What is AlphaCor?
The cornea is the clear window at the front of the eye. Damage to the cornea caused by injury or disease can seriously impair vision, making it necessary to replace the cornea to restore sight. Traditionally, this has been achieved by transplanting human tissue.
The artificial cornea is designed to replace a diseased or damaged cornea or failed human graft. Its dimensions, flexibility, hydrophilicity and optics allow it to be implanted, and to perform, in a similar manner to a donor corneal graft. As the AlphaCor is manufactured from a polymer and donor tissue is not required in routine cases, the need for systemic immunosuppressant drugs following implantation has also been minimized.
AlphaCor is manufactured in a single piece from a specialized polymer (type of plastic) called poly (2-hydroxyethylmethacrylate) or PHEMA. The device has a clear central optic that is surrounded by an opaque sponge-like perimeter. This spongy 'skirt' allows the patient's cells to grow into it, effectively anchoring the artificial cornea in place.
What makes AlphaCor different from other 'artificial corneas' or keratoprostheses (KPros)?
Our clinical results are significantly better than any alternative keratoprosthesis which has been developed. Most traditional keratoprostheses are rigid or complex devices and their implantation may require procedures destructive of other parts of the eye, such as the iris, and/or implantation of additional devices, such as drainage tubes to reduce eye pressure, frequently raised by such KPros. Surgery of this type is often quite destructive to the eye and the surgery is non-reversible. The AlphaCor device, in contrast, lies within the plane of the original cornea without affecting other parts of the eye and can be replaced with human donor tissue or a new AlphaCor in the event of a complication. A donor graft performed after an AlphaCor is removed may fail but it will restore the patient to the pre-AlphaCor status in most cases place the patient in the same position as prior to the AlphaCor.
AlphaCor is indicated where human donor tissue is not a viable option -i.e. the ophthalmologist would expect a donor graft to fail, judged by a number of factors that might include previous failed grafts and presence of blood vessels in the diseased cornea. Additionally, the lack of need for systemic steroids or immunosuppressives may make a doctor prefer AlphaCor over a donor graft in cases where the patient is not fit enough to receive the medications, often associated with complications and the eye meets the required criteria. These factors are prior corneal graft failure, two or more quadrants of vascularization, a history of bullous keratopathy and unsuitability for systemic medications such as steroids. The AlphaCor is not a solution for all cases of corneal blindness as many types of corneal disease do well with donor grafts, and it is not suitable for patients with severely dry, disordered or inflamed eyes, or those with a history of ocular herpes simplex infections. Additionally, patients who are heavy smokers may be unsuited unless they can stop smoking as this may cause staining of a device after implantation and reduce vision...
Will AlphaCor restore vision in the blind?
AlphaCor holds the potential to substantially to increase the independence and quality of life of many patients affected by corneal blindness. Results show that full visual potential can be restored. While some patients have achieved 20/20 visual acuity after AlphaCor, acuity outcomes are affected by patient-related factors and refractive correction, i.e. use of glasses or contact lenses. In the clinical studies, the average best-corrected post-operative gain in visual acuity is 2 lines of vision on the standard Snellen Eye Chart.
20/20 vision has been the "standard" for good vision for over one hundred years and generally means that one can see at 20 feet what a "normal" person is expected to see at 20 feet. 20/20 is a measurement of the vision in ONE eye against a given standard. The metric equivalent would be 6/6, that is, one seeing at six meters what a normal person is expected to see at six meters.
"Many patients in the clinical trials experienced a visual improvement that enabled them to be re-classified from legally blind to functionally sighted, with some benefiting from substantial improvements. Although many of the patients chosen for the study had poor visual potential due to other diseases in the eye, most patients saw an improvement in vision and no patient lost structural integrity to their affected eye" said Associate Professor Dr. Crawford, Chief Clinical Investigator during AlphaCor trials.
How well will the patient be able to see after the operations?
Although AlphaCor is made to act as a clear lens with around the same focusing power as a natural cornea, it is difficult to predict how good vision will be in an individual patient.
Just after the first operation, when the cornea is covered by other tissues to assist healing, little vision is possible. When this tissue is opened three months later to reveal the artificial cornea, vision is restored to some extent.
This should allow most patients sensation of light, dark, movement and color. The things they see may not be in focus (just as a normal corneal graft can give disappointing vision).
After surgery, vision might be able to be improved by spectacles or other means.
If a patient has good vision in the other eye, it is unlikely that an eye with the AlphaCor would be better than their other eye, but might give useful additional sight. However, if the other eye is of little use, the AlphaCor eye may well become the one you depend upon for vision.
Most of the patients who have received an AlphaCor to date have had outcomes varying from a little improvement in vision to regaining the ability to read. A small percentage of patients have experienced worsening in their sight due to complications. It is important to remember that the visual potential of an eye depends upon the health of all parts of the eye. If a patient also had glaucoma or retinal problems, for example, their vision might still be limited even if the artificial cornea itself worked perfectly.
What does AlphaCor surgery involve?
The surgery itself is similar to the implantation of a donor cornea, where part of the cornea is removed and the AlphaCor is put in its place.
The technique differs from a normal corneal graft because the rim of the AlphaCor is held within the host tissue and is inserted into place through a small cut at the top of the eye, which is stitched at the end of the operation.
The operation is usually completed by formation of a flap of tissue from the conjunctiva (the outer layer of the 'white' of the eye) that is used to cover the surface of the front of the eye. This means that the eye does not look normal after the operation, but the conjunctival flap is important because it allows the AlphaCor to heal into place under the protection of this natural bandage.
Approximately three months after the initial surgery, a second, smaller operation is performed. At this stage, tissue covering the AlphaCor at the front of the eye is removed to allow light to enter the eye. The eye then looks more normal, although still different from a normal eye. The colored part of the eye (the iris) is not fully exposed because part of the remaining cornea covers it and tends to look blue-gray in color. The white part of the AlphaCor also makes the colored part of the eye seem smaller. The white part of the eye may also seem to have larger blood vessels than the other eye.
Is AlphaCor approved by the FDA?
AlphaCor was approved for sale by the Food and Drug Administration in the United States in late 2002, complementing regulatory approvals in Europe, Canada and Australia. It is currently being marketed for use worldwide by accredited ophthalmic surgeons.
How is the surgery performed?
The surgical technique used to implant the AlphaCor has evolved with the development of the device and is designed to avoid minimize the risk of the complications usually associated with artificial corneas. In the two-stage procedure, the artificial cornea is first inserted into a specially created pocket in the patient's cornea, covered, usually, with a healing membrane from the patient's conjunctiva and allowed to rest for up to 3 months. Stage 2 then involves the removal of a small section of the patient's cornea in front of the optic to make vision possible.
How long has the idea of an artificial cornea been around?
The concept of an artificial cornea has been around for centuries. Attempts have included various materials including crystals, glass and Perspex. None of these were very compatible with human tissue. Recent attempts have seen devices made from more modern materials, but these are generally two-piece, rigid devices. The cosmetic outcome of these devices is not good and they have been associated with high complication rates in most published clinical studies, including infection and glaucoma.
Would patients have this procedure instead of having a corneal transplant?
Human corneal transplantation is a very successful procedure, but there are some groups of patients where the long term graft survival is very poor. As a result there is little point in attempting transplantation in these patients in whom the natural cornea may be so scarred and vascularised that the chance of graft rejection is very high. In some cases, use of an artificial cornea is the only realistic hope of regaining corneal clarity.
How many patients have received AlphaCor?
As of July 31, 2003 there have been 72 devices implanted worldwide in Australia, Austria, Indonesia, Italy, Norway, Singapore and the United States. Thirteen patients have received an AlphaCor implant in the U.S.
Is AlphaCor covered by insurance and what is the cost?
Department of Health and Human Services Center for Medicare and Medicaid has granted AlphaCor Artificial Cornea Transitional Pass-through status as a new technology and may be reimbursed by Medicare effective July 1, 2003. The coding for this reimbursement is C1818: Integrated Keratoprosthesis. This pass-through code is limited to hospital outpatient services provided to Medicare beneficiaries.
Pass-through codes are not used by private payers at this time, although some insurance carriers may cover the procedure based on the individual patient's medical status.
Is Argus Biomedical affiliated with Lions Eye Institute?
Argus Biomedical Pty Ltd. is a private company based in Perth, Western Australia, which acquired the exclusive rights from the Lions Eye Institute of Western Australia to commercialize the AlphaCor, artificial cornea, , developed by the Biomaterials and Polymer Research Group at the institute.
Researchers have been working at the LEI for over 10 years to develop a device that can address the shortfall in demand for human corneal tissue and treat those conditions not suitable for human grafts. The development of the AlphaCor has been driven by these needs.
How many people will benefit from AlphaCor?
Globally, there are approximately 10 million people with corneal blindness and only 100,000 corneal transplants performed per annum. North America, Europe and Australia/New Zealand account for 62% of all corneal transplants. However, in developing countries, such as India, only 15,000 human transplants are performed per annum, while the estimated demand there is over 200,000 transplants per annum. Human corneal transplants are the most commonly performed and successful type of organ transplant. Success rates are greater than 90% for some diagnoses such as keratoconus. Studies suggest that approximately 20% of corneal transplants are rejected; however, failure rates vary significantly depending on the cause of the disease and increase over the time of follow-up.
Who is on the management team at Argus Biomedical?
Leadership at Argus Biomedical is provided by:
- James McCollum, CEO - 20 years experience in ophthalmology related business, including senior management positions with CooperVision, VISX and other device companies.
- Ben Constable, General Manager, Perth - 7 years experience in ophthalmic business development and new ventures; prior corporate and legal background.
- Celia Hicks, M.D., PhD. FRCOphth, Medical Director - an Ophthalmologist and research scientist with an extensive publication record related to ophthalmic biomaterials and clinical trials, responsible for AlphaCor's development through clinical evaluation.
- Calvin London, PhD., Chief Operating Officer - Former manager of Delta West (Pharmacia) facility in Perth and former Global Vice President of Quality Assurance for Schein and INO Therapeutics in the US.
- David Toner, Production Manager - Systems engineer with more than 10 years experience in production and quality assurance with Mitsubishi and Baush & Lomb Europe.