Measurement of intraocular pressure: a study of its reproducibility

Intraocular pressure was measured with Goldmann applanation tonometers by two independent examiners in 420 eyes. A difference between measurements of at least 3 mm Hg occurred in 30% of the eyes. Some evidence suggests that the differences between pressure measuremens were caused by actual changes of intraocular pressure rather than by instrument inaccuracy of technician error.