Diagnosis and Treatment of Allergic Diseases of the Eye

Abstract

Allergens and other ocular irritants can be deposited directly onto the surface of the eye from the surrounding environment, deposited on hair and skin, or rubbed, wiped, or washed into the eye. There is a net flow with gravity of sebum and trapped particles from the hair that can easily enter the eye. Substances can also gain access to ocular tissue via the systemic circulation. Many agents can be concentrated and secreted in tears, causing allergic or irritative conjunctivitis. Finally, compounds have a more difficult route of entry into the posterior structures of the eye. The cornea and the lens serve as an effective barrier for most agents that are administered topically, and there is a blood-retinal barrier, analogous to the blood-brain barrier, that protects the eye from the systemic circulation. Molecules cross this barrier based on size, charge, and lipid solubility.