Strabismus - Causes, Symptoms and Treatment

Strabismus is a condition of the eye in which the visual axes of both eyes are not aligned properly as is the case normally. Both eyes appear to be looking in a different direction. Simply explained, it is when both the eyes are not able to focus properly, either due to the defect in the ocular muscles or due to the brain's inability to coordinate their movement.

There are various types of Strabismus known to experts in optics, but for the layman, there are four broad types of Strabismus: Exotropia, Esotropia, Hypertropia and Hypotropia.

Divergent Strabismus or Exotropia is a condition in which visual axes of the eyes are incoherently focused outward or in a diverged manner, while Convergent Strabismus or Esotropia is a condition in which the visual axes of the eyes are focused inward. Hypertropia and Hypotropia are Vertical Strabismus, in which one of the eyes is moved abnormally to the upward and downward direction respectively. The most common forms of Strabismus are Divergent and Convergent Strabismus.

The condition is dangerous because not only does it creates difficulty in vision and can impair the victim to have a good depth perception but also because of the reliance on the dominant eye for visual sensation. As the brain adapts to focusing on just one eye as the primary source of visual sensation, this could gradually lead to the reduced use of the other eye, which could even lead to blindness in that eye. It is also clearly a cosmetic problem, having adverse psychological effects.

Causes

The causes of Strabismus divide it into two major types: Paralytic Strabismus and Non Paralytic Strabismus. Paralytic Strabismus is caused by the defect in the cranial nerves connecting to the eye. This condition is often considered to be indicative of a lesion in the cranial nerve. The nerves most prone to the lesion formation are cranial nerve III (oculomotor), IV (trochlear) and V (abducens). But this is not the cause in most of the cases.

In Non Paralytic or Concomitant Strabismus, the problem is not related to the nerves. Instead, it is caused by a defect in the refraction of both eyes. This simply means that there is no lesion plaguing the nerve of the eye in this case.

Symptoms

The symptoms of Strabismus are clear and obvious. If both the eyes do not seem to be coherent in their movement and the gaze of both the eyes is not coordinated and in one direction, the person is clearly suffering from Strabismus. One eye in victims of Strabismus will always function normally, while the other eye is focused on a different direction, outward, inward, upward or downward.

Diagnosis

The condition of Strabismus can be diagnosed by an optometrist, an optician or an ophthalmologist or a medical doctor specializing in eye and its diseases. The diagnosis is completed by carrying out a simple cover test. The condition will only be Strabismus if the vision of the defective eye is absolutely normal when the dominant or normal eye is covered.

Treatment

The aim of the treatment of Strabismus is to ensure that the patient gets normal binocular vision. However, since the condition involves the risk of blindness or amblyopia, it is treated by making the patient wear an eye patch on the dominant and normal eye, so that the weaker eye catches up gradually. This is one of the oldest management methods for Strabismus.

The treatment of the Strabismus could vary according to the case and requirement. It could preferably be attempted to correct the vision with glasses and prism lenses. However, extreme Strabismus could even require surgery. Early treatment in children can help recover from the problem.