Squint: Treat it early

"A squint needs to be treated as early as possible to ensure good visual development," Consultant Ophthalmologist Dr. M. Nandakumar warns, as putting off treatment by a few years can cause serious impairment to sight, thereby decreasing chances of good visual improvement.

What is a squint?

Squint is a misalignment of the two eyes that causes each of the eyes to look in different directions. Common in children, it may occur in adults too. While some forms of squint are hereditary, the majority are not, happening for the first time in individuals with no family history of squints. Though nutritional deficiencies are not directly responsible for squint, a general lack of health can aggravate the condition.

Causes of a squint

The movement of each eye is controlled by six muscles. Each of these muscles acts along with its counterpart in the other eye to keep both eyes aligned properly. A squint happens because of improper development of eye muscles or their neurological control mechanisms that are responsible for coordination of eyes.

This could be due to weak muscles, muscle development disorder or a neurological disorder. In rare cases, squints can be congenital (from birth). However, more common are the acquired squints seen both in children and adults.

Dr. Nandakumar states that the ability to see things develops in the first six years or so of childhood (called the critical period). "If something interferes with the vision during that time, a squint can develop," he says.

Errors in the focusing of light by the eye called refractive errors that remain unchecked or not corrected adequately with glasses are among the common causes for squint.

Alternatively if a child has cataract, a tumour in the eye or a retinal or nerve problem because of which light cannot enter their eyes, chances are that he/she might acquire a squint.

Further, as a person ages, his eye muscles too can grow weak, causing a squint. Occasionally, a muscle paralysis can cause a sudden squint while diabetes, hyper tension, injury from accidents that cause pressure to the brain can also result in a squint with double vision. The misalignment may be the same in all directions of the gaze or merely in one as in a squint due to nerve palsy.

What happens during a squint?

Under normal circumstances, when both eyes have good vision and are well coordinated, they focus on the same object. Each of the eyes sends a picture of the object, viewed from a slightly different angle to the brain which in turn joins them to form one three dimensional picture with depth perception. (Depth perception allows a viewer to accurately judge the distance to each object.) This is known as binocular vision.

In a squint, a person lacks depth perception because of weaker vision in one eye. With improper coordination, two different images reach the brain causing confusion.

This may cause an individual to either ignore one image from the deviated eye or thus lose depth perception. This long-standing suppression of one image from the deviating eye leads again to permanent poor vision in the squinting eye called amblyopia or lazy eye.

A squint can also be hidden or latent - not visible to self or others. Such people tend to have other problems such as eye strain from reading too much or working on the computer too long. In such people a squint can sometimes be seen at the end of a tiring day.

"Very few have perfectly balanced eyes,” the doctor clarifies saying that most have some amount of imbalance that can easily go unnoticed. In very healthy people other muscles of the eye itself attempt to compensate for the imbalance so that vision is not affected.

Nevertheless, viral infections such as Chikungunya, stress, excessive eye strain, poor diet, pregnancy in persons with a hidden squint, can wear out the body's compensatory mechanisms and the once invisible squint may now manifest.

Squints in infants

The eyes of a newborn are rarely aligned at birth. Most establish it in the first 3-4 weeks. The doctor considers it vital for parents to examine their infants /children carefully to see if their child has a squint - with pupils turning inwards or outwards. "They have to take it seriously," he stresses.

How serious a problem is a squint?

Aside from cosmetic reasons, a squint can cause vision problems that gradually worsen. It can also lead to a lazy eye - where one eye refusing to function, will allow the other eye to do all the work. Dr. Nandakumar assures that a lazy eye if detected before 8-9 years of age can be easily corrected to a great extent. A patch would have to be worn over the good eye, which forces the lazy eye to function, eventually restoring normal vision.

A check by an ophthalmologist can ascertain cause for the squint, identify which muscles are weak or lazy and how they could affect vision, before providing the required treatment that could restore binocular vision and straighten eyes.

A squint in a child should never be ignored "The earlier you treat, better the chances of restoring binocular vision and straightening eyes," he says. Treatment could include either correction of refractive error by wearing glasses, making the child use eyes equally (occlusion therapy), exercise for mild squints or surgery or a combination of these methods.

Although surgery time is less than an hour, good follow-up is required to see if vision is recovering, the doctor advises. Occasionally multiple surgeries are required. Congenital squints should be treated within the first year.

One can reduce the risk of getting squints by checking the need for glasses. Ideally, Dr. Nandakumar recommends that a child's eyes are thoroughly checked prior to entering pre-school. Thereafter annual checks are recommended to protect vision, which is closely linked to the learning process.