Authors' reply

Internuclear ophthalmoplegia (INO) presents with limited adduction and abducting nystagmus, which was not present in our patient; convergence / accommodative paresis presents with poor near vision, which was preserved in our patient; saccadic intrusions / oscillations were unlikely as there were no involuntary movements noticed on examination; pre-existing decompensated phoria was again unlikely as there was no history indicative of this, although decompensation occurs if fusion is disrupted, due to decreased vision in one eye; and finally a monofixation syndrome was unlikely considering 20/20 vision in each eye.