Reproducibility of LASIK flap thickness using the Hansatome microkeratome

PURPOSE: To evaluate the actual versus the expected thickness of laser in situ keratomileusis (LASIK) flaps and to determine the factors that affect flap thickness. SETTING: Centre For Sight, Queen Victoria Hospital, East Grinstead, United Kingdom. METHODS: A retrospective analysis of LASIK procedures in 757 consecutive eyes was done. The surgery was performed by a single surgeon using 2 Hansatome microkeratomes (Bausch & Lomb) with 160 microm and 180 microm heads. Patient age, preoperative manifest refraction, automated keratometry, preoperative central pachymetry, and intraoperative stromal pachymetry were evaluated to determine whether they influenced the actual flap thickness. RESULTS: Bilateral LASIK was performed in 343 patients (686 eyes). The 160 microm head was used in 641 eyes (84.6%) (Group 1) and the 180 microm head, in 116 eyes (15.4%) (Group 2). The mean preoperative manifest refraction spherical equivalent (SE) was -3.9 diopters (D) +/- 4.5 (SD) (range +7.4 to -25.0 D) in Group 1 and -4.4 +/- 3.7 D (range +7.1 to -12.9 D) in Group 2. The mean preoperative keratometry reading was 43.6 +/- 1.8 D (range 36.0 to 48.6 D) and 43.6 +/- 1.8 D (range 35.9 to 47.0 D), respectively; the mean preoperative central pachymetry was 543 +/- 35 microm (range 447 to 643 microm) and 548 +/- 31 microm (range 453 to 613 microm), respectively; and the mean flap thickness was 116.4 +/- 19.8 microm and 117.3 +/- 18.0 microm, respectively. The difference between the actual and the expected flap thickness in each group was statistically significant (P<.001). There was no significant difference in the actual flap thickness between the 2 Hansatomes. The preoperative SE and central pachymetry were the only factors that influenced the actual flap thickness (P<.05); thin flaps were more common with increasing myopia and increasing corneal thickness. CONCLUSIONS: Spherical equivalent and preoperative pachymetry were the principal factors that influenced flap thickness. Preoperative keratometry values and patient age did not influence the actual flap thickness.     

Laser in situ keratomileusis flap thickness using the Hansatome microkeratome with zero compression heads

PURPOSE: To evaluate predictability and possible factors affecting flap thickness in laser in situ keratomileusis (LASIK) using the Hansatome microkeratome (Bausch & Lomb Surgical) with zero compression heads. SETTING: Zentrum für Refraktive Chirurgie Münster, Münster, Germany. METHODS: A prospective nonrandomized comparative (self-controlled) trial analyzing flap thickness in 153 consecutive patients having LASIK using the Hansatome microkeratome with zero compression was conducted. Two hundred thirty-eight eyes that had uncomplicated primary LASIK (n = 237) or secondary LASIK (n = 1) by the same surgeon and same technique using 4 different microkeratomes of the same model were evaluated. Each keratome cut was performed with a new Accuglide (Bausch & Lomb) blade in a 160 microm (n = 89), 180 microm (n = 128), or 200 microm (n = 21) Hansatome zero compression head coupled to a 8.5 mm (n = 106) or 9.5 mm (n = 131) suction ring. Only Hansatome elements with the same serial numbers were combined. Ultrasound subtraction pachymetry was routinely used to determine intraoperative flap thickness. Flap thickness was correlated with microkeratome head dimension, suction ring size, preoperative keratometry obtained by Orbscan IIz (Bausch & Lomb), preoperative corneal thickness as obtained by ultrasound pachymetry, refractive error, and age. RESULTS: Measured intraoperative flap thickness was significantly different (P<.01) from predicted flap thickness. The mean flap thickness was 97 microm +/- 18 (SD) (range 65 to 163 microm), 111 +/- 20 microm (range 61 to 177 microm), and 131 +/- 20 microm (range 89 to 162 microm) for the 160 microm, the 180 microm, and 200 microm heads, respectively. There was a good correlation between microkeratome head and corneal flap thickness. However, there was a variability between devices. There was a low correlation between baseline ultrasound pachymetry at the time of surgery and corneal flap thickness (r = .26) and a small effect of ring size. There was no correlation with keratometry, refractive error, or age. CONCLUSIONS: There was a remarkable difference in the flap thickness of microkeratomes of the same make and model. This emphasizes the need to measure intraoperative flap thickness and to evaluate every microkeratome separately. Factors affecting flap thickness seem to be more device dependent than patient related; obtaining flap thickness in the first eye did not enable predictions of the flap thickness in the fellow eye.     

Factors that affect corneal flap thickness with the Hansatome microkeratome

PURPOSE: To evaluate factors that influence corneal flap thickness with the Hansatome microkeratome. METHODS: One hundred thirty-two eyes of 70 patients underwent laser in situ keratomileusis (LASIK). Corneal flap thickness was measured by subtracting the intraoperative corneal bed pachymetry measurement from intraoperative total corneal pachymetry. Variables examined included plate thickness, ring size, blade use, temperature, humidity, barometric pressure, age, average keratometric power, and preoperative corneal thickness. RESULTS: Mean flap thickness using a 180-microm plate was 143 +/- 19 microm (range 61 to 207 microm). Mean flap thickness using a 160-microm plate was 119 +/- 20 microm (range 83 to 159 microm). The difference was statistically significant (P < .05). Mean flap thickness using a 180-microm plate and the same blade on the right and left eye was 151 +/- 21 microm (range 113 to 200 microm) and 137 +/- 21 microm (range 91 to 191 microm), respectively. The 14-microm difference was statistically significant (P < .001). There was a slight negative correlation of flap thickness with humidity. There was a positive correlation with preoperative corneal thickness (pachymetry). CONCLUSION: The Hansatome tended to cut thinner flaps than anticipated based on the plate used. Flaps cut on the first eye were thicker than the second eye using the same blade. Thicker corneas tended to lead to thicker flaps. There was no correlation between flap thickness and microkeratome ring size, temperature, barometric pressure, patient age, or average keratometric power.     

Reproducibility of corneal flap thickness in laser in situ keratomileusis using the Hansatome microkeratome

PURPOSE: To evaluate the reproducibility of flap thickness during laser in situ keratomileusis (LASIK) and to analyze the effect of preoperative central corneal thickness and corneal keratometric power on flap thickness. SETTING: Department of Ophthalmology, Cerrahpasa Medical School, Istanbul, Turkey. METHODS: One hundred forty eyes with a mean preoperative pachymetry of 554.4 microm +/- 36.3 (SD) and a mean keratometry of 43.5 +/- 1.9 diopters had LASIK using the Hansatome automated microkeratome (Bausch & Lomb Surgical) and a 193 nm argon-fluoride excimer laser (Summit SVS Apex Plus). The 180 microm microkeratome plate was used in all procedures. Corneal thickness was measured with an ultrasonic pachymeter (Advent, Mentor O&O Inc.) before and during the flap procedure, and the difference was taken as flap thickness. The data were analyzed using a 1-tailed t test and Pearson correlation coefficient. RESULTS: The mean flap thickness was 120. 8 +/- 26.3 microm. There was a low correlation between baseline central corneal thickness and corneal flap thickness (P =.6, r = 0. 046). There was no correlation between preoperative keratometry and flap thickness (P =.01, r = 0.203). CONCLUSIONS: The Hansatome microkeratome does not always produce a corneal flap of the intended thickness. Factors other than keratometry and pachymetry must affect flap thickness.     

Flap measurements with the Hansatome microkeratome

PURPOSE: To evaluate flap thickness, flap diameter, and hinge length during laser in situ keratomileusis (LASIK) and to correlate these measurements with preoperative keratometric power, central corneal thickness, and patient refraction, gender, and age. METHODS: In this prospective study of 50 eyes of 28 patients (mean age 31 +/- 6.6 yr; range, 24 to 43 yr) results of LASIK for myopia were analyzed (mean spherical equivalent refraction of -7.16 +/- 1.69 D; range, -2.75 to -13.50 D). Corneal flaps were created using the Hansatome microkeratome (Baush & Lomb Surgical) with a 160-microm plate and a 9.5-mm suction ring. Corneal thickness was evaluated using an ultrasonic 50-MHz pachymeter (Sonogage Corneo Gage Plus) and the mean keratometric power was measured with a Corneal Analysis System videokeratographic unit (EyeSys). Data were analyzed using t-test, Pearson product moment correlation coefficient, and Spearman's rho non-parametric correlation coefficients. RESULTS: Mean corneal flap thickness was 142.6 +/- 20.8 microm (range, 107 to 177 microm), mean flap diameter was 9.9 +/- 0.3 mm (range, 9.2 to 10.5 mm), and mean hinge length was 6.2 +/- 0.4 mm (range, 5.2 to 7 mm). Statistically significant correlations (P<.05) were found between mean keratometric power and flap hinge length, mean keratometric power and flap diameter, preoperative spherical equivalent refraction and flap diameter, corneal thickness and flap hinge length, as well as patient age and corneal thickness. CONCLUSIONS: The Hansatome microkeratome was an effective and safe instrument in the creation of corneal flaps for LASIK. Consideration of preoperative keratometric power and corneal thickness may help to reduce or avoid complications.     

角膜原位磨镶术中负压吸引对眼球结构影响的分析

目的 研究角膜原位磨镶术中负压吸引对眼球结构改变的影响.方法 对64例(105只眼)行角膜原位磨镶术的近视眼患者分别在Hansatome角膜板层刀负压吸引眼球前以及吸引过程中用A型超声测量仪进行前房深度,晶状体厚度,玻璃体腔长度以及眼球长度测量,比较负压吸引前及吸引过程中上述指标的改变,探讨其意义.结果 患者年龄最大37岁,最小18岁,平均22.4岁,等值球镜度(-4.50±1.75)D,负压吸引前超声测量前房深度,晶状体厚度,玻璃体腔长度,眼轴长度分别为(3.62±0.29)mm,(3.68±0.34)mm,(17.79±1.01)mm,(25.09±0.99)mm;负压吸引中上述指标分别为(3.76±0.26)mm,(3.52±0.26)mm,(17.95±1.01)mm,(25.23±1.01)mm.负压吸引后前房深度,玻璃体腔长度和眼轴长度分别增加0.14mm,0.16mm和0.14mm,差异有统计学意义(P＜0.01);晶状体厚度减少0.15mm,差异有统计学意义(P＜0.01).结论 LASIK手术中负压吸引可引起眼球结构改变,导致前房深度,玻璃体腔长度以及眼轴长度增加,晶状体厚度减少,手术中应尽量减少负压吸引时间,降低负压对眼球的影响.     

A comparative confocal microscopy analysis after LASIK with the IntraLase femtosecond laser vs Hansatome microkeratome

PURPOSE: To evaluate and compare confocal microscopy findings between a femtosecond laser and a mechanical microkeratome. METHODS: Eighteen eyes of nine patients underwent LASIK. Corneal flaps were created with the femtosecond laser in the right eyes and a mechanical microkeratome in the left eyes. The corneal flap interface was analyzed in all eyes with a confocal microscope at 1 week and 1 month postoperatively. RESULTS: All eyes showed small reflective particles at the corneal flap interface. The mean number of reflective particles was not statistically significantly different at 1 week (P = .078) and 1 month (P = .28) using a femtosecond laser and a mechanical microkeratome. CONCLUSIONS: Confocal microscopy findings at the corneal flap interface showed a similar number of particles using both systems.     

两种不同制瓣方式对LASIK术角膜瓣厚度的影响

目的:比较Ziemer LDV飞秒激光与Moria M2机械板层刀不同制瓣方式对LASIK术角膜瓣厚度的影响。 方法：选取近视患者100例200眼（近视度数-2.00~-12.00D,散光度数0.00 ~ -3.50D）,分别应用Ziemer LDV飞秒激光（设定角膜瓣切削厚度110μm）与Moria M2 （110刀头）微型角膜刀制作角膜瓣,各50例 100眼。术后1wk,应用眼前节RTVue FD-OCT 测量,每个角膜上 0°,45°,90°,135°四条子午线所在截面上中心点、距离中心1,2,3mm特定7个点（共计28个点）的角膜瓣厚度测量,并作分析比较。 结果:角膜瓣中央点厚度:Ziemer LDV飞秒激光组108.69±11.75μm,Moria M2 微型角膜刀组130.75±13.36μm,所有观测点（共28点）两组间有明显统计学差异（P<0.01）。角膜中心点厚度与预计值差值比较:Ziemer LDV飞秒激光组 9.70±6.84μm,Moria M2 微型角膜刀组 21.63±11.79μm。Ziemer LDV飞秒激光组预计值差值明显低于Moria M2 微型角膜刀组（t=17.493,P＜0.01）。Ziemer LDV飞秒激光组与Moria M2微型角膜刀组同一截面中各点角膜瓣厚度值差异有统计学差异（P<0.01）。 结论:角膜瓣制作方式相比,在角膜瓣的精确性、可预测性等方面 Ziemer LDV飞秒激光优于Moria M2 微型角膜刀。Ziemer LDV组与Moria M2 机械板层刀组都未表现角膜瓣厚度的均匀性。     

Lower intraoperative flap complication rate with the Hansatome microkeratome compared to the Automated Corneal Shaper

PURPOSE: The purpose of this study was to retrospectively compare the incidence of intraoperative flap complications, such as partial flaps, donut-shaped flaps, central corneal cuts, and complete caps with the Hansatome and Automated Corneal Shaper (ACS) microkeratomes. METHODS: All laser in situ keratomileusis (LASIK) procedures performed by a single surgeon with the Hansatome or Automated Corneal Shaper in which intraocular pressure was verified with a pneumotonometer were reviewed. RESULTS: A total of 90 eyes had LASIK with the ACS microkeratome. Six of the ACS eyes (6.7%) had intraoperative flap complications (4 partial flaps, 1 donut-shaped flap, 0 central corneal cuts, 1 complete cap). Partial flaps and donut-shaped flaps were replaced without laser application and the procedure repeated 2 to 3 months later. Two of these eyes lost 2 lines and one lost 1 line of spectacle-corrected visual acuity at 6 months after repeat LASIK. The eye with the donut-shaped flap was treated with transepithelial photorefractive keratectomy (PRK) and had no change in spectacle-corrected visual acuity at 6 months after PRK. The eye with the complete cap had no change in spectacle-corrected visual acuity after laser ablation. Five hundred ninety-eight (598) eyes had LASIK with the Hansatome microkeratome. Two of the Hansatome eyes (0.3%) had a flap complication (1 partial flap and 1 donut-shaped flap). The first eye retained spectacle-corrected visual acuity at 6 months after repeat LASIK. The second eye had transepithelial PRK to eliminate the donut shaped flap with no loss of spectacle-corrected visual acuity at 6 months after surgery. The difference in flap complications between the two procedures was statistically significant (P < .01). There were no flap displacements following surgery in either group. CONCLUSION: Intraoperative flap complications are less likely to occur with the Hansatome microkeratome than with the ACS microkeratome.     

应用眼前节相干光断层扫描仪测量机械板层角膜刀所制准分子激光原位角膜磨镶术后的角膜瓣厚度

目的 探讨准分子激光原位角膜磨镶术(LASIK)中使用不同厚度的微型板层角膜刀(90、110、130刀头)制作角膜瓣的可预测性、均匀性及其影响因素.方法 对照病例研究.选择LASIK术后87例(174只眼)患者,其中手术中使用MoriaⅡ微型角膜刀90刀头组26例(52只眼),110刀头组29例(58只眼),130刀头组32例(64只眼).应用眼前节相干光断层扫描仪(OCT)测量患者角膜上0.、45.、90.及135.共4条子午线所在截面的角膜瓣厚度,先在每条子午线所在截面选取5个点,再于每个角膜瓣上测量20个点的角膜瓣厚度.3种刀头所制角膜瓣偏差情况采用线性混合效应模型分析,以P＜0.05作为差异有统计学意义.结果 MoriaⅡ微型角膜刀90、110、130刀头组制作的角膜瓣中央区厚度均值分别为(119.23±15.65)、(140.42±12.26)及(165.92±17.00)μm.3种刀头所制角膜瓣皆为中间薄、周边厚,形状近似一凹透镜.其中角膜瓣中央部厚度变异小,而旁中央和周边部厚度变异较大,差异有统计学意义(F=212.419,P＜0.05).右眼角膜瓣厚度均值(19.58±0.44)μm,高于左眼(16.55±0.44)μm;入刀侧角膜瓣厚度差值均值(21.30±0.55)μm,高于出刀侧差值均值(14.36±0.64)μm,差异均有统计学意义(F=25.341,44.461;P＜0.05).结论 3种刀头所制角膜瓣中央区厚度预测性均较好.角膜瓣厚度并非均匀一致,预计值越厚的角膜瓣其厚度变异越大,因手术顺序所致右眼角膜瓣比左眼角膜瓣厚,入刀侧角膜瓣厚于出刀侧角膜瓣.     

Zyoptix XP与Hansatome角膜板层刀制作角膜瓣特点比较

目的比较Zyoptix XP与Hansatome角膜板层刀制作角膜瓣的特点,为临床使用提供参考。方法50例（100眼）近视眼患者随机分成两组,每组25例（50眼）,分别用Zyoptix XP120刀头、8.5mm负压环与Hansatome角膜板层刀160刀头、8.5mm负压环制作角膜瓣。制瓣前后分别用超声角膜测厚仪测量角膜厚度,计算实际角膜瓣厚度。制瓣后分别测量角膜瓣横径、纵径和蒂的长度,进行成组的两两比较t检验以及相关性分析,评价两种角膜板层刀制瓣特点。结果Zyoptix XP与Hansatome两组患     

Corneal flap thickness with the Moria M2™ microkeratome and Med‐Logics calibrated LASIK blades

Purpose: This study aimed to compare and study potential factors that affect the accuracy of corneal flap thickness created in laser‐assisted in situ keratomileusis (LASIK) using the Moria model 2 (M2?) head 130 microkeratome with the Med‐Logics calibrated LASIK blades Minus 20 (ML –20) and Minus 30 (ML –30). Methods: Corneal thickness in 200 (164 myopic and 36 hyperopic) eyes (100 patients) was measured by ultrasonic pachymetry preoperatively and intraoperatively after flap cutting. A total of 100 eyes were treated with the ML –20 and 100 with the ML –30. The right eye was operated before the left eye in each patient, using the same blade. In an additional group of 40 eyes, the left eye was operated first. Results: Mean corneal flap thickness using the ML –20 blade for an intended flap thickness of 140 μm was 129.1 μm (standard deviation [SD] 15.6, range 104–165 μm) in right eyes and 111.5 μm (SD 14.5, range 78–144 μm) in left eyes. Mean corneal flap thickness using the ML –30 blade for an intended flap thickness of 130 μm was 127.1 μm (SD 16.6, range 90–168 μm) in right eyes and 109.9 μm (SD 16.8, range 72–149 μm) in left eyes. Conclusions: Both microkeratome blade types cut thinner flaps than were intended. There was substantial variation in flap thickness. The first flap to be cut with a particular blade was considerably thicker than the second flap cut with the same blade. Based on these data, we recommend the use of disposable single‐use microkeratomes rather than these ML blades.     

Central flap necrosis after LASIK with microkeratome and femtosecond laser created flaps

PURPOSE: To report nine cases of severe central flap inflammation and necrosis after LASIK. METHODS: A retrospective chart review was conducted on 17,100 LASIK cases performed at two laser centers in Indiana from January 1995 through May 2005. All patients with central lamellar flap necrosis were identified. RESULTS: Severe central flap inflammation and necrosis occurred in nine eyes of eight patients. Six patients underwent flap creation with a mechanical microkeratome and two with a femtosecond laser. Of eight eyes with > 2-month follow-up, one lost at least two lines of best spectacle-corrected visual acuity and two experienced a hyperopic shift in spherical equivalent refraction. Typically, inflammation was minimal the day after surgery, peaked 5 to 10 days later, and subsided by 60 days. Six of nine cases were treated by lifting the flap and irrigating the stromal bed. In each of these cases, few or no inflammatory cells were observed in the stromal bed, the posterior flap surface was intact, and the central portion of the anterior flap had a jelly-like consistency. CONCLUSIONS: Central lamellar flap necrosis appears to differ from diffuse lamellar keratitis because the location of stromal inflammation is not in the flap interface but rather in the flap anterior stroma. Treatment with corticosteroids seemed to have little effect on outcomes. This is thought to be the first documentation of central lamellar flap necrosis following the use of a femtosecond laser.     

Corneal flap thickness with the Moria M2 single-use head 90 microkeratome

PURPOSE: To analyse the accuracy of corneal flap thickness created in laser-assisted in situ keratomileusis (LASIK) using the Moria Model 2 (M2) single-use head 90 microkeratome. METHODS: The corneal thickness of 300 (266 myopic and 34 hyperopic) eyes of 150 patients was measured by ultrasonic pachymetry preoperationally and intraoperationally after flap cut. The Moria M2 single-use head 90, intended to create a flap with a thickness of 120 microm, was used in all eyes. The right eye was always operated first and the left eye second, using the same blade. RESULTS: Mean corneal flap thickness was 115.4 microm (standard deviation [SD] 12.5) in the two eyes, 115.7 microm (SD 12.4, range 73-147 microm) in right eyes and 115.1 microm (SD 12.6, range 74-144 microm) in left eyes. Mean horizontal flap diameter was 9.1 mm (SD 0.2) and mean hinge length 4.1 mm (SD 0.1). There were no free flaps, incomplete flaps or flaps with buttonholes in the study. Occasional iron particles were observed in three (1.0%) eyes. CONCLUSIONS: As with most microkeratomes, the single-use head 90 microkeratome cut thinner flaps than were intended. The range of the cuts was relatively wide. However, thin flaps did not increase the rate of flap-related complications. The difference between the first and second eyes was not significant.     

Comparison of the femtosecond laser and mechanical microkeratome for flap cutting in LASIK

AIM: To compare refractive results, higher-order aberrations (HOAs), contrast sensitivity and dry eye after laser in situ keratomileusis (LASIK) performed with a femtosecond laser versus a mechanical microkeratome for myopia and astigmatism.METHODS: In this prospective, non-randomized study, 120 eyes with myopia received a LASIK surgery with the VisuMax femtosecond laser for flap cutting, and 120 eyes received a conventional LASIK surgery with a mechanical microkeratome. Flap thickness, visual acuity, manifest refraction, contrast sensitivity function (CSF) curves, HOAs and dry-eye were measured at 1wk; 1, 3, 6mo after surgery.RESULTS:At 6mo postoperatively, the mean central flap thickness in femtosecond laser procedure was 113.05±5.89 µm (attempted thickness 110 µm), and 148.36±21.24 µm (attempted thickness 140 µm) in mechanical microkeratome procedure. An uncorrected distance visual acuity (UDVA) of 4.9 or better was obtained in more than 98% of eyes treated by both methods, a gain in logMAR lines of corrected distance visual acuity (CDVA) occurred in more than 70% of eyes treated by both methods, and no eye lost ≥1 lines of CDVA in both groups. The difference of the mean UDVA and CDVA between two groups at any time post-surgery were not statistically significant (P＞0.05). The postoperative changes of spherical equivalent occurred markedly during the first month in both groups. The total root mean square values of HOAs and spherical aberrations in the femtosecond treated eyes were markedly less than those in the microkeratome treated eyes during 6mo visit after surgery (P＜0.01). The CSF values of the femtosecond treated eyes were also higher than those of the microkeratome treated eyes at all space frequency (P＜0.01). The mean ocular surface disease index scores in both groups were increased at 1wk, and recovered to preoperative level at 1mo after surgery. The mean tear breakup time (TBUT) of the femtosecond treated eyes were markedly longer than those of the microkeratome treated eyes at postoperative 1, 3mo (P＜0.01).CONCLUSION:Both the femtosecond laser and the mechanical microkeratome for LASIK flap cutting are safe and effective to correct myopia, with no statistically significant difference in the UDVA, CDVA during 6mo follow-up. Refractive results remained stable after 1mo post-operation for both groups. The femtosecond laser may have advantages over the microkeratome in the flap thickness predictability, fewer induced HOAs, better CSF, and longer TBUT.     

飞秒激光与显微板层刀制作角膜瓣的LASIK手术短期效果比较

目的 比较飞秒激光制瓣和角膜板层刀制瓣LASIK手术的临床效果.设计 回顾性病例系列.研究对象 北京同仁医院88例(172眼)应用Intralase FS60飞秒激光制瓣后行LASIK手术患者和122例(242眼)M2角膜板层刀制瓣LASIK手术患者.方法 将飞秒激光制瓣LASIK手术的患者(I-LASIK)为I组;角...     

Contrast sensitivity after LASIK flap creation with a femtosecond laser and a mechanical microkeratome

PURPOSE: To compare the effects on contrast sensitivity of the IntraLase femtosecond laser for flap creation (IntraLASIK) and standard LASIK for myopia. METHODS: Two hundred eyes of 100 consecutive patients underwent LASIK treatment using the VISX S2 laser system. The femtosecond laser (15 kHz IntraLase) was used for flap creation in 100 eyes (50 patients) and a mechanical microkeratome (Carriazo-Barraquer) was used in 100 eyes (50 patients). Best spectacle-corrected contrast sensitivity was measured before and 6 months postoperatively in the IntraLASIK and mechanical LASIK groups. The IntraLASIK and mechanical LASIK-induced changes in contrast sensitivity were compared under photopic (85 cd/m2) and mesopic (5, 2.5, and 0.1 cd/m2) conditions. RESULTS: Contrast sensitivity for eyes after IntraLASIK did not differ from preoperative values at the photopic level (85 cd/m2). However, under mesopic conditions, a statistically significant reduction (P < .01) in contrast sensitivity was found at high spatial frequencies (12 and 18 cpd), although no significant contrast sensitivity differences were observed at low and middle spatial frequencies (P > .01 for 1.5, 3, and 6 cpd). No statistically significant differences were found between IntraLASIK and mechanical LASIK for 1.5, 3, and 6 cpd at any luminance level (P > .01). IntraLASIK showed better contrast sensitivity than mechanical LASIK under mesopic conditions at 12 cpd and photopic and mesopic conditions at 18 cpd (P < .01). CONCLUSIONS: IntraLASIK surgery demonstrated better contrast sensitivity at high spatial frequencies under photopic and mesopic conditions than mechanical LASIK.     

眼前节OCT测量法对FS200飞秒激光和Moria 90刀头行薄瓣LASIK中角膜瓣形态比较

背景 薄瓣准分子激光角膜原位磨镶术(LASIK)是角膜屈光手术的主流方法,越来越多的薄瓣LASIK应用飞秒激光制作角膜瓣,傅里叶眼前节OCT角膜瓣厚度及形态的测量为角膜瓣和角膜基质层厚度的控制提供了依据,但应用眼前节OCT测量法对FS200飞秒激光和Moria 90刀头行薄瓣LASIK中角膜瓣形态进行比较的研究较少. 目的 利用傅里叶频域OCT测量法比较应用Wavelight FS200飞秒激光和传统微型角膜刀Moria 90刀头制作的角膜瓣形态及其厚度,评价两种方法制作角膜瓣的特点. 方法 选取2011年12月至2012年6月在南京同仁医院眼科行FS200飞秒激光辅助LASIK和Moria 90刀头行LASIK的患者各30例30眼,于术后1个月应用傅里叶频域OCT(OPTOVUE RTVue-100)测量和比较两种方法所制的中央角膜瓣厚度以及角膜0°和90°径线所在截面上特定10个点的角膜瓣厚度. 结果 FS200飞秒激光制瓣组术眼中央角膜瓣厚度值为(112±3)μm,全角膜瓣平均厚度值为(112±3) μm,分别低于Moria 90刀头制瓣组的(121±7) μm及(128±11) μm,差异均有统计学意义(P=0.031、0.030),FS200飞秒激光制瓣组角膜瓣厚度的变异范围也明显小于Moria 90刀头制瓣组.FS200飞秒激光制作的角膜瓣形态规整、均一,形状近似规则的平面,其中央、旁中央、周边厚度的差异无统计学意义(P=0.320).Moria 90刀头制作的角膜瓣中间薄,周边厚,近似弯月形透镜,其中央、旁中央、周边区角膜瓣厚度的差异有统计学意义(P=0.038).FS200飞秒激光制瓣组各测量点角膜瓣厚度与预期角膜瓣厚度(110 μm)的平均差为(3±4)μm,而Moria 90刀头制瓣组为(17±10) μm,两组间差异有统计学意义(P=0.009).结论 傅里叶眼前节OCT测量表明,Wavelight FS200飞秒激光制作角膜瓣精确度高,可控性强,稳定性好,且操作更安全,是薄瓣LASIK的首选.傅里叶眼前节OCT是评价LASIK术后角膜瓣形态和厚度的有用工具.     

角膜瓣厚度对LASIK效果的影响

目的　探讨角膜瓣厚度对准分子激光原位角膜磨镶术(LASIK)手术效果的影响。方法　选择行LASIK手术的中高度近视71眼,按角膜瓣厚度12 0 μm为标准分成两组。Ⅰ组角膜瓣超过12 0 μm ;Ⅱ组角膜瓣低于或等于12 0 μm。随诊半年取得数据进行统计学处理。结果　Ⅰ组术前角膜厚度(5 3 7 . 88±2 9 . 62 ) μm ,角膜瓣厚度(13 6 .81±15 . 8) μm ;Ⅱ组术前角膜厚度(5 15 . 95±3 3 . 8) μm ,角膜瓣厚度(10 1 . 2 6±12 . 78) μm ,两组角膜瓣厚度数据采取均数t检验,P值小于0 . 0 5 ,差异有显著意义。术后视力与术前预测视力差值进行统计学处理P值0 . 911,大于0 . 0 5 ,差异无显著意义。结论　厚度小于12 0 μm的角膜瓣与厚度大于12 0 μm的角膜瓣对LASIK术后视力恢复均无影响。故针对角膜较薄而近视度较高者采用做薄瓣的方法同样可以取得好的效果。