Measurement of the subarachnoid pressure of the optic nerve in human subjects.
OBJECTIVE
We measured the subarachnoid pressure of the optic nerve in 16 patients scheduled for ocular enucleation or evisceration.


METHODS
We measured the subarachnoid pressure of the optic nerve directly with an electronic digital manometer in 16 patients scheduled for enucleation or evisceration for various blinding conditions. The nerve was exposed via a medial orbitotomy, and the subarachnoid pressure of the optic nerve was measured 5 mm posterior to the optic nerve head. The subarachnoid pressure of the optic nerve was also measured in five patients who were placed in the Trendelenburg position (head declined at a 30-degree angle) for three minutes.


RESULTS
The subarachnoid pressure of the optic nerve varied from 4 to 14 mm Hg in the 16 patients tested. The mean subarachnoid pressure of the optic nerve was 8.5 mm Hg in the 16 patients tested. An increase of 1 to 2 mm Hg in the subarachnoid pressure was observed in all five patients placed in the Trendelenburg position.


CONCLUSIONS
Subarachnoid pressure of the optic nerve can be measured in vivo in humans. The values obtained are consistent with the known physiologic range of intracranial pressure. There was no statistically significant correlation between subarachnoid pressure of the optic nerve and age or cause of blindness. The subarachnoid pressure of the optic nerve varies over a wide range.
Liu
D
D
Department of Ophthalmology, University of Southern California School of Medicine, Doheny Eye Institute, Los Angeles 90033-4684.
Michon
J
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D015353:Eye Enucleation; D017234:Eye Evisceration; D005260:Female; D006801:Humans; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009900:Optic Nerve / Q000502:physiology*; D011187:Posture; D013346:Subarachnoid Space