title: Studies of intrastromal corneal ring segments for the correction of low to moderate myopic refractive errors.
abstract: OBJECTIVE
  Intrastromal corneal ring segments (ICRS) were investigated for safety and reliability in the correction of low to moderate myopic refractive errors.
  
  
  METHODS
  Initially, 74 patients with spherical equivalent refractive errors between -1.00 and -4.25 diopters (D) received the ICRS in 1 eye. After 6 months, 51 of these patients received the ICRS in the contralateral eye. The total number of eyes investigated was 125. The outcome measures were uncorrected and best-corrected visual acuity, predictability and stability of the refraction, refractive astigmatism, contrast sensitivity, and endothelial cell morphology.
  
  
  RESULTS
  The 89 eyes with 12-month follow-up showed significant improvement with uncorrected visual acuities of 20/16 or better in 37%, 20/20 or better in 62%, and 20/40 or better in 97%. Cycloplegic refraction spherical equivalents showed that 68% of the eyes were within +/- 0.50 D and 90% within +/- 1.00 D of the intended correction. Refractive stability was present by 3 months after the surgery. Only 1 patients had a loss greater than 2 lines or 10 letters of best spectacle-corrected visual acuity, but the patient's acuity was 20/20. Refractive cylinder, contrast sensitivity, and endothelial cell morphology were not adversely affected. The ICRS was removed from the eyes of 6 patients. Three removals were prompted by glare and double images occurring at night; 3 were for nonmedical reasons. All patients returned to within +/- 1.00 D of their preoperative refractive spherical equivalent, and no patients lost more than 1 line of best corrected visual acuity by 3 months after ICRS removal.
  
  
  CONCLUSIONS
  The ICRS safely and reliably corrects myopic refractive errors between -1.00 and -4.50 D.
authors.affiliation: Shiley Eye Center, University of California, San Diego, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Schanzlin
mesh_terms: D000328:Adult; D002452:Cell Count; D003315:Cornea / Q000166:cytology / Q000601:surgery*; D004728:Endothelium, Corneal / Q000473:pathology; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011446:Prospective Studies; D019736:Prostheses and Implants; D019919:Prosthesis Implantation; D012029:Refraction, Ocular; D012449:Safety; D016896:Treatment Outcome; D014792:Visual Acuity