The relation between glaucomatous damage and optic nerve head mechanical compliance.

Histologic studies seem to imply that the mechanical compliance of the optic nerve head, namely, its displacement under a given pressure, may be altered in glaucoma. We have developed a method to noninvasively measure the optic nerve head displacement. In postmortem human glaucomatous eyes, the optic nerve head compliance decreased as the visual field worsened (n = 15, r = -.34). The mean difference between the optic nerve head displacement of the two eyes in subjects with symmetric clinical findings differed significantly from the mean in subjects with asymmetry. In the latter group, the lower value was always measured in the more affected eye. No significant correlation was found between age and the optic nerve head compliance. Overall, the results indicate that, in glaucoma, there is a stiffening of the mechanical support of the optic nerve head.