Einflussgrößen auf die Applanationstonometrie - ein praxisorientierter Überblick

Abstract

Applanation tonometry has been the gold standard in clinical ophthalmology for more than fifty years. The most popular factor is central corneal thickness that is now routinely considered in glaucoma management. However, other individual features of the cornea can also play a key role for the interpretation of the applanation values. Other factors influencing applanation tonometry that have been well known for decades include tear film, fluorescein illumination etc., and should be kept in mind. According to the available literature the absence of a correct calibration cannot be neglected.

The influence of intraocular pressure on the damping of a coupled speaker–air–eye system

“…The results correlate well with GAT measurements in the physiologically desired IOP range from 10 to 20 mmHg (Giaconi et al, 2016). However, the measurement uncertainty of air-puff tonometers of 5 mmHg is larger than that of the GAT (Rosentreter et al, 2011;Derka, 1980). Besides the dominant use for out-patient screening tests, airpuff tonometers do not meet clinical requirements of an uncertainty of < 3 mmHg and cannot be used in the home environment (Grigorian et al, 2015).…”

“…The Goldmann Applanation Tonometer (GAT), initially described in 1955 (Rosentreter et al, 2011;Goldmann and Schmidt, 1957), is still the clinical gold standard for IOP measurements and has an uncertainty of 1-2 mmHg (Cook et al, 2012), which can increase to 3.8 mmHg in interindividual comparison (Rosentreter et al, 2011). It detects the static force that is needed to indent the cornea with a glass stamp to a predefined flattened area with a diameter of 3.06 mm.…”

“…It detects the static force that is needed to indent the cornea with a glass stamp to a predefined flattened area with a diameter of 3.06 mm. The IOP can then be calculated according to the Imbert-Fick law (Rosentreter et al, 2011;Goldmann and Schmidt, 1957). Aside from the medical experience of the user (Rosentreter et al, 2011), the uncertainty of the result also depends on the thickness and age-related material parameter changes in the cornea (Tonnu et al, 2005).…”

“…The IOP can then be calculated according to the Imbert-Fick law (Rosentreter et al, 2011;Goldmann and Schmidt, 1957). Aside from the medical experience of the user (Rosentreter et al, 2011), the uncertainty of the result also depends on the thickness and age-related material parameter changes in the cornea (Tonnu et al, 2005). In addition, the measurement requires a local anesthetic, and the procedure is unpleasant, carries infection risks, and can only be performed by physicians and optometrists.…”