title: Excimer laser photorefractive keratectomy for the correction of hyperopia using an erodible mask and axicon system.
abstract: OBJECTIVE
  The purpose of the study is to evaluate photorefractive keratectomy for the correction of hyperopia using the erodible mask and Axicon system.
  
  
  METHODS
  Forty-three patients (43 eyes) with a mean refraction (spherical equivalent) of +4.54 diopter (D) (range, +1.75 to +7.50 D) were treated using a Summit Technology "Apex Plus" excimer laser. This system uses an erodible mask to create a 6.50-mm diameter hyperopic correction over the axial cornea. An Axicon then is used to fashion a 1.50-mm "blend zone" around the correction. On the basis of preoperative refractions, patients were assigned to 3 groups: 2 groups of 14 patients underwent either "+2.00 D" or "+3.00 D" corrections and 15 patients had "+4.00 D" corrections.
  
  
  RESULTS
  All patients had a reduction in their hyperopia with an overcorrection, especially in the first month after surgery and some stability in the refractive change at 3 to 6 months. The mean manifest refraction (n = 43) at 6 months was -0.17 D (range, +4.50 D to -3.125 D). Patient satisfaction was high. At 6 months, all eyes had an improvement in unaided near visual acuity. Unaided distance acuity was improved in 37 eyes (86%). A ring of haze 6.5 mm in diameter appeared in all eyes 1 month after surgery. Night halo measurements at 6 months showed no differences from preoperative levels. Flicker contrast sensitivity and forward light scatter (glare) measurements showed no differences after surgery.
  
  
  CONCLUSIONS
  In this short-term study, photorefractive keratectomy for hyperopia using the erodible mask and Axicon system appeared to be a promising procedure. Visual performance, in terms of flicker contrast sensitivity, forward light scatter, and night halos, was not compromised. There was an overcorrection based on the manufacturer's algorithms. Manipulation of the treatment algorithms should improve future predictability.
authors.affiliation: Department of Ophthalmology, United Medical and Dental Schools, St. Thomas' Hospital, London, England, United Kingdom.
authors.forename: D P
authors.initials: DP
authors.lastname: O'Brart
authors.forename: C G
authors.initials: CG
authors.lastname: Stephenson
authors.forename: K
authors.initials: K
authors.lastname: Oliver
authors.forename: J
authors.initials: J
authors.lastname: Marshall
mesh_terms: D000328:Adult; D000368:Aged; D015350:Contrast Sensitivity / Q000502:physiology; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D019466:Glare; D006801:Humans; D006956:Hyperopia / Q000503:physiopathology / Q000601:surgery*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000295:instrumentation*; D011183:Postoperative Complications; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D014945:Wound Healing / Q000502:physiology