During an eye test, eye doctors use eye charts to measure how well you see in the distance. The classic example of an eye chart is the Snellen eye chart, developed by Dutch eye doctor Hermann Snellen in the 1860s.
In the TEST window, press the TEST key in order to access: the eye-chart tests are situated on the left column, which corresponds to the group test 1 yellow key.
Select a test and press CHANGE in order to start it. The test comprehends three eye-chart lines with increasing visual acuity value. In the right edge and in the bottom are showed the data related to the displayed table.
In order to display or hidden these data, press the DATA key. All eye-chart tests have the same functions:
• the UP and DOWN keys permit to increase or decrease the visual acuity value;
• the CHANGE key allows to choose in a pseudo-random way other stimuli to display;
• the left arrow and right arrow keys permit to modify the contrast of the table displayed, according to the logarithmic scale of the sensitivity to the contrast.
In order to change the display of the table, you can use the CHAR, LIN and DIM keys:
the CHAR key allows to display a single type,
the LIN key allows to display either a single or more lines,
the DIM key allows to display lines with equal or increasing visual acuity.
There are two other possible displays by pressing the RED e GREEN key; the table will be divided with a green background on the right and a red one on the left.
The BLACK and WHITE key, on the contrary, allows to invert the background colour with the eye-chart one. Obviously, whichever is your display, it is possible to change the displayed stimuli by pressing the CHANGE key. The test works according to a scale chosen in the Scale SETUP menu, as displayed in this window.
With the single type display, by pressing the CHAR key, it is possible to insert the Crowding effect by pressing the RED and GREEN key on the remote control.
DMD Med Tech s.r.l.
via Monviso 14 10090 Villarbasse (TO) ITALY
Phone#: +39.011.952.8282 Fax#: +39.011.952.840
www.visualacuitytesteyechart.com