A 42-year-old male, asymptomatic, was ophthalmologically assessed for a check-up of his type II diabetes of 3 years' evolution. On physical examination, corrected visual acuity was 1.0 in both eyes. The anterior pole was within normal and the intraocular pressure was 16 mmHg in both eyes. Intrinsic and extrinsic motility was normal. Indirect ophthalmoscopy showed a right optic nerve with band or bow-tie atrophy and left papilla described as pale; there were no signs of diabetic retinopathy.

A visual field was performed (Humphrey 30-2 Allergan Humphrey test, San Leandro, California, USA) showing right homonymous hemianopsia. In view of the suspicion of an intracranial space-occupying lesion, a brain computed tomography (CT) scan was performed in which a 2 cm diameter calcification was observed in relation to the amygdala and the head of the left hippocampus. Brain MRI showed a heterogeneous lesion in the head of the left hippocampus, with calcification and an adjacent haemorrhagic area.

The colour test was normal. On pre-surgical cerebral arteriography and vascular mapping, the patient presented an allergic reaction to contrast with cutaneous manifestations, which subsided after treatment with antihistamines.
Surgical intervention was performed by craniotomy and a complete resection of the lesion was performed. Pathological examination of the lesion revealed a subependymoma. The definitive diagnosis was subependymoma of the temporal horn of the left lateral ventricle with involvement of the retrochiasmatic pathway and optic atrophy in the left band.
In the last ophthalmological examination, the patient remained unchanged, with the same degree of atrophy of the optic nerves and the rest of the examination was normal.

