Lab 4 - Posterior Pole

Question 1

What is the pathophysiology of AMD?

Answer 1

AMD is an age-related disease which affects the macula.

In AMD, RPE recycling function decreases with age, and leads to a buildup of waste material (lipofuscin, drusen)

This in turn leads to RPE degeneration (causing detachment), photoreceptor death (geographic atrophy) and Bruch’s membrane disruption (neovascularisation, oedema)

Question 2

What is the pathophysiology of optic neuritis?

Answer 2

Inflammation of the ONH, associated with multiple sclerosis. Demyelination of the CNS impairs the conduction of nerve impulses. Optic neuritis can also be idiopathic, or associated with other inflammatory/infectious conditions.

Question 3

What is the pathophysiology of papilloedema?

Answer 3

Swelling of the ONH secondary to raised ICP.

Raised ICP is transmitted through the optic nerve head sheath, leading to compression of nerve fibres at the lamina cribrosa. This impairs axoplasmic flow and results in leakage and swelling, vascular obstruction and dilation. Eventually, retinal swelling and ONH ischaemia will occur.

Question 4

What is the pathophysiology of AAION?

Answer 4

Arteritic anterior ischaemic optic neuropathy (AAION) is linked with the inflammatory condition giant cell arteritis.

Occlusion of the short posterior ciliary arteries cuts off blood flow to the prelaminar and laminar portions of the ONH. This results in ischaemic injury to the anterior portion of the ONH

Question 5

What is the pathophysiology of NAAION?

Answer 5

Non-arteritic anterior ischaemic optic neuropathy is linked to non-inflammatory disease of small blood vessels. It involves damage to the ONH as as result of ischaemia.

Question 6

What is the pathophysiology of pseudopapilloedema/ONH drusen?

Answer 6

Drusen are buried but can be exposed with age as the overlying axons become atrophied.

Question 7

Describe what you would see upon fundoscopy of a patient with dry AMD

Answer 7

• Drusen

- RPE abnormalities

Question 8

Describe what you would see upon fundoscopy of a patient with wet AMD

Answer 8

• Drusen
• RPE abnormalities
• choroidal neovascularisation
• geographic atrophy

Question 9

Describe what you would see upon fundoscopy of a patient with optic neuritis

Answer 9

ONH usually appears normal, but can show temporal disc pallor in one eye, indicative of a previous episode of optic neuritis

Question 10

Describe what you would see upon fundoscopy of a patient with papilloedema

Answer 10

Blurred ONH margins, haemorrhages, elevation

ONH enlarged/swollen, absence of cup

Cotton wool spots

Paton lines, especially temporally

Macular oedema

Drusen-like deposits on disc surface

If atrophic, would also observe ONH pallor with indistinct margins

Question 11

Describe what you would see upon fundoscopy of a patient with AAION

Answer 11

Strikingly pale, oedematous ONH with flame haemorrhages at disc margin
- retinal pallor, cherry red spot

Question 12

Describe what you would see upon fundoscopy of a patient with NAAION

Answer 12

diffuse/sectoral hyperemic disc swelling with flame haemorrhages

Small disc with no central cup on the disc at risk

Question 13

Describe what you would see upon fundoscopy of a patient with ONH drusen

Answer 13

Drusen on ONH, ONH elevation confined to the disc, spontaneous venous pulsations