All:
Regarding Mark's excellent question re: patents, I am posting
from SNRS home page. Please note first sentence which refer's
to the patent rights........Regards, Skane
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A White Paper on Laser Thermal Keratoplasty (LTK)
Sunrise Technologies holds fundamental method and apparatus patents for a corneal reshaping technology called Laser Thermal Keratoplasty, (LTK). This technique is non-invasive, since corneal tissue is not cut or removed, and is particularly effective for farsighted persons who require low to moderate correction (1-3 diopters)-i.e., low hyperopes who were able to see perfectly both at a distance and at close range all of their lives until the onset of presbyopia (inability of the eye to focus on nearby objects due to advancing age), which exacerbates their farsighted condition. It is also very effective for surgically-induced hyperopia, especially for overcorrected post-PRK patients for whom LTK represents an essential safety net.
The technique works by heating specific corneal tissue through infrared laser beams produced by a solid-state holmium laser. Corneal tissue comprises water, collagen, and other biomolecules. When gently heated, collagen molecules are modified in structure and biomechanical properties, which results in a change to the shape of the cornea and to its refractive power. This is the principle used by Laser Thermal Keratoplasty (LTK) to correct certain refractive errors.
Refractive errors are present in most of the world's population as myopia (nearsightedness - which affects about 20% of the population), hyperopia (farsightedness - which affects about 55% of the population), and astigmatism (uneven focus). Myopia is typically detected in young patients and requires immediate correction. Low to moderate hyperopia can be present in young patients but typically does not require immediate use of glasses, as young patients automatically correct this refractive error using their own lens accommodation. However, as the lens accommodative power diminishes with age, these patients start experiencing reading problems. Historically, vision correction has generally consisted only of prescribing the use of glasses or contact lenses.
The correction of refractive errors using surgical techniques began to be publicized during the 1980s and was available mainly for the correction of myopic defects. It is estimated that over 300,000 patients per year are undergoing RK (radial keratotomy), a surgical procedure in which tiny incisions are made in the cornea. Since this procedure can be performed by a trained surgeon using only a knife, no prior approval was required from the FDA. Although this procedure has achieved clinical success in the correction of low to moderate myopia, it involves certain surgical risks and can have negative side effects, which range from fluctuation of vision during the day to starbursts at night, etc. RK is not suitable for treating hyperopia.
In the late 1980s, clinical studies were begun for a surgical laser procedure to correct myopia by vaporizing corneal tissue, as opposed to the incisional technique used with RK. This procedure, PRK (PhotoRefractive Keratectomy), utilizes an excimer laser to ablate (remove) central corneal tissue to flatten corneal curvature. Since PRK requires a medical laser device, FDA approval is required prior to this procedure becoming commercially available in the United States. In late 1995, the FDA announced its approval of the Summit excimer laser system for PRK, and in 1996 VISX announced approval. Other systems are pending FDA. PRK is used primarily for the treatment of myopia; this is the only approved indication at present. Although PRK is now considered safe and effective, it possesses its own risk factors, side effects, and complications. At present, it is not clear which form of refractive surgery will prevail for the correction of low to moderate myopia. A new form of combined surgery is on the horizon (LASIK) and may ultimately replace the PRK procedure.
Sunrise believes that its original LTK methodology represents the best option presently available for correcting mild hyperopia and possibly future indication of presbyopia, having successfully treated over 4,000 eyes internationally. Sunrise started its U.S. clinical trials under an Investigational Device Exemption (IDE) in late 1992, and moved to its expanded Phase IIa trial in July of 1996. If the historical FDA approval process used for the excimer laser (PRK) is required, plans to begin Phase III studies in 1997. In this case, Sunrise does not expect FDA approval before 2000, since Phase III requires at least a two-year follow-up on between 300-500 patients. Based on 1-2 year follow-up studies performed on an initial base of more than 100 patients, Sunrise believes that its LTK technique can provide stable refractive correction with acceptable levels of regression over an extended period.
Sunrise believes that refractive correction procedures will become commonplace in the next 10 years and that millions of patients per year will be treated on a worldwide basis, notwithstanding the relatively high cost (currently up to $2,000 per eye at present) and the absence of public or private insurance reimbursement. Unless and until a corrective procedure for hyperopia receives FDA approval, only myopia will be treated, leaving Sunrise's targeted patient base intact. In addition, PRK studies show that a certain percentage of myopic patients treated with the excimer laser are overcorrected (becoming hyperopic and therefore experiencing a new and more serious set of vision problems). These overcorrected post-PRK patients are ideal candidates for Sunrise LTK treatment, which is proving itself as the only remedy available today for this form of surgically-induced hyperopia.
The Sunrise LTK system is presently being marketed in over 15 countries, with more than 45 systems delivered to date outside the United States. In September 1996, Sunrise received clearance to apply the CE mark to the LTK system. Sunrise currently to increasing its international marketing focus in Canada, Mexico, and the Caribbean, where low to moderate hyperopia/presbyopia as well as overcorrected post-PRK U. S. residents can correct their condition while the LTK procedure is not available in the U.S. Sunrise believes that as PRK becomes commercially available and accepted in the United States, international acceptance of LTK as well as PRK will accelerate, and that a significant international market for LTK will develop well before FDA approval.
The Sunrise LTK system presently sells for less than half of the cost of an excimer laser system for PRK and is also significantly less expensive to operate. Sunrise expects that its systems will be purchased by the growing number of vision correction centers being established in the United States and most developed countries. The Sunrise system is a perfect complement in the armamentarium of the modern refractive surgery center.
Sunrise holds basic method and apparatus patents for the thermal modification of corneal collagen to achieve refractive correction. Sunrise intends to vigorously protect and exploit its patent position.
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