Alignment Assessment (Hirschberg)
Title: Alignment Assessment (Hirschberg)
Author: Katherine Hu, 4th Year Medical Student, Saint Louis University
The Hirschberg test (also known as the corneal light reflex test) is a quick and simple way to check ocular alignment. This assessment is particularly useful for testing for strabismus (misalignment of the eyes) in newborns, young children, patients with poor vision, patients that are not able to fixate or track well – or in any situation where a full motility evaluation is not feasible.
To perform the assessment:
- Use a light source, such as a penlight or finhoff transilluminator.
- Instruct the patient to focus their gaze on your light source.
- From a distance of 2 feet, shine your light source equally into the patient’s eyes at midline.
- Observe the reflection of light off the cornea, which should appear as a pin-point white light near the center of the pupil in each eye.
If there is normal alignment, the reflection will appear in the same position in each pupil. If there is misalignment of the eyes, the location of the corneal reflex will appear asymmetric and “off center” of the pupil in the deviating eye. The relative difference in the position of the reflex will be in the opposite direction as the eye deviation. For example, in an esotropia (where there is inward deviation of the eye), the light reflex will appear outwardly displaced from the center of the pupil; in a hypertropia (where there is an upward deviation of the eye) the light reflex will appear inferiorly displaced from the center of the pupil.
For every 1 millimeter of deviation from the center of the pupil, it will take approximately 15 diopters of prism to correct the misalignment.
This can be visually estimated with the Hirschberg test, or physically measured with the Krimsky test, where a prism is placed in front of the deviating eye until the corneal reflex is re-centered in the pupil.
Young children and patients of Asian descent can appear “cross-eyed” without a true misalignment. This pseudostrabismus is most commonly due to a flat nasal bridge with prominent epicanthal skin folds. These facial features can obscure the medial sclera and create an optical illusion of misalignment. In this case, the eyes may appear to be esotropic, but the corneal reflexes will appear symmetric and in the center of each pupil.
Additional patient examples (courtesy of Dr. Marielle Young):
Bradford, Cynthia A. Basic Ophthalmology. San Francisco, CA: American Academy of Ophthalmology, 2004.
Disclosure (Financial or other): None