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February 1983

Instantaneous Tonometry

Author Affiliations

From the Department of Ophthalmology and the Oscar Johnson Institute (Dr Moses), and the Computer Systems Laboratory-Biomedical Computer Laboratory (Dr Arnzen), Washington University School of Medicine, St Louis.

Arch Ophthalmol. 1983;101(2):249-252. doi:10.1001/archopht.1983.01040010251014

• Respiration and arterial pulse cause intraocular pressure to cyclically vary around a mean pressure. Both the respiratory and arterial pulse waves approximate sine waves, and we have represented the IOP cycle as the sum of sinusoidal pressure waves. A rapidly acting tonometer may record any portion of the IOP cycle. We have computed the probability that a single pressure measurement will lie within a given interval around mean IOP and the probability that the mean of several such measurements will lie within a given range of mean pressure. The probability that an IOP estimate will lie in a given range of mean IOP decreases as the IOP cycle amplitude increases but increases as the number of tonometric measurements averaged together increases.