K K EYE Institute

STRABISMUS / SQUINT

What is Strabismus or Squint?

It is a condition in which the eyes are not straight and are not properly aligned and thus point in different directions. One eye may look straight ahead, while the other eye turns inward or turns outward or turns upward or turns downward.

The squint may be present throughout or it may be intermittent i.e., the squint may be seen only at certain times such as when the child is tired or day dreaming, etc. It is usually present from birth but can occur later in life also.

How do the eyes work together?

Six eye muscles, controlling the eye movement, are attached to the outside of each eye. In each eye, two muscles move the eye from side to side. The other four muscles move it up or down and at an angle.

To focus the eyes on an object, all the muscles in each eye must work together in a balanced manner. Failure of the eye muscles to work together causes Squint. The brain controls these eye movements. When both eyes have normal vision and are straight (i.e., not squinting) the eyes aim at the same spot and the brain fuses the two images from each eye into a single three-dimensional image. When one eye squints the brain receives two different images, which do not exactly overlap. In a young child, the brain learns to ignore the image of the squinting eye and sees only the image from the straight or better-seeing eye (commonly called AMBLYOPIA). The child loses the 3-D image or depth perception.

Early treatment can save vision. It is critical that this condition be diagnosed and corrected at an early age since children with uncorrected strabismus may go on to develop amblyopia. If the Squint is operated upon after the age of eight, only a cosmetic result can be achieved as the eyes are already developed by then and the child will continue to see with only one eye even after the squint is corrected by surgery.

Adults and Teenagers who develop strabismus often have double vision because the brain is already trained to receive images from both eyes and hence when the squint develops the brain cannot ignore the image from the squinting eye.

Amblyopia (Lazy Eye)

Good vision develops during childhood when both eyes are straight. Strabismus may cause reduced vision— known as amblyopia, in the squinting eye. In such a case the brain recognizes the image of the better-seeing eye and ignores the image from the squinting or amblyopic eye. This occurs in approximately half the children who have strabismus, but have not been treated in time

Amblyopia can be treated by patching the ‘good’ eye to strengthen and improve vision in the weaker eye. If amblyopia is detected in the first few years of life, treatment is usually successful. If treatment is delayed, amblyopia can become permanent. As a rule, the earlier amblyopia is diagnosed and treated, the better the visual result. Thus, the treatment of amblyopia in the form of patching is a MUST for the development of vision in children with strabismus. Parents and guardians play a vital role in this timely intervention

What is false or pseudo-strabismus?

Certain children may appear to have strabismus when, in fact, they do not. An extra fold of skin near the inner eye, a broad, flat nose or eyes that are unusually close together may also produce the effect of false (or pseudo) strabismus. False strabismus should disappear as the child’s face grows.

What causes Strabismus?

The exact cause of strabismus is not fully understood.

Since the brain controls the eye movements, strabismus is also seen among children with disorders that affect the brain such as: Cerebral palsy, Down’s syndrome, Hydrocephalus, Brain tumors, etc., Squint is often seen in children born prematurely or with low birth weight. A cataract or eye injury or any other condition that causes visual deprivation can also cause strabismus.

How is strabismus treated?

Treatment for strabismus works towards:

  • Preserving the vision,
  • Straightening the eyes, and
  • Restoring binocular (two-eyed) vision.

Strabismus cannot be outgrown, nor will it improve by itself. Treatment to straighten the eyes is required. The types of treatments may be used alone or in combination, depending on the type of strabismus and its cause.

  • Glasses with or without patching are commonly prescribed to improve focusing and redirect the line of sight, enabling the eyes to straighten.
  • Medication in the form of eye drops or ointment may be used, with or without glasses. Injected medication may be used to selectively weaken an overactive eye muscle.
  • Surgery may be performed on eye muscles to straighten the eyes if nonsurgical means are unsuccessful.
  • Eye exercises, a limited form of treatment, may be recommended either before or after surgery to teach proper eye coordination

Eye Exercises using the Synaptophore:

In some cases of mild muscle weakness the eye muscles can be made stronger, by doing exercises, using a machine called the Synaptophore. A total of about 6 sessions of eye exercises will be required. These eye exercises will need to be carried out on a daily basis using the Synaptophore machine at the hospital. Each session requires about half an hour.

In case a patient is suffering from Amblyopia / Lazy eye, the stimulation of the retina with the help of the Synaptophore can be beneficial in improving vision in the affected eye. For this too, 6 or more sessions of eye exercises of half an hour each will be required using the Synaptophore machine.

Surgery for Strabismus

  • Strabismus surgery is usually a safe and effective treatment for misalignment of the eyes.
  • It is not, however, a substitute for requirement of glasses or amblyopia therapy, and these may be required even after surgery.
  • When strabismus surgery is performed on children, a general anesthetic is required. Local anesthesia is an option for adults.
  • The recovery is quite fast and most people are able to resume their normal activities within a few days.
  • After surgery, glasses or prisms may be useful.
  • In some cases, surgery is done in stages to keep the eyes straight.
  • As with any surgery, eye muscle surgery too has certain risks. These include under or over correction, transient (temporary) double vision, infection and risks related to anesthesia as well as other visual complications.

Botulinum Toxin

Botulinum Toxin, a new drug approved by the United States Food and Drug Administration for limited use, can be an alternative to eye muscle surgery for some individuals. An injection of this drug into an eye muscle temporarily relaxes the muscle, allowing the opposite muscle to tighten and straighten the eyes. Although the effects of the drug wear off after several weeks, in some cases the misalignment may be permanently corrected.

Prevention Measures

  • Avoid marriages between blood relations.
  • Take your child to a Children’s Eye Specialist regularly from an early age.
  • Treat all eye defects among children as early as possible.
  • Convergence exercises help to coordinate the eye movements.

A squint is not a sign of luck—it may indicate poor vision. Get it checked immediately.

© 2012 K K EYE Institute - Pune India.