title: Overnight orthokeratology experience with XO material.
abstract: OBJECTIVE
  To evaluate long-term safety and effectiveness of overnight orthokeratology in a large sample of myopes by using three different lens designs and the highly gas-permeable Boston XO material (Bausch & Lomb, Rochester, NY).
  
  
  METHODS
  A total of three hundred forty-two subjects, 99 of whom were juveniles, were enrolled in the investigation at 26 clinical centers in the United States and Canada. Three different lens designs in Boston XO material were used. Subjects were limited to a measured visual need for correction of myopia less than or equal to 4.00 diopters and astigmatism less than or equal to 1.50 diopters with best-corrected Snellen visual acuity of 20/40 or better. Refractive error and unaided visual acuity were used to determine the effectiveness of the procedure at short-term (1 month) and long-term (12 months). The safety of the procedure was determined by the symptoms reported, and slitlamp findings suggested physiologic rejection of the procedure.
  
  
  RESULTS
  One hundred thirty-three adults and 68 juveniles completed the 12-month study. More than 60% of the subjects reached 20/20 vision or better at the end of 1 month of overnight lens wear, and this number remained stable during the next 11 months. A reduction in myopia of 70% and of more than 90% was measured at the 1- and 12-month visits, respectively. Safety data indicate a decrease in symptoms and in general a decrease in positive slitlamp findings with time.
  
  
  CONCLUSIONS
  The procedure with all three lenses in Boston XO material is effective. However, the safe use of orthokeratology lenses is predicated on the emphasis of clear patient direction on how to wear and take care of the lenses followed by regular examinations by an eye care practitioner.
authors.affiliation: Borish Center for Opthalmic Research, School of Optometry, Indiana University, Bloomington, IN 47405, USA. sonip@indiana.edu
authors.forename: P Sarita
authors.initials: PS
authors.lastname: Soni
authors.forename: Tracy T
authors.initials: TT
authors.lastname: Nguyen
mesh_terms: D000293:Adolescent; D000328:Adult; D003261:Contact Lenses; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000628:therapy*; D011446:Prospective Studies; D011474:Prosthesis Design; D012029:Refraction, Ocular; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity