P5 - Vision

Question 1

What is the primary function of rods?

Answer 1

rods

• -> contrast (light and dark)
• -> responsible for night vision

Question 2

What is the primary function of cones?

Answer 2

cones

• -> colour differentiation
• -> 3 sets of cones with peak sensitivities at light wavelengths of 564 nm (red), 534 nm (green) and 420 nm (blue)

Question 3

2 types of photoreceptors?

Answer 3

rods and cones

Question 4

What is the fovea?

Answer 4

fovea

• -> region of highest visual acuity
• -> mostly cones

Question 5

Where are rods found?

Answer 5

rods

• -> evenly distributed throughout retina
• -> except in the fovea where it is not found at all!

Question 6

What causes the blind spot?

Answer 6

blind spot

–> the optic disc where nerves and retinal blood cells enter and exit is devoid of photoreceptors

Question 7

What generates 65-70% of focusing power of the eye?

Answer 7

the cornea (avascular transparent epithelial layer at outer surface of the eye)

Question 8

What is the retina?

Answer 8

retina

• -> light sensitive tissue that lines the inner surface of the eye
• -> contains photoreceptors