title: Topographic predicted corneal acuity with intrastromal corneal ring segments.
abstract: OBJECTIVE
  To evaluate predicted optical quality of the central anterior corneal surface before and after the intrastromal corneal ring segment (ICRS) refractive procedure using a clinical videokeratoscope and software index developed for that purpose.
  
  
  METHODS
  Predicted corneal acuity, a topographically derived index provided with the EyeSys System 2000 videokeratscope, representing potential optical quality of the cornea, was assessed preoperatively and at postoperative month 3 in 94 eyes that received an ICRS to treat -1.00 to -6.00 D of myopia. Predicted corneal acuity was calculated by determining the difference between a measured cornea and its best-fit ellipses for reflected ring circumferences within the central 3 mm diameter zone.
  
  
  RESULTS
  Preoperative predicted corneal acuity was 20/10 in 92 of 94 eyes (98%). At month 3 after the ICRS procedure, 48 (51%) of moderately myopic eyes were corrected to 20/20 or better, 96% (90 eyes) were corrected to 20/40 or better, and 98% of eyes (92 eyes) had a predicted corneal acuity of 20/10. For the eyes with a predicted corneal acuity of 20/10, spectacle-corrected visual acuity was normally distributed between 20/10 and 20/25.
  
  
  CONCLUSIONS
  Predicted corneal acuity did not change significantly from baseline in eyes with an ICRS. This suggests that topographic irregularities in the central 3 mm of the cornea detectable by predicted corneal acuity software were not induced in the central cornea with the ICRS.
authors.affiliation: Northwest Corneal Services and the Corneal Topography Reading Center, Portland, OR 97223, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Holmes-Higgin
authors.forename: T E
authors.initials: TE
authors.lastname: Burris
authors.forename: P A
authors.initials: PA
authors.lastname: Asbell
authors.forename: D S
authors.initials: DS
authors.lastname: Durrie
authors.forename: D J
authors.initials: DJ
authors.lastname: Schanzlin
mesh_terms: D003319:Corneal Stroma / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D005500:Follow-Up Studies; D006801:Humans; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D014792:Visual Acuity