Human vision and function/Part 1: How the eye works/1.4 Anatomy of the visual pathway/Answers

1. Define “visual field”.

An area in space perceived by the eye/total area we are able to see.

2. Define “visual pathway”

Wiring from the eye to the brain, with the destination being the occipital cortex (primary visual cortex)

3. What are the boundaries of the human visual field in on eye?

50-60 degrees sup, 60 deg nasally, 70-75 degrees inferiorly, 90-110 degrees temporally

4. What is the impact of the convex lens shape of the lens of the eye on how we see objects in our visual field?

The lens inverts images as they enter the eye so objects on the right hand side are processed by the left side of each eye.

5. Describe what happens to the nerve fibres from the retina when they approach the optic chiasm.

The nasal fibres (from the nasal retina) cross over at the chiasm but the temporal fibres (from the temporal retina) remain on the same side.

6. A tumour compressing the optic nerve from the temporal side of the left eye will affect the vision on which side of the visual field?

The right visual field will be affected.

7. At what structure does the optic tract terminate?

At the Lateral Geniculate nucleus

8. What condition most commonly affects the optic radiations?

Stroke

9. Which part of a person’s visual field is most sensitive?

The centre of the visual field – where the macula is located.

10. Why is it important to accurately map a person’s visual field?

To detect ocular pathology early and to demonstrate changes to the field over time.