This is an excellent thread. The lists are extremely well organized. Very helpful.
Take a look at SNRS
July 22 FDA
Posted on Yahoo, from an Opthalmic publication
4860 of 4864 Studies show Ho:YAG LTK for hyperopia, presbyopia effective and safe
Phase 3 FDA data says LTK is safe for corrections up to +2.5 D. Presbyopes from û0.25 D to +0.75 D were successfully treated, as well.
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July 15, 1999
SEATTLE ù With the first major wave of studies complete or nearly complete, non-contact holmium laser thermokeratoplasty (LTK) appears safe and effective for both the correction of hyperopia and presbyopia, according to a number of researchers presenting papers at the annual meeting of the American Society of Cataract and Refractive Surgery.
In the treatment of hyperopia, studies conducted in the United States, Germany and Canada concluded that LTK is an effective, safe, predictable and complication-free treatment for hyperopia up to 2.5 D.
As a treatment for presbyopia ù where LTK's market potential is enormous ù results also were very good. German and U.S. investigations both reported predictability, stability and low rates of complication.
Perhaps most importantly, the new wave of study data put to rest lingering concerns regarding regression following LTK. Transient myopic shift was widely reported in the first month, but the procedure stabilizes from that point onward. Alterations to the modern LTK procedure have worked to reduce or eliminate the reversal of its positive visual effects over time.
Non-contact Ho:YAG LTK has been in development for several years. The technique relies on heat generated by the absorption of infrared laser energy to thermally modify stromal collagen and shrinking it without causing tissue necrosis. The contracted pockets, or spots, that result after the corneal curvature, make it more steep. In most LTK cases, two concentric rings of 6 mm and 7 mm, and consisting of eight equally spaced spots, are created on the corneal surface.
Hyperopia
---LTK spots 1 month after surgery.
In a phase 3 U.S. Food and Drug Administration (FDA) study to assess the safety and efficacy of the Sunrise Technologies Inc. (Fremont, Calif.) Sun 1000 Corneal Shaping Ho:YAG laser for LTK treatment of hyperopia, lead investigator Douglas D. Koch, MD, professor of ophthalmology at Baylor College of Medicine in Houston, reported that the procedure met or exceeded FDA targets established for efficacy, safety, stability and predictability.
Dr. Koch reported on 648 patients treated with LTK for hyperopia of between 0.75 D and 2.5 D. Ninety-four percent of patients had at least 6 months of follow-up. Patients enrolled in the study were age 40 or over, had stable, previously diagnosed hyperopia and uncorrected visual acuities of 20/30 or worse.
Patients were divided into two groups: low and moderate. Patients with hyperopia below 1.99 D were placed in the low group, while those with hyperopia between 2 D and 2.5 D were placed in the moderate group.
The treatment procedure consisted of two concentric 6 and 7 mm rings, with eight spots in each. Seven pulses of Ho:YAG energy were delivered to each spot with a repetition rate of 5 Hz. Each ring, therefore, took 1.4 seconds of treatment, with pulse energies varying according to preoperative hyperopia.
Results
ôIn addition to the FDA [effectiveness endpoint] criteria, it was important to look at the actual improvement from baseline refraction in vision, which from the patients' standpoint might actually be more important than meeting some of the specified targets,ö Dr. Koch said. ôWe were looking for a reduction of hyperopia of at least 0.5 D and an improvement of at least two lines or more of uncorrected vision.ö
In terms of stability, FDA guidelines require a change of less than 1 D of manifest spherical equivalent between two refractions, at least 3 months apart in 95% of cases.
ôThe change in manifest spherical equivalent at 12 months in the low hyperopia group was 0.5 to 1.5 D, or 64% of cases, and in excess of that in 28%,ö he said. ôWe got even higher corrections in the moderate group, with 39% of them in the 1.5 to 2.5 D range.ö
Over time, regression was minimal. Between 3 and 6 months, there was about 0.3 D of drift while between 6 and 12 months, the amount increased to about 0.4 D.
ôSo we readily meet FDA criteria,ö he said.
In terms of predictability, the FDA requires 50% to be within 0.5 D and 75% within 1 D of target value at 6 months; 65% of the study patients were within one-half diopter at 6 months, while 88% were within 1 D, 13% above the FDA target.
Efficacy also exceeded FDA guidelines. Regulators require that 85% of patients have uncorrected vision of 20/40 or better at 6 months. Dr. Koch reported 86% had achieved this level. Seventy-five percent of patients were 20/30 or better uncorrected, while 57% were 20/25 or better and 38% were 20/20 or better. Ninety percent of moderate hyperopes and 78% of low hyperopes improved by greater than two lines. Improvement of more than four lines of uncorrected vision occurred in 65% of moderate hyperopes.
Spectacle dependence decreased dramatically. Prior to surgery, 79% of low hyperopes and 90% of moderate hyperopes needed eyeglasses most of the time, while only 13% did postoperatively.
Patient satisfaction, however, also depends on managing expectations.
ôIt is important to educate patients and understand their expectations both preoperatively and postoperatively,ö he said.
It's safe
Safety, according to Dr. Koch, was excellent.
ôThe safety profile of this laser is extraordinary,ö he said. Any reported loss in excess of two lines of visual acuity in the study was due to cataract and not related to any aspect of the treatment. No steroids or corticosteroids were used in these patients.
ôOverall, we are excited by this,ö he said. ôWe think these data are very promising.ö
Sunrise will present these data to the FDA this summer, with possible approval for the Sunrise laser sometime late this year.
German and Canadian studies confirm Dr. Koch's FDA evaluation. In a 3-year, 123 patient study of LTK, Till Anschutz, MD, in private practice in Gaggenau, Germany, found that the procedure is effective in hyperopia of 2.5 D or less. After 3 years, he identified no relevant visual complications and good stability and no significant regression.
Guillermo Rocha, MD, in private practice in Brandon, Canada, participated in joint Canadian-Mexican study for patients with hyperopia ranging from 0.75 D to 2.50 D and less than 0.75 D of astigmatism. He studied 38 eyes of 28 patients, with a minimum 6-month follow-up. Fifty-two percent of his patients were within 0.5 D of their intended correction, while 89% were within 1 D. Ninety-four percent of patients had uncorrected visual acuity for distance of 20/40 or better. Transient myopic shift with astigmatism was reported in the first month. It later stabilized. Near uncorrected visual acuity was 20/20 in 100% of patients. There were no visually significant complications.
Presbyopia
A low-cost and dependable treatment for presbyopia is the Holy Grail of refractive surgery. New studies of LTK suggest it may be one answer. By inducing a small amount of myopia in presbyopes and creating monovision, they can function most of the time without eyeglasses.
ôThis is one of the areas of LTK that we are most excited about,ö said Alan B. Aker, MD, in private practice in Boca Raton, Fla., who presented study results on behalf of Peter J. McDonnell, MD.
Fifty-three patients were enrolled in the five-site study. All patients were over age 40, and all had a stable pretreatment refraction within the range of û0.25 D to +0.75 D. Patients enrolled needed uncorrected near visual acuity of 20/50 or worse.
Treatment is similar to that used on hyperopes. Two eight-spot concentric circles of 6 and 7 mm are created.
ôWe varied the pulse energy according to what we were trying to achieve, and prior to treatment we did a contact lens trial to find out if the patient could tolerate monovision,ö Dr. Aker explained.
89% within 1 D
Dr. Aker said 44% of study patients were within 0.5 D of their intended correction 3 months post-operatively. Eighty nine percent were within 1 D of their target at 3 months. Following surgery, 81% of patients had near visions of 20/40 or better uncorrected.
ôThere's a shift in spherical equivalent toward myopia and a marked improvement in near visual acuity with no complications or adverse reactions in the study,ö Dr. Aker said. ôLTK seems very safe and effective for the treatment of presbyopia.ö
In a 3-year retrospective study of LTK for presbyopia, Dr. Anschutz also concluded it was safe and effective.
ôA binocular presbyopic correction with LTK is an encouraging procedure with an improvement in near uncorrected visual acuity,ö he reported. ôTransient myopic induction, however, must be accepted.ö
For Your Information:
Alan B. Aker, MD, can be reached at 1445 N.W. Boca Raton Blvd., Boca Raton, FL 33432; (561) 338-7722; fax: (561) 338-7785. Dr. Aker is a Sunrise Technologies Inc. investor. He is not a paid consultant for any companies mentioned in this article.
Till Anschutz, MD, can be reached at Konrad-Adenauerstr. 3, Gaggenau 76571, Germany; (49) 7225-96460; fax: (49) 7225-964696. Dr. Anschutz has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.
Douglas D. Koch, MD, can be reached at 6565 Fannin NC 205, Houston, TX 77030-2703; (713) 798-6443; fax: (713) 798-3027. Dr. Koch has no direct financial interest in any of the products mentioned in this article. He is a paid consultant for Sunrise Technologies Inc.
Guillermo Rocha, MD, can be reached at Unit 2, 335 18th St., Brandon, MB R7A 5A8 Canada; (204) 727-1954; fax: (204) 725-1206. Dr. Rocha has no direct financial interest in any of the products mentioned in this article. He is a paid consultant for Sunrise Technologies Inc.
For information on the Sun 1000 Corneal Shaping System, contact Sunrise Technologies Inc., 47265 Fremont Blvd., Fremont, CA 94538; (510) 623-9001; fax: (510) 623-9008
Large short position that needs to cover before FDA meets.
Fred |
