Pupillary Involvement in Miller Fisher Syndrome

Miller Fisher Syndrome is characterised by the classical triad of ophthalmoplegia, ataxia, and areflexia. Ophthalmoparesis without ataxia, without areflexia, or with neither have been attributed as atypical forms of MFS. We report two patients with MFS who had tonic pupils and raised anti-GQ1b antibody titres. Bilateral dilated pupils (either tonic or fixed) can be a manifestation of MFS and anti-GQ1b immunoglobulin G (IgG) antibodies are useful to confirm the diagnosis in unexplained cases. The site of involvement is thought to be the ciliary ganglion or short ciliary nerves.