II. Indications
- Testing for Strabismus (Exotropia or Esotropia)
III. Technique: General
- Test with both a near object and a far object
- Repeat each test 3 times for reproducibility
- Choose an interesting object for a child to fixate on (e.g. small toy, penlight)
IV. Technique: Cover Test
- Child fixates on a point (e.g. small toy, penlight)
- Cover one eye
- Observe for movement of uncovered eye
- Abnormal or positive test suggests manifest strabsimus (tropia)
- Cover other eye and repeat test
V. Technique: Cover-Uncover Test
- Child fixates on a point (e.g. small toy, penlight)
- Cover one eye for 1-2 seconds
- Rapidly uncover the eye
- Observe for movement of previously covered eye from a deviated position back to fixation on object
- Abnormal or positive test suggests latent Strabismus (phoria)
- Cover other eye and repeat test
VI. Technique: Alternate Cover Test
- Child fixates on a point (e.g. small toy, penlight)
- Cover one eye for 1-2 seconds
- Rapidly uncover the first eye and cover the second for 1-2 seconds
- Rapidly uncover the second eye and cover the first again for 1-2 seconds
- Observe for refixation (suggests hidden phoria)
VII. Interpretation (based on movement of uncovered eye)
VIII. Interpretation: False Results
- Causes of False Positive Cover Test
- Inattention of child
- Causes of False Negative Cover Test
- Amblyopia of uncovered eye prevents re-fixation
IX. References
- Berson (1987) Ophthalmology Study Guide, AAO, p. 104
- Essman (1992) Am Fam Physician 46(4):1243-52 [PubMed]
- Mills (1999) Am Fam Physician 60(3):907-16 [PubMed]
- Simon (2001) Am Fam Physician 64(4):623-8 [PubMed]
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Related Studies
| 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 |
