Strabismus commonly termed as “crossed eyes” is a condition in which both the eyes do not align in the same direction when viewing the objects and thereby do not focus at the same object at a time. Normally, the muscles surrounding the eyes work together so that both the eyes point in the same direction at the same time. Any impairment in the muscular co-ordination causes strabismus and as a result, each eye may focus on different objects at a time and the brain receives two different images one from each eye which may lead to confusion. Because of multiple inputs the brain fails to recognize the images viewed by the weaker eye. Strabismus if left untreated may lead to loss of vision in that eye, a condition called amblyopia or “lazy eye”.
Strabismus most often begins in early childhood. Adult strabismus may be the residual childhood strabismus or the condition developed in adulthood. Certain medical conditions such as diabetes, thyroid disease, myasthenia gravis, brain tumour, head trauma, and stroke may increase the risk of developing this condition later in life.
An individual with strabismus may have eye fatigue, double vision, overlapped or blurred images, a pulling sensation around the eyes, difficulty in reading, and depth perception loss.
Diagnosis of strabismus is made with a detailed examination of the eyes. Eye tests such as corneal light reflex, cover or uncover test, retinal exam, standard ophthalmic examination, and visual acuity may be done to determine how much the eyes are out of alignment. Neurological examination may also be performed.
Visual acuity test: In this test, you will be asked to read the letters on the chart (Snellen chart) or a card placed at 4 to 6 metres away. This enables the physician to assess your visual ability to see the smallest objects.
Standard ophthalmic examination: It includes a series of tests performed to examine your vision and the health of your eyes.
The treatment options for strabismus include eye muscle exercises, use of eyeglasses containing prisms, botulinum toxin (Botox) injections and surgical correction. Eye muscle exercises help to train your eyes to focus together. These exercises are usually used to treat convergence insufficiency, a form of adult strabismus in which the eyes fail to align themselves in viewing closer objects or reading. Your doctor may also prescribe eyeglasses containing prisms to correct mild double vision associated with adult strabismus. Botox injections are prescribed in conditions where strabismus is caused by overactive eye muscles. Surgical correction is recommended in cases where the muscles are unable to move for focusing and during the surgery the muscles around the eye are tightened or relaxed to correct the misalignment.