Our eyelids work much like the windshield wipers on our cars. The lids wipe across our cornea cleaning it and constantly restoring a new layer of tear film. If the cornea is not kept moist, a dry eye or exposure keratitis may develop. It is much like chapped lips and leads to dry, burning, gritty eyes.
After brain injury, the rate of blinking may slow and the completeness of the blinks may decline. The patient may be making only occasional partial blinks. This leaves the lower portion of the cornea to dry and become uncomfortable.
The simple addition of artificial tears and reminders to the patient to blink fully and frequently can manage this problem. In severe cases, silicone tear duct plugs may inserted to reduce the loss of tears from the eye down the normal draining tubes. This is equivalent to placing a stopper in the bathtub.The result is more tears in the eye.