Visual pathway

Question 1

What range of wavelengths can the human visual system detect?

Answer 1

400–700 nm (visible light).

Question 2

What provides most of the eye’s focusing power?

Answer 2

The cornea (~70% of focusing).

Question 3

What equation defines refractive power?

Answer 3

Diopters = 1 / focal distance (m).

Question 4

What are the three key regions of the retina?

Answer 4

Optic disk (blind spot), macula, fovea.

Question 5

List the retinal cell layers from surface to photoreceptors.

Answer 5

Ganglion → amacrine → bipolar → horizontal → photoreceptors.

Question 6

Why does the fovea give highest visual acuity?

Answer 6

High cone density + small receptive fields + lateral displacement of cells → direct light path.

Question 7

Why is peripheral vision lower acuity?

Answer 7

High rod density with large receptive fields and slower responses.

Question 8

Which retinal fibres cross at the optic chiasm?

Answer 8

Nasal retina fibres cross; temporal fibres stay ipsilateral.

Question 9

Where do most optic tract fibres synapse?

Answer 9

Lateral geniculate nucleus (LGN) of the thalamus.

Question 10

What inputs do parvocellular and magnocellular LGN layers receive?

Answer 10

Parvo (3–6): cones (colour, high acuity); Magno (1–2): rods (motion, low light).