L5: Glaucoma

Question 1

What is glaucoma?

Answer 1

Progressive optic neuropathy
- Mostly caused by high IOP, but can have normal IOP and just have increased sensitivity to changes in pressure

• Characteristic damage to optic nerve
• Associated visual field loss

Leading cause of preventable irreversible blindness

Question 2

Glaucoma: sneak thief of sight?

Answer 2

Insidious disease –> develops very slowly & usually not noticed until 50% of vision lost

Unless PACG: headache, nausea, malaise in short-term

Question 3

Aqueous production & outflow - where?

Answer 3

Produced in ciliary processes into anterior chamber

Primary drainage through trabecular meshwork; some through uveoscleral pathway

Question 4

Pathophysiology - mechanical theory

Answer 4

Increased IOP

• -> Direct compression of optic nerve fibres
• -> Interruption of axoplasmic flow
• -> Loss of cell bodies & nerve fibres

Question 5

Pathophysiology - vascular/ischaemic theory

Answer 5

Decreased perfusion at optic nerve

• -> Disturbance of vascular autoregulation
• -> Changes in systemic haemodynamics

Question 6

Risk factors

Answer 6

High IOP/normal IOP with increased sensitivity to pressure changes

Elderly

Family history –> genetic mutations

Myopia

Diabetes –> retinopathy

Question 7

IOP

Answer 7

Average: 15-16mmHg
High: 21mmHg or higher

IOP fluctuates throughout the day –> indicative of glaucoma if big fluctuations
- Highest at night

Question 8

What are the main mechanisms of action of glaucoma drugs?

Answer 8

Decrease aqueous production

• Beta blockers
• Carbonic anhydrase inhibitors

Increase aqueous drainage

• Prostaglandin analogues
• Miotics (parasympathetic agonists)

Both
- Alpha agonists

Question 9

Corticosteroids

Answer 9

Different people respond to different extents

High responders = higher increase in IOP

Question 10

Risk factors for being high responder to corticosteroids

Answer 10

Glaucoma patients
Family history of glaucoma
Elderly patients
Children
High myopia
Diabetes