Squint is a condition in which both eyes do not look in the same direction, together. In the following article, Dr YK Amdekar explains this condition in detail along with the common characteristics, treatment methods, and corrective measures.

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Introduction

Squint is a condition in which both eyes do not look in the same direction. This happens when the eye muscles of both eyes do not work together. When one eye is focusing on an object, the other eye is off the direction. The affected eye does not look in the direction of the gaze.

The affected eye is turned inwards, outwards, upwards or downwards though most commonly, the eye turns inwards or outwards and rarely up and down. This condition is also termed strabismus. It may be mild and not easily noticeable. Such a child may turn their head or neck to one side to suppress the vision from the affected eye to avoid double vision. Squint may be intermittent or present all the time. Intermittent squint is normal in the first two months of life and it disappears by the age of 4 months. It may develop transiently in a normal person when tired.

Classification of squint

Other characteristics may include-

• It may be a constant or an intermittent squint
• It may manifest when the eye is open or when the eye is covered, referred to as latent squint
• In concomitant squint, the degree of squint is the same in all directions which means all eye muscles are working but not synchronously as their movements are not aligned
• Non-concomitant squint manifests only in one direction but not in the other direction

Causes of squint

Some babies are born with a squint that persists beyond the age of four months and hence is permanent. The exact cause of such a congenital squint is not known and often, familial.

However, squint may develop anytime later in life as a result of refractive errors (myopia, hypermetropia), diseases of eye muscles (including paralysis of muscles), retinoblastoma, brain defects (midbrain lesions involving 3rd, 4th and 6th cranial nerve nuclei, cerebral palsy, abnormalities such as Down’s or Noonan syndrome) and also the affection of nerves.

Is squint harmful?

1. A child with a squint may stop focusing with the affected eye called amblyopia or lazy eye resulting in disuse of nerve pathways functioning and is at the risk of a permanent loss of vision if not corrected in time.
2. Binocular vision is due to a vision focused from both the eyes together and it results in a three-dimensional view of the object as perceived by the brain. Thus, a child with a squint may not develop binocular vision.
3. In the case of children with a squint, both eyes focus on different spots but the brain learns to ignore the out of focus image and so there is usually no double vision unlike in adults.
4. Squint in a child is also a cosmetic problem that affects the child psychologically causing diffidence.

Clinical approach

It is the parents who report a squint in their child but, but a physician should also look for it, especially if it is mild and ignored by parents to seek advice, or when it is latent. Squint persistent beyond the age of four months or worsening squint at any age needs proper evaluation.

1. The first step is to rule out neurological disorder. Signs of raised intracranial pressure, paresis including that of eye muscles and cerebellar signs must be looked for and also developmental delay in a child with abnormal physiognomy.
2. Once a neurological disease or defect is ruled out, it is ideal to refer the child to an ophthalmologist. It is not easy to check refraction or fundus examination in a young child.
3. Routine testing of vision at birth and again at 6-8 weeks of age, thereafter at preschool and school-age is ideal. Squint and amblyopia should be diagnosed as early as possible for a better outcome.

Managing squint eye

Glasses may be required for refractive errors. Amblyopia is treated with a patch on a normal eye so as to force the brain to use the affected eye. Vision therapy improves visual skills and abilities. It is training with the help of lenses, prisms, filters, patches, electronic gadgets and balance boards. It is used for improving lazy eye and improve binocular vision problems. At times, corrective surgery may be necessary though under-correction or over-correction is a possibility.

Disclaimer- The views and opinions expressed in this article are those of the author's and do not necessarily reflect the official policy or position of M3 India.