Local ocular immunotherapy for experimental allergic conjunctivitis.

PURPOSE We studied the efficacy of eyedrops as local ocular immunotherapy against experimental allergic conjunctivitis. METHODS Guinea pigs were sensitized with an intraperitoneal injection of ovalbumin (OA). Three weeks after the sensitization, a low concentration (10 microg/mL) of OA eyedrops was administered once a day for 3 weeks. Six weeks after the sensitization, an allergic inflammation was provoked with 20 mg/mL of OA eyedrops. RESULTS In conjunctival clinical scores 30 minutes after the allergen challenge, there was no significant difference between the controls and the treated group. The total number of inflammatory cells in the conjunctiva 8 hours after the allergen challenge was significantly decreased in the treated group (60.8 +/- 23.2 cells/field) compared with the control group (199.1 +/- 83.4 cells/field). Eosinophils in the conjunctiva 24 hours after the allergen challenge were also significantly decreased in the treated group (22.1 +/- 15.5 cells/field) compared with the control group (50.3 +/- 15.0 cells/field). CONCLUSIONS In this study, local ocular immunotherapy mainly suppressed the late phase reaction of allergic inflammation. These results coincide with previous studies of immunotherapy in which a subcutaneous injection was used. Local ocular immunotherapy is effective against experimental allergic conjunctivitis.