Allergy to Ophthalmic Preservatives

Jison Hong; Leonard Bielory


Curr Opin Allergy Clin Immunol. 2009;9(5):447-453. 

In This Article

Preservatives and Hypersensitivity Reactions in the Eye

There are many adverse reactions associated with topical ophthalmic medications. Most of these reactions are toxic and result from chemical irritation. Only about 10% of all adverse reactions to topical ophthalmic drugs are truly allergic. Furthermore, allergies (IgE and cell mediated) are more commonly caused by the active pharmaceutical agents, such as neomycin or sulfa-based agents and rarely by preservatives or other additives.[1,2] As the incorporation of preservatives in topical ophthalmic solutions becomes more common, sensitization toward preservatives is increasing. The salts of benzalkonium have been classified as being moderately allergenic (4–11% skin test positive) whereas mercurial products are strongly allergenic (13–37% of skin tests are positive). True allergic sensitization by other preservatives (chlorhexidine and chlorobutanol) is unusual.

The different types of hypersensitivity reactions can be separated into the following categories: allergic reactions (IgE-mast cell mediated hypersensitivity), cicatrizing allergic conjunctivitis (type II and III hypersensitivities) due to antibody localizing to ocular tissue or immune complexes deposition and allergic contact conjunctivitis, a type IV hypersensitivity reaction (Table 1).[3–5] The term allergy in the ophthalmological literature is commonly used interchangeably with immunological responses of any type and does not necessarily denote an IgE-mast cell mediated process.