Background <p>Vernal keratoconjunctivitis (VKC) is a chronic, recurrent allergic eye disease that can significantly impair quality of life in children. Although rare in Canada and more common in hot, dry climates, VKC should be considered in persistent conjunctivitis. Diagnosis may be challenging when symptoms occur outside typical seasonal patterns or when allergy testing is inconclusive.</p> Case presentation <p>An 11-year-old male presented with a six-month history of bilateral conjunctival redness and swelling with seasonal nasal and palatal pruritus and sneezing. Symptoms began atypically in February and progressed to photophobia and early vision changes. Clinical images demonstrated perilimbal Horner–Trantas dots with marked conjunctival inflammation, ecchymosis, and chemosis. Epicutaneous testing and serum IgE showed only mild sensitization to cat dander. Symptoms partially improved with olopatadine and resolved with topical loteprednol, though attempts to taper resulted in recurrence. VKC was diagnosed based on clinical features and photographic findings. The patient was transitioned to olopatadine and treated with oral rupatadine. After ophthalmology assessment and steroid taper, he remained stable on daily antihistamine therapy and later discontinued medications with only mild intermittent ocular symptoms. Repeat skin testing was negative.</p> Conclusions <p>VKC is uncommon in Canada, but may lead to vision-threatening complications if a patient is not appropriately seen by an ophthalmologist and it goes unrecognized. It should be considered in cases of conjunctivitis that are unresponsive to antihistamines, even when seasonal patterns or allergen sensitization are unclear. Topical and oral antihistamine combination is effective in stabilizing VKC symptoms, with the addition of topical steroids if needed for flares. VKC treatment can require a prolonged course.</p>