Acquired Colour Vision Defects

Question 1

What can cause acquired CV defects?

Answer 1

Medication
Injury/Trauma
Disease

Question 2

What are Kollner’s classifications of acquired CV defects?

Answer 2

Blue-yellow blindness
Progressive red-green blindness

Question 3

What are some features of acquired CV defects?

Answer 3

Can be monocular
VA and VFs can be affected
Severity varies dependant on cause
Prevalence equal between genders
Not easily classified

Question 4

What occurs in blue-yellow blindness?
What type of disease does it tend to occur in?

Answer 4

Blue-yellow perception changes first, followed by red-green later
Retinal disease

Question 5

What occurs in red-green blindness?
What type of disease does it tend to occur in?

Answer 5

Blue-yellow and red-green both affected, but red-green more noticeable
Optic nerve or cortex affected

Question 6

What is Kollner’s type 1 classification and what are they associated with?

Answer 6

Red-green - similar to protans (reduced L wavelength sensitivity)
Progressive cone dystrophies
Chloroquine toxicity

Question 7

What is Kollner’s type 2 classification and what are they associated with?

Answer 7

Red-green - similar to deutans (reduced M wavelength sensitivity)
Optic neuropathy
Ethambutol toxicity

Question 8

What is Kollner’s type 3 classification and what are they associated with?

Answer 8

Blue-yellow - similar to tritans (reduced S wavelength sensitivity)
Cataract
Glaucoma
AMD
DR

Question 9

What happens to CV when a cataract develops?

Answer 9

The yellowing of the lens causes a shift in the wavelengths transmitted to the retina (yellow lens absorbs blue wavelengths) so blue-yellow defect occurs - vision becomes more yellow

Question 10

How can CV testing help clinically?

Answer 10

Helps to detect retinal disease early - before any other symptoms are noticed.

Question 11

What type of defect is seen in AMD and why?

Answer 11

Type 3 (blue-yellow)
Blue cones more easily damaged

Question 12

What type of defect is seen in DR?

Answer 12

Type 3 (blue-yellow)

Question 13

What type of defect is seen in POAG and why?

Answer 13

Type 3 (blue-yellow)
Due to damage of ganglion cells/blue cones due to increased IOP

Question 14

What type of defect is seen in Optic Neuritis and why?

Answer 14

Progressive red-green
Demyelination of optic nerve

Question 15

What is achromatopsia?

Answer 15

No CV - black and white vision

Question 16

What is anomia?

Answer 16

Inability to name colours appropriately

Question 17

What is hemiachromatopsia?

Answer 17

Loss of colour in one half of vision (due to damage only on one side of vision)

Question 18

When is the most common time that a medication will cause CV defects?

Answer 18

Prolonged treatment or dose exceeded

Question 19

What are some examples of drugs which can cause red-green defects?

Answer 19

Ibuprofen
Chloroquine
Streptomycin

Question 20

What is an example of a drug which can cause blue-yellow defects?

Answer 20

Chloroquine

Question 21

What can chloroquine cause other than CV defects? Is the effect reversable?

Answer 21

Bull’s eye maculopathy
Not reversable

Question 22

What are some examples of toxins which can cause red-green defects?

Answer 22

Carbon monoxide
Lead
Thalium

Question 23

What is cyanopsia?

Answer 23

Vision is ‘tinged’ blue after cataract removal - brain had adapted and was ‘adding’ blue back in when cataract present. Recedes after 2-3 weeks.

Question 24

What defect can Leber’s optic atrophy cause?

Answer 24

R-G with deutan bias

Question 25

What defect can retinal detachment cause?

Answer 25

B-Y

Question 26

What defect can retinitis pigmentosa cause?

Answer 26

B-Y

Question 27

What defect can Stargardt’s disease cause?

Answer 27

R-G, no bias

Question 28

For which diseases does CV change before other signs are manifest?

Answer 28

DR (CV loss before retinopathy)
Glaucoma (CV loss before VF defect)

Question 29

In optic neuritis, what percentage of cases have a CV defect?

Answer 29

100%

Question 30

What is chloroquine used to treat?

Answer 30

Rheumatoid arthritis
Anti-malarial