Beginning in 1949 with the pioneering work of Jose Barraquer, there has been an interest in using natural corneal tissue to change the refractive properties of the eye. In recent years, non-allogenic, synthetic corneal implants have received marketing approval in the United Stated and Europe for refractive purposes. Although synthetic implants are made of biocompatible materials, they are not equivalent to an allogenic implant in terms of biocompatibility.
The Allotex TransForm lenticule is a piece of acellular cornea, sterilized with electron beam radiation and shaped to a particular shape using a laser. The availability of precise laser shaping systems and sterile corneas are the key factors that make the use of allogenic implants possible.
The TransForm lenticule is applied under a femtosecond created corneal flap on a stromal bed. The goal is to enhance the visual performance of the patient with a material that is 100% biocompatible and precisely shaped for the
The Allotex TransForm lenticule is biocompatible, highly precise, and shelf stable at room temperature. It is formed lenticule comprised of sterile allogenic corneal tissue designed to alter the shape of the anterior surface of the cornea, thereby adjusting the point of focus on the retina. The tissue derives from human corneas, procured under strict ethical standards from an Eye Bank Association of America (EBAA) approved eye bank. After minimal processing by the eye bank the corneas undergo a validated electron beam (e-beam) sterilization process and are then transferred to Allotex for further processing.
The Allotex processing consists of slicing the cornea into sheets of various thickness, along the lamellar plane, using a micro-cryotome. These sheets are then further cut into discs using an appropriately sized biopsy punch, producing corneal blanks of a nominal thickness of 50 um and a 3.5 mm diameter. These corneal blanks are then placed in an environmentally controlled chamber to under excimer laser (wavelength 193 nm) shaping to produce the desired shape. All steps involving shape formation and changes of shape are monitored by high resolution optical coherence tomography (OCT) to insure that the lenticules are accurately produced. The formed lenticules then undergo an additional e-beam sterilization.
The lenticules are designed to be placed directly on top the recipient’s stroma which has been exposed by the creation of a thin, femtosecond laser created flap. After placement the flap is the laid down over the TransForm lenticule and smoothed in the normal fashion. The final shape, after laser sculpting, is 2-3.5 mm in diameter, with a central thickness of 15-25 microns. The diameter is such that the patient is expected to have improved near and intermediate vision and will also retain distance vision from the rays entering the pupil around the periphery of the TransForm lenticule .
Lions VisionGift, the provider of the Allotex allogenic tissue, procures, cleans and sterilizes cornea for shipment to Allotex. Terminal sterilization is performed by electron beam.
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