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Refractive effect from Hyperion LTK system may last 10 years or more
The change in manifest refraction over 15 years is 0.95 D.
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NEW YORK — The refractive effect of the Hyperion LTK system from Sunrise Technologies for treatment of mild-to-moderate hyperopia can last 10 years or more, according to a new longevity analysis.
“The reduction in hyperopia after non-contact laser thermal keratoplasty (LTK) is long-lasting for 16 and 32 spots,” said Sandra C. Belmont, MD, a clinical investigator for Sunrise Technologies International Inc. (Fremont, Calif.).
The holmium laser applies energy to the periphery of the cornea, which causes a steepening of the center of the cornea. Energy heats the stroma in the periphery by placing eight spots around the cornea simultaneously at an optical zone of 6 mm. In a radial pattern, another set of eight spots is then applied simultaneously at 7 mm.
Last June, the Hyperion LTK system was approved for the temporary reduction of hyperopia in patients with +0.75 D to +2.5 D of manifest refraction spherical equivalent (with less than or equal to ±5 D of astigmatism).
“Patients must also be at least 40 years old and have documented stability of refraction for the prior 6 months, as demonstrated by a change of less than or equal to 0.5 D in spherical and cylindrical components of the manifest refraction,” said Dr. Belmont, director of the Laser Vision Correction Center and Corneal Service at New York Weill Cornell Medical Center of New York Presbyterian Hospital.
Patient results
To date, Dr. Belmont has treated about 200 patients with the Hyperion LTK system. “Patients are very happy with their results. For the first 3 to 4 weeks, they are overcorrected at about –1 D. Then there is a drift back to plano for distance vision,” she said. Most of these patients achieve 20/30 or better undercorrected at 3 months, and are stabilized for distance.
Patients can also be treated for monovision. “One eye can be treated for distance and the other eye overcorrected, so that the patient can read. Since approval, I would say 60% of my patients are monovision,” Dr. Belmont said. For patients contemplating monovision, she insists on a contact lens trial.
The magnitude of correction with this novel treatment can diminish over time. “Age-related drift toward hyperopia contributes to the loss of effect after the initial 2 years,” said Dr. Belmont, who presented a paper on longevity of non-contact LTK at the European Society of Cataract and Refractive Surgeons winter meeting in Cannes, France. “Sunrise Technologies has established new algorithms to show that this procedure has an effect that should last out to 10 years and beyond,” she said.
Longevity analysis
For the new longevity analysis, a least square model was used to graph the change in MRSE versus the logarithm of time in months to determine the best fit. Actual clinical data provided an excellent straight line fit, Dr. Belmont said. The LTK effect was found to be long-lasting: 15.5 years (16 spots) and 270 years (32 spots) for most patients, when using no less than 238 mJ. After the initial 2 years and continuing over the next 13.5 years, “the overall effect lost is 0.95 D, of which almost half can be attributed to normal hyperopic drift in patients over 40 years old,” Dr. Belmont said. Using 32 spots, all loss in effect is attributable to normal hyperopic drift.
Some of the patients involved in the original trial have now been followed for about 4 years. “These patients are stable. Of the initial 100 patients I treated, only one has been retreated.” As these patients lose accommodation during the natural aging process, “the chances of needing re-treatment in their 50s is a real potential,” Dr. Belmont said.
Multiple benefits
“For the first time, there is a procedure that has been specifically designed for the over 40-year-old hyperopic/presbyopic patient. Within 2.8 seconds, using a virtually painless technique, you can gently reshape the cornea for the correction of hyperopia, without touching the cornea or making an incision,” Dr. Belmont said. Potential adverse events such as corneal flap complications, glare and infection with LASIK are also avoided.
“I don’t foresee any long-term risks of LTK for hyperopia,” said Dr. Belmont, who by conducting endothelial cell counts has seen no change in the endothelium. “If I did, this would be a concern. Patients have to understand they will be myopic for a period of about a month until they stabilize.”
“These patients are really the most underserved and handicapped of the refractive population because they lose the ability to focus at any distance — near, intermediate or far,” Dr. Belmont said. “I’m very excited about this technology and truly believe it will eventually become the treatment of choice for low-to-moderate hyperopia.”
For Your Information:
- Sandra C. Belmont , MD, can be reached at 525 E. 68th St., Starr Pavilion-849, New York, NY 10021; (212) 746-2020; fax: (212) 746-3002; e-mail: lvcc@med.cornell.edu.
- Sunrise Technologies can be reached at 3400 W. Warren Ave., Fremont, CA 94538; (510) 771-2389; fax: (510) 771-2292; Web site: www.sunrise.md.