Ocular volume and ocular rigidity

The coefficient of ocular rigidity ( K) was measured in enucleated human eyes by the injection of known volumes of fluid and measuring the rise in pressure. The intraocular volume of each eye was calculated from profile photographs of the globe and the scleral thickness measured by a light-scattering technique. K showed a highly significant negative correlation with ocular volume but a coefficient of rigidity which included the volume of the individual eye did not show a significant correlation with ocular volume. There was no correlation between K and scleral thickness but K tended to be higher in older eyes. In 17 out of 20 eyes K decreased as the level of pressure at which it was measured increased. The results suggest that the lower ocular rigidity of myopic eyes is largely due to their greater ocular volume and not to any abnormal distensibility of the sclera.