[Ocular challenge protocol with a DPT/DF mixture for the diagnosis of local allergic conjunctivitis. Report of 2 cases (pediatric and adult)].

Background: Ocular allergy encompasses pathologies mediated by type I hypersensitivity, affecting the ocular surface. For diagnosis, it is essential to take a clinical history, perform an examination, and verify sensitization to aeroallergens using in vivo and/or in vitro tests. There are cases of patients with negative serum IgE levels, low serum IgE levels, and persistent symptoms and clinical manifestations. In these cases, ocular challenge tests are useful to confirm local allergy.

Cases report: Case 1: A 10-year-old male diagnosed with allergic conjunctivitis. Skin prick tests were negative. Serum IgE 35 IU/ml, tear sIgE, DPT 0.37 kUA/L, DF 0.14 kUA/L. Case 2: A 28-year-old male diagnosed with allergic conjunctivitis. Skin tests were negative: serum IgE 1 IU/ml, tear sIgE DPT 0.12 kAU/L, DF 0.1 kAU/L. An ocular challenge was performed with a DPT/DF mixture containing a standardized ALK-abelló extract mixture-DPT/DF-10,000 AU/ml. The TOSS (Total Ocular Symptom Score) scale was used to confirm the ocular challenge. The challenge was positive in both patients for DPT/DF [100 AU/ml] in a 1:100 dilution, with a TOSS score of 8 points each. A provocation test was performed on a healthy control patient. No local ocular reaction occurred. TOSS score = 0 points. Outcome: Patients were receiving topical ocular drug treatment.

Conclusion: Local reactions were positive in both patients, confirming local ocular allergy. A standardized allergen extract (ALK-abelló) with a DPT/DF mixture of 10,000 AU/ml was used, and the test was positive at 100 AU/ml at a 1:100 dilution. No local ocular reaction was observed in a healthy control patient at the highest concentration (10,000 AU/ml) and at a 1:1 dilution. Ocular challenge with a standardized DPT-DF extract is a safe and reproducible test that confirms local allergic conjunctivitis in both pediatric and adult patients. No adverse effects were observed with the presented protocol.