SQUINT – Causes, Problems with Squint, Clinical Manifestations, Diagnostic Evaluations and Management 

SQUINT – Causes, Problems with Squint, Clinical Manifestations, Diagnostic Evaluations and Management

Squint (strabismus) is a misalignment of the two eyes so that both the eyes are not looking in the same direction. This misalignment may be constant, being present throughout the day or it may appear sometimes and the rest of the time the eyes may be straight. It is a common condition among children. It may also occur in adults.

CAUSES OF 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. This misalignment may be the same in all directions of gaze, or in some conditions the misalignment may be more in one direction of gaze, e.g., in squint due to nerve palsy.

Sometimes a refractive error hypermetropia (long sight) may lead to inward deviation of the eye. Poor vision in an eye because of some other eye disease like cataract, etc. may also cause the eye to deviate. Therefore it is important in all the cases of squint, especially in children, to have a thorough eye checkup to rule out any other cause of loss vision.

PROBLEMS WITH SQUINT

When the eyes are 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 amblyopia.

An adult cannot ignore the image from the either eye, and therefore has double vision. This can be very annoying and may interfere with work

 

CLINICAL MANIFESTATIONS

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. Most establish alignment at 3-4 weeks of age. Therefore squint in any child who is more than one month old must be taken seriously and should be evaluated by an ophthalmologist.

• Crossed eyes
• Double vision
  
• Eyes that do not align in the same direction
  
• Uncoordinated eye movements (eyes do not move together)
  
• Vision loss in one eye, includes a loss of the ability to see in 3-D (loss of depth perception)
  

DIAGNOSTIC EVALUATION

A physical examination will include a detailed examination of the eyes. Tests will be done to determine the strength of the eye muscles.

Eye tests include

• Retinal exam
• Standard ophthalmic exam
  
• Visual acuity
  
• A neurological examination will also be performed
  

 

MANAGEMENT FOR SQUINT

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.

In a child, the treatment of squint and any associated amblyopia should be started as soon as possible. A delay in treatment may decrease the chances of getting a good alignment and the vision. Amblyopia treatment is aimed at the underlying cause but may include glasses, eye patching or eye drops.

Surgery cannot replace the need for glasses. If the child has significant refractive error, glasses are a must. In some cases wearing glasses may correct squint. In other cases, wearing glasses help the eyes to see clearly. This clear vision is very important for the treatment of amblyopia and also for maintaining the coordination of eyes, once they have been aligned by surgery.