title: Stereopsis in refractive surgery.
abstract: OBJECTIVE
  To examine stereopsis in myopic refractive surgery patients undergoing sequential bilateral and unilateral treatment.
  
  
  METHODS
  Prospective, observational, cohort study.
  
  
  METHODS
  
  
  
  METHODS
  Clinical practice.
  
  
  METHODS
  Eighty-three patients were studied; 55 had sequential bilateral and 28 had unilateral treatment. Mean age was 32 years. Stereopsis was measured using a multitarget red-green anaglyph stereo vision test. Only patients with fine preoperative stereopsis were included in the study. Repeat measurements were taken one week laser-assisted in situ keratomileusis (LASIK) or three weeks laser epithelial keratomileusis (LASEK) after treatment of one eye in all patients. Further measurements were taken at six and 12 weeks in unilaterally treated patients and after treatment of the fellow eye in bilaterally treated patients.
  
  
  RESULTS
  A total of 38.6% of patients retained fine stereopsis (28 to 41 seconds of arc) over a range of anisometropia from 0.625 to 4.375. Moderate stereopsis (66 to 526 seconds of arc) was recorded 28.9% in the presence of 1.375 to 5.525 diopters of anisometropia. Poor/absent stereopsis (< or =2000 seconds of arc) was found in 32.5% in the presence of 2.1 to 8.0 diopters of anisometropia. A strong correlation was found between stereopsis and anisometropia, but interpatient variability was found. Uncorrected visual acuity (UCVA) in the untreated eye of > or =20/200 was associated with retention of fine stereopsis. Unilaterally treated patients showed improvement in stereopsis at six weeks after surgery. Sequential bilateral treatment had no deleterious effect on stereopsis.
  
  
  CONCLUSIONS
  Loss of stereopsis was strongly correlated with anisometropia. UCVA in the untreated eye was a good indicator of postoperative stereopsis. Stereopsis improved during the postoperative adaptation period in unilateral treatments. Bilateral sequential treatment has no long-term effect on stereopsis.
authors.affiliation: Mater Private Hospital, Eccles Street, and University College Dublin, Dublin, Ireland.
authors.forename: Caitriona
authors.initials: C
authors.lastname: Kirwan
authors.forename: Michael
authors.initials: M
authors.lastname: O'keefe
mesh_terms: D000328:Adult; D015858:Anisometropia / Q000503:physiopathology; D003315:Cornea / Q000503:physiopathology / Q000601:surgery; D003867:Depth Perception / Q000502:physiology*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology* / Q000601:surgery*; D010468:Perceptual Disorders / Q000503:physiopathology; D011446:Prospective Studies; D014787:Vision Tests; D014792:Visual Acuity