title: Change in convergence and accommodation after two weeks of eye exercises in typical young adults.
abstract: BACKGROUND
  Although eye exercises appear to help heterophoria, convergence insufficiency, and intermittent strabismus, results can be confounded by placebo, practice, and encouragement effects. This study assessed objective changes in vergence and accommodation responses in naive young adults after a 2-week period of eye exercises under controlled conditions to determine the extent to which treatment effects occur over other factors.
  
  
  METHODS
  Asymptomatic young adults were randomly assigned to one of two no-treatment (control) groups or to one of six eye exercise groups: accommodation, vergence, both, convergence in excess of accommodation, accommodation in excess of convergence, and placebo. Subjects were tested and retested under identical conditions, except for the second control group, who were additionally encouraged. Objective accommodation and vergence were assessed to a range of targets moving in depth containing combinations of blur, disparity, and proximity/looming cues.
  
  
  RESULTS
  A total of 156 subjects were included. Response gain improved more for less naturalistic targets where more improvement was possible. Convergence exercises improved vergence for near across all targets (P = 0.035). Mean accommodation changed similarly but nonsignificantly. No other treatment group differed significantly from the nonencouraged control group, whereas encouraging effort produced significantly increased vergence (P = 0.004) and accommodation (P = 0.005) gains in the second control group.
  
  
  CONCLUSIONS
  True treatment effects were small, significantly better only after vergence exercises to a nonaccommodative target, and rarely related to the response they were designed to improve. Exercising accommodation without convergence made no difference to accommodation to cues containing detail. Additional effort improved objective responses the most.
authors.affiliation: Infant Vision Laboratory, School of Psychology & Clinical Language Sciences, University of Reading, United Kingdom; Orthoptic Department, Royal Berkshire Hospital, Reading, United Kingdom. Electronic address: a.m.horwood@reading.ac.uk.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Horwood
authors.affiliation: Infant Vision Laboratory, School of Psychology & Clinical Language Sciences, University of Reading, United Kingdom.
authors.forename: Sonia S
authors.initials: SS
authors.lastname: Toor
authors.affiliation: Infant Vision Laboratory, School of Psychology & Clinical Language Sciences, University of Reading, United Kingdom.
authors.forename: Patricia M
authors.initials: PM
authors.lastname: Riddell
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D003290:Convergence, Ocular / Q000502:physiology*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009799:Ocular Physiological Phenomena; D009988:Orthoptics / Q000379:methods*; D013285:Strabismus / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D011795:Surveys and Questionnaires; D013997:Time Factors; D055815:Young Adult