When a person has a squint, their eyes are not looking in the same direction. One eye “moves away”, trying to fix on an object or another person. If this happens, it’s a sign that the brain is no longer able to put the images together correctly. As a result of squinting, the affected person experiences what is known as “double vision.”
Contrary to popular opinion, squinting (medically called strabismus) is neither harmless nor cute, nor simply a flaw in someone’s appearance. Strabismus is a visual impairment that causes disorders of binocular and three-dimensional vision and requires consultation with an ophthalmologist.
Acute double vision or acute squinting are ophthalmological emergencies.
A characteristic of squinting is the misalignment of the eyes, which causes them to look in different directions. The origin of strabismus is usually the deviation of one of the two eye axes from the normal position (i.e. parallel position) inwards or outwards.
However, a squint is often accompanied by other symptoms:
The individual symptoms depend on the respective form of squinting:
Latent squint (known as heterophoria): In this case, the eye muscles are not balanced and the human brain is able to compensate for this imbalance and cause the two visual impressions to merge, which in turn leads to normal vision. This form of squinting is often imperceptible or only becomes visible when the affected person is exposed to factors that promote squinting – such as fatigue, stress, alcohol, mental stress or a general illness. Accompanying symptoms include headaches, rapid fatigue, blurred vision or double vision.
Concomitant or non-paralytic squint (concomitant strabismus): With this type of squinting, it is not possible for the affected person to independently compensate for the imbalance of the eye muscles, which means that the visual axes of both eyes cannot automatically point towards the same object, which is why the different viewing angles remain even when the eyes move. A mild form of farsightedness is often seen with this type of squint. If the patient only squints with one eye, this eye may also suffer from amblyopia (a lazy eye). Accompanying symptoms may also include head misalignment or shaking eyes.
Incomitant or paralytic squint (incomitant strabismus): Here, one or more of the outer eye muscles fail completely, with the squinting angle also changing depending on the direction of vision. Paralytic squint is a sudden onset condition, which is why the symptoms are perceived all of a sudden. It is typical to see double vision, with those affected also reporting dizziness and nausea. In addition, many patients try to compensate for the double vision by holding their head crooked.
If you suddenly develop a squint, you should see a doctor immediately.
As a squint can be both congenital and acquired, the condition has many causes. On the one hand, it can be due to genetic factors, on the other hand to risk factors during pregnancy or childbirth, but it can also be due to refractive disorders of the eye (including refractive errors) or occur due to injuries.
In the case of refractive disorders, the light rays penetrating the eye are not focused on the retina and thus cause a blurred vision. The shape of the eye or cornea or age-related stiffness of the lens may limit this focusing capacity of the eye.
Specifically, the following factors may be responsible for squinting:
Strabismus is often already obvious: The typical eye position leads to a clear diagnosis. However, the accompanying symptoms mentioned above may also give the doctor an indication of strabismus.
The first step is to check whether there is a secondary squint or a connection with another disease. If the ophthalmologist’s examination reveals no abnormalities – apart from the squint – the refractive power of the eyes is measured and glasses prescribed if necessary.
If, on the other hand, the doctor diagnoses a paralytic squint, magnetic resonance tomography (i.e. an MRI scan) is usually necessary. The underlying cause of the squint is then treated further by the relevant specialists.
The ophthalmologist can also use various eye tests as well as orthoptic (ophthalmological) tests to diagnose the squint. A very important test is the cover test, which first covers one eye. The ophthalmologist then checks whether the eye position of the uncovered eye changes or remains the same. If the eye readjusts itself, this may be an indication of the presence of a concomitant squint. In the uncover test – as it is known – on the other hand, the uncovered eye attempts to merge the seen images by means of additional movements. In this case, there may be a latent squint.
If you develop a squint suddenly, on the other hand, you have to see an ophthalmologist as soon as possible. The doctor can then carry out the appropriate tests and discuss suitable treatment.
The good news is that squinting can generally be easily managed by initiating therapy at an early stage.
If strabismus is detected in childhood or toddlers, conservative therapy is usually sufficient to treat the squint and the affected children therefore usually do not have to have surgery. For adults, too, conservative treatment is preferable to surgery.
Regular check-up appointments should be made to ensure that the progress of each treatment is documented. After an eye operation, it goes without saying that you need to attend the agreed follow-up appointments and strictly follow the instructions of your treating doctor.
In medicine, squint refers to the persistent or recurrent misalignment of one eye (the monolateral strabismus) or both eyes (alternating strabismus). A characteristic of squinting is the misalignment of the eye or eyes, as the gaze always goes in different directions.
Doctors also refer to squinting as “primary strabismus”, which means the squint occurs without any other eye disease. By contrast, the term “secondary strabismus” refers to squinting that is caused by another disease. For example, blindness of an eye – regardless of its cause – can lead to squinting because the blind eye no longer participates in the process of vision.
Important information: If double vision occurs suddenly in conjunction with symptoms such as drooping corners of the mouth or one-sided paralysis, this may also indicate a stroke.
People squint when there is an imbalance in the eye muscles. There are six external muscles of each eye that control the movement of the eyeball; in addition, there are two internal eye muscles that control the size of the pupil and vision at a distance. While squinting, the eye muscles are imbalanced.
In medicine, a distinction is made between the inward squint (convergent squint or esotropia), where an eye is turned inward towards the nose, and the outward squint (divergent squint or exotropia). If the eye is turned up or down, this is called vertical strabismus. And when the eye is rotated around the visual axis, the specialist may describe this as a rolling squint.