6. Anomoloscopes and Lantens

Question 1

Describe the use of anomaloscope used for CV testing?

Answer 1

It is the gold standard and mainly used for red- green CV defects.
It is used in CV centers for occupational testing.
Anomaloscope provides COMPLETE diagnosis of Red-Green colour defect.

Question 2

Anomaloscope is the only test that differentiates between?

Answer 2

Dichromats from anomalous trichromats

Question 2

Anomaloscope is the only test that differentiates between?

Answer 2

Dichromats from anomalous trichromats

Question 3

Hue arrangement tests detect what?

Answer 3

Detect Protan, Deutran and Tritan defects.

Question 4

Is D15 and City University test good for screening?

Answer 4

No not good for screening, but good for classification and useful to assess severity.

Question 5

Anomoloscope is used to test monocularly or binocularly?

Answer 5

Monocular - one eye piece. Each eye tested separately.

Question 6

How is anomoloscope used?

Answer 6

PART 1: Patient asked to ‘match’ two halves of the field.
PART 2: Examiner pre-sets red- green fields and patient tries to match the colour with the yellow field only.
This adjustments are made using the dials on the side.

Question 7

What is recorded as results from the anomoloscope?

Answer 7

Record the value of yellow if a match is made.

Question 8

Why can dichromats match all red- green combinations with yellow?

Answer 8

All 3 anomaloscope primaries fall on a common colour confusion line for protanopes and deuteranopes.

Question 9

In the graph where the values of yellow are plotted against the values of red- green mixture values, the intensity of the yellow of protanopes changes but deuteranopes do not, why?

Answer 9

Due to loss of long wavelength of photopigments of the red sensitive cone protanope has on the luminance function of the eyes apparent brightness.

Question 10

Describe the luminance function of % of light absorbed in relation to wavelength of normal patients compared to deuteranopes compared to protanopes?

Answer 10

Deuteranopes have similar sensitivity to light as normal trichromats to light.
Protanopes: sensitivity to light has shifted (less sensitive to longer wavelengths of light).

Question 11

What is the key concept of setting the anomaloscope?

Answer 11

Anomaloscope is set so that all red- green mixtures look the same perceived luminance to normal trichromats.

Question 12

How are anomalous trichromats differentiated from dichromats using the graph that has: monochrome scale on the y- axis and colour mixture scale on the x-axis?

Answer 12

Diagonal complete line: Protanope.
Diagonal incomplete line: Protanomalous trichromat.
Horizontal complete line: Deuteranope.
Horizontal incomplete line: Deuteranomalous trichromat.

Question 13

Lanterns are only used for?

Answer 13

Occupational testing

Question 14

Lanterns have what 3 principles?

Answer 14

1. Inform patients the colour names before performing the test by showing them colours at the start and giving them names.
2. Some will present pairs or single- you need to explain patients which one you will be doing first- ask patient to name the colours that they see at the top first followed by the colour they see at the bottom next.
3. Each of the lights are presented for a fixed time.

Question 15

Do lantern tests specify the quantify the CV defect?

Answer 15

This test does not specify or quantify the colour vision defect. It is used for occupational testing only.

Question 16

What is the main task in lantern tests?

Answer 16

Colour naming

Question 17

What is considered as a failure in lantern test?

Answer 17

A single error is considered to be a failure.
Any time a colour is misnamed.

Question 18

What are the 2 steps used when a patient comes in for CV test that is useful for occupational purposes?

Answer 18

STEP 1: Identify the visual standards
STEP 2: Give advice based on clinical evidence. (Anomaloscope and lantern testing is done at specialized centers).

Question 19

The variability in the results from test results depends on?

Answer 19

Depends on the colour vision test used.

Question 20

What does colour assessment and diagnosis (CAD) use?

Answer 20

Uses Dynamic Luminance Contrast Noise

Question 21

How is CAD assessment done?

Answer 21

Done using computer.
4 boxes are presented with the brightness changing randomly from dark to light- this gets rid of any background contrast clues.
On this boxes are coloured targets that are moving along 4 diagonal positions.
Patient has to identify each time they see the colour move and the direction in which the colour is moving.

Question 22

A minimum of how many tests are required to identify red- green defects?

Answer 22

Minimum of 2 tests required to identify, detect, classify and grade a defect.