title: For how long can regression continue after photorefractive keratectomy for myopia?
abstract: OBJECTIVE
  The presence and degree of regression were assessed from 18 to 30 months after photorefractive keratectomy (PRK).
  
  
  METHODS
  A total of 449 eyes (449 patients) were treated with an Aesculap Meditec 193-nm Arf Excimer laser. These 449 eyes were followed during the first 24 months after PRK, and 252 of these eyes were followed for 24 to 30 months.
  
  
  RESULTS
  Thirty (6.7%) of the 449 eyes followed for up to 24 months showed good refractive results during the first year and a half but regressed thereafter and required retreatment. Late regression was confined to subjects with pretreatment myopia above -4.0 diopters (D) and was the same in low- and high-myopic eyes between 18 and 24 months post-PRK. However, between 24 and 30 months, regression was higher in low-myopic eyes, where it reached -0.55 D, than in high-myopic eyes, where it was -0.21 D. This lower frequency of regression in high-myopic eyes is attributed to the relatively high rate of retreatment in this group during the first 18 months after PRK.
  
  
  CONCLUSIONS
  Although the findings indicate a fairly low rate of regression after 24 months, there still are insufficient data on which to predict when regression post-PRK stabilizes.
authors.affiliation: Assaf Harofeh Medical Center, Zerifin, Israel.
authors.forename: D
authors.initials: D
authors.lastname: Haviv
authors.forename: L
authors.initials: L
authors.lastname: Hefetz
authors.forename: D
authors.initials: D
authors.lastname: Krakowsky
authors.forename: S
authors.initials: S
authors.lastname: Abrahami
authors.forename: U
authors.initials: U
authors.lastname: Kibarski
authors.forename: P
authors.initials: P
authors.lastname: Nemet
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000503:physiopathology* / Q000601:surgery; D018903:Photorefractive Keratectomy; D012029:Refraction, Ocular / Q000502:physiology; D014785:Vision, Ocular / Q000502:physiology