Haag-Streit Perkins MK3 Manual De Instrucciones página 18

en
5.6 Measurement
The Perkins tonometer should be held so that the thumb rests on the milled wheel
(Fig 2, 8) controlling the spring. The light is switched on by turning the thumb-wheel
until the scale reading (Fig 2, 9) is just above zero.
If the forehead rest (Fig 1, 1) is to be used, the stem (Fig 1, 3) should be extended after
loosening the locking screw (Fig 1, 2). When the forehead rest is correctly positioned,
tighten the locking screw and the instrument can then be brought towards the patient
so that the face of the prism comes into contact with the cornea.
For ease of use, hold the tonometer obliquely with the handle slanted away from the
nose (see section 5.4). Care should be taken to prevent the prism touching the eyelid
margin.
When seen through the viewing lens (Fig 2, 7) the semicircles of fluorescein should now
be clearly visible and appear equal in size, denoting that the contact point is central on
the cornea.
The light is switched off by turning the thumb-wheel until the scale reading (Fig 2, 9) is
below zero.
Measurement of the force necessary to flatten a corneal surface of constant
ø 3.06 mm size.
Figure 5
Dial indicator: 1
Force: 9.81 mN
Pressure: 1.33 kPa = 10mm Hg
18
correct applanation
too light applanation
too heavy applanation
decentred