What Is the Hirschberg Test?

closeup photo of a person

The Hirschberg test is a rapid, painless screening for strabismus, a disorder in which the eyes are not aligned with each other. Care providers can administer this test on newborns, young kids, or patients of any age as part of a standard eye checkup.

If indicators of strabismus are discovered after the initial screening, additional tests may be suggested to understand more about the issue and generate treatment suggestions. 

What Does the Hirschberg Test Look Like?

The test itself is a simple method. The doctor instructs the patient to stare into a bright light that is directed forward into their eyes. It is usually a pen light or an ophthalmoscope utilized as a hand-held light source.

Doctors direct their light source evenly into the patient’s eyes at midline from a distance of 2 feet. Looking at the reflection of light off the cornea, it should appear as a pin-point light around the center of each pupil.

In humans with properly positioned eyes, light reflects from the center of the cornea, directly above the pupil. If it moves across the eye, it means the patient’s eyes aren’t fully aligned.

Hirschberg test deviations can identify strabismus that’s invisible to the naked eye. In those cases, the light may strike one pupil squarely and then pass below, above, or to the side of the other.

When doctors see that the eyes appear to be misaligned, they can assess the degree of deviation to establish the seriousness of strabismus. 

Additional Testing Can Be Necessary

Usually, doctors don’t want to frighten their patients with the initial diagnosis, so several other tests, with minimally invasive procedures, are available to confirm it. 

Such a test is the Krimsky Method, which provides more precise deviation measurements. After performing the Hirschberg, a prism bar is placed in front of the eye with the deviation, and the doctor gradually raises the amount of prism until the reflex is centered in both eyes.

The Hirschberg test, along with other methods of evaluating the eyes, can be used in the primary diagnosis of strabismus. Patients may need further tests once they begin therapy. 

This can be useful in gauging the efficacy of a treatment plan and the patient’s level of response to the same plan. 

Some individuals find relief by doing eye exercises, while others may require corrective lenses, a patch over one eye, or even medication. More severe consequences might arise if strabismus is left untreated for a long period of time.

Pseudostrabismus As a Phenomenon

People of Asian descent may seem “cross-eyed” despite no real misalignment of the eyes. 

The most prevalent cause of this pseudostrabismus is a flattened nasal bridge with large epicanthal skin folds. These facial characteristics might conceal the medial sclera, giving the appearance of misalignment. 

This phenomenon is also common with infants of all descendents. Since newborns and young children lack a completely developed nasal bridge, their eyes may seem to be crossed inwards. That’s why deploying the Hirschberg test as soon as possible can identify if your child is at risk of actual esotropia or if it just merely looks like one.

Strabismus In Infants Is More Common Than You Think

Parents who are sent to an eye expert after finding something unusual during an examination should not be alarmed. Eye care for infants and younger children is critical, and many pediatricians prefer to be safe over potentially creating additional complications. 

The eye doctor will evaluate what tests are necessary or advised to diagnose any issues. If a problem is detected and the physician believes the child requires treatment, the findings can be addressed with the parents so they can be informed about treatment choices.

The Takeaway

The Hirschberg test is an amazing method of swiftly assessing younger kids and cooperative patients since it doesn’t require much effort. The only thing that is expected from the patient is to look directly into the light. Okay, they may shed a small tear or two, but besides that, no other complications can arise. 

Although, Hirschberg testing can sometimes be misleading. There is a possibility to discover a deviation that looks like strabismus, but it may be a result of an abnormal angle of kappa or anomalous correspondence. 

When the testing results don’t add up, additional screening of the retinal anatomy and overall visual system will help.

Although screenings are wonderful at spotting possible concerns, a trained optometrist or pediatric ophthalmologist will be able to utilize more information to identify the wider and more comprehensive picture of your kid’s visual system.