Visionix VX22NP - How Do I Use Pelli Robson Test

VX22NP-VX22LP-VX22CP User Manual
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When the result is displayed, an image is automatically saved on the USB key with the date and the
hour.
3. How do I use Pelli Robson test?
It is a test of contrast with letters. The test is done at 1m and there are different levels of
contrast. The size of the letters is always the same.
Call the test
➢ Press the button of the group with which the test is associated (1,2 or3) until the test
appears.
Explanation of the information bar
RE, LE, Bino : The current test is for right eye, left eye or both eyes.
1/16 … 16/16 Indication of the number of he test. The test is stopped as soon as 2/3 of the
letters are not seen.
S: … Contrast sensibility (Log= 1/C))
C : … Contrast (%)
D : … Distance (always 1m)
Distribution
Each level of contrast corresponds to a distrubution of letters:
Log(Contrast sensibility) Contrast Distribution
0,00
100%
H S Z
0,15
67%
D S N
0,30
33%
C K R
0,45
22%
Z V R
0,60
17%
N D C
0,75
13%
O S K
0,90
11%
O Z K
1,05
9,5%
V H Z
1,20
8,3%
N H O
1,35
7,4%
N R D