title: Efficacy of diagnostic monocular occlusion in revealing the maximum angle of exodeviation.
abstract: OBJECTIVE
  To determine the efficacy of diagnostic monocular occlusion in revealing the maximum angle of exodeviation compared with repeated measurements taken during three or more consecutive examinations in the outpatient clinic.
  
  
  METHODS
  We retrospectively analysed 185 patients with intermittent exotropia in an institutional referral centre. The angle of exodeviation was measured at distance and near fixation on three or more consecutive examinations in the outpatient clinic. Then 1 day of diagnostic monocular occlusion was performed and the angle of exodeviation was measured.
  
  
  RESULTS
  After diagnostic monocular occlusion, the mean angle of deviation at distance (23.5 prism dioptres (PD)) and near fixation (23.5 PD) was significantly smaller compared with the average maximum angle of deviation before occlusion at distance (27.0 PD) and near fixation (25.2) (p=0.001, 0.022). However, 26 patients (14.1%) showed an increase of ≥5 PD in their distant angle after occlusion and 57 patients (30.8%) showed an increase of ≥5 PD in their near angle of deviation. After occlusion, 39.1% (9/23) of divergence excess (DE)-type, 20.0% (3/15) of convergence insufficiency (CI)-type and 2.7% (4/147) of basic-type exotropia were converted to other types. Patients with hyperopia were more likely to show a significant increase of ≥5 PD during near fixation.
  
  
  CONCLUSIONS
  Diagnostic monocular occlusion could be useful in patients with DE-type or CI-type exotropia and with hyperopia. In other cases, however, it has a limited role in determining the maximum angle of exodeviation compared with multiple examinations.
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jeong Mo
authors.initials: JM
authors.lastname: Han
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Yang
authors.affiliation: Department of Ophthalmology, Seoul National University College of Medicine, Seoul, Korea Department of Ophthalmology, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Jeong-Min
authors.initials: JM
authors.lastname: Hwang
mesh_terms: D002648:Child; D005099:Exotropia / Q000145:classification / Q000175:diagnosis* / Q000601:surgery; D005260:Female; D006801:Humans; D008297:Male; D009801:Oculomotor Muscles / Q000601:surgery; D013508:Ophthalmologic Surgical Procedures; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D012683:Sensory Deprivation; D015349:Vision, Monocular; D014792:Visual Acuity
keywords: Muscles