OPTIC NERVE DECOMPRESSION FOR OPTIC NERVE COMPRESSION

Optic nerve is the second cranial nerve which carries visual information from the eye ball to the brain. During its course from the orbit to the brain it is very closedy related to the lateral wall of the sphenoid sinuses. Using endoscopes this nerve can be safely approached through the nose. Endoscopic approach is far more simpler than the previously described approaches. Some times following head injury, even a trivial one in the region of the forehead, one may develop sudden blindness, due to fracture fragments pressing on the optic nerve. Though the impact is on the forehead, the forces are transmitted to the optic canal area and the fracture occurs there. Optic canal is a tightly packed compartment and there is little scope for expansion and any haematoma, oedema or fracture fragment can produce blindness. This is an emergency which requires immediate attention, since any delay will result in permanent blindness. Medical fraternity is not aware of this condition and many times patients are told “ Nothing can be done”. It is important to suspect this condition in patient sustaining injury over the forehead just above the eye, followed by sudden blindness, especially when the eye ball is normal.

A CT scan should be ordered, in which a fracture fragment may be demonstrated. Whether the CT scan shows fractures or not, in the absence of injury to the eye ball, emergency optic nerve decompression is advised. Emergency optic nerve decompression done within the first 48 hours carries an excellent chance of regaining 80-90% of vision. Thereafter the prognosis declines. Using Endoscopic techniques the optic nerve and the orbit can be decompressed ever under local anaesthesia with very little morbidity. Other lesions such as fibrous dysplasias, pneumo sinus dilantans, mucoceles and tumours can compress the optic nerve. Endoscopic optic nerve decompression helps in such patients as well.