Sources of error with use of Goldmann-type tonometers
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Updated: Nov 8, 2026

Comparison of Agreement and Accuracy using Binocular Wavefront Optometer with Autorefractor and Phoropter
Published on: September 16, 2025
1Eye Foundation of Kansas City, Department of Ophthalmology, University of Missouri-Kansas City School of Medicine.
Abstract:
There are many sources of error in the use of Goldmann-type applanation tonometers. In clinically normal corneas hypofluorescence of the precorneal tear film, accommodation, the Valsalva maneuver and vertical gaze are preventable causes of large tonometric errors. Repeated tonometry may induce a decline in the intraocular pressure (IOP). Variations in the corneal resistance to indentation between eyes cause significant errors. The most significant cause of error in clinically abnormal eyes is corneal epithelial edema, which causes a marked underestimation of IOP. Measurements obtained with Goldmann-type tonometers can be used with confidence to monitor changes in the IOP of an individual, but should not be relied on to determine the absolute manometric pressure within an eye or to compare the IOPs in eyes of different individuals.
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