Types of field loss

Question 1

What is bitemporal hemianopia? What can cause it?

Answer 1

Temporal loss in both fields
Due to crossing of nasal fibres in chiasm - if chiasm damaged this field defect is caused.
Could be a pituitary tumour, chiasm lesion or other lesion pushing down from above

Question 2

What does homonymous mean?

Answer 2

VF loss is on the same side of the field (i.e. R or L side, not nasal or temporal) in both eyes, so damage is post-chiasm

Question 3

What does heteronymous mean?

Answer 3

VF loss is on opposite sides of the field in each eye

Question 4

Which defects DO cross the horizontal midline?

Answer 4

Photoreceptor defects

Question 5

Which defects DON’T cross the horizontal midline?

Answer 5

RNFL defects

Question 6

Which defects DON’T cross the vertical midline?

Answer 6

Optic tract and beyond