Assessment of a New Goldmann Applanation Tonometer

The classic Goldmann applanation tonometer has been further developed. The applanation principle has been retained, while the internal force transmission and the pressure gauging have been optimized, and the display of results digitized.

The purpose of the study is to compare the standard Goldmann applanation tonometer AT900 with the new version of the device, and to test the reliability and reproducibility of measurements, as well as its safety.

Patients at the Department of Ophthalmology, University of Bern, will be included after informed consent. The study has been approved by the local ethical committee. Routine ophthalmologic examination will be performed and inclusion criteria evaluated. Measurements will be taken with the two tonometers in random order. Prior to pressure measurement, central corneal thickness will be measured with a non-contact method (Optical Low Coherence Reflectometry, OLCR pachymeter, Haag-Streit, Koeniz, Switzerland).

Inclusion criteria

• patient willing to participate and signed informed consent

Exclusion criteria

• patient under 18 y of age
• patient pregnant
• not steady fixation, nystagm
• corneal scars or corneal disease
• astigmatism higher than 2.5 diopters
• corneal surgery in the past
• microphthalmos or buphthalmos
• contact lens wear
• dry eye syndrome
• blepharospasm
• active inflammation of conjunctiva, cornea or uvea
• known allergy to topical oxybuprocain for topical anaesthesia
• known allergy to fluorescein solution (used for applanation tonometry)