Additionally, oral antibiotics and vitamin B6 may be given. Allergic conjunctivitis may be due to pollen, house dust mites, molds, mildew and food allergy as well as odors from new carpets and recently finished floors. There is no way to diagnose an allergy directly. For this reason, allergic conjunctivitis is a diagnosis of exclusion, that is we exclude all other causes and what is left is allergy. If a cause can be determined, the elimination of the cause will often result in the resolution of the allergy.
Cats can develop a specific type of conjunctivitis known as eosinophilic conjunctivitis.
The diagnosis is made by performing a conjunctival scraping and examining the cells with a microscope. The predominant type of cells is a white blood cell known as the eosinophil. It is called this because of the way it retains stains. Although the cause for eosinophilic conjunctivitis is unknown, several causes of eosinophilic conjunctivitis have been proposed. These include herpesvirus, allergy and other virus infections.