Testing colour vision requires elaborate apparatus for scientific investigation. There are two objectives in testing for colour blindness (i) the exact nature of the defect and (ii) whether the subject is likely to be a source of danger to the community.

1. PRACTICE OF COLOUR VISION
Presenter: SHAYRI PILLAI
Liberia Eye Centre
JFK Memorial Medical Centre
August 19, 2019

2. INTRODUCTION
Testing colour vision requires elaborate apparatus for scientific
investigation. There are two objectives in testing for colour
blindness
 (i) the exact nature of the defect and
 (ii) whether the subject is likely to be a source of danger to the
community.
Parson disease of eye Section III i Ocular Examination Techniques : page 108

4. PROCEDURE
 The patient sits in a normally lit room with one eye cover . Using the
uncovered eye, the patient looks at a series of test cards. Each card
contains a multicolored dot pattern with number or symbol in each
color pattern.

5.  Doctor is informed if patient can identify the number or
symbol. Numbers, shapes, and symbols should be easy
to distinguish from their surrounding dots if patient has
normal color vision.
 If there is color vision impairment, patient might not be
able to see the symbols or have difficulty distinguishing
patterns among the dots.
 After checking one eye, the same is done for the other.
It’s possible to have a normal result on the color vision
test but still experience a loss of color intensity in one
eye or the other.

6.  Consist of coloured litho graphic plates in which bold numerals
are
represented in dots of various tints which are readily confused
with those that are colour defective.
 Normal trichromats can easily read the numbers, some of
which cannot be distinguished by the various types of colour
defectives.
 Stilling's original tests have now been largely replaced by the
Japanese test of Ishihara which largely identified red green
anomalies.
ISOCHROMATIC CHARTS

8. FARNSWORT-MUNSELL 100-HUE TEST
It identifies hue discrimination by an error score; the
greater the score the poorer the colour vision. Patients with
toxic optic neuropathy display a characteristic pattern.
Parson disease of eye Section III i Ocular Examination Techniques : page 109

10. LANTERN TEST
The subject names various colours shown by a lantern, and is
judged by the mistakes he makes. Much here depends upon
the size of the apertures of the lantern and the nature and
intensity of the light source. Many lanterns are worse than
useless. The Edridge-Green lantern is efficient if used by an
expert.

11. HOLMGREN WOOLS
These consist of a selection of skeins of coloured wool
from which the candidate is required to make a series of
colour matches.
This test has been much criticized, but if properly carried
out, gross defects of colour vision are easily recognized
Parson disease of eye Section III i Ocular Examination Techniques : page 109

12. .

13. AMERICAN HARDY-RAND-RITLER (H-R-
R)TEST
Test identifies blue-yellow anomalies.
.

14. Thank you!
Excellence Equity Efficiency
L V Prasad Eye Institute