Zeiss AT 030, Product Documentation Set

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Instruction for use 3 Description of the device
AT 030 3.4 Functional description
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3.4 Functional description
The AT 030 applanation tonometer may only be used according to
its indication for use if it is used in combination with a slit lamp. In
this combination, the slit lamp fulfills the following functions:
mechanical attachment of the tonometer, illumination and
magnified observation of the produced measuring pattern. During
operation, the ZEISS slit lamp does not have any impact on the
applanation tonometer, neither has the applanation tonometer any
impact on the functioning of the ZEISS slit lamp.
Following ZEISS slit lamps are compatible to AT 030: SL 120,
SL 130, SL 220, SL 800 and ZEISS VISULAS laser slit lamps.
The AT 030 applanation tonometer was designed for ZEISS slit
lamps according to the principle applied by Professor Goldmann.
The measuring device, containing a measuring prism with built-in
optical doubling system, is mounted on the slit lamp using a
dedicated tonometer holder and the applanation surface is
observed through the microscope of the slit lamp.
Further progress has been achieved by the use of a comparatively
small applanation surface requiring only small measuring forces, as
introduced by Professor Goldmann.
Professor Goldmann discovered that the counteracting forces of
corneal rigidity and capillary attraction of tear fluid neutralize each
other at an applanation surface of 3.06 mm diameter, so that the
applied force corresponds to the intraocular pressure.
The AT 030 works on the principle of force variation due to the
expansion of a spring. Therefore, it does not require any mainte-
nance or readjustment.
The measurement accuracy and repeatability of the AT 030
measuring results corresponds to the requirements of
ISO 8612:2009.