Microkeratome chronicles: Management of a free flap

Background: In LASIK (laser in situ keratomileusis), a hinged corneal flap is made, which enables the flap to be lifted and the excimer laser to be applied to the stromal bed. If the hinge of the corneal flap detaches from the cornea, the flap is called a free cap. A free cap is a rare intra-operative complication of LASIK most commonly associated with the use of a microkeratome on corneas with flat keratometry, which predisposes to a small flap diameter. Free caps are preventable and treatable. Rarely does the complication lead to a severe or permanent decrease in visual acuity. Purpose: As free caps are avoidable, prevention is critical. Our video gives some tips and tricks on how to avoid a free flap and also focuses on how to manage a cut through a free flap. Synopsis: If a free cap is created, the surgeon must decide whether to continue with excimer laser ablation or to abort the procedure. When to abort: If the stromal bed is irregular, the flap is replaced without applying laser ablation. Without ablation, generally, there is no change in refractive error or significant loss of visual acuity. When to continue: If the stromal bed is regular and the cap is of normal thickness, the surgeon may proceed with ablation. To prevent desiccation, the free cap should be handled with caution and should be placed on a drop of balanced salt solution. The free cap should be placed epithelial facing up, along with a bandage contact lens. The endothelial cell pump mechanism typically allows the cap to re-adhere tightly. Highlights: Risk factors for a free cap are generally anatomic or mechanical. Especially in flat corneas, an appropriate ring and stop size should be chosen looking at the nomogram on the basis of the keratometry values. Deep orbits and deep-seated eyes should be looked for as PRK is a better option in such cases. Inadequate suction should be dealt with a lot of care, and once this is done, the vacuum should be stopped. Re-docking of the microkeratome with suction can be done again. Prior testing of the microkeratome and a good verbal anesthesia are a few more such important points to be pondered upon. This video gives us such tips and is a comprehensive video for a novice surgeon performing microkeratome LASIK

An inadvertent usage of the deep stromal lenticule in anterior lamellar keratoplasty – An emancipator technique

Anterior lamellar keratoplasty (ALK), of late, has gained popularity because of its prolonged graft survivability as a result of reduced endothelial cell loss. A 56-year-old female with bilateral granular corneal dystrophy was taken up for ALK in the left eye. Because of unforeseen errors during the procedure, the surgeon was obliged to customize a novel technique by using a deep stromal lenticule after removal of Descemet’s membrane. Post-op visual recovery was equivalent to conventional ALK with complete epithelization of the graft. This new or adapted technique has an added advantage for surgeons to prevent forfeiture of the valuable donor tissue. In the developing world, manual dissection is still the primary technique of lamellar keratoplasty and many precious corneas get wasted because of intra-operative unintended errors of dissection and trephination. Therefore, this novel technique holds its importance in saving the precious corneal tissue, especially in developing countries, and opens a new area for exploration.

Microkeratome-assisted ultrathin Descemet's stripping automated endothelial keratoplasty: A randomized trial comparing single-pass versus double-pass technique

Purpose: To compare the outcomes of two techniques, for preparation of microkeratome-assisted ultrathin grafts for Descemet's stripping automated endothelial keratoplasty (DSAEK). Methods: The study involved 20 eyes of 20 patients with pseudophakic bullous keratopathy, randomized into two groups. Group 1 eyes underwent microkeratome-assisted DSAEK using the single-pass technique for lenticule preparation, whereas group 2 eyes underwent microkeratome-assisted DSAEK using the double-pass technique. Patients were followed up till 6 months, postoperatively. Best-corrected visual acuity (BCVA) at final follow-up was considered as the primary outcome measure, whereas graft thickness (GT) contrast sensitivity and endothelial cell loss were considered as the secondary outcome measures. A P value of <0.05 was considered as statistically significant. Results: Baseline characteristics of two groups were comparable. The mean central GT was comparable in both groups at 6 months follow-up [group 1: 98 ± 24.46 ?m, group 2: 129 ± 31.46 ?m (P = 0.18)]. Both groups fared equally in terms of BCVA (P = 0.33). Contrast sensitivity was significantly better in group 1 eyes (P = 0.045). A statistically significant negative correlation was found between postoperative BCVA and postoperative GT (R = ?0.728, P = 0.016). The percentage endothelial cell loss was slightly higher in group 2 eyes, although not statistically significant. Two eyes in group 2 experienced complications during lenticule preparation. None of the eye experienced any complication in the postoperative period. Conclusion: Both techniques provided grafts with comparable thickness and endothelial cell loss and were associated with comparable BCVA, at final follow-up visit. The contrast sensitivity was, however, better in eyes receiving grafts prepared with the single-pass technique.

Influenceofmicrokeratomeand femtosecond laser on vision and corneal flap thickness used in corneal flap making / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To study and compare the influence situation of corneal flap made by microkeratome and femtosecond laser for the vision and corneal flap thickness in patients. METHODS:Totally 120 patients(240 eyes) with myopic refractive surgery in our hospital from June 2014 to May 2015 were randomly divided into Group A (microkeratome group) with 60 cases (120 eyes) and Group B (femtosecond laser group) with 60 cases (120 eyes). Then the vision situation and corneal flap thickness indexes of two groups at different time after the treatment were compared. RESULTS:The vision situation between the two groups at different time after the treatment all had no significant differences (all P>0.05),while the corneal flap thickness related indexes of Group B at different time after the treatment were all better than those of Group A (all P<0 05). The evaluation indexes of two groups after the treatment all had significant differences (all P<0.05). CONCLUSION: The indexes of corneal flap made by femtosecond laser are better than those of microkeratome,and the influence of two methods for the vision is no obvious.

Effects of LASIK on ocular surface by femtosecond laser or mechanical microkeratome for creating corneal flap / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To investigate the effects of laser <i>in situ</i> keratomileusis(LASIK)on ocular surface by femtosecond laser or mechanical microkeratome for creating corneal flap, and to study the effect of different corneal flap method on ocular surface after operation. <p>METHODS: This study included 218 cases(436 eyes)myopia patients from January 2016 to January 2017 in our hospital for refractive surgery, their medical records were retrospectively analyzed. They all underwent LASIK surgery treatment and complained of different degree of dry eye postoperatively, foreign body sensation and discomfort. Mechanical microkeratome was used in 61 cases(122 eyes)of patients and they were as control group, with femtosecond laser, 157 cases(314 eyes)were set as observation group. We compared dry eye symptom scores, corneal fluorescein staining(FL)score, break-up time(BUT)and basic tear secretion test(SⅠt)between the two groups preoperatively and postoperatively 1wk, 1, and 3mo. <p>RESULTS: Before surgery, dry eye symptoms scoring of two groups had no statistically significant difference(<i>P</i>>0.05); the scores of the two groups were significantly different before and after surgery(<i>P</i><0.05); postoperatively 1wk, dry eye symptoms score of control group was greater than that of the observation group with significant difference(<i>P</i><0.05), the sores at 1 and 3mo after surgery were not different between the two groups(<i>P</i>>0.05). There was no significant differenc on the preoperative BUT between the two groups(<i>P</i>>0.05). BUT before and after surgery was significantly different of both groups(<i>P</i><0.05). BUT of control group was significantly lower than that of observation group postoperatively(<i>P</i><0.05). Before surgery, FL score of two groups had no statistically significant difference(<i>P</i>>0.05); the scores of the two groups were significantly different before and after surgery(<i>P</i><0.05); postoperatively 1wk and 1mo, FL score of control group was greater than that of the observation group with significant difference(<i>P</i><0.05), the sores at 3mo after surgery were not different between the two groups(<i>P</i>>0.05). Before surgery, SⅠt of two groups had no statistically significant difference(<i>P</i>>0.05); the scores of the two groups were significantly different before and after surgery(<i>P</i><0.05); postoperatively 1wk and 1mo, SⅠt of control group was lower than that of the observation group with significant difference(<i>P</i><0.05); SⅠt at 3mo after surgery were not different between the two groups(<i>P</i>>0.05). Two groups of patients had no serious postoperative complications occurred.<p>CONCLUSION: Compared with the mechanical microkeratome for creating corneal flap, LASIK with femtosecond laser for creating corneal flap has less effect on ocular surface and has mild symptoms of dry eye, the effect time is also shortened.

Changes of tear film after LASlK with corneal flap created by femtosecond laser and microkeratome / 国际眼科杂志(Guoji Yanke Zazhi)

To observe the changes of tear film on the patients after laser in situ keratomileusis(LASlK)with corneal flap created by femtosecond laser and microkeratome. ●METHODS: Totally 150 patients (300 eyes) with myopia received operation of LASlK. Patients were divided into two groups according to the methods of making corneal flap. The patients of group one were assigned to receiving LASlK with corneal flap creation by lntralase femtosecond laser (190 eyes of 95 patients), group two were assigned to receiving LASlK with corneal flap creation by microkeratome ( 110 eyes of 55 patients ). Dry eye symptom score, tear break-up time (BUT), Schirmer Ⅰtest(Slt), corneal fluorescein staining(FL)were recorded preoperatively and postoperatively at 1wk; 1, 3 and 6mo. ●RESULTS: Dry eye symptom score: there existed obvious differences at 1wk; 1, 3mo between two groups(P0. 05). BUT: there existed obvious differences at 1wk, 1, 3mo between two groups(P0. 05). SchirmerⅠ test: there existed obvious differences in the 1wk, 1, 3mo between two groups(P0. 05). FL: there existed obvious differences in the 1wk, 1, 3mo between two groups(P0. 05). ●CONCLUSlON: The early stability of tear film decrease after operation in both of the two groups. The dry eye symptoms are lighter and recover faster.

Influence of femtosecond laser making-flap on surface characteristics of porcine cornea / 中华实验眼科杂志

Background The application of femtosecond laser in the corneal refractive surgery has made great progression recent years,but the morphology characteristic of corneal stroma surface after making-flap of femtosecond laser is closely concerned.Objective This study was to analyze the influence of photodisrnption of femtosecond laser on the corneal stroma surface and to investigate the effect of different laser pulse energy on the sudace ultrastructure of corneal stroma.Methods Corneal flaps were made with Visu Max femtosecond laser in 16 fresh porcine eyes with the pulse energy 125 nJ,155 nJ and 195 nJ respectively,and Moria-M2 microkeratome was used as control.Scanning electron microscopy (S-3400N Hitachi High-Technologies Corp) was used to observe and compare the ultrastructural characteristic of corneal stroma bed surface after making of corneal flap.Results The corneal strnma was evaporated and created a smooth surface when photodisrnption happened in the femtosecond laser group.Residual tissue bridges could been exhibited among the cavitation bubbles under the scanning electron microscope.Corneal strnma surface was smooth in the 125 nJ pulse energy group,but some tissue bridges still were visible.In the 155 nJ pulse energy group,much more smooth surface was seen without tissue bridges and mechanical damages on the corneal surface.However,the surface quality was worse and many tissue bridges and grooves existed in the 195 nJ pulse energy group.In addition,different sizes of slots caused by big cavitation bubbles were visible with the round and oval shape.The edges were regular and sharp with small damage zone after cutting with femtoseeond laser.However,many elevated fibril tissues could be seen on the corneal surface after making of flap with microkeratome.Many crimp and irregularity tissues were found on the surface.Blunt surface and indentations appeared in the cutting edge.Conclusions The mierostrueture of corneal stroma surface is more smoother after making of corneal flap with fentosecond laser in comparison with microkeratome.Pulse energy of 155 nJ is preferably during the making-flap with femtosecond laser.

Comparison of flap thickness, visual outcomes, and higher order aberrations in eyes that underwent LASIK flap creation using a femtosecond laser versus a mechanical microkeratome

Objective@#To compare the predictability of flap thickness, visual and refractive outcomes, and higher order aberrations in eyes that underwent myopic LASIK using either a Technolas femtosecond laser or a Zyoptix XP mechanical microkeratome for flap creation.@*Methods@#The study involved a total of 44 eyes of 22 patients who underwent LASIK. Flap creation was randomized to using the Technolas femtosecond laser in one eye and Zyoptix XP microkeratome in the contralateral eye. Flap thickness was measured intraoperatively using ultrasonic pachymetry and postoperatively using the Visante ASOCT. Refractive outcome, visual acuity (VA), higher order aberrations, and contrast sensitivity were compared between the two groups.@*Results@#Twenty-two patients had LASIK for myopia or myopic astigmatism. Using ultrasonic pachymetry intraoperatively, the mean flap thickness was 134 (±10) um and 124 (±23) um in the femtosecond (FS) and microkeratome (MK) groups respectively. Comparing the deviation of the actual from the intended flap thickness, the FS group had statistically lower standard deviation compared to the MK group (p=0.04). Using the AS-OCT, the mean flap thickness at 3 months postoperatively was 119 (±10.82) um and 123 (±15.77) um in the FS and MK groups respectively. The difference in standard deviation between the two groups did not reach statistical significance (p=0.19). The mean spherical equivalent at 3 months was -0.45D (±0.42) and -0.13D (±0.16) respectively. Eightynine percent (89%) of eyes had uncorrected VA of 20/20 or better in both groups. All eyes attained best corrected VA of 20/20 or better in both groups. Differences in total higher order aberrations (p=0.09) and contrast sensitivity scores (p=0.47) were not statistically different between the two groups. @*Conclusion@#Flap thickness predictability was better using the Technolas femtosecond laser compared to the XP microkeratome blade. Visual and refractive outcomes, higher order aberrations, and contrast sensitivity were comparable between the 2 groups.

Comparison of flaps created with the Moria M2 microkeratome with regular blade Versus Med-Logics 0 blade / 中华实验眼科杂志

BackgroundFlap creation is one of the most important steps during laser in situ keratomileusis (LASIK). As the microkeratome blade technology is developing, the accuracy, uniformity and reproducibility of corneal flaps created by the microkeratome blade are of high clinical concern. ObjectiveThe aim of this trial was to compare the features of corneal flaps created using the Moria M2 microkeratome 110 μm-knife with regular blade versus the Med-Logics O blade. MethodsA pilot and prospective study was designed. Two hundred and four eyes of one hundred and two patients were enrolled in this clinical trial. The patients were divided into the Moria M2 microkeratome 110 μm-knife with Med-Logics 0 blade group ( 110-0 group) ( 102 eyes) and Moria M2 microkeratome with 110 μm-knife with regular blade group (110 group) (102 eyes),with the matched demography. Fourier-domain optical coherence tomography ( RTVue OCT) was used to measure flap thickness using 28 settings on the 204 corneas at one week postoperatively. The features of the LASIK flaps were analyzed on the basis of the outcomes. Written informed consent was obtained from each patient prior to LASIK. Results There was no statistically significant difference in uncorrected visual acuity and the mean spherical equivalent between the 110-0 group and 110 group ( Z =-0. 375,P =0. 708 ; u =0. 056, P =0. 956 ) one week after LASIK. The mean flap thickness of the 110-0 group was considerably thinner than that of the 110 group ( 133.28+15.41μ m versus 142.81 ±10. 07μm) ( u =-5. 227,P＜0. 001 ). The corneal flaps in both the 110-0 group and in 110 group showed a meniscus shape. The nasal flap thickness of the right eyes was not evidently different from that of temporal ( P＞0. 05 ) , but in the left eyes, nasal flap thickness was obviously thicker than the temporal flap thickness (P＜0. 05) in both groups. The mean deviation between the achieved and attempted flap thickness ( 130 μm) were (17.46±2.28) μm in the 110-0 group and ( 16. 82±6. 12) μm in the 110 group, showing a significant difference between them ( u ==0. 517, P=0. 608 ).ConclusionsThe shape of flaps created using the Moria M2 110-0 is more uniform and closer to the expected thickness of 130 μm than the ones created using the Moria M2 110 microkeratome.

Comparison of the Flap Complication Rate Between Microkeratomes for LASIK

PURPOSE: To compare intraoperative and postoperative flap complication rate between the Hansatome Excellus and Zyoptix XP microkeratomes for LASIK surgery. METHODS: The intra- and post-operative flap complication rate, in 323 eyes of 167 patients operated on using the Hansatome microkeratome were compared with 260 eyes of 132 patients that were operated on using the Zyoptix XP microkeratome. RESULTS: The Hansatome group showed an intraoperative complication incidence of 2.7% compared to 0.4% for the Zyoptix XP group (p0.05). There was no incidence of visually significant complications in either group. CONCLUSIONS: The Zyoptix XP showed a significantly decreased intraoperative flap complication rate compared to the Hansatome Excellus microkeratome. The preoperative K value is an important factor for safe LASIK.

Comparison of Clinical Result of LASIK using between Femtosecond Laser and Microkeratome for Correction of Myopia

PURPOSE: To compare results between in femtosecond laser and microkeratome LASIK correction of myopia METHODS: We retrospectively analyzed the result of 94 eyes of 47 patients in the femtosecond group (F) and 103 eyes of 52 patients in the microkeratome group (M). All patients had undergone LASIK using either a femtosecond laser or a microkeratome for making of flap. Patients were divided into groups I (6D or =6D) according to preoperative myopia. Each patient was followed up for over 6 months with measurements of uncorrected visual acuity and manifest refraction at 1 week and 1, 3, and 6 months after operation. Complications during and after the operation were reviewed retrospectively in two groups 6month after the operation. RESULTS: In groups F-I, F-II, M-I, and M-II, postoperative 6-month uncorrected visual acuity was 0.98+/-0.08, 0.96+/-0.09, 0.97+/-0.03, 0.98+/-0.09. At the 6-month follow-up, there were no significant differences between the two groups in uncorrected visual acuity and mean spherical equivalent. Corneal opacity was found in 3 eyes in group M and complication related with flap was found 1 eye in group F and 4 eyes in group M. CONCLUSIONS: During a 6-month follow up, LASIK using either a femtosecond laser or a microkeratome has an similar effect in uncorrected visual acuity and mean spherical equivalent. Thus LASIK for using femtosecond laser can be used as an alternative procedure to correct myopia.

Predictability of Donor Lamellar Graft Thickness and Diameter Using a Microkeratome in Porcine Eyes

PURPOSE: To evaluate the thickness and diameter of a lamellar graft with microkeratome and to determine its usefulness as a donor lamellar graft for microkeratome-assisted lamellar keratoplasty. METHODS: Thirty-six porcine eyes were randomly assigned to three groups according to the microkeratome (Automated Corneal Shaper(R)) depth plate: group 1 (#300 micrometer plate, 13 eyes), group 2 (#400 micrometer plate, 12 eyes), and group 3 (#450 micrometer plate, 11 eyes). Free corneal buttons were made with the corneal shaper after a uniform suction duration of 10 seconds. Central corneal thicknesses were measured with an automated ultrasound pachymeter prior to the procedure. After the lamellar graft was made, the remaining corneal thickness was measured with the same method. The difference between the two values was hypothesized to be the lamellar graft thickness. In addition, the diameter of lamellar graft was measured by calipers. RESULTS: The mean lamellar graft thicknesses in groups 1, 2, and 3 were 218.2+/-26.6 micrometer (72.7%), 312.3+/-26.7 micrometer (78.1%) and 345.7+/-36.7 micrometer (76.8%), respectively. There were no significant differences between the three groups according to the results brought by the microkeratome depth plates (p=0.239). The mean lamellar graft diameters in groups 1, 2, and 3 were 8.49+/-0.28 mm, 8.43+/-0.26 mm and 8.58+/-0.28 mm, respectively. There were no significant differences between the three groups (p=0.368). No relationship was found between lamellar graft thickness and diameter (r=-0.009, p=0.480). CONCLUSIONS: These results suggest that in forming donor lamellar grafts with microkeratome plates, thicker resection depth is needed because the actual lamellar graft were shown to be thinner than the target values. However, lamellar grafting is thought to be unsuitable for lamellar keratoplasty because it results in considerable thickness variability.

Contrast analysis of corneal flap thickness using Moria M290 and 110 microkeratome / 上海第二医科大学学报

Objective To analyze the corneal flap thickness in laser in situ keratomileusis(LASIK) using Moria M2 microkeratome and to identify the related factors. Methods Sixty patients with LASIK were divided into two groups: M2 90 group,using the Moria M2 90 microkeratome,n=30;M2 110 group,using the Moria M2 110 microkeratome,n=30.All were performed on both eyes with the right one treated first.Subtraction pachymetry was used to measure corneal flap thickness which was analyzed statistically with the data including age,preoperative corneal diameter,curvature,corneal thickness and refraction. Results In the 30 patients of M2 90 group,the mean corneal flap thickness of right eye and left eyes were(128.03?12.03)?m(105~156 ?m) and(123.40?12.38) ?m(92~147 ?m),respectively,and the corneal flap thickness were statistically different between the right and left eyes(P

Clinical Evaluation of New Microkeratome

PURPOSE: To determine dimensions and quality of flaps created with Zyoptix(TM) XP microkeratome. METHODS: Ninety-nine eyes of 50 patients were enrolled in this prospective study. LASIK procedures were performed by a single surgeon, using Zyoptix(TM) XP microkeratomes (Bausch & Lomb) with 160 micrometer, 180 micrometer and 200 micrometer heads and suction rings with intended flap diameters (IFD) of 8.5 mm and 9.5 mm. Patients' age, preoperative manifest refraction value, keratometry reading, preoperative central corneal thickness, stromal bed thickness, and flap diameter were recorded. To calculate flap thickness, subtraction pachymetry was used. The microscopic quality of the flap and stromal bed was graded from 0 to 100. RESULTS: The mean thickness of flaps created by Zyoptix(TM) XP microkeratome was 107.56+/-13.61 micrometer with the 160 micrometer head, 132.99+/-21.03 micrometer with the 180 micrometer head, and 134.32+/-14.75 micrometer with the 200 micrometer head. The actual flap diameter was 9.18 mm for an IFD 8.5 mm and 9.96 mm for an IFD of 9.5 mm. Subjective assessment of the flap and stromal bed, respectively, was 98.32+/-2.24 and 97.94+/-3.85 with the 160 micrometer head, 97.86+/-1.73 and 97.97+/-2.22 with the 180 micrometer head, and 97.79+/-1.17 and 97.72+/-1.10 with the 200 micrometer head. CONCLUSIONS: Flaps created with Zyoptix(TM) XP microkertome were reproducible in their dimensions. The flaps and stromal beds were of high quality.

Preoperative Factors related to Corneal Flap Thickness in LASIK using Microkeratome

PURPOSE: To identify factors that may be related to variations in corneal flap thickness in LASIK using the Moria M2 microkeratome. METHODS: The charts of patients having LASIK based on steep keratometry nomogram using Moria M2 microkeratome (head : 110 micrometer) and excimer laser (VISX STAR S2, USA) in our department of ophthalmology from March, 2003, to May 2005, were reviewed retrospectively. A total of 195 eyes were enrolled in the investigation. We analyzed relationship between corneal flap thickness and preoperative factors including central corneal thickness, steep keratometer, corneal diameter, suction ring using multiple regression analysis. RESULTS: Mean corneal flap thickness was 119.37+/-21.21 micrometer. There was a statistically significant positive correlation between flap thickness and central corneal thickness (p<0.05). No correlation was found between flap thickness and other preoperative factors including steep keratometer, corneal diameter and suction ring. CONCLUSIONS: Mean corneal flap thickness using the Moria M2 110 micrometer head was 119.37+/-21.21 micrometer, little thicker than our expectation. When surgery is performed based on steep keratometry nomogram using Moria M2 microkeratome, if intraoperative factors are excluded, there is a trend toward thicker flap thickness with thicker central corneal thickness, whereas steep keratometer, corneal diameter or suction ring have no influence on flap thickness.

LASIK of Customized Microkeratomy by Selection of Microkeratome Heads

PURPOSE: To compare the intraoperative and postoperative complication rates and visual outcomes with M2 130 head (thick flap group) and M2 110 head (thin flap group). METHODS: One-hundred-ninety-five eyes of 104 patients who underwent LASIK with the Moria M2 microkeratome and Allegretto-wave laser were reviewed retrospectively. Selection of M2 heads was based on preoperative pachymetry and estimated ablation depth. Intraoperative and postoperative flap-related complications, mean postoperative uncorrected visual acuity (UCVA), and mean spherical equivalent (MSE) were evaluated and compared. RESULTS: Mean follow-up was 8.1 months. The number of eyes, preoperative MSE and mean corneal thickness of M2 130 were 115, -4.04+/-1.63diopter (D) and 549.40+/-39.16 micrometer, and 85, -6.61+/-3.43D and 525.16+/-24.53 micrometer, respectively, in the 110 head group. Mean UCVA and MSE at postoperative 1 week, 3 months and 6 months were 1.00+/-0.18, -0.26+/-0.49D; 1.07+/-0.68, -0.40+/-0.51D; and 1.01+/-0.22, -0.51+/-0.50D, respectively, in the 130 head group, and 0.90+/-0.23, -0.46+/-1.02D; 0.91+/-0.23, -0.67+/-0.79D; 0.85+/-0.46, -0.75+/-0.88D, respectively, in the 110 head group. There were no significant differences in intraoperative and postoperative flap-related complication rates between the two groups (p=0.316). There were no statistically significant differences in postoperative mean UCVA or MSE between the two groups (p>0.05), except for MSE at the third and sixth postoperative months (p=0.005, 0.013). CONCLUSIONS: Proper selection of M2 heads by preoperative pachymetry allowed for an adequate residual stroma bed with good visual outcome. Utilizing one single microkeratome and switching between two heads was advantageous and cost-effective.

Comparision of Corneal Endothelial Change in Femtosecond Laser and Microkeratome LASIK

PURPOSE: To compare the corneal endothelial cell change in Femtosecond laser and microkeratome LASIK operation. METHODS: This study involved 31 eyes (16 patients) that had LASIK using a femtosecond laser (group 1). The control group comprised 32 eyes (16 patients) that had conventional LASIK using microkeratome. We measured the endothelial cell using a non-contact specular microscope preoperatively and at postoperative 1, 2 and 6 months. RESULTS: The preoperative and postoperateive 1, 2, and 6 months cell densities were, respectively: (group 1) 3039+/-335.2, 3012.9+/-373.0, 3008.2+/-240.2, 3009.1+/-250.5; (group 2) 2984.8+/-334.4, 2972.7+/-290.0, 2968+/-323.2, 2968+/-319.1. The coefficients of variation were, respectively: (group 1) 32.6+/-5.3, 33+/-7.2, 32.2+/-5.9, 31.7+/-5.8; (group 2) 32.3+/-5.3, 33.6+/-6.2, 35.5+/-4.8, 34.1+/-5.1. Respective hexagonality measurements were: (group 1) 59.2+/-11.7, 56+/-12.1 55.1+/-13.5, 57.2+/-11.6; (group 2) 57.6+/-9.8, 57.4+/-10.7, 56.5+/-11.6, 57.1+/-11.1. CONCLUSIONS: There was no statistical difference in corneal endothelial change between the two groups (p>0.05). LASIK using the femtosecond laser seemed to be a safe choice when considering corneal endothelial change.

The Availability and Safety of the Microkeratome in LASIK

PURPOSE: To evaluate the reproducibility of the flap thickness in LASIK using Moria M2 microkeratome and to examine the safety and the complication rate intraoperatively and postoperatively. METHODS: 92-Ninety-two consecutive eyes of 50 patients that received LASIK using the Moria M2 microkeratome were reviewed. The mean of the predictable corneal flap thickness was compared with the mean of the created corneal flap thickness, and intraoperative and postoperative complication and safety were evaluated. RESULTS: The average corneal flap thicknesses were 140+/-15.16 micrometer with 130 micrometer head and 108.01+/-16.72 micrometer with 110 micrometer head. There was no statistically significant correlation between the predictable corneal flap thickness and the created corneal flap thickness with the 130 micrometer head (p=0.001, one-sample t-test), but there was a stastistically significant correlation with the 110 micrometer head (p=0.573, one-sample t-test). CONCLUSIONS: The M2 Moria microkeratome created a desirable thickness with the 110 micrometer head, and we can expect postoperative stability of the remaining corneal thickness. The complication rate both intraoperatively and postoperatively was very low.

The Effect of Repeated Use of the Disposable Blade in Automated Microkeratome on the Corneal Flap Dimensions and Cut Quality

PURPOSE: To evaluate changes in the blade, flap dimensions, and stromal bed with repeated use of disposable blade in LASIK (laser in situ keratomileusis) surgery. METHODS: A keratome was used to make a corneal flap in pig cadaver eyes, with the blades being reused up to five times. The thickness and diameter of each corneal flap was measured. Scanning electron microscopy of the stromal beds and blade cutting edges was performed to determine the effect that repeated use of the blade had on the stromal bed, and on the cutting edge of the blade. RESULTS: The thickness/diameter of flap was 169.73 +/- 7.55 micro meter/8.60 +/- 0.23 mm after single use and 142.93 +/- 13.10 micro meter/8.72 +/- 0.20 mm after being used five times, with both demensions decreasing as the blade was used more. The edge of the blade became blunt and irregular and the cutting surface rough and irregular with continual use. CONCLUSIONS: During LASIK surgery, reused blades became blunt, causing a thin flap, rough cutting face, and complications such as irregular astigmatism clinically.

Comparison of Complications of the Corneal Flap following LASIK by Three Different Manual Microkeratomes

PURPOSE: To compare and analyze intraoperative and postoperative complications of corneal flap in the LASIK procedures using different types of manual microkeratomes (MLK, LSK, disposable Barron). METHODS: Eight hundred sixty-two eyes were retrospectively evaluated to study the effects of 3 different microkeratomes on the frequency of complications, managements, and postoperative best visual acuity. The eyes were grouped according to the microkeratomes used in making corenal flap: Group 1 (334 eyes) treated with MLK(SCMD, USA); Group 2 (256 eyes), LSK(Moria, France); Group 3 (272 eyes), disposable Barron(Katena, USA). RESULTS: Mean follow-up period was 6.3 months and mean age was 29.2 years (range 20 39). Complications of corneal flap were observed in 74(7.9%) of 862 eyes. Intraoperative flap complications occurred in 15 eyes (4.5%), 6 eyes (2.4%) and 3 eyes (1.2%) in each group, respectively. The postoperative flap complications were observed in 24 eyes (7.2%), 17 eyes (6.7%) and 9 eyes (3.3%) in each group. The postoperative best corrected visual acuity decreased by 2 lines or more in 2 eyes (0.6%), 1 eye (0.4%) and none (0%) of each group. CONCLUSIONS: The incidence of corneal flap-related complications by manual microkeratomes was relatively low. Disposable Barron microkeratome showed the lowest complication rate in our series. It also has an advantage of easy maneuverability, and reproducibility (equal size and thickness of corneal flap).