MATERIAL and METHODS: A surgical anatomical evaluation was made of twenty optic canals in ten cadavers fixed in 10% formaldehyde. These were evaluated together with measurements of the ophthalmic artery and histological sections of the surrounding structure.

RESULTS: The ophthalmic artery separated from the carotid at different positions. In our material, eight (40%) left the carotid from the upper internal part, six (30%) from the front internal part, four (20%) from the upper central part, and two (10%) emerged at the end of the cavernous segment of the middle of the carotid at a steep angle. In none of the material did the ophthalmic artery originate from any other vascular structure than the carotid. Whatever position the ophthalmic artery was in within the canal on entry, it followed the outer walls of the canal and left the canal in the lower external section of the optic nerve. In the literature, work on this area has been limited to examining the anatomical values and variations in the optic canal. The results in the present study have been obtained by combining the data with surgical anatomy.

CONCLUSION: This is a method of transcranial decompression of the optic canal which is safe for the vascular structures in and around the optic canal providing certain points are kept in mind. Keywords : Ophtalmic artery, Optic canal, Decompression, Optic nerve