The Onlay procedure is intended to be easy to perform, taking no more than 15 minutes. It will be less invasive than LASIK as it involves adding to the cornea rather than tissue removal.
A survey of key vision practitioners globally indicated that a reversible, additive, refractive procedure such as corneal onlay, represents the future of permanent surgical correction of refractive errors. The Onlay is intended to correct most refractive conditions (including presbyopia, hyperopia, myopia and astigmatism) by placing a small thin biocompatible lens just under the epithelial layer on the front surface of the cornea, akin to an “implanted contact lens”, without the inconvenience associated with conventional contact lenses such as cleaning or sterilizing the lenses; dry eye or foreign body sensations. The entire procedure is intended to be minimally invasive with no corneal stromal or ocular incisions and minimal (epithelial only) wound healing response.
The outcome should be more predictable than LASIK and does not need expensive equipment such as a laser. Unlike LASIK it removes no corneal tissue and is intended to be completely reversible with no permanent functional or structural damage. Thus, in some countries it may be able to be performed by optometrists as well as ophthalmologists. A survey of key vision practitioners and opinion leaders globally indicated that reversible refractive procedures such as Corneal Onlay represent the future for permanent surgical correction of refractive errors.
The scientific basis for the material was established over the many years of research by understanding and testing the material properties and characteristics necessary to keep the cornea healthy and developing a specific material that would meet these criteria. These studies focused on the optimization, reproducibility, transparency and biocompatibility and biological model testing of a series of highly porous materials made from proprietary polymers and surface treatments enabling epithelial overgrowth.
The final prototype implantable lenses were also tested in phase 1 clinical trials, with three patients showing exceptional biological compatibility with the lenticule implanted in the body (stroma) of the cornea for over 4 years. Tests of biocompatibility, transparency and clinical tolerance are continuing. High quality, precise lenticules especially designed for optimum vision are now being manufactured for clinical trials.
The Onlay lenticule is designed for placement immediately under the superficial layer of corneal tissue (the epithelium), using a simple surgical procedure that involves either (a) removal of the epithelium and placement of the lenticule on the surface of the body of the cornea using a suitable adhesive – three types of which have been developed, or (b) inserting the lenticule into a small pocket created between the epithelium and the body of the cornea (stroma). In either scenario the epithelium is intended to grow over the Onlay, adhere firmly and support a normal tear film.
Various aspects of the technology are already well developed, including the materials and their biocompatibility in the human cornea; the ability of the treated lenticule surface to support an epithelial layer and innovative optical models for predicting optical and visual outcomes. The polymer materials used in the Onlay lenticule (and adhesives and coatings) are the subject of patents and patents pending.
The transparent, microporous synthetic polymer in our Corneal Onlay lenticule has also been thoroughly tested for cytotoxicity, extractables and biocompatibility. Lenticules have been shown to support full thickness epithelial overgrowth and attachment in an edge-pocket model. In order to prove the actual Corneal Onlay concept, a collagen-coated Onlay was secured with an ocular adhesive on a cat’s eye. The Onlay remained in place and supported the growth and adhesion of corneal epithelial tissue on the anterior surface of the lens and a fully formed tear film. The histological examination conducted after 92 days (see Figure below) showed a normal epithelium with five to six cell layers over the lens.
