Allergic contact dermatitis of the eyelids from topical ophthalmic medications. The role of β-blockers: Diagnostic and management problems

Background: β-blockers, i.e. β-adrenergic receptors antagonists, are drugs which are widely used in local medications for the treatment of open-angle glaucoma. Allergic contact dermatitis (ACD) due to the β-blockers contained in eyedrops are rare, but it can be difficult for dermatologists to diagnose and manage because of the low sensitivity to patch tests with such drugs and of the possible cross-reactions between them. Materials and methods: in four glaucoma patients with signs of eczema on their eyelids (in two cases conjunctivitis was also present) patch tests were carried out using haptens of the SIDAPA standard series, of a palpebral series and from our series of vehicles and preservatives. Moreover, we tested the eyedrops' components and another series containing β-blockers that the patients had never used before. Results: all patients reported positive reactions to patch tests containing the suspected β-blockers. Moreover, in two of these patients reactions to β-blockers that were never used before were observed. Conclusions: The diagnosis and management of patients with ACD caused by eye medications containing β-blockers can be difficult: in fact patch tests used with commercial ophthalmic medications are not sensitive enough and we lack a standardized pattern of skin tests with greater diagnostic efficacy. We suggest patch testing on the classical sites (back or forearm) at a higher concentration than those contained, at present, in the ophthalmic products available on the market. If the tests are negative, it is advisable to carry out modified skin tests, such as a scratch test, to stimulate greater absorption by the palpebral skin. Moreover, it is also advisable to test all patients with a series of alternative β-blockers in order to discover possible cross-reactions, as well as testing alternative medications.