Corneal Light Reflex

Facts About Corneal Light Reflex

As the term suggests, corneal light reflex involves the eye, more precisely both eyes, and is a vision test, usually given to young children, to check for strabismus, a condition in which the eyes are not properly aligned.



The Corneal Light Reflex Test - The corneal light reflex test is quite simple, so long as the child cooperates by holding still and fixing a steady gaze. A light beam, such as one from a small penlight, shines towards a point directly above the child's nose or the center of the child's forehead, while the child gazes straight ahead at a target object (not the light source itself). The location of the reflected light in each pupil is then observed.

The position of the reflected light in the iris indicates whether the child has, or is acquiring, an eye misalignment problem. As simple as the corneal light reflex test is, it does have a drawback in that it cannot always detect very minute misalignment. The test does however detect strabismus when it is severe enough to be causing vision problems.

The corneal light reflex test is mostly given to infants and children up to around 8 years of age. It probably goes without saying that giving the test to a 2 month old infant can be a challenge at times unless the infant can be persuaded or coaxed to look steadily at the target, which obviously needs to be an object that will hold its interest long enough for the necessary observations to be made.

The term light reflex is somewhat of a misnomer as it is a reflection of light in the eye and not a reflex of the eye muscles that is being measured or observed. Strabismus, the misalignment of the eyes, is very often due to genetics and the misalignment is not due to muscular action so much as it is with the part of the brain that controls the eye muscles and nerves.

Depending upon the severity of the misalignment, a child with strabismus will often have double vision, especially when it comes to seeing nearby objects, but in more severe cases the double vision occurs with distant objects as well.

The Brain Tries To Help - The brain usually does a magnificent job of attempting to compensate for eye disorders, as anyone who has one eye that is weaker than the other will agree. The fault in one eye may at times be completely masked out when both eyes are open. This is not always the case however, and when strabismus is obviously causing a vision problem, corrective lenses will usually be necessary. When strabismus occurs in infancy the brain sometimes tries to cope with the situation by effectively "turning off” the signals from the optic nerve of one eye, a loss in binocular vision being the result. At other times the brain manages to merge the images seen in each eye by a process called fusion, where vision becomes normal although the eyes are not in alignment. This process usually does not happen if the misalignment occurs when the child is several years old, and eyeglasses will definitely be needed to cure the problem.

Testing All Children - Not all children are subjected to corneal light reflex testing. Probably not more than 3% of all children have the kind of eye misalignment addressed here, and in the majority of instances when it may be present, the condition is not severe enough to cause any problem. Still, it's a good idea to subject a child to the test if it appears to be having vision problems, one problem of course being that very young children may not even be aware of they have a problem, thinking double vision or other symptoms are simply the way things are supposed to be. It would certainly make sense to test all children when they reach school age, especially since the test itself does not require elaborate equipment, takes little time, and only requires only a person trained to know what to look for to carry it out.