Local conjunctival immunotherapy: the effect of dermatophagoides pteronyssinus local conjunctival immunotherapy on conjunctival provocation test in patients with allergic conjunctivitis

Background: we evaluated the effect of local conjunctival immunotherapy (LCIT) with standardized dermatophagoides pteronyssinus (Dp) extracts on antigen-specific conjunctival provocation test (CPT) in patients with allergic conjunctivitis in a double blind, placebo-controlled study. We use the CPT because in our experience is the more objective parameter to evaluate the sensitivity to allergens in this patients. Methods: the patients were selected on the basis of symptoms, positive prick test, positive CPT and elevated serum and tears total and specific IgE. The CPT was assessed with increased dilution of Dp extracts instilled into the lower fornix. Conjunctival hyperemia, tearing, itching, burning and swelling of eyelids were scored according a 4-point rating scale. Patients were randomly assigned to 2 groups of 12. The first group was treated with Dp extracts and the second group with placebo during 6 months. A drop of diluted antigen was instilled in both eyes daily, in 2-fold increased concentrations, the first 10 AU/ml. The maintenance dose was 1,000 AU/ml or the maximal dose which did not provoke symptoms. The symptoms were controlled with oral and/or local antihistamines. We evaluated the CPT before and after the treatment. The patients did not receive antihistamines during the 15 previous days to carrying-out the CPT. Results: ten of the twelve patients of the active group complete the treatment. One of the patients dropped out of the study because experienced local reaction with a dose of 1,000 AU/ml and refused to continue with the treatment. Other patient was disqualified for failure to comply with the protocol. One patient, which experienced itching and tearing with a dose of 1,000 AU/ml, tolerate 100 AU/ml. We continue with this dose until the end of treatment. The remaining patients tolerate 1,000 AU/ml as maintenance dose. A significant difference was observed in the score of CPT between LCIT treated patients and placebo group after 6 month of LCIT. Conclusions: we propose LCIT as a useful alternative to traditional subcutaneous immunotherapy in patients with allergic conjunctivitis.