[Optic nerve tract injuries (author's transl)].

The length of the optic nerve tracts exposes them to damage from cranial injuries. The intraorbital segment of the optic nerve is vulnerable, as bone protection is incomplete and frontal injuries frequent, while indirect lesions of the optic nerve due to trauma raise diagnostic problems in comatose patients. Study of photomotor reflexes and VEP supplies valuable information. Unilateral mydriasis is not a sign of blindness, but of a lesion of the IIIrd nerve, which, may be compressed during engagement of the temporal lobe in the tentorium cerebelli region. The mydriasis indicates the side of the lesion and the need for urgent treatments. Surgical decompression of the optic canal should be performed for indirect optic nerve injuries when visual deficiency appears or becomes worse during the few days following the trauma. Visual loss noted most characteristically in chiasma lesions is bitemporal hemianopsia. In cases of optic nerve injuries, temporal campimetric deficiency in the other eye is evidence of an associated chiasma lesion. The chiasma may also be damaged following apparently mild frontal blows. Campimetric deficiency in retrochiasmatic lesions indicates the side of the lesion and, on some occasions, its precise location.