Strabismus or strabismus is a visual disorder in which the eyes are not correctly aligned and point in different directions.
This is not only an aesthetic problem, but can also cause symptoms in the eyes.
One eye can see straight ahead, while the other eye deviates, after:
Strabismus may persist into adulthood in the following cases:
- In case of non-treatment.
- In case of relapses, for example, by abandoning preventive measures, if presbyopia occurs. The problem is that strabismus persists, so therapies must never be interrupted.
Strabismus can occur constantly or intermittently, meaning the eye deviates only sometimes, for example in stressful situations due to a medical condition.
Types of strabismus
- Heterophoria: latent strabismus, which occurs only under certain circumstances. The deviation remains latent (usually absent) by the mechanism of fusion (process during image creation) and can be compensated by muscle contractions.
- Heterotropia: manifest strabismus, a permanent and constant deviation of one eye.
Classification depending on the direction of strabismus
Concomitant strabismus means that the deviation of the eye persists regardless of the viewing angle. This disorder is divided into:
- Infantile esotropia (inward strabismus or strabismus convergens) exists when the eye deviates inwards; it is the most common form of childhood strabismus, which is already present at birth or occurs within the sixth month. In children with esotropia, the part of the brain that controls the ability of both eyes to see together is not insufficiently developed.
- Accommodative esotropia is the most common form of internal strabismus, which occurs mainly in farsighted children who are 2 years or older. This type of squint, as a rule, is caused by the effort for a sharp vision: when the child tries to see clearly, the eyes deviate inwards.
- Exotropia (outward strabismus or strabismus divergens) means deviation of the eyes outwards, another common type of strabismus.
Exotropia occurs when a child focuses on distant objects.
This form of strabismus can occur from time to time, especially if the child is dreaming with his eyes open or is sick or tired.
In the case of non-accompanying squint, the deviation changes depending on the direction of view.
Strabismus can also be described by its cause.
The cranial nerves responsible for eye movements are numbers III, IV and VI. If these are weakened or paralyzed, this can lead to strabismus.
Examples of paralysis strabismus are paralysis of the third cranial nerve and paralysis of the
superior obliquus muscle.
Restrictive strabismus – here the movement is hindered.
Other classifications of strabismus
- If the same eye is always affected, the squint is unilateral,
- Reciprocal (alternating) strabismus occurs when sometimes the right eye and sometimes the left eye deviates.
The terms hypertropia and hypotropia are used to describe the constant vertical deviation.
- Hypertropia is the deviation of the eye upwards.
- Hypotropia occurs when the eye deviates downwards. The cause is a dysfunction of the eye muscle.
What are the causes of strabismus?
Strabismus can be caused by problems with the eye muscles, the nerves that transmit the information to the muscles, or the control center of the brain that controls eye movements.
It can also have other causes, such as:
- Eye injuries. Trauma can cause strabismus by:
1) brain damage that alters the control of eye movements;
2) Damage to the nerves that control the eye muscles.
3) Damage to the eye muscles, directly or after trauma to the eye socket.
- Weak eyesight (amblyopia).
- Neurological diseases (stroke, traumatic brain injury, incomplete or complete cerebral palsy, paralysis of the eye muscles).
In newborns, strabismus is physiological and transient, it can last for the first 6 months; the causes are:
- lack of control of the eye muscles,
- Fatigue of the eyes.
What are the risk factors for the development of strabismus?
- Family history – People whose parents or siblings squint are more likely to develop strabismus.
- Refractive errors – People with uncorrected, pronounced farsightedness, myopia, or astigmatism may develop strabismus due to a greater effort to focus objects.
- Diseases – people with conditions such as Down syndrome.
Other risk factors
- Premature birth or low birth weight
- Retinopathy of prematurity
- Eye diseases, such as cataracts, severe ptosis, and corneal scarring
Idiopathic strabismus (of unknown cause) is the most common type.
Other diseases that can cause strabismus:
- Duane syndrome
- Moebius syndrome
- Endocrinopathies: e.g. thyroid diseases
- Fracture of the orbital wall.
Symptoms of strabismus
The symptoms of strabismus may be present all the time or come and go.
- Vision fatigue
- Incorrect posture that favors the appearance of neck pain
- Double vision
- Converging eyes, i.e. eyes that are not aligned in the same direction
- Uncoordinated movements of the eyes (the eyes do not move together)
- Loss of depth perception
- Dizziness, orientation difficulties
What is the therapy for strabismus?
Squinting people have different treatment options to improve coordination and alignment of the eyes:
- Glasses or contact lenses
- Prism lenses
- Treatment of vision in case of poor eyesight
- Surgery on the eye muscle
Glasses or contact lenses may be prescribed to patients with uncorrected farsightedness.
For some patients with accommodative esotropia, this is the only treatment required. Once farsightedness is corrected, the eyes need to make less effort to focus and can stay straight.
Prism glasses are special lenses that can bend the light entering the eye, thus reducing the degree of rotation that the eye must have when seeing objects.
Vision therapy is a structured program of visual activities designed to improve eye coordination and focus. Visual therapy trains eyes and brain to work better together.
These eye exercises are a helpful support for:
- difficulty of eye movements,
- focusing the eye,
- Strengthening the eye-brain connection.
When is strabismus surgery necessary?
In most cases, surgery is the only way to treat a constant squint.
In some cases, the ideal age for surgery is between the ages of 2 and 3, in other cases, waiting until the age of 6 or longer.
The success of strabismus surgery depends on many factors, including the direction and extent of eye curvature. In some cases, at least two interventions may be required.
The procedure consists of:
- change of the place where the muscles attach to the eyeball;
- Shortening of weak muscles to increase tension.
Strabismus surgery can also effectively align the eyes of adults with long-standing strabismus.
In many cases of adult strabismus, however, a distinct degree of amblyopia may remain, even after the affected eye has been correctly aligned.
The sooner squinting eyes are operated, the more likely it is that the affected eye will develop normal sharpness and both eyes will work correctly and in a coordinated manner.
In children, the operation is performed under general anesthesia, in adults on an outpatient basis with local anesthesia.
After the procedure due to strabismus
Patients who have undergone surgery must remain under observation after the procedure, regardless of whether they have been treated under general or local anesthesia with sedation.
Children can return to school after two days. Adults are not allowed to drive themselves on the day of the procedure and the day after.
It may be necessary to wait a week before returning to work.
Double vision can last from a few hours to a week, rarely longer.
The pain is mild and usually used:
- over-the-counter painkillers such as ibuprofen (Dolormin) or paracetamol (ben-u-ron),
- cold compresses.
Adults and older children may be prescribed a medication for pain by the doctor.
After the strabismus operation, you are not allowed to go swimming for two weeks.
The eye remains reddened for one or two weeks, rarely longer, especially during follow-up surgery.
Possible risks of strabismus surgery
The occurrence of possible complications after strabismus surgery that affect vision or eye health is extremely rare. However, there are risks associated with any operation such as:
- Eye redness;
- remaining deformity;
- double vision;
- corneal erosion;
- Vision loss;
- Retinal detachment;
- anesthesia incident;
- Rupture of the visual muscle.
Results of surgery for strabismus
Strabismus operations are performed frequently; in most patients, a great improvement in eye alignment is observed after surgery.
In some cases, a new procedure or prism lenses may be necessary to align the eyes properly.
Each case of strabismus is unique and should be discussed with the ophthalmologist to understand the goals and expectations of the surgery.
What is my child’s long-term prognosis?
This depends on the underlying cause of the child’s squint.
In all cases, the sooner the diagnosis of strabismus is made, the more effective the treatment.