The effect of intraocular pressure and glaucomatous damage on intraocular pressure pulse amplitudes

Bilateral recordings with the applanating suction cup tonograph on eyes of 85 persons with and without glaucoma show that the intraocular pressure pulse amplitudes (IOPA) increase in size with the intraocular pressure (IOP) from an average of 1.85 mmHg at 12 mmHg IOP to 4.8 mmHg at 37 mmHg IOP. This relation resembles the one found between IOP increments and IOP by the injection of 157 equal volumes of saline into 10 eyes of human cadavers. The resemblance indicates that the IOPA versus IOP relation of the live eyes in all essentials is explained by systolic net equal-volume inputs of blood into eyes with elastic properties determined by the cornea and sclera. --IOPA are of equal size in eyes with and without glaucomatous cups and visual field defects. Since IOPA are produced mainly by volume changes in the choroid, it is concluded that the choroid is not among the tissues undergoing a general pressure atrophy in the glaucoma (cases of absolute glaucoma were not studied).