Cover uncover test may be performed following the steps given below:
- Introduction and permission (ask if patient uses glasses)
- Sit at the level of the patient
- Check gross visual acuity (finger counting monocularly)
- Observer for:
a. Abnormal head posture (head rotation, chin lift/depression, head tilt)
b. Ptosis (3rd nerve)
c. Lid retraction (thyroid eye disease)
d. Proptosis (thyroid eye disease)
- Give a distant target (6/60 line of Snellen’s) and perform the following steps:
a. First cover fixating eye in manifest squint.
b. Remove cover and see if the same eye takes up fixation or fixation goes to the other eye (constant/alternating).
c. If alternating, then repeat for the other eye as well.
d. Cover right eye and see if left eye moves
e. Uncover right eye and see for phorias
f. Cover left eye and see if right eye moves
g. Uncover left eyes to confirm phorias.
- Do alternate cover test.
- Give near target and repeat above mentioned steps.
- Give far distant target and repeat the above mentioned steps
- Perform extraocular movements
- Krimsky test (prism in front of normal eye)
- Prism reflection test (prism in front of the deviating eye)
- Prism cover test (prism in front of the deviating eye and perform alternate cover test)
Note: If the patient wears glasses, above mentioned steps will be repeated both for far and near with glasses.