Description

ABOUT STRABISMUS

Strabismus is the misalignment of the eyes. There are 6 extraocular muscles in each eye. Strabismus develops if one or more of these are too weak or strong. While one eye gazes straight, the other can look inward, outward, upward or downward. Sometimes deviation is seen in both eyes. Deviation of the eyes can be permanent or temporary, depending on the cause of strabismus. There is no single cause of strabismus. Strabismus may occur for different reasons.

Early diagnosis is very important in the treatment of strabismus. If the first eye examination is delayed, esthetic issues in addition to permanent poor vision problems can develop in the children’s eyes. Children should be examined by a pediatric ophthalmologist immediately after birth and regularly during childhood even if they have no eye-related complaints.

Causes of Strabismus 

There is no single cause of strabismus. A complicated pregnancy, complicated delivery, the child’s development and diseases may lead to strabismus. Genetic predisposition also plays a role in strabismus. If a family member has deviation in the eyes, children are more likely to have strabismus.

The cause of strabismus developing after 2 years of age is usually eye disorders. In a child with disposition to strabismus, deviation of the eye may start after an inflammatory disease or trauma (falls, surgeries, accidents).

The center managing the movement of eye muscles is located in the brain, so nerve palsy can also cause deviations in the eyes. Palsy of the nerves entering the eyes can develop under certain conditions including accidents, head trauma, inflammatory diseases and hypertension and diabetes at an advanced age. In such cases of strabismus, treatment may vary depending on whether the palsy is permanent or not. Deviations occurring due to muscle palsy may result in lazy eye in children and in double vision in older patients and therefore must be treated.

Symptoms of Strabismus

• Misalignment of the eyes

• Watering of the eyes

• Pain

• Headache

• Double vision

• Loss of three dimensional vision

• Blurred vision

• The head or face turned to one side

Some of the deviations seen during infancy and childhood are cases of pseudostrabismus. Pseudostrabismus is a misleading appearance caused by wide nasal bridge and eyelids. It is essential to have an eye examination to clarify this condition fully.

Constant deviation in the same eye indicates that this eye has poorer vision and is therefore significant. Hence, infants and children with deviation in a single eye should be taken for an eye exam immediately.

TYPES OF STRABISMUS

Latent Strabismus

Latent strabismus is strabismus that manifests itself when one of the eyes is covered. Latent strabismus is a common eye disorder in Turkey. When both eyes are open, the brain keeps the eyes aligned thanks to a combining mechanism. However, when one of the eyes is closed, this mechanism is disrupted and a deviation occurs in the closed eye.

In such cases, the patient normally doesn’t notice the deviation and presents with complaints such as eye fatigue, redness, pain, dryness and headache. If the patient already has a vision problem, these complaints appear earlier. In particular, the patient suffers from headache after reading. Latent strabismus can be treated with appropriate eyeglasses and orthoptic exercises (done with special devices).

Congenital Strabismus

Congenital strabismus usually appears between 3-6 months and 1 year of age. The angle of deviation is very high and noticeable by almost everyone. Typically, such cases of strabismus do not develop as a result of a refractive error (hyperopia etc.). Infants may have mild or moderate hyperopia but the deviation cannot be corrected even if glasses are worn. This type of strabismus may be accompanied by an upward misalignment. Early, undelayed treatment is important. Ideally, the strabismus should be corrected surgically at 1.5 years of age. This way the infant can start to use both eyes normally instead of one and lead a healthy life.

Strabismus Associated with Refractive Errors

Strabismus associated with refractive errors mostly appears between 1-1.5 and 3 years of age. These children have moderate or high hyperopia and their strabismus can be corrected by glasses fully or partially. They have a typical history. Strabismus may develop suddenly or after a fever or fall. Often, patients have a higher diopter in one eye and are also at risk of lazy eye. Most such strabismus cases can be treated by glasses and patching. If strabismus cannot be corrected completely and vision is distorted when both eyes are used simultaneously to focus on an object, strabismus surgery might be necessary.

Strabismus Associated with Muscle Palsy

Muscle palsy may develop during infancy and young age after trauma, particularly head trauma, difficult delivery and high fever. Rarely it may develop because of a tumor, cyst or structural disorder inside the head. In adults it may occur after a trauma or frequently develop with diseases that affect the central nervous system, such as diabetes, thyroid diseases and MS.

Typically, there is double vision in this kind of strabismus and while it is resolved rapidly in young patients, it is permanent in older patients. The head is typically tilted to one side and one eye is squinted. In children, if the angle of deviation is high, the brain immediately excludes the eye with deviation in order to eliminate double vision in the short term and amblyopia starts in that eye. In adults, double vision persists as long as strabismus is present and causes adoption of a peculiar head position. Double vision makes life difficult. Many cases of strabismus associated with palsy may gradually improve and finally disappear within one year. So it is necessary to wait. Generally, a surgical intervention is not performed in this period but Botox is used commonly so that strabismus improves at an earlier stage and double vision is corrected. If the angle of deviation is low, double vision can be prevented by special prismatic glasses.

Strabismus in Older Patients

While rarely occurring during infancy as well, this type of strabismus often starts during childhood or adolescence. It usually takes the form of outward misalignment. It is intermittent in the beginning and misalignment is not always present; it forms when the patient gazes into space or looks into the distance. It may develop as a result of over-actioning outer muscles or weakness of inner muscles. Surgical intervention is required in cases of constant misalignment which affects binocular vision. Orthoptic treatment may be useful in some cases of intermittent strabismus.

Specific Strabismus

Sometimes there can be congenital structural and functional disorders in the eye muscles or the nerves moving these muscles, and this may cause strabismus. If this leads to lazy eye and causes adoption of a specific head position, treatment is necessary for children to regain binocular vision. Glasses, patching and orthoptic treatment and surgical treatment are used as necessary in such cases of strabismus.

TREATMENT OF STRABISMUS

Since strabismus has many causes, treatment changes from person to person. Strabismus is an eye disorder which can be treated at any age.

Treatment with Glasses 

Some types of strabismus develop due to a refractive error. Strabismus is corrected when the patient starts wearing glasses. The use of glasses is sufficient in these types of strabismus.

Treatment with Patching 

This treatment method can be used if the patient has lazy eye.

Orthoptic treatment

Orthoptic treatments involve physical therapy for eye muscles. They are used to strengthen some muscles and enhance binocular vision. Enhancing binocular vision fixes or recovers depth perception. This function of the eyes ensures that eyes are aligned and has a very important role in our daily life. For instance, it helps us be more comfortable and successful while driving or in sports that require distance and time management, such as basketball and tennis.

Surgical intervention

Congenital strabismus often doesn’t require the wearing of glasses and should be operated at an early stage (6 months – 1 year of age). The majority of strabismus cases appear at around 2-3 years and are usually completely corrected by glasses. Surgical treatment is required for strabismus which doesn’t improve with glasses. Strabismus surgeries are mostly performed under general anesthesia. Anesthesia is given by doctors specialized in pediatric anesthesia. Lazy eye can be prevented and 3-dimensional vision can be achieved with early diagnosis and treatment in strabismus. Therefore, a child with suspected strabismus should be taken to an ophthalmologist specialized in strabismus before waiting for him/her to reach a certain age.

Botox

Botulinum Toxin (BOTOX) can be used for the treatment of strabismus in some cases. Botox is effective and can be used for treatment purposes in palsy-related strabismus, in patients who have undergone surgery but could not achieve total recovery and in patients whose eyes are misaligned due to thyroid eye disease. Double vision often accompanies strabismus which develops suddenly due to palsy and it is a very difficult condition for the patient. In this kind of strabismus, the general tendency is to wait for 6-8 months but Botox can be used to improve double vision during this waiting period. Complete recovery is possible if treatment is started immediately after strabismus develops.

NYSTAGMUS

Shaking eyes (Nystagmus) is the involuntary movement of the eyes. It can be congenital or appear during infancy or later. Nystagmus has no single cause. It can have many different causes. And it can develop without affecting vision. It can be noticed through shaking of the head during infancy. In this case, nystagmus often either improves or disappears entirely towards primary school age. However, shaking eyes can develop due to poor vision or neurological factors as well. Differential diagnosis is very important in patients with nystagmus since the disease is associated with many causes and treatment options which vary accordingly. Treatments for these patients include eyeglasses, telescopic spectacles, eye drops, medication and surgery when required.