A noninflammatory, usually bilateral protrusion and thinning of the CORNEA, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. Two closely related noninflammatory corneal ectasias are pellucid marginal degeneration and keratoglobus.
Determination of which one of two or more diseases or conditions a patient is suffering from by systematically comparing and contrasting results of diagnostic measures.