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Jean-marc Legeais - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructural and Histologic Studies of Femtosecond Laser Incisions in Human Cornea
Investigative Ophthalmology & Visual Science, 2005Co-Authors: David Donate, Olivier Albert, Karsten Plamann, J.-p. Colliac, Philippe Sabatier, Gérard Mourou, P. Denis, C. Burillon, Y. Pouliquen, Jean-marc LegeaisAbstract:Purpose: The authors present ultrastructural and histologic studies of femtosecond laser incisions in human cornea. Methods: We use a CPA femtosecond laser designed to match current instrumentation for femtosecond surgery, i.e. a Nd:Glass femtosecond laser at a 1065 nm wavelength. The repetition rate is adjustable from 1 to 10 KHz, with maximum pulse energy of 60 µJ. The human cornea samples are fixed to an anterior chamber system that can be moved in 3D by micrometric precision motors in front of a fixed objective delivering the fs laser pulses. Human corneas are provided by the French Eye Bank. Laser energy range for cornea treatment goes from laser induced optical breakdown threshold up to ten time this threshold. Ultrastructural and histologic are then obtained using transmission electronic microscopy TEM and scanning electron microscopy (SEM). Results: Observations of the cornea structures (i.e. epithelium, Bowman Membrane, stroma, Descemet Membrane and endothelium) presents no noticeable side damages like burned collagen or cells damage. Results does not vary with pulse energy (in the experimental energy range : 2 J/cm2 to 50 J/cm2) except for excessive delamination due to the shock wave propagation at high energy. Conclusions: The use of femtosecond laser pulses for keratoplasty implies use of energy higher than the one used for refractive surgery in transparent cornea. Our results demonstrate that cornea ultrastructure is not altered by this higher energy pulses opening the way to surgery in oedematous cornea.
Joseph Colin - One of the best experts on this subject based on the ideXlab platform.
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Comparison of front-surface corneal topography and Bowman Membrane specular topography in keratoconus.
Journal of cataract and refractive surgery, 2012Co-Authors: David Touboul, Elodie Trichet, Perry S. Binder, Delphine Praud, Camille Seguy, Joseph ColinAbstract:Purpose To define the contribution of the corneal epithelium in corneal topography in keratoconus and discuss the implications regarding combined topography-guided photorefractive keratectomy and corneal collagen crosslinking (CXL). Setting French National Reference Center for Keratoconus, Bordeaux, France. Design Case series. Methods Specular topographies were performed before and immediately after epithelial removal during conventional CXL surgery in patients with keratoconus. Results The study included 1 eye with forme fruste keratoconus, 4 eyes in Krumeich stage I, and 3 eyes in stage II. The mean simulated maximum keratometry (K) increased by 2.87 diopters (D) after epithelial removal. The mean effective refractive power increased by a mean of 4.01 D and the astigmatic refractive power, by a mean of 2.17 D. The difference in mean axis deviation was not significant. The mean inferior–superior ratio irregularity index increased 1.51 units. All K and refractive readings except astigmatic refractive axis were significantly increased after epithelial removal. All regularity indices increased significantly without the epithelium. The amplitude of variations in K readings made it difficult to predict the refractive changes after custom laser photoablation based on epithelial-based topography. Conclusions The astigmatism refractive axis did not change significantly; therefore, this axis could be useful for astigmatic corrections, whereas the spherical component would not be useful. Topographic changes after epithelial removal can be important but not intuitive in keratoconus eyes. This should be considered in custom topography-guided photoablation strategies when attempting to correct refractive errors at the time of CXL. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.
Perry S. Binder - One of the best experts on this subject based on the ideXlab platform.
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femtosecond laser assisted intrastromal arcuate keratotomy to reduce corneal astigmatism
Journal of Cataract and Refractive Surgery, 2013Co-Authors: Theresa Ruckl, Perry S. Binder, Alois K Dexl, Alexander Bachernegg, Veronika Reischl, Wolfgang Riha, Josef Ruckhofer, Gunther GrabnerAbstract:Purpose To report the initial results of intrastromal arcuate keratotomy performed with a femtosecond laser to treat corneal astigmatism. Setting Department of Ophthalmology, Paracelsus Medical University, Salzburg, Austria. Design Interventional case series. Methods Patients with corneal astigmatism (naturally occurring or after cataract surgery) were treated with an iFS femtosecond laser to perform paired arcuate cuts on the steep axis completely placed within the corneal stroma. Patients were followed for 6 months after surgery. Preoperative and postoperative (1-day, 1-week, and 1-, 3-, and 6-month) examinations included corrected and uncorrected visual acuities, manifest refraction, corneal topography, endothelial cell count, and corneal pachymetry. A subjective questionnaire was used to evaluate patient satisfaction. Results The study enrolled 16 patients. No perforations occurred, and all incisions were placed at the planned locations. After a 6-month follow-up, the mean refractive cylinder was reduced significantly from 1.41 diopters (D) ± 0.66 (SD) to 0.33 ± 0.42 D (P Conclusion The femtosecond laser allowed the effective creation of precise, purely intrastromal, arcuate incision patterns with an excellent safety profile, rapid recovery, and stability of vision without the known risks associated with incisions that penetrate Bowman Membrane. Financial Disclosure Dr. Binder is a paid consultant to Abbott Medical Optics, Inc. Dr. Grabner has received travel grants in the past and has at times served as medical advisor to Abbott Medical Optics, Inc., Santa Ana, California, USA. No other author has a financial or proprietary interest in any material or method mentioned.
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Comparison of front-surface corneal topography and Bowman Membrane specular topography in keratoconus.
Journal of cataract and refractive surgery, 2012Co-Authors: David Touboul, Elodie Trichet, Perry S. Binder, Delphine Praud, Camille Seguy, Joseph ColinAbstract:Purpose To define the contribution of the corneal epithelium in corneal topography in keratoconus and discuss the implications regarding combined topography-guided photorefractive keratectomy and corneal collagen crosslinking (CXL). Setting French National Reference Center for Keratoconus, Bordeaux, France. Design Case series. Methods Specular topographies were performed before and immediately after epithelial removal during conventional CXL surgery in patients with keratoconus. Results The study included 1 eye with forme fruste keratoconus, 4 eyes in Krumeich stage I, and 3 eyes in stage II. The mean simulated maximum keratometry (K) increased by 2.87 diopters (D) after epithelial removal. The mean effective refractive power increased by a mean of 4.01 D and the astigmatic refractive power, by a mean of 2.17 D. The difference in mean axis deviation was not significant. The mean inferior–superior ratio irregularity index increased 1.51 units. All K and refractive readings except astigmatic refractive axis were significantly increased after epithelial removal. All regularity indices increased significantly without the epithelium. The amplitude of variations in K readings made it difficult to predict the refractive changes after custom laser photoablation based on epithelial-based topography. Conclusions The astigmatism refractive axis did not change significantly; therefore, this axis could be useful for astigmatic corrections, whereas the spherical component would not be useful. Topographic changes after epithelial removal can be important but not intuitive in keratoconus eyes. This should be considered in custom topography-guided photoablation strategies when attempting to correct refractive errors at the time of CXL. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.
David Donate - One of the best experts on this subject based on the ideXlab platform.
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Ultrastructural and Histologic Studies of Femtosecond Laser Incisions in Human Cornea
Investigative Ophthalmology & Visual Science, 2005Co-Authors: David Donate, Olivier Albert, Karsten Plamann, J.-p. Colliac, Philippe Sabatier, Gérard Mourou, P. Denis, C. Burillon, Y. Pouliquen, Jean-marc LegeaisAbstract:Purpose: The authors present ultrastructural and histologic studies of femtosecond laser incisions in human cornea. Methods: We use a CPA femtosecond laser designed to match current instrumentation for femtosecond surgery, i.e. a Nd:Glass femtosecond laser at a 1065 nm wavelength. The repetition rate is adjustable from 1 to 10 KHz, with maximum pulse energy of 60 µJ. The human cornea samples are fixed to an anterior chamber system that can be moved in 3D by micrometric precision motors in front of a fixed objective delivering the fs laser pulses. Human corneas are provided by the French Eye Bank. Laser energy range for cornea treatment goes from laser induced optical breakdown threshold up to ten time this threshold. Ultrastructural and histologic are then obtained using transmission electronic microscopy TEM and scanning electron microscopy (SEM). Results: Observations of the cornea structures (i.e. epithelium, Bowman Membrane, stroma, Descemet Membrane and endothelium) presents no noticeable side damages like burned collagen or cells damage. Results does not vary with pulse energy (in the experimental energy range : 2 J/cm2 to 50 J/cm2) except for excessive delamination due to the shock wave propagation at high energy. Conclusions: The use of femtosecond laser pulses for keratoplasty implies use of energy higher than the one used for refractive surgery in transparent cornea. Our results demonstrate that cornea ultrastructure is not altered by this higher energy pulses opening the way to surgery in oedematous cornea.
David Touboul - One of the best experts on this subject based on the ideXlab platform.
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Comparison of front-surface corneal topography and Bowman Membrane specular topography in keratoconus.
Journal of cataract and refractive surgery, 2012Co-Authors: David Touboul, Elodie Trichet, Perry S. Binder, Delphine Praud, Camille Seguy, Joseph ColinAbstract:Purpose To define the contribution of the corneal epithelium in corneal topography in keratoconus and discuss the implications regarding combined topography-guided photorefractive keratectomy and corneal collagen crosslinking (CXL). Setting French National Reference Center for Keratoconus, Bordeaux, France. Design Case series. Methods Specular topographies were performed before and immediately after epithelial removal during conventional CXL surgery in patients with keratoconus. Results The study included 1 eye with forme fruste keratoconus, 4 eyes in Krumeich stage I, and 3 eyes in stage II. The mean simulated maximum keratometry (K) increased by 2.87 diopters (D) after epithelial removal. The mean effective refractive power increased by a mean of 4.01 D and the astigmatic refractive power, by a mean of 2.17 D. The difference in mean axis deviation was not significant. The mean inferior–superior ratio irregularity index increased 1.51 units. All K and refractive readings except astigmatic refractive axis were significantly increased after epithelial removal. All regularity indices increased significantly without the epithelium. The amplitude of variations in K readings made it difficult to predict the refractive changes after custom laser photoablation based on epithelial-based topography. Conclusions The astigmatism refractive axis did not change significantly; therefore, this axis could be useful for astigmatic corrections, whereas the spherical component would not be useful. Topographic changes after epithelial removal can be important but not intuitive in keratoconus eyes. This should be considered in custom topography-guided photoablation strategies when attempting to correct refractive errors at the time of CXL. Financial Disclosure No author has a financial or proprietary interest in any material or method mentioned.