Squint Surgery

What is strabismus (Squint)?

Strabismus is a condition in which the eyes point in different directions. Other terms used to describe strabismus are "squint", "wandering eye", "cross eyed", or a "lazy eye". It is a common condition among children. It may also occur in adults.

What causes squint?

The exact cause of squint is not really known. The movement of each eye is controlled by six muscles. Each of these muscle acts along with its counterpart in the other eye to keep both the eyes aligned properly. A loss of coordination between the muscles of the two eyes leads to misalignment.

What causes strabismus in adults ?

1.  The most common type of adult strabismus involves patients with misaligned eyes from childhood. This problem starts at a time when the patient can suppress (that is, 'turn off') one eye and thus avoid double vision... 
2.  Weakness of one or more eye muscles caused by damage to the nerves which stimulate the muscles. This usually results in the sudden onset of double vision caused by the eyes becoming misaligned... 
3.  Poor vision in one eye for whatever reason may eventually cause that eye to drift outwards or inwards. 
4.  Inflammation of the eye muscles can cause these muscles to become stiff and this may lead to strabismus and double vision. Thyroid eye disease is and example of such a condition.

What are the problems associated with strabismus in adults?

When the eyes are not aligned properly, each of the eyes is focusing on a different object and sends signal to the brain. These two different images reaching the brain lead to confusion and may have either of the two effects:

A child would ignore the image coming from the deviated eye, and thus sees only one image. But in the process, he loses the depth perception. This suppression of the image from the deviating eye results in poor development of vision in this eye, which is known as amblyopic.

An adult can not ignore the image from either eye, and therefore has double vision. This can be very annoying and may interfere with work. This double vision can be very trouble-some as it may interfere with everyday tasks and could disqualify the them from driving. In patients who are struggling to overcome strabismus and keep their eyes together, symptoms such as headaches, "eye strain" and intermittent double vision are common.

How is strabismus detected ?

In a child, the parents may notice the deviation of eyes. It is important to remember that the eyes of a newborn are rarely aligned at birth. Strabismus may be noted by the patient themselves (especially if it is causing double vision) or by family and friends. Strabismus is often detected by an Optometrist during a routine eye examination or by a patient’s General Practitioner. 

What are the treatment options ?

Glasses : – in some case prescribing glasses can enable the patient to realign their eyes. 
Prisms : – plastic prisms of the appropriate strength can be stuck on to the spectacle lenses to correct the misalignment of the eyes. 
Botox injections : – Botulinum toxin is a drug, which if injected into a muscle causes it to become weakened for 3-4 months. It is frequently used in the management of patients with strabismus.
 Surgery : – In many cases of strabismus, surgery is the only effective treatment.

The aims of treatment of squint in order of importance are:

  • Preserve or restore vision
  • Straighten the eyes
  • Restore binocular vision

First of all, the eyes are checked to see if they have any refractive error that may be responsible for squint. If there is any significant refractive error present, it is treated first. In some cases (accommodative squint) a correction of refractive error is all that may be required to treat squint.

Next the eyes are checked for presence of amblyopia. It is important to treat the amblyopia before the surgery for squint. The parents are explained about the importance of this treatment, as their cooperation is very crucial for the success of this treatment.

The squint is treated by surgery of either one or both the eyes. The surgery involves weakening or strengthening of the relevant muscles to restore the balance and to get a good coordination. In some cases with double vision, prisms may be added in the glasses to ease the symptoms.