Applanation tonometry and correction according to corneal thickness.
OBJECTIVE
In previous studies, it has been shown that the central corneal thickness influences the measurement values of applanation tonometry. The aim of this study is to answer the question as to which values and with what frequency the tonometer readings as based on corneal thickness have to be corrected in the patients attending an ophthalmic practice.


METHODS
The corneal thickness was measured in 579 patients using ultrasound pachymetry under the conditions prevailing in a medical practice; from the thickness obtained, the correction values for intraocular pressure were calculated.


RESULTS
Correction values of +/-2 mm Hg and above were found in half of the patients examined, and correction values of +/-3 mm Hg and above in a good quarter of the patients. The correction value was +/-4 mm Hg and more in every fifth patient.


CONCLUSIONS
Corneal thickness does, in fact, influence the results of applanation tonometry to a clinically relevant degree.
Department of Ophthalmology, St. Elisabeth Hospital, Rodalben (Palatinate), Germany.
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Stodtmeister
D000368:Aged; D000886:Anthropometry; D002138:Calibration; D003315:Cornea / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000000981:diagnostic imaging / Q000473:pathology*; D014065:Tonometry, Ocular / Q000592:standards*; D014463:Ultrasonography