Three out of four people squint latently. Find out how to identify heterophoria and what to do about it.


Under the medical term heterophoria hides the so-called latent strabismus. It only occurs when there is stress, drinking alcohol, fatigue or a concussion. Heterophoria is revealed in the so-called covering test. Learn more about the latent strabismus (heterophoria) here.

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in doctor's letters or on incapacity certificates. H50H49

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  • Heterophoria: Not uncommon

  • Heterophoria: symptoms

  • Heterophoria: therapy

Heterophoria: Not uncommon

Heterophoria is also colloquially called latent or hidden squint, because it can usually be well balanced. This means that sufferers have no complaints.

The background of the phenomenon is as follows: The individual traction of the eye muscles varies from eye to eye. If you focus an object with both eyes, this difference is compensated by the sensory processing of the brain - so you notice nothing of it. This becomes visible only when the two eyes no longer work together properly. The heterophoria occurs, for example, when someone is very tired or has drunk alcohol.

This latent squint is not so rare: estimates suggest that 70 percent of all people are affected. Most people have an individual line of sight for each eye, which, however, is suppressed when both eyes are looking at a common point.

This covering test serves to determine the heterophoria: As soon as an eye is covered, it corrects under the closed hand its focus on its favorite position. This can be determined by the ophthalmologist. The covering test also serves to measure the squint angle. For this purpose, the correction angle is determined by various instruments, the eye must perform when it works together again from its favorite position with the second eye.

Heterophoria: symptoms

Heterophoria must be distinguished from the rest of strabismus. Latent strabismus is a norm variant that is even more common than two eyes, with fully aligned visual axes. Since the brain corrects the visual axes, there is a spatial visual pressure and a complete processing of the image information.

As a rule, a latent squint remains unnoticed. In most cases, the ophthalmologist or neurologist randomly identifies the heterophoria in a routine examination without the patient having previously known about his heterophoria. It can be conspicuous if there is a lot of alcohol or fatigue in the game. In these situations, it may happen that the synchronization of both eyes no longer works completely. Some people then complain about headaches or double images.

Heterophoria: therapy

A therapy of heterophoria is necessary only in rare cases. It usually consists of movement exercises that restore the muscular balance. Other patients become symptom-free if they are fitted with glasses that closely match their eye values. If someone still has discomfort despite the glasses, a special prism goggle, with the help of which the angular deficiency vision is corrected, can be used.

Because the heterophoria has no disease value, there are very few scenarios where surgery is really necessary.

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