title: Conductive keratoplasty for the correction of low to moderate hyperopia: U.S. clinical trial 1-year results on 355 eyes.
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.
  
  
  METHODS
  Nonrandomized comparative (self-controlled) trial.
  
  
  METHODS
  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 < or =0.75 D of cylinder. Patients were 40 years of age or older.
  
  
  METHODS
  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).
  
  
  METHODS
  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 < or =20/20 in 56%, < or =20/25 in 75%, and < or =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.
authors.affiliation: Southern Vision Institute, New Orleans, Louisiana 70115, USA. marguerite.mcdmc@aol.com
authors.forename: Marguerite B
authors.initials: MB
authors.lastname: McDonald
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hersh
authors.forename: Edward E
authors.initials: EE
authors.lastname: Manche
authors.forename: Robert K
authors.initials: RK
authors.lastname: Maloney
authors.forename: Jonathan
authors.initials: J
authors.lastname: Davidorf
authors.forename: Moataz
authors.initials: M
authors.lastname: Sabry
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D002452:Cell Count; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D004564:Electrocoagulation / Q000379:methods*; D005260:Female; D006801:Humans; D006956:Hyperopia / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D011183:Postoperative Complications; D011446:Prospective Studies; D012449:Safety; D013552:Swine; D016896:Treatment Outcome; D014481:United States; D014792:Visual Acuity