Description Of Models; Commissioning; Operation; Astigmatism - Haag-Streit AT 910 Instructions For Use Manual

ENGLISH DEUTSCH FRANÇAIS
BQ 900
BX 900
Various

3.6 Description of models

•
The Applanation Tonometer AT 900 model R can be left on the slit lamp perma‑
nently. 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.
•
The Applanation Tonometer AT 900 model T is set on the guide plate over the slit
lamp axis, for tonometry purposes. The instrument can be moved between two
positions on the guide plate for observation through the right or left eyepiece. The
sensor arm with the measuring prism projects from the underside into the beam
path of the microscope and the illumination.
•
The Applanation Tonometer AT 900 model BQ has a working position and two
resting positions. To set the correct angle of incidence of the illumination, the to‑
nometer is swivelled and the illumination apparatus is positioned to the left of the
tonometer bracket. In this position, the patient's left and right eyes can be easi‑
ly examined (no 60° position). The applanated surface is observed monocularly
through the right eyepiece of the stereo microscope.
•
The Applanation Tonometer AT 870 is positioned over the slit lamp's (from oth‑
er manufacturer) microscope. The feeler arm projects into the microscope and
illumination beam path from above. The tonometer is ready for use with a single
swivel movement of the feeler arm.
NOTE!
The instructions for appliances from other manufacturers are to be ob‑
served.
4.

Commissioning

WARNING!
It is imperative to read the 'Safety' chapter and to observe its precautions
before operating the equipment.
NOTE!
A smooth operation can only be guaranteed with the use of original
HAAG‑STREIT measuring prisms and Tonosafe.
8
01-IFU_AT900-7006000-04240_eng.indd 8
ITALIANO ESPAÑOL PORTUGUÊS
5.

5.1 Astigmatism

•
If the cornea is spherical, measurements can be taken on any meridian, but it is
most convenient to measure on the 0° meridian.
•
The choice of meridian is of significance, however, when measuring eyes with
corneal astigmatism greater than 3 dioptres, since the flattened area is not circu‑
lar but elliptical.
•
It has been calculated that, in cases of greater corneal astigmatism, a surface of
7.354 mm
(mark (A)) to the meridian of the greatest radius.
Example: If the corneal astigmatism measures
the 120° graduation mark on the prism is set on the mark (A)
of the prism holder.
If, on the contrary, the measurements are
then the 30° graduation mark is set on the mark (A), meaning that simply the axis
position of the largest radius is placed on the mark (A).

5.2 How pressure is measured

The applanation tonometer functions according to the 'Goldmann method': measure‑
ment of the pressure required to maintain a uniform applanation of the surface of the
cornea.
•
The readings obtained are based on the assumption that a cornea with a 'nor‑
mal' thickness is being measured. (a different corneal thickness leads to changes
in the measured IOP) A 'normal' corneal thickness is considered to fall within the
range of 530 to 560 Mikrometer.
•
If wrong measuring results are suspected, please conduct a functional verification
in accordance with Section 'Maintenance'.

5.3 Preparing the patient

© HAAG‑STREIT AG, 3098 Koeniz, Switzerland − HS‑Doc. no. 1500.7006000.04240 – 24. Edition / 2018 – 04
NEDERLANDS SVENSKA

Operation

WARNING!
Reusable measuring prisms must be cleaned and disinfected after ev‑
ery examination.
(ø 3.06 mm) is applanated if the measuring prism is at an angle of 43°
2
6.5 mm / 30° = 52.0 dpt / 30° and
8.5 mm / 120° = 40.0 dpt / 120°
6.5 mm / 120° = 40.0 dpt / 120° and
8.5 mm / 30° = 52.0 dpt / 30°
(A) 43°
03.05.2018 10:11:13