Ophthalmic Manifestations in 18 Patients with Botulism Diagnosed in Porto, Portugal Between 1998 and 2003

Abstract

Botulism is a rare but potentially lethal disease in which ophthalmic signs and symptoms are among the very earliest manifestations. The aim of this study was to investigate the epidemiological and clinical features of botulism-infected patients admitted to a general hospital in Porto, Portugal. We performed a retrospective chart review of all botulism patients admitted to São João Hospital between January 1998 and January 2003. We excerpted data on epidemiology, ophthalmic and non-ophthalmic manifestations, and treatment. We identified 18 patients in nine registered outbreaks. In two patients (11%), ophthalmic manifestations preceded systemic manifestations; in six patients (33%), ophthalmic and systemic manifestations occurred simultaneously; in ten patients (56%), systemic manifestations occurred first. Ophthalmologists had examined only seven patients and made the correct diagnosis in five. The most common ocular symptoms were blurred near vision (100%), blurred distant vision (94%), and diplopia (44%). Accommodation impairment was documented in all seven patients examined by ophthalmologists. Ophthalmic manifestations were among the earliest and most prominent manifestations of botulism in this series, as in earlier reports. The diagnosis should be suspected when impaired accommodation and gastrointestinal symptoms occur together.