A 57-year-old man was treated for a corneal ulcer with a penetrating keratoplasty, followed by six weeks of a regimen of 4 to 8 mg of dexamethasone injected subconjunctivally daily. Before therapy, he was clinically well and 10% eosinophils were noted on his differential white blood cell count. He developed a gastric peptic ulcer with hemorrhage and severe strongyloidiasis of the stomach and duodenum that worsened as the ulcer responded to medical therapy. The strongyloidiasis resulted in physiologic gastric outlet obstruction by decreasing gastrointestinal motility. There was evidence of hyperinvasive and disseminated strongyloidiasis, complicated by meningitis and Serratia marcescens bacteremia. He survived and received thiabendazole treatment for strongyloidiasis, which was successful. Subconjunctival corticosteroids caused a systemic effect that changed asymptomatic Strongyloides infection into hyperinvasive strongyloidiasis.