Influence of intraocular pressure on axial elongation.

The role of intraocular pressure (IOP) on axial elongation was studied by the following three experiments. 1) Thickness of the sclera in the lid-sutured-myopia of three monkeys was examined by light microscopy. The sclera of the experimental eye in the posterior pole was thinner than that of the control eye, but no differences were found in the equatorial and limbal parts of the sclera. 2) By increasing IOP, the scleral wall extensibility in 8 normal, enucleated rabbit eyes was measured by placing the foil strain gauges on the sclera. Extensibility of the sclera in the posterior pole showed a different response from that at the equator and in the limbus. 3) IOPs of the 184 human myopic eyes were measured by a Mackay-Marg tonometer in various postures. IOP elevations in high myopia and postural variations of IOP were obtained. From these experiments, it was suggested that IOP seemed to be one of the main factors in increasing the axis to the posterior pole.