Two independent studies of first degree relatives with clinically normal eyes revealed that the ocular pressure level is genetically determined and that the mode of inheritance is polygenic multifactorial in nature.
Armaly MF. The Genetic Determination of Ocular Pressure in the Normal Eye. Arch Ophthalmol. 1967;78(2):187-192. doi:10.1001/archopht.1967.00980030189011