Ultrasonographic measurement of the posterior coats of the eye and their relation to axial length.

In 159 eyes with a spherical correction varying from +14.0 to -27.0 diopters, the axial length and thickness of posterior ocular coats were measured ultrasonographically. As proven in experimental studies, retina, choroid, and sclera were resolved in a considerable percentage of cases by combining A- and B-mode techniques of modern ultrasonographic equipment. The presumed close inverse correlation between the axial length of the eye and ocular coat dimensions was confirmed by statistical analysis. These values were used to calculate the approximative volume of the posterior half of the ocular coats. There was evidence for a constant tissue volume regardless of the difference in surface and axial length parameters between hyperopic and myopic eyes. Results are discussed and compared with theories of axial growth under physiological and pathological conditions.