title: Binocular function changes produced in response to overnight orthokeratology.
abstract: OBJECTIVE
  To analyze the binocular function changes produced on subjects undergoing overnight orthokeratology (OK) treatment over short-term (3 months) and long-term (3 years) wear.
  
  
  METHODS
  A prospective, longitudinal study on young adult subjects with low to moderate myopia was carried out. Binocular function was assessed by the following sequence of tests: Distance and near horizontal phoria (Von Graefe technique), distance and near horizontal vergence ranges (Risley rotary prisms), accommodative convergence/accommodation (AC/A) ratio (gradient method) and the near point of convergence (standard push-up technique). The short-term sample consisted of: 21 subjects in the control group, 26 in a corneal refractive therapy (CRT) treatment lenses group and 25 in a Seefree treatment lenses group. Those subjects were evaluated at baseline and at a 3-month follow-up visit. Twenty one subjects were old CRT wearers that attended a 3-year follow-up visit (long-term group).
  
  
  RESULTS
  A statistically significant difference over the 3-month treatment was found for divergence at distance: the break point decreased 1.4 Δ (p = 0.0006) in the CRT group and the recovery point increased 1.2 Δ (p = 0.001) in the Seefree group. Also, the Seefree group had an exophoric trend of 2.3 Δ at near (p = 0.02) and a base-out break decrease of 2.3 Δ (p = 0.03). For the long-term group, only the base-out break point at distant vision showed a statistically significant difference of 4.9 Δ (p = 0.02).
  
  
  CONCLUSIONS
  OK induces minimal changes in the binocular function for either short-term or long-term periods, apart from a near exophoric trend over the short-term period.
authors.affiliation: Department of Optics II (Optometry & Vision) Faculty of Optics & Optometry, Complutense University of Madrid, Arcos de Jalon 118, 28037, Madrid, Spain. gemafelipe@gmail.com.
authors.forename: Gema
authors.initials: G
authors.lastname: Felipe-Marquez
authors.affiliation: Department of Optics II (Optometry & Vision) Faculty of Optics & Optometry, Complutense University of Madrid, Arcos de Jalon 118, 28037, Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Nombela-Palomo
authors.affiliation: Applied Vision Research Group, Department of Optics II (Optometry & Vision) Faculty of Optics & Optometry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Catalina
authors.initials: C
authors.lastname: Palomo-Álvarez
authors.affiliation: Instituto Balear de Oftalmología, Balearic Islands, Palma, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Cacho
authors.affiliation: Contactology and Optometry Research Group (GICO), Department of Optics II (Optometry & Vision) Faculty of Optics & Optometry, Complutense University of Madrid, Madrid, Spain.
authors.forename: Amelia
authors.initials: A
authors.lastname: Nieto-Bona
mesh_terms: D000328:Adult; D005099:Exotropia / Q000503:physiopathology / Q000534:rehabilitation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000534:rehabilitation*; D054158:Orthokeratologic Procedures / Q000379:methods*; D011446:Prospective Studies; D013997:Time Factors; D015348:Vision, Binocular / Q000502:physiology*; D055815:Young Adult
keywords: Binocular function; Contact lenses; Fusional vergences; Myopia; Orthokeratology; Phoria