Fig. 2. Optic tract lesion. An 8-year-old girl with one month of headache and horizontal diplopia from right VI nerve palsy. Acuity was 20/25 in both eyes, and there was a relative afferent pupil affect in the right eye. A. Visual fields showed mildly incongruent right hemianopia. B. She had “twin peaks” papilledema in the right eye and nasal disc swelling in the left eye. C. MRI showed a parasellar mass, involving left more than right, which was a hypothalamic glioma. (From Rosen ES, Eustace P, Thompson HS, Cumming WJK [eds]: Neuro-Ophthalmology. London: Mosby, 1998.)