New Treatments: Local Conjunctival Immunotherapy

In December of 2010, a study was conducted by researchers Kasetsuwan, Chatchatee and Reinprayoon from the Allergy & Immunology Society of Thailand and published in the Asian Pacific Journal of Allergy & Immunology. The study focused on the use of local conjunctival immunotherapy (LCIT) to desensitize patients to the allergen. We know that a person with allergic conjunctivitis has an allergic, inflammatory response when an allergen binds to the IgE antibody. If you remember, the binding of antigen to the IgE activates the mast cells to release histamine and other mediators to induce the inflammatory response. In immunotherapy, patients receive an antigen dose low enough that it doesn't elicit an immune response, but the body is stimulated into producing more antibodies against the antigen. With each increasing dose of antigen, the body's immune response becomes desensitized to the antigen. In other words, under normal antigen exposure, the body is less likely to elicit an immune response, effectively decreasing the allergic response.

In the study, researchers synthesized allergen extracts in eye drops, which they gave to nine out of the eighteen patients. The other nine patients served as the control group, receiving salt solution eye drops that had no therapeutic effect. The two groups of patients were given their respective eye drops once daily for six months. All subjects enrolled in the study must have exhibited an allergic reaction to house dust mites via a skin prick test.

To determine the efficacy of the LCIT, the researchers used a conjunctival provocation test (CPT). This test is representative of the immune response to an allergen; a lower CPT score means a reduced allergic reaction. The results of the study showed a significant reduction in CPT scores for the experimental group receiving the allergen extract eye drops, compared to the control group. However, when comparing symptoms of the allergic response, there proved to be no significant difference between the experimental and control group. What does this mean?

Although the LCIT works in theory, it may not work in reality. This is often the case for many treatments; they look great on paper and should work, but when applied to real human models, they prove ineffective. However, the fact that CPT scores were reduced, means that the researchers must be on to something. There was no alleviation of symptoms, but that doesn't mean that immunotherapy should be ruled out. This was only one study and there has been a lot of research and buzz around allergen immunotherapy; it may be the future of allergic conjunctivitis. If you are interested in immunotherapy as a solution to your allergic conjunctivitis, contact a certified allergist.   

For more information about immunotherapy, visit the Mayo Clinic and the American Academy of Allergy Asthma & Immunology.