colourblindness

Question 1

What is Morning Glory Syndrome characterized by?

Answer 1

• Malformation of optic disc
• Peripapillary scleral defect
• Absence of lamina cribrosa
• Axial retrodisplacement of optic nerve
• Large optic disc
• Radial pattern of blood vessels

It involves a sieve-like area formed in the sclera allowing optic fibers to move out.

Question 2

What happens if the lamina cribrosa is absent?

Answer 2

Axial retrodisplacement of optic nerve

It refers to the fenestrated lamina of sclera that allows fibers of the optic nerve to pass through.

Question 3

What are the characteristics of myelinated nerve fibers in the optic disc?

Answer 3

• Normal optic disc: Non-myelinated
• No visual loss
• White streaks around optic disc if myelinated

Myelination occurs only in the intraorbital part of the optic nerve.

Question 4

Define colour blindness (CB).

Answer 4

• Anopia: Non perception
• Anomaly: Defect in perception

Primary colours affected include Red (Protan), Green (Deutra), and Blue (Trita).

Question 5

What are the types of congenital colour blindness inheritance?

Answer 5

• X-linked recessive inheritance (m>F)
• Genes affected: Red (L cones), Green (M cones), Blue (S cones)

Chromosome X is associated with red and green cones, while chromosome 7 is associated with blue cones.

Question 6

What are the acquired causes of colour blindness?

Answer 6

• Optic nerve diseases (e.g., due to ethambutol)
• Macular disease (except Stargardt’s disease)
• Sildenafil
• Old age
• Digoxin

Glaucoma is excluded from these causes.

Question 7

What is Dyschromatopsia?

Answer 7

Defective colour vision

It includes various types of colour perception anomalies.

Question 8

What is Achromatopsia?

Answer 8

Absent colour vision

Individuals can only differentiate between black and white.

Question 9

What does dichromatic vision imply?

Answer 9

• Anopia for 1 colour
• Can perceive other colours

Types include Protanopia, Deutranopia, and Tritanopia.

Question 10

What is heméralopia?

Answer 10

Day blindness

Question 11

What are the types of trichromatic anomalous vision?

Answer 11

• Protanomaly
• Deutranomaly
• Tritanomaly

These conditions are associated with autosomal recessive inheritance.

Question 12

What is the effect of blue colour blindness?

Answer 12

Yellowish tinting of vision (xanthopsia)

It is a specific type of colour perception anomaly occurring at old age or d/t digoxin

Question 13

What is the Ishhara chart used for?

Answer 13

To detect color vision deficiencies

Cannot detect tritan defects; blue color problems are ignored.

Question 14

What principle does the Hardy Rand Ritler test use?

Answer 14

Pseudoisochromat principle

Includes 24 plates with shapes and 38 plates with numbers and lines, leading to false positives and false negatives.

Question 15

What is the most accurate test for severity of color blindness?

Answer 15

Nagel’s anomaloscope

It is considered the most accurate test for assessing color blindness severity.

Question 16

Which test is known as the most sensitive test for color vision deficiencies?

Answer 16

Farnsworth Munsell 100 hue test

It has 85 hue caps and can detect all types of color vision deficiencies.

Question 17

What does the Farnsworth Munsell 15 hue test differentiate between?

Answer 17

Congenital and acquired color blindness

This test helps in identifying the type of color vision deficiency.

Question 18

What is the purpose of the Lantern test?

Answer 18

Vocational color blindness testing

This test is considered obsolete and uses 85 hue caps.

Question 19

True or false: The Farnsworth Munsell 100 hue test has 85 hue caps.

Answer 19

ट्रू

The Farnsworth Munsell 100 hue test has 85 hue caps, while the 15 hue test differentiates between types of color blindness.