Ametek Reichert ClearChart 4P User Manual page 30

Installation, Features, & Functions
Remote Control Functions
When the lowest level of contrast seen at all five frequencies has been determined, press
CONT
the UP arrow button again and a plot of a contrast sensitivity curve will appear on the
(cont.)
display. Contrast Sensitivity is calculated using the Michaelson formula where L(max)
represents the highest luminance and L(min) the lowest luminance:
The chart will display a green line that is a reference line for a contrast sensitivity curve
and a red line that plots the patient's contrast sensitivity for each sine wave frequency.
The frequency and contrast sensitivity data can also be exported to a USB drive.
The COLOR button accesses the test charts for color vision testing. A selection of twenty
four charts is available for testing color vision deficiencies. These charts are digital
COLOR
renderings of the American Optical H.R.R. Psuedoisochromatic Plates developed by Le
Grand H. Hardy, M.D., Gertrude Rand, PH.D., and M. Catherine Rittler, B.A. in 1955. The
H.R.R. images can be used as a tool to identify the need for further color vision screen-
ing. Press the RIGHT arrow button to display each chart in the sequence. Press the
COLOR button again to exit the test.
The first four charts in the sequence, A, B, C and D, are demonstration plates. The fourth
chart has no symbols.
The first 6 Plates separate individuals with possible color deficiencies from those with
normal vision. Listed below are normal responses to the images seen on each plate.
Any errors in Plates 1 – 6 indicate possible color vision deficiencies. No further errors
in Plates 7 – 20 indicate a mild defect unclassified as to type.
Errors in Plates 7 –11 but not in 12 – 16 indicate a mild Red/Green defect.
30
(continued)
1 2
Plate 1
X
Plate 2
O
Plate 3 O
Normal
∆
Plate 7
Plate 8 X
∆
Plate 9
Plate 10 O X
Plate 11 O X
CS = L(max) - L(min)
L(max) + L(min)
3
Plate 4
Plate 5
Plate 6
Protanopia Deutanopia
O
(continued)
4
X
O X
O
13785-101 Rev. F