Expression of HLA-G in human cornea, an immune-privileged tissue.

Human leukocyte antigen (HLA)-G retains the capacity to modulate immune responses, favoring the establishment of tolerance in solid-tissue allotransplants. To better understand the mechanisms that promote corneal allograft survival, we investigated whether HLA-G was an immunoregulatory factor involved in corneal immunology. We therefore sought HLA-G expression in corneal tissues. Corneal transplantation consists in replacing the center of a diseased cornea with normal corneal tissue. Two corneal parts are not used in such surgery: diseased central corneal tissue and peripheral normal cornea. For this study, we used healthy corneas obtained from deceased donors and diseased corneas obtained from patients with pseudophakic bullous keratopathy or keratoconus who had undergone corneal transplantation. Immunohistochemical analysis carried out on the cryopreserved corneas showed a positive immunohistochemical staining with anti-HLA-G, anti-HLA-A, -B, and -C, and anti-HLA class I monoclonal antibodies. Staining was obtained for keratocytes, epithelial cells, and endothelial cells from both healthy and pathologic human corneas, revealing the presence of HLA class I proteins, including HLA-G. HLA-G transcripts were detected in normal cornea by reverse transcriptase-polymerase chain reaction with a classical pattern of alternative splicing. The detection of HLA-G protein in adult corneas leads to the conclusion that this protein may contribute to the maintenance of the privileged immune status of cornea

Léiomyomes utérins embolisés (aspects IRM, corrélations anatomopathologiques, proposition pour une classification radio-histologique, intégration en réseau Bayésien)

TOURS-BU Médecine (372612103) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Phacoémulsification par microincision 1.8 mm : étude de l astigmatisme et de l asphéricité cornéenne

REIMS-BU Santé (514542104) / SudocSudocFranceF

Kératoplasties transfixiantes en z assistées par laser femtoseconde (étude anatomo-clinique)

Avec près de 3000 interventions pratiquées chaque année en France, la kératoplastie transfixiante est une procédure qui bénéficie d un siècle d évolution. Depuis 2006, le chirurgien a la possibilité de pratiquer les trépanations à l aide du laser femtoseconde. Ce laser à impulsions ultracourtes permet des incisions cornéennes complexes, grâce au principe de photodisruption. L objectif de ce travail est de réaliser une étude anatomo-clinique sur une série de kératoplasties transfixiantes en Z assistées par laser femtoseconde. Cette étude rétrospective a concerné 15 patients opérés entre 2007 et 2009 à l Hôtel-Dieu de Paris. Un an après la chirurgie, l acuité visuelle moyenne a été mesurée à 0.45 logMar et l astigmatisme à 3.8D. L ablation du sujet a été réalisée à 6 mois dans 80% des cas. L étude histologique a mis en évidence une incision homogène, avec peu de lésions liées aux effets secondaires du laser. Les résultats fonctionnels de cette série ont été équivalents à ceux obtenus après trépanation mécanique. Les résultats histologiques corroborent ceux de la littérature, qui montrent que la découpe est de bonne qualité avec peu de dégâts tissulaires. La kératoplastie transfixiante assistée par laser femtoseconde représente une avancée chirurgicale mais n a pas démontré pour l instant sa supériorité par rapport au trépan mécanique. L absence d amélioration évidente et les contraintes exigées par la technique expliquent sa diffusion encore limitée. Des évolutions devront donc être réalisées, sur l autofocalisation et sur la longueur d onde des lasers, avant de s imposer comme technique de référenceWith around 3000 procedures carried out every year in france, penetrating keratoplasty has benefited from technical developments for one century. Since 2006, surgeon has the opportunity to practice trephinations with femtosecond laser. This ultra-short impulsions laser allows complex corneal incisions, thanks to the photodisruption principle. This work objective was to realise an anatomo-clinical study based on a series of pentrating keratoplasties zig-zag incision performed with femtosecond laser. This retrospective study has included 15 patients operated from 2007 to 2009 at Hôtel-Dieu hospital in paris. One year after surgery, the average visual acuity measured was 0.45 logMar and the astigmatism was 3.8D. Suture removing has been realised after 6 months in 80% of cases. The histological study showed an homogenic incision, with few lesions linked with secondary effects of the laser. Functional results of this series have been similar to those obtained after mechanical trephination. Histological results corroborated litterature ones, which showed that the cutting was highly qualitative and with rare tissue damages. Penetrating keratoplasty assisted by femtosecond laser represents a surgical advanced but has not proved at this time a real superiority compared to the mechanical trephine. The absence of any obvious improvement and the constraints required by this technique explained its limited spreading. Technical developments would have to be realised in the future, on the laser autofocalisation and wave-length, before being able to asert itself as a refering techniqueST QUENTIN EN YVELINES-BU (782972101) / SudocSudocFranceF

Self-focusing and spherical aberrations in corneal tissue during photodisruption by femtosecond laser

International audienceThe use of ultrashort pulse lasers is current in refractive surgery and has recently been extended to corneal grafting (keratoplasty). When performing keratoplasty, however, permanent degradation of the optical properties of the patient's cornea compromises the penetration depth of the laser and the quality of the incisions, therefore causing unwanted secondary effects. Additionally, corneal grafting needs considerably higher penetration depths than refractive surgery. Little data are available about the interaction processes of the femtosecond pulses in the volume of pathological corneas—i.e., in the presence of spherical aberrations and optical scattering. We investigate the influence of the focusing numerical aperture on the laser–tissue interaction. We point out that at low numerical apertures (NAs), tissue damage is produced below and above the focal region. We attribute this phenomenon to nonlinear self-focusing effects. On the other hand, at high NAs, spherical aberrations become significant when focusing at high depths for posterior surgeries, which also limit the cutting efficiency. As high NAs are advisable for reducing unwanted nonlinear effects and ensure accurate cutting, particular attention should be paid to aberration management when developing clinical femtosecond lasers

Keratoprosthesis With Biocolonizable Microporous Fluorocarbon Haptic: Preliminary Results in a 24-Patient Study

BACKGROUND: Most complications of a keratoprosthesis occur at the tissue-to-implant interface. The ideal prosthesis would eliminate this interface by having the tissue actually grow into the supporting material. We present a prospective clinical human study of a novel biocolonizable keratoprosthesis in 24 eyes of 24 patients. DESIGN: To promote implant stability, the 9-mm—diameter haptic was fashioned using a custom-made microporous fluorocarbon with a 4-mm—diameter, 2.67-mm—long, central optic made of medical grade polymethylmethacrylate, giving a global visual field of 110° to 130°. Only bilaterally blind patients with untreatable corneal diseases were included in the study. The haptic was inserted into a lamellar pocket delaminated in the stroma, and the optic was positioned through a hole trephined in the central cornea. RESULTS: The average follow-up was 15.7 months (range, 4 to 28 months). The host corneal fibroblasts penetrated and proliferated into the peripheral microporous fluorocarbon and provided anchorage between the cornea and prosthesis. Seventeen patients (70.8%) had visual acuity improvements. Mean corrected final visual acuity was 20/100 (range, 20/30 to 20/400). Five anatomic failures occurred in the first 6 months (three extrusions, one dislocation of the optic, and one endophthalmitis). We had one case (4.1%) of treatable glaucoma. We successfully removed four of five retroprosthetic membranes that had occurred. No retinal detachment occurred. CONCLUSION: The biocompatible inert microporous polymer did not eliminate all mechanical complications associated with a keratoprosthesis

In situ multiphoton microscopy for monitoring femtosecond laser eye surgery

International audiencePurpose: The authors present a multiphoton microscope set–up mounted on a microsurgery experimental system using a Nd:glass femtosecond laser. The system allows for non–linear optical imaging before, during, and after the surgical intervention. Methods: The femtosecond laser is a CPA system with a regenerative amplifier delivering pulses at a wavelength of 1.06 µm, pulse durations of typically 400 fs and a maximum energy of 60 µJ. The repetition rate is adjustable from single shot up to 10 kHz. The delivery system provides spot sizes down to the micron range and peak power densities well above 1015W/cm2. The human corneas are mounted on an anterior chamber system, which is installed on a computer controlled step motor positioning system. Photons generated by non–linear processes in the cornea travel backwards through the front part of the beam delivery optics and are captured by a photomultiplier tube behind a dichroic mirror. The signal is filtered by a lock–in amplifier tuned to the laser repetition rate and recorded by a personal computer. Scanning the sample permits the acquisition of 2D or 3D images. Results: When working above the ablation threshold, the set–up permits to induce laser cuts following complex geometries in human cornea. Penetrating and lamellar cuts could be performed. Below the ablation threshold the femtosecond laser pulses create secondary photons by the stimulation of non–linear processes in the samples. The interaction process could be identified as being predominantly second harmonic generation (SHG) and, to a lesser extent, two–photon fluorescence. The images obtained from the multi–photon module permitted to monitor, control and optimise the surgical intervention in situ without the need to move the sample or to match results from different characterisation methods. Conclusions: The combination of multiphoton imaging and corneal surgery necessitates only minimal modifications of the optical system of a femtosecond surgical laser system which do not compromise its performance. It is demonstrated that a combined system significantly improves parameter control and the monitoring of the surgical intervention