The Experts below are selected from a list of 990 Experts worldwide ranked by ideXlab platform
Norbert Pfeiffer - One of the best experts on this subject based on the ideXlab platform.
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irregularity of the posterior corneal surface after curved interface femtosecond laser assisted versus Microkeratome assisted descemet stripping automated endothelial keratoplasty
Cornea, 2013Co-Authors: Jan M Vetter, Christina Butsch, Melissa Faust, Irene Schmidtmann, Esther M Hoffmann, Walter Sekundo, Norbert PfeifferAbstract:Purpose:During donor tissue preparation for Descemet stripping automated endothelial keratoplasty (DSAEK), either Microkeratome or femtosecond laser can be used for intrastromal cutting. We compared morphological and functional outcomes after DSAEK using both cutting techniques.Methods:In this retro
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irregularity of the posterior corneal surface during applanation using a curved femtosecond laser interface and Microkeratome cutting head
Journal of Refractive Surgery, 2012Co-Authors: Jan M Vetter, Carsten Holtz, Urs Vossmerbaeumer, Norbert PfeifferAbstract:PURPOSE To evaluate the irregularity of the posterior corneal surface and intrastromal dissection during the preparation of donor tissue for Descemet stripping automated endothelial keratoplasty (DSAEK) using a curved interface femtosecond laser and Microkeratome. METHODS Sixteen human donor corneas unsuitable for transplantation were divided into two groups: a femtosecond (FS) laser group (n=7) using the VisuMax femtosecond laser (Carl Zeiss Meditec) and a Microkeratome group (n=9) using the Amadeus II Microkeratome (Ziemer Ophthalmic Group). The corneas were fixed on artificial anterior chambers. Horizontal cross-sections were obtained using spectral-domain optical coherence tomography prior to applanation, during applanation, as well as during and after intrastromal dissection at 450-μm corneal depth. The posterior surface and the dissection line were evaluated for irregularity by fitting a second-order polynomial curve using regression analysis and obtaining the root-mean-square error (RMSE). Groups were compared using analysis of variance. RESULTS The RMSE of the posterior surface prior to applanation was 9.7 ± 3.1 μm in the FS laser group and 10.2 ± 2.3 μm in the Microkeratome group. The RMSE increased to 50.7 ± 9.4 μm and 20.9 ± 6.1 μm during applanation and decreased again to 10.6 ± 1.4 μm and 8.1 ± 1.8 μm after applanation in the FS laser and Microkeratome groups, respectively. The RMSE of the intrastromal cut was 19.5 ± 5.7 μm in the FS laser group and 7.7 ± 3.0 μm in the Microkeratome group (P<.001). CONCLUSIONS Our results show significantly greater irregularity with the curved interface femtosecond laser-assisted cleavage compared to Microkeratome-assisted corneal dissection, possibly due to applanation-derived deformation of the posterior cornea.
Jan M Vetter - One of the best experts on this subject based on the ideXlab platform.
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irregularity of the posterior corneal surface after curved interface femtosecond laser assisted versus Microkeratome assisted descemet stripping automated endothelial keratoplasty
Cornea, 2013Co-Authors: Jan M Vetter, Christina Butsch, Melissa Faust, Irene Schmidtmann, Esther M Hoffmann, Walter Sekundo, Norbert PfeifferAbstract:Purpose:During donor tissue preparation for Descemet stripping automated endothelial keratoplasty (DSAEK), either Microkeratome or femtosecond laser can be used for intrastromal cutting. We compared morphological and functional outcomes after DSAEK using both cutting techniques.Methods:In this retro
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irregularity of the posterior corneal surface during applanation using a curved femtosecond laser interface and Microkeratome cutting head
Journal of Refractive Surgery, 2012Co-Authors: Jan M Vetter, Carsten Holtz, Urs Vossmerbaeumer, Norbert PfeifferAbstract:PURPOSE To evaluate the irregularity of the posterior corneal surface and intrastromal dissection during the preparation of donor tissue for Descemet stripping automated endothelial keratoplasty (DSAEK) using a curved interface femtosecond laser and Microkeratome. METHODS Sixteen human donor corneas unsuitable for transplantation were divided into two groups: a femtosecond (FS) laser group (n=7) using the VisuMax femtosecond laser (Carl Zeiss Meditec) and a Microkeratome group (n=9) using the Amadeus II Microkeratome (Ziemer Ophthalmic Group). The corneas were fixed on artificial anterior chambers. Horizontal cross-sections were obtained using spectral-domain optical coherence tomography prior to applanation, during applanation, as well as during and after intrastromal dissection at 450-μm corneal depth. The posterior surface and the dissection line were evaluated for irregularity by fitting a second-order polynomial curve using regression analysis and obtaining the root-mean-square error (RMSE). Groups were compared using analysis of variance. RESULTS The RMSE of the posterior surface prior to applanation was 9.7 ± 3.1 μm in the FS laser group and 10.2 ± 2.3 μm in the Microkeratome group. The RMSE increased to 50.7 ± 9.4 μm and 20.9 ± 6.1 μm during applanation and decreased again to 10.6 ± 1.4 μm and 8.1 ± 1.8 μm after applanation in the FS laser and Microkeratome groups, respectively. The RMSE of the intrastromal cut was 19.5 ± 5.7 μm in the FS laser group and 7.7 ± 3.0 μm in the Microkeratome group (P<.001). CONCLUSIONS Our results show significantly greater irregularity with the curved interface femtosecond laser-assisted cleavage compared to Microkeratome-assisted corneal dissection, possibly due to applanation-derived deformation of the posterior cornea.
Terrence P Obrien - One of the best experts on this subject based on the ideXlab platform.
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descemet stripping automated endothelial keratoplasty effect of anterior lamellar corneal tissue on off storage condition on descemet stripping automated endothelial keratoplasty donor tissue
Cornea, 2008Co-Authors: Takeshi Ide, Sonia H Yoo, George D Kymionis, James M Goldman, Victor L Perez, Terrence P ObrienAbstract:Purpose:To compare the effect of storing Descemet-stripping automated endothelial keratoplasty (DSAEK) tissue with anterior lamellar corneal tissue (ALCT)-on versus -off.Methods:An in vitro model was used with corneoscleral rims and DSAEK quality paired corneas. After Microkeratome-assisted excision
Thomas Kohnen - One of the best experts on this subject based on the ideXlab platform.
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corneal architecture of femtosecond laser and Microkeratome flaps imaged by anterior segment optical coherence tomography
Journal of Cataract and Refractive Surgery, 2009Co-Authors: Burkhard Von Jagow, Thomas KohnenAbstract:Purpose To assess and compare the morphology of laser in situ keratomileusis flaps (LASIK) created by a 60 kHz femtosecond laser and a mechanical Microkeratome. Setting Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. Methods Anterior segment optical coherence tomography (AS-OCT) (Visante) was used to assess 1 week postoperatively the morphology of 20 LASIK flaps created with the IntraLase femtosecond laser or the Zyoptix XP Microkeratome. The flap diameter and flap thickness were assessed at 20 measuring points across each flap. First, the repeatability of the AS-OCT flap measurement was evaluated. On this basis, the dimensions of femtosecond laser flaps and Microkeratome flaps were tested and their regularity, reproducibility, and accuracy compared. Results The method was approved with a repeatability of maximum 8.9 μm. The femtosecond laser flaps were more regular than the Microkeratome flaps (P = .02). The reproducibility of flap morphology was not different in the central 1.0 mm radius area (P = .26); however, the femtosecond laser was significantly more precise than the Microkeratome in the peripheral area (P = .001). The mean thickness of the femtosecond laser flap was significantly more accurate than the mean thickness of the Microkeratome flap (P = .01), with a mean deviation of +16.9 μm and 40.8 μm, respectively. Conclusions The flap architecture created with the femtosecond laser was more regular and accurate than the flap architecture created with the Microkeratome.
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intraindividual comparison of epithelial defects during laser in situ keratomileusis using standard and zero compression hansatome Microkeratome heads
Journal of Cataract and Refractive Surgery, 2004Co-Authors: Thomas Kohnen, E Terzi, A Mirshahi, Jens BuhrenAbstract:Abstract Purpose: To determine the difference between the standard and a modified (zero-compression) Hansatome ® Microkeratome head (Bausch & Lomb) in the incidence of epithelial defects. Setting: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. Methods: Ninety-three patients (186 eyes) with a mean age of 39.1 years ± 9.5 (SD) having laser in situ keratomileusis (LASIK) in both eyes were enrolled in a prospective randomized study using intraindividual comparison. In 1 eye, the flaps were created with the Hansatome Microkeratome using the standard Hansatome head and in the other eye, the flaps were created with a Microkeratome head with a modified design (zero-compression head). Intraoperative evaluation of epithelial defects was done using a standardized protocol. Statistical evaluation was performed with McNemar and Bowker tests. Results: Epithelial defects occurred in 21 eyes (22.6%) in which the standard head was used and in 2 eyes (2.1%) in which the zero-compression head was used. In the former group, 15 (16.1%) of the epithelial defects were larger than 1.5 mm 2 ; the remaining 6 (6.4%) were smaller than 1.5 mm 2 . In the latter group, both epithelial defects were smaller than 1.5 mm 2 ; both patients also had an epithelial defect in the eye in which the standard Hansatome head was used. The difference between the 2 Hansatome heads in the incidence ( P P Conclusions: The Hansatome Microkeratome with a zero-compression head significantly reduced the occurrence of intraoperative epithelial defects. The change in the construction of the Hansatome head is a useful improvement in LASIK technology.
William M Bourne - One of the best experts on this subject based on the ideXlab platform.
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subbasal nerve density and corneal sensitivity after laser in situ keratomileusis femtosecond laser vs mechanical Microkeratome
Archives of Ophthalmology, 2010Co-Authors: Sanjay V. Patel, Jay W Mclaren, K M Kittleson, William M BourneAbstract:Objective:To compare changes in subbasal nerve density and corneal sensitivity after laser in situ keratomileusis (LASIK) with the flap created by a femtosecond laser (bladeless) vs a mechanical Microkeratome. Design: In a randomized paired-eye study, 21 patients received myopic LASIK with the flap created by a femtosecond laser in one eye and by a mechanical Microkeratome in the fellow eye. Eyes were examined before and at 1, 3, 6, 12, and 36 months after LASIK. Central subbasal nerve density was measured by using confocal microscopy. Corneal mechanical sensitivity was measured by using a gas esthesiometer and was expressed as the ratio of mechanical threshold in eyes that received LASIKtomechanicalthresholdinconcurrentcontroleyes. Results: Subbasal nerve density and corneal sensitivity did not differ between methods of flap creation at any examination. Mean (SD) nerve density was decreased at 1 month (bladeless, 974 [2453] µm/mm 2 ; Microkeratome, 1308 [2881] µm/mm 2 ) compared with the preoperative examination(bladeless,10883[5083]µm/mm 2 ,P.001; Microkeratome, 12464 [6683] µm/mm 2 , P.001) and remained decreased through 12 months (P.001). Mechanical threshold ratios did not differ from that at the preoperative examination through 36 months for either LASIK treatment; when all LASIK eyes were combined, the mechanical threshold ratio was transiently higher (decreased sensitivity) at 1 month (1.29 [0.85]) compared with the preoperative examination (0.89 [0.73], P=.05). Conclusions: The planar configuration of the femtosecond laser flaps is not associated with faster reinnervation compared with the Microkeratome flaps. The prolonged decrease in subbasal nerve density after LASIK is not accompaniedbyaprolongeddecreaseincornealsensitivity. Trial Registration: clinicaltrials.gov Identifier NCT00350246
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femtosecond laser versus mechanical Microkeratome for lasik a randomized controlled study
Ophthalmology, 2007Co-Authors: Sanjay V. Patel, Jay W Mclaren, Leo J. Maguire, David O. Hodge, William M BourneAbstract:Purpose To compare corneal haze (backscattered light) and visual outcomes between fellow eyes randomized to LASIK with the flap created by a femtosecond laser (bladeless) or with the flap created by a mechanical Microkeratome. Design Randomized, controlled, paired-eye study. Participants Twenty-one patients (42 eyes) received LASIK for myopia or myopic astigmatism. Methods One eye of each patient was randomized to flap creation with a femtosecond laser (IntraLase FS, IntraLase Corp., Irvine, CA) with intended thickness of 120 μm, and the fellow eye to flap creation with a mechanical Microkeratome (Hansatome, Bausch & Lomb, Rochester, NY) with intended thickness of 180 μm. Patients were examined before and at 1, 3, and 6 months after LASIK. Main Outcome Measures Corneal backscatter, high-contrast visual acuity, manifest refractive error, contrast sensitivity, and intraocular forward light scatter were measured at each examination. Flap thickness was measured by confocal microscopy at 1 month, and patients were asked if they preferred the vision in either eye at 3 months. Results Corneal backscatter was 6% higher after bladeless LASIK than after LASIK with the mechanical Microkeratome at 1 month ( P = 0.007), but not at 3 or 6 months. High-contrast visual acuity, contrast sensitivity, and forward light scatter did not differ between treatments at any examination. Flap thicknesses at 1 month were 143±16 μm (bladeless, mean ± standard deviation) and 138±22 μm (mechanical Microkeratome), with no statistical difference in variances. At 3 months, 5 patients preferred the bladeless eye, 7 patients preferred the Microkeratome eye, and 9 patients had no preference. Conclusions The method of flap creation did not affect visual outcomes during the first 6 months after LASIK. Although corneal backscatter was greater early after bladeless LASIK than LASIK with the mechanical Microkeratome, patients did not perceive a difference in vision.
