title: Anterior segment changes produced in response to long-term overnight orthokeratology.
abstract: OBJECTIVE
  To evaluate the effect of overnight orthokeratology (OK) on anterior chamber depth (ACD), posterior radius of corneal curvature (PRCC) and axial length (AL) over one year.
  
  
  METHODS
  In this prospective longitudinal study, measurements were made in 34 right eyes of 34 subjects at baseline, 15 days, 1 and 12 months after starting OK treatment. ACD and PRCC measurements were obtained using a Pentacam system and AL was measured using an IOL-Master. ACD and PRCC were measured along the horizontal and vertical meridians at 1 mm intervals. These measurements were expressed as the distance from the center in the nasal (N), temporal (T), superior (S) and inferior (I) directions.
  
  
  RESULTS
  A significant reduction in ACD was observed in both meridians during treatment. PRCC flattened significantly in the (T) direction after 15 d (1 mm, p < 0.05), at the corneal center after 15 d (p < 0.01), in the (T) direction after 1 month (1 mm, p < 0.05), in the (S) direction after 12 months (1 mm p < 0.05), in the (N) direction after 12 months (1 mm p < 0.05), in the (N) and (T) directions after 12 months (3 mm, p < 0.05) and in the (T) direction after 12 months (4 mm p < 0.05), at the corneal center after 12 months (p < 0.01). AL was significantly reduced during treatment (p < 0.05).
  
  
  CONCLUSIONS
  A long period of OK reduces ACD and AL and changes PRCC.
authors: Department of Optics II, University School of Optics, Madrid, Spain. ana.gmesa@gmail.com
authors: Ana
authors: A
authors: González-Mesa
authors: César
authors: C
authors: Villa-Collar
authors: Amalia
authors: A
authors: Lorente-Velázquez
authors: Amelia
authors: A
authors: Nieto-Bona
mesh_terms: D000328:Adult; D000867:Anterior Chamber; D058452:Axial Length, Eye; D003261:Contact Lenses; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009216:Myopia / Q000628:therapy*; D054158:Orthokeratologic Procedures / Q000379:methods*; D010781:Photography / Q000379:methods / Q000592:standards; D011446:Prospective Studies; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult