ERRORS OF REFRACTION IN PEDIATRICS

Normal vision means child is able to appreciate an object at a certain distance in its different proportions and colours.

When the baby is born, the two eyes don’t move together and there is absence of fixation to the light.

Around three months of age, the baby starts fixating the eyes on the light and around six to eight months of age both the eyes start moving together. Eyes start following the light source in different directions. When the eyes don’t move together it will look as if the baby has developed a squint.

Initially in earlier age the eyes are usually Hypermetropic (far-sighted) which gradually over a period of time changes into normal eyes. At times the eyeball may enlarge more and the child may develop myopia (near sightedness).

Normal eye: Here the parallel rays of light are focused on the retina and child is able to see clearly which is many a times described as 6/6 or 20/20 vision. In other words also described as emetropia.

Hypermetropia: In this condition the eyeball is shorter in length and the parallel rays of light are focused behind the retina leading to clear vision for distant object but has to strain for near. When the strain is more a child may develop convergent squint. This may occasionally lead to Amblyopia (lazy eye). Many a time convergent squint may be corrected by giving plus number spectacles (glasses) to the child.

Myopia : In this condition due to elongated eyeball size the parallel rays of light are focused in front of the retina leading to blurred vision for distant objects. Child may face symptoms like glare and photophobia and may develop divergent squint. Giving minus number glasses can treat myopia.

Astigmatism: In this condition the curvature of the front surface of the eye known as cornea is different in different meridians (axes). There may be a higher power in one meridian compared to the other. Due to this unevenness of the cornea, the rays of light are focused unevenly on the retina, resulting in a distorted image formation. For example: A circular image appears oval. The child may try to see objects by tilting the head, squinting the eyes or by blinking excessively.

Nystagmus: Here there is an involuntary oscillation of both the eyes associated with a refractive error. It is generally associated with albinism (absence of pigment melanin). Patient may face photophobia (intolerance to light) which can be treated by prescribing tinted glasses correcting the refractive error also.

Last updated on 02-05-2001