Clinical Application of Laser Welding in Cornea Transplant

Welding of biological tissues induced by laser radiation can integrate or substitute traditional suturing procedures employed in various surgical fields, with remarkable advantages, such as simplification of the surgical technique, reduction of the surgery time, and faster healing process of the wound, without the typical foreign-body reaction caused the presence of the suture wire.
Regarding development and application of laser welding techniques in ophthalmic surgery studies were started in 1996 by a research group leaded by Roberto Pini, physicist of the Institute of Applied Physics (IFAC-CNR) and by Luca Menabuoni, ophthalmic surgeon. Aim of these researches was to investigate the application of laser welding of corneal tissue to replace traditional suturing in cornea transplant (penetrating keratoplasty) and in cataract surgery. After a pre-clinical experimental phase, necessary to achieve the approval from the Italian Ministry of Health, this technique was successfully applied for the first time in humans in June 2000.
Welding of the cornea is produced by photothermal activation of the collagen (the main constituent of the cornea), which takes place by irradiating the wound to be sutured with low power laser light, such as the one emitted by a diode laser.
The surgical laser device, designed and constructed by IFAC-CNR, is a diode laser emitting in the near infrared at 805 nm, and is equipped with a sterilizable fiberoptic delivery system, including at the end a small hand piece to be used under the surgical microscope. An exogenous chromophore (i.e. a bio-compatible dye) is associated with laser irradiation. Such a dye is topically applied in the wound to absorb laser light, and to produce a selective and localized welding effect.
Clinical results, obtained up to now on about 40 patients, indicated that the laser procedure is safe, with no side effects, and, more important, the healing process is faster and more effective with respect to the one provided by conventional suturing.
These researches have been carried out in 2003 within the frame of a project entitled "OPTOMED-Innovative technologies in Ophthalmology" supported by the Regional Board of Tuscany and by the DG Regio of the European Union. OPTOMED was aimed at development and industrial transfer of new procedures and instruments for ophthalmic surgery, such as the diode laser and the laser welding technique we set up to assist corneal transplant. The partnership was composed of eight enterprises involved in laser technology, ophthalmic instruments and pharmaceutical products, of four public research centers (including IFAC-CNR), and of four Ophthalmic Clinics of Universities and public hospitals of Tuscany.

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