Immediate rigidity of an eye. I. Whole, segments and strips.

The immediate stress-strain relation (rigidity) of the tunic of an eye and of its parts has been determined by many investigators. Although mechanical experiments on segments and strips from the eye are useful in themselves, the data from them cannot be quantitatively summed to yield valid whole-eye rigidity data. A continuous fast injection was found to be equivalent to rapid incremental injections in determining pressure-volume relations. The difference between live-eye rigidity and enucleated-eye rigidity is discussed. The difference can be either neglected as insignificant or explained as a result of the expulsion of a small amount (4%) of the total blood volume of the eye.