Vernal keratoconjunctivitis (VKC) is a bilateral, chronic, external ocular inflammatory disease of unknown cause. It is a fairly common disease in hot, dry environments, representing as much as 3% of severe ophthalmic diseases and up to 33% of all eye pathology seen among young patients in eye clinics in Central Africa. Symptoms and signs can persist for years with an important visual morbidity and social impact. Corneal changes (e.g. corneal ulcers) can be sight threatening, occurring in up to 10% of VKC children. Topical steroid therapy remains the current standard treatment, but in developing countries its use often is chronic and not medically supervised, potentially leading to bacterial infections, steroid-induced glaucoma and cataract. Chromoglycate drops have less side effects but lack the power to control a flare-up. Topical cyclosporine has the potential to offer an efficient but safer alternative to steroid drops in the management of VKC in an African setting. Its safety and efficiency in the management of vernal keratoconjunctivitis have been described in several uncontrolled studies and double-blind, placebo-controlled trials, but those studies were relatively small and involved populations outside Africa with predominantly palpebral and mixed forms of VKC. Controversy still remains on the efficiency of cyclosporine in severe forms of allergic conjunctivitis like VKC. We therefore undertake a larger prospective randomized double-masked, standard treatment controlled clinical trial in Central Africa to compare the short-term efficiency of cyclosporine A (CsA) 2% eye drops, solved in olive oil vehicle, with that of steroid drops in predominantly limbal forms of VKC. During 4 weeks the participants will be randomised to either cyclosporine or dexamethasone as attack treatment for VKC. The 4 weeks thereafter all participants will receive chromoglycate drops as maintenance treatment. Additional objectives are to document any difference in rebound phenomenon while on chromoglycate during the maintenance phase between the 2 treatment groups and to evaluate safety and tolerance of the test medication.