Haag-Streit R900 Tonometer

Haag-Streit AT 900 Tonometer Model R


The Haag-Streit Applanation Tonometer AT 900 model R (also known as the R900 Tonometer) has been the gold standard in tonometry for decades.



The Haag-Streit Applanation Tonometer AT 900 model R can be left on your slit lamp permanently. It is fastened to the microscope on a mounting base and swivelled in front of the microscope for the examination. The observation of the applanated surface is conducted monocularly – only through the left eyepiece.

Compatible with Haag-Streit BM 900 Slit Lamps

Disposable tonometer prisms (such as Tonosafe™) or resusable Goldmann measuring prisms can be used with all Haag-Streit tonometers.


  • The measurement of the ocular pressure is carried out on the patient sitting at the slit lamp in conjunction with other routine microscopic examinations.
  • High accuracy of the measurement - the average deviation in any one single examination does not exceed ± 0.5 mm Hg.
  • The intraocular pressure in mm Hg is found by multiplying the drum reading by ten.
  • Scleral-rigidity is not to be taken into account as the small volumetric displacement of 0.56 mm3 increases the intraocular tension by about 2.5 % only.
  • Repeated measuring procedures do not reduce the ocular pressure, as no massaging effect occurs.
  • The instrument stays permanently mounted to the slit lamp and is swung into place when IOP readings are required.