Which of the following is an example of an acidic agent that can cause corneal damage?

• A. Lime
• B. Ammonia
• C. PAVA
• D. Airbag residue

Answer: (C)

Acidic agents injure the cornea primarily by causing surface protein coagulation, which damages the epithelium and can lead to irritation and epithelial loss without as deeply penetrating than strong alkalis. PAVA, or pelargonic acid vanillylamide, is an acidic riot-control irritant, so its acidic component can produce corneal surface damage when it contacts the eye. The other options are bases: lime (calcium hydroxide) and ammonia are strong alkaline substances that tend to penetrate more deeply and cause more extensive injury. Airbag residue isn’t known chiefly as an acidic ocular irritant and tends to irritate mainly through particulates or non-acidic chemical residues. Thus, the acidic agent among these is PAVA.