Conductive keratoplasty for the correction of low to moderate hyperopia: U.S. Clinical trial 1-year results on 355 eyes☆
Presented in part at the Annual Meeting of the American Academy of Ophthalmology, New Orleans, Louisiana, November, 2001.
Received 11 November 2001; accepted 11 April 2002.
Abstract
Objective
To document the 1-year safety, efficacy, and stability results of 355 eyes treated in the multicenter study of conductive keratoplasty (CK) used to correct low to moderate hyperopia.
Twenty surgeons at 13 centers performed CK on the eyes of all patients enrolled in a multicenter, 2-year, U.S. phase III clinical trial. Treated eyes had +0.75 to +3.00 diopters (D) of hyperopia and ≤0.75 D of cylinder. Patients were 40 years of age or older.
Intervention
Low-energy, high-frequency current was applied directly into the peripheral corneal stroma through a delivery tip inserted at 8 to 32 treatment spots. The number of treatment spots was increased for increasing levels of hyperopia, but the amount of radiofrequency energy remained constant. Emmetropia was intended. All eyes were treated once (there were no retreatments).
Main outcome measures
Data from 355 eyes with 1 year of follow-up were analyzed for safety and stability, and data from 318 eyes were analyzed for efficacy and predictability, as well as stability and safety. All patients reported on satisfaction and quality of vision after surgery.
Results
At 1 year, uncorrected visual acuity was ≤20/20 in 56%, ≤20/25 in 75%, and ≤20/40 in 92% of eyes. The manifest refractive spherical equivalent refraction was within 0.50 D in 63%, within ±1.00 D in 89%, and within ±2.00 D in 99%. Seven of 355 eyes lost 2 lines of best spectacle-corrected visual acuity at 1 year, but no eye lost >2 lines. One eye of 355 had induced cylinder of >2.00 D. The cycloplegic refractive spherical equivalent changed a mean of 0.25 ± 0.50 D between months 3 and 6, 0.11 ± 0.41 D between months 6 and 9, and 0.11 ± 0.35 D between months 9 and 12. Refractive stability seemed to be attained by 6 months and remained stable through 12 months. Histology and confocal microscopy showed deep penetration of the treatment into the stroma. Endothelial cell counts were not changed by the treatment.
Conclusions
CK seems to be safe, effective, and stable for correcting low to moderate spherical hyperopia in patients 40 years old or older. Treatment penetration is deep and cylindrical in shape, and it does not damage the corneal endothelium. Uncorrected visual acuity, predictability, and stability are as good as or better than those obtained with other techniques used to correct hyperopia.
1Southern Vision Institute, New Orleans, Louisiana, USA
2Cornea and Laser Vision Center, Teaneck, New Jersey, USA
3Stanford University School of Medicine, Palo Alto, California, USA
4Maloney Vision Institute, Los Angeles, California, USA
Reprint requests to Marguerite McDonald, MD, Southern Vision Institute, 2820 Napoleon Avenue, New Orleans, LA 70115, USA.
☆ The members of the Conductive Keratoplasty United States Investigators Group are listed in the appendix.
Drs. Hersh, Manche, Maloney, and Davidorf and the Conductive Keratoplasty Investigators Group participated as clinical investigators in this Food and Drug Administration phase III study sponsored by Refractec, Inc. (Irvine, CA). These authors participate on Refractec’s Medical Advisory Board and are paid for their time. They otherwise have no proprietary or financial interest in the ViewPoint conductive keratoplasty system from Refractec, Inc. Dr. Moataz Sabry was not an investigator but provided the confocal microscopy photographs. Dr. Marguerite McDonald is a paid medical monitor for the phase III study on conductive keratoplasty by Refractec, Inc.
The nature of the procedure was explained to all participating patients, and they all signed informed consent forms before undergoing the procedure.
ABSTRACT