Gritty, scratchy, or sandy sensations in the eyes are not uncommon, particularly with aqueous deficiency. The tear film acts as a protective barrier between the surface of the eye and the eye lids. When the aqueous layer is deficient, the protective nature of the tear film may be compromised, exposing the nerve endings on the surface of the eye.
If the meibomian glands are even slightly inflamed, there may be a sensation of scratchiness or grittiness, like sand in the eye, or like eyelashes in the eye.
Map-dot-fingerprint, also known as Cogan’s dystrophy, is a condition where the corneal tissue spontaneously disintegrates. There is evidence that map-dot-fingerprint is hereditary. Scratchiness is a common symptom, and may be accompanied by Dry Eye symptoms.