I. Indications

  1. Testing for Strabismus (exotropia or esotropia)

II. Technique: General

  1. Test with both a near object and a far object
  2. Repeat each test 3 times for reproducibility
  3. Choose an interesting object for a child to fixate on (e.g. small toy, penlight)

III. Technique: Cover Test

  1. Child fixates on a point (e.g. small toy, penlight)
  2. Cover one eye
  3. Observe for movement of uncovered eye
    1. Abnormal or positive test suggests manifest strabsimus (tropia)
  4. Cover other eye and repeat test

IV. Technique: Cover-Uncover Test

  1. Child fixates on a point (e.g. small toy, penlight)
  2. Cover one eye for 1-2 seconds
  3. Rapidly uncover the eye
  4. Observe for movement of previously covered eye from a deviated position back to fixation on object
    1. Abnormal or positive test suggests latent Strabismus (phoria)
  5. Cover other eye and repeat test

V. Technique: Alternate Cover Test

  1. Child fixates on a point (e.g. small toy, penlight)
  2. Cover one eye for 1-2 seconds
  3. Rapidly uncover the first eye and cover the second for 1-2 seconds
  4. Rapidly uncover the second eye and cover the first again for 1-2 seconds
  5. Observe for refixation (suggests hidden phoria)

VI. Interpretation (based on movement of uncovered eye)

  1. Normal: uncovered eye maintains current position
  2. Exotropia: Eye moves inward to pick up fixation
  3. Esotropia: Eye moves outward to pick up fixation

VII. False results

  1. Causes of false positive Cover Test
    1. Inattention of child
  2. Causes of false negative Cover Test
    1. Amblyopia of uncovered eye prevents re-fixation

Images: Related links to external sites (from Google)

Ontology: Alternate eye cover test result (C0278242)

Concepts Laboratory or Test Result (T034)
SnomedCT 67150001
English ACT - Alternate cover test, Alternate cover test, Alternate cover test (finding), Alternate eye cover test result
Spanish prueba de oclusión alternada (hallazgo), prueba de oclusión alternada

Ontology: Cover uncover test findings (C0278243)

Concepts Laboratory or Test Result (T034)
SnomedCT 67641002
English Cover-uncover test, Cover-uncover test (finding), Cover uncover test findings
Spanish prueba de cubrir y descubrir (hallazgo), prueba de cubrir y descubrir

Ontology: Cover test findings (C0444883)

Concepts Finding (T033)
SnomedCT 11813006, 264830009
English cover test result, cover test, covered test, Cover test, Eye screen test, CT - Cover test, Cover test (finding), Cover test findings, Cover test findings (finding), Cover test finding (finding), Cover test finding
Spanish prueba de la pantalla ocular, prueba de oclusión (hallazgo), prueba de oclusión, prueba del ojo cubierto - hallazgo (hallazgo), prueba del ojo cubierto - hallazgo