Answer: All of the above ocular alignment tests are helpful in assessing this patient with ocular misalignment.
What is the Hirschberg test?
Hirschberg test involves using a penlight to assess the corneal light reflex and its alignment with the center of the pupillary axis. In a patient with a normal Hirschberg test, the reflection of the penlight should be located in the exact same position in each pupil.
Hirschberg test on our patient is shown below:
Reflection of the penlight is located temporally to the center of right pupil and in the center of left pupil. This indicates the right eye is turned inward, while the left eye is properly aligned.
What is the Cover-uncover test?
The Cover-uncover test is used to determine if there is a heterotropia, or eye deviation that is present “all of the time.” In this test, an occluder is used to cover the patient’s eye for a few seconds. The uncovered eye is then observed for any changes in fixation. The same procedure is done for the other eye, making certain to approach the fellow eye temporally rather than crossing over the nose to occlude it.
Cover-uncover test: When the right eye is covered, the left eye does not move and maintains fixation. When the left eye is covered, the right eye shifts outward to pick up fixation, but when the cover is removed, the right eye once again turns inward.
What is the Alternate-cover test?
The alternate-cover test is used to determine if there is a heterophoria or latent eye deviation. In this test, an occluder is rapidly switched back and forth between the eyes. The uncovered eye is observed for any changes in fixation. The angle of deviation can be measured using a prism (measured in diopters).
When the occluder is alternated between right and left eye, the uncovered eye deviates 15 prism diopter (PD) in the outwards direction.
What is cycloplegic refraction?
Cycloplegic refraction is a procedure that allows the examiner to assess refractive error. This is typically performed in children as these patients tend to over-accommodate, which can lead to inaccuracies when doing manifest refraction using the phoropter. To overcome this, cycloplegic eye drops can be used to paralyze the ciliary muscle. This results in temporary loss of accommodation.
Cycloplegic refraction on our patient reveals the following: Hyperopia OU (+3.00). No astigmatism.
Click below for a demonstration of some of the above tests:
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