileusis (LASIK). SETTING: University-based retractive surgery practice. METHODS: Twenty-eight eyes of 18 patients having LASIK were evaluated. Preoperative and postoperative corneal sensation at the nasal flap hinge, at the central cornea, and within the temporal flap edge were measured before and after LASIK for a 3 week period using the Cochet-Bonnet esthesiometer (Luneau). RESULTS: Corneal sensation initially decreased in all 3 positions of the flap measured after LASIK; the greatest decrease was in the central cornea. Near preoperative corneal sensation returned by 3 weeks. The degree of sensation loss did not appear to correlate with the ablation depth. CONCLUSION: Corneal sensation is significantly decreased for approximately 2 to 3 weeks after LASIK, centrally greater than nasally at the flap hinge or temporally within the flap edge, but it generally returns to near the preoperative level by 3 weeks postoperatively.     

IntraLase FS60和Femto LDV飞秒激光制作角膜瓣的特点

目的 探讨应用IntraLase FS60飞秒激光和Femto LDV飞秒激光制作的准分子激光原位角膜蘑镶术（LASIK）角膜瓣的特点.方法 前瞻性对照研究.拟行LASIK手术的近视患者60例（120眼）,根据角膜瓣制作方法不同分为两组,IntraLase FS60飞秒激光和Femto LDV飞秒激光组,每组各30例（60眼）.两组均制作预计110 μm厚度的角膜瓣.术前所有患者均进行常规检查并记录相关资料,包括年龄、屈光度、角膜曲率、角膜厚度等.术后1周,应用眼前节光学相干断层扫描仪（Visante OCT）分别测量每个角膜上0°、45°、90°和135°四条经线所在截面上特定5个点的角膜瓣厚度,并对每个角膜瓣上20个测量点的瓣厚度进行对比分析.采用独立样本t检验、单因素方差分析对相关数据进行统计学处理,分析角膜瓣的重现性、规整性和精确性.结果 角膜瓣重现性：术后1周,IntraLase FS60组和Femto LDV组中央区角膜瓣厚度均值分别为（111.2±3.3）μm和（108.1±3.0）μm,全角膜瓣厚度为（110.8±2.3）μm和（109.0±2.2）μm,变异范围为（22.0±6.6）μm和（23.7±5.8）μm,两组差异均无统计学意义（P均＞0.05）.角膜瓣均一性和规整性：两组角膜瓣厚度的均值均匀分散在预计值110 μm周围,差异均无统计学意义.IntraLase FS60组中央、旁中央、周边区域的角膜瓣厚度差异无统计学意义（F=1.213,P=0.300）;Femto LDV组中央和周边区域角膜瓣厚度差异存在统计学意义（F=3.925,P=0.021）,其他区域角膜瓣厚度差异无统计学意义.两组中各自双眼鼻侧和颞侧角膜瓣厚度对比,组间差异均无统计学意义.角膜上四条经线所在截面的平均角膜瓣厚度差异也无明显统计学意义.角膜瓣精确性：角膜上每个对应点的角膜瓣厚度与预计值110 μm差值的最大均值,IntraLase FS60组为6.2μm,Femto LDV组为6.7 μm.两组中与预计值差值≤5 μm的测量点,IntraLase FS60组有694个（占57.83%）,Femto LDV组有646个（占53.83%）,差异无统计学意义.结论 应用飞秒激光制作LASIK角膜瓣,具有较好的重现性和较高的精确性,角膜瓣形态均一、规整.IntraLase FS60飞秒激光和Femto LDV飞秒激光制作的角膜瓣形态特点相似.     

Creation of an extremely thin flap using IntraLase femtosecond laser

A 43-year-old woman had laser in situ keratomileusis (LASIK) using the IntraLase femtosecond laser (IntraLASIK) to create 110 microm flaps. Despite uneventful flap formation, the flaps in both eyes were extremely thin, making it difficult to lift them. The flap in the right eye resembled an epi-LASIK epithelial flap. It was lifted uneventfully. The flap in the left eye was stretched and torn on lifting, and the procedure was therefore postponed. After 6 months, the IntraLASIK surgical procedure was repeated in the left eye using a thicker and smaller flap than in the first procedure. Despite the improvements associated with using an IntraLase femtosecond laser, thinner-than-intended corneal flaps can occur. Early recognition of such a flap can prevent further complications.     

准分子激光角膜表层切削术后的止痛措施

准分子激光角膜表层切削术因降低角膜膨隆的风险和避免准分子激光原位角膜磨镶术(LASIK)角膜瓣相关的并发症而受到青睐。但术后严重疼痛不适为表层切削的主要缺陷,因此表层切削术后疼痛不适的控制显得尤其重要。我们总结了表层切削术后疼痛的机制以及降低术后疼痛的措施的进展。     

Confocal assessment of the corneal response to intracorneal lens insertion and laser in situ keratomileusis with flap creation using IntraLase

PURPOSE: To assess the response of the cornea to hydrogel intracorneal lens (ICL) insertion or laser in situ keratomileusis (LASIK) with IntraLase (IntraLase Corp.) at the cellular level. SETTING: Department of Ophthalmology, University of Texas Southwestern Medical Center, Dallas, Texas, USA. METHODS: Twenty patients (29 eyes) were evaluated by in vivo confocal microscopy 1 to 6 months postoperatively: 20 eyes had LASIK with flap creation by IntraLase, and 9 eyes had ICL insertion (8 following IntraLase). RESULTS: For LASIK with IntraLase, keratocyte activation and/or interface haze was detected in 8 of 20 eyes. The remaining eyes had interface particles but no cell activation. Keratocyte activation was generally limited to a few cell layers adjacent to the interface. However, 2 patients exhibited multiple layers of activation and increased extracellular matrix (ECM) reflectivity (haze) surrounding the interface by confocal microscopy. Both patients also had clinical haze and photophobia. For ICLs, following insertion, 5 of 9 eyes had activated keratocytes adjacent to the implant surfaces. The largest amount of cell activation and ECM haze detected by confocal microscopy was in 2 patients with significant clinical haze. Structures with an epithelioid morphology were detected on some implant surfaces. Epithelial thickness was 33.3 microm +/- 2.3 (SD) in the ICL eyes and 49.2 +/- 6.5 microm in the LASIK with IntraLase eyes. CONCLUSIONS: Both LASIK with IntraLase and ICL insertion following IntraLase induced keratocyte activation, which may underlie clinical observations of haze in some patients. Intracorneal lens implant also induced thinning of the overlying corneal epithelium.     

Corneal flap thickness in laser in situ keratomileusis using an SCMD manual microkeratome.

PURPOSE: To evaluate corneal flap thickness in laser in situ keratomileusis (LASIK) and to measure variables correlated with corneal flap thickness. SETTING: Kangnam St. Mary's Hospital, Department of Ophthalmology, College of Medicine, The Catholic University of Korea, Seoul, Korea. METHODS: This prospective study comprised 69 eyes of 66 patients having LASIK with the VISX Star laser and SCMD manual microkeratome. Corneal thickness, keratometry, and refractive error were measured preoperatively, the time taken to complete the corneal flap and its thickness were recorded intraoperatively, and visual outcome was followed postoperatively. Corneal flap thickness was calculated as the thickness of the corneal stromal bed subtracted from the total corneal thickness. RESULTS: Mean corneal flap thickness was 137.18 microns +/- 33.66 (SD). The thickness in 32 eyes (46.4%) was less than 135 microns, in 17 eyes (24.6%) from 135 to 165 microns, and in 20 eyes (29.0%) greater than 165 microns. There was no relationship between corneal flap thickness and degree of myopia, steepening of cornea, or time taken to complete the flap. However, the thickness of the corneal flap increased with the thickness of the cornea. Visual outcome was slightly better in the group with thick corneal flaps than in the one with thin corneal flaps, although the difference was not statistically significant. CONCLUSION: Corneal flap thickness was variable in LASIK using the SCMD microkeratome. There was a correlation between corneal flap thickness and preoperative corneal thickness.