Glaucoma

Question 1

What is the most common form of glaucoma?

Answer 1

POAG

Question 2

What is the leading cause of irreversible blindness in the developed world?

Answer 2

POAG

Question 3

Name RFs for POAG

Answer 3

• HTN
• DM
• Hypercholesterolaemia
• Age
• Smoking
• Myopia

Question 4

Mutations in which chromosomes have been linked to POAG?

Answer 4

Chromosome 1 and 3p

Question 5

What gene mutation is associated with earlier onset glaucoma and higher pressures? What does it code for?

Answer 5

GLC1A gene ( Chromosome 1 open angle glaucoma gene

Codes for TIGR (TM inducible glucocorticoid response) or MYOC (myocillin)

Question 6

What does the GLC1A gene stand for?

Answer 6

Chromosome 1 open-angle glaucoma genet

Question 7

What does TIGR protein stand form?

Answer 7

TM inducible Glucocorticoid response

Question 8

How does the GLC1A gene mutation affect patients with glaucoma?

Answer 8

More likely to have earlier age of onset
Higher peak IOP
More likely to need surgery

Question 9

How does high IOP affect the optic nerve?

Answer 9

Pressure induced ischaemia of the capillary bed of the optic nerve and direct mechanical pressure reducing axoplasmic flow in the axons passing through the lamina cribrosa

Question 10

Which nerve fibre bundles in the ON are most likely to be affected in POAG?

Answer 10

Nerve fibres passing into the ON above or below the horizontal line on the temporal side of the disc

And the prelaminar fibres

Question 11

Apart from High IOP, which other mechanism can contribute glaucomatous damage to the optic disc?

Answer 11

Occlusive disease leading to poor perfusion of the posterior ciliary arteries –> ischaemic optic atrophy

Question 12

What are the risk factors for PACG?

Answer 12

• Age
• Hypermetropia
• History of blunt trauma

Question 13

Name causes for secondary open angle glaucoma?

Answer 13

The angle is obstructed by matter:

• Cells and protein in inflammation e.g. uveitis
• Pseudoexfoliation syndrome
• Tumour cell infiltration
• Haemorrhage in trauma
• Phacolytic glaucoma

Question 14

What is phacolytic glaucoma?

Answer 14

Caused by high molecular weight proteins that have leaked through and INTACT capsule in a hypermature cataract, blocking the TM

Question 15

What exam findings may be present in phacolytic glaucoma?

Answer 15

• Open iridocorneal angle
• Corneal oedema
• Pseudohypopyon (lens material and macrophages)

Question 16

Name causes for Secondary Closed angle glaucoma

Answer 16

The chamber angle is displaced and closed mechanically

• Rubeosis iridis
• Tumours of the eye e.g. Melanoma, forcing the lens forward
• Anterior or posterior psynichiae in uveitis
• Phacomorphic glaucoma - due to an intumescent lens