Ocular Infections

Abstract

Ocular Defense MechanismTHE major natural barriers to surface infection are the tears and conjunctiva in combination with eyelid action. The cornea, except for tight zonula occludens at the epithelial layer, is relatively defenseless but is washed constantly by tears containing secretory IgA and lysozyme. The normal conjunctiva contains an extraordinary number of infiltrative inflammatory cells (about 300,000 per milliliter) and is rich in all immunologic components, including secretory IgA; this combination provides a defense mechanism that maintains a reasonable surface flora to discourage colonization with more noxious potential invaders. In addition to enormous numbers of lymphocytes, plasma cells and . . .