37,38 - CV

Question 1

Inherited vs acquired CV?

Answer 1

• Present at birth
• Doesn’t change with age
• Classified and diagnosed easily
• BE affected
• VA and VF normal
• Red green mostly
• Males more likely
• Occur after birth
• Type + severity changes w/ time
• Hard to classify
• Monocular differences in severity
• Decreased VA and VF defects
• More incidence in blue/yellow
• Both genders affected

Question 2

Isochromatic line convergence where?

Answer 2

Protan = 0.75, 0.25
Deutan = 1.40, -0.40
Tritan = 0.17, 0

Question 3

Verriest aquired CV classificaition?

Answer 3

Type 1 (acquired R-G)
- Protan-like, mild to severe confusion in R-G hues.
- Moderate to severe VA decrease
Type 2 (acquired R-G)
- Deutan-like, mild to severe confusion in R-G hues w/ mild B-Y hue loss
- Moderate to severe VA decrease
Type 3 (acquired B-Y)
- Tritan-like, mild to moderate confusion of B-Y hues w/ lesser impairment to R-G
- VA normal or moderately reduced.

Question 4

What’s Kollner’s rule?

Answer 4

“B-Y colour defects arise in retinal disorders. ON disorders give R-G defects”
Lots of exceptions, many R-G start w/ B-Y defect.

Question 5

Police CV test?

Answer 5

Ishihara 24 plates edition.
3 or more errors -> 100hue, D15, or farnsworth lantern + C100
If fail 2nd set of tests or is protan defect.

Question 6

Armed forces CV test?

Answer 6

CP-A = pass w/ ishihara
CP-B = fail ishihara but pass lantern
CP-C = fail both
A = Rifles, SAS (air)…
C = Priest, chaplain…

Question 7

Civic aviation authority CV test?

Answer 7

Class 1, 2, or 3 medical certificate requires ishara 24 palte edition pass.
If fail, stage 2 = run one of the lantern tests and anomaloscope or CAD or D15
Medical certificate given if:
- Pass Holmes wright lantern
- Pass fanrsowrth lanter AND anomalscope are not protan/protanomolous
- Pass CAD
- Pass D15
If fail stage 2, do stage 3
- PAPI where right angle shows 2 red + 2 white lights and any other angle doesn’t work.

Question 8

Can CVD ppl fly?

Answer 8

As long as they can distinguish colours used in air. If fail class 1, can have class 2 but onloy fly during day.

Question 9

Marines CV test?

Answer 9

Must past lantern

Question 10

Railyways and firemen CV test?

Answer 10

1) Ishihara. If fail, do real world test
2) No CV needed

Question 11

How to test CV in CEE

Answer 11

Tests:
- Ishihara – monocular, random order
- D15 – monocular
– If fail, repeat + binocular (learning effect)
– If pass, desat 15
- C100 – by this point know if inhertied or acquired, if not sure do monocular, 7 readings on average
- OPTEC 900 – binocular
- Anomaloscope – monocular if unknown, binoc if known inherited
- CAD
- 100 hue – For occupational testing, not for looking for acquired defects.