TYPES OF 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 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.
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.