To report two patients with positive ice tests who had diplopia and blepharoptosis caused by something other than ocular myasthenia gravis.

A 35-year-old female presented with a one-week history of inability to adduct the left eye and left blepharoptosis. Although the ice test was positive, serum anti-acetylcholine receptor binding antibody and the repetitive nerve stimulation test were negative. Brain angiography showed an aneurysm of the left posterior communicating artery, leading to the diagnosis of left pupil-sparing oculomotor nerve palsy. A 25-year-old female presented with an 8-month history of intermittent horizontal diplopia and blepharoptosis in the right eye. The ice test was positive, however serum anti-acetylcholine receptor binding antibody and the repetitive nerve stimulation test were negative. Anti-nuclear antibody was positive (titer 1:160).

The ice test is a useful screening test for myasthenia gravis. However, a series of differential diagnoses including blepharoptosis and ocular motility disorder should be considered because these conditions also show a positive result in the ice test.