Glaucoma

Question 1

what is the normal flow of aqueous humour?

Answer 1

produced by the ciliary processes in the posterior chamber. It then flows through the pupil and out through the trabecular meshwork and into the canal of Schlemm.

Question 2

how does increased pressure damage the optic nerve?

Answer 2

o Raised intraocular pressure causes mechanical damage to axons
o Raised intraocular pressure causes ischaemia of the nerve axons by reducing blood flow at the nerve head

Question 3

what is a glacuoma?

Answer 3

raised pressure in the eye

Question 4

what are the different types of glaucoma?

Answer 4

Primary Glaucoma
Congenital Glaucoma
Secondary Glaucoma

Question 5

what are the different types of primary glaucoma?

Answer 5

o Chronic open angle

o Acute and chronic closed angle

Question 6

what are the different types of congenital glaucoma?

Answer 6

o Primary
o Secondary to maternal rubella infection
o Secondary to inherited ocular disorders

Question 7

what are the different types of secondary glaucoma?

Answer 7

o	Trauma
o	Ocular surgery
o	Associated with other ocular disease
o	Raised episcleral venous pressure 
o	Steroid induced

Question 8

what are the causes of chronic open angle glaucoma?

Answer 8

• High intraocular pressure
• Older age
• Afro Caribbean
• FH
• Myopia
• Thin cornea
• Migraine
• Systemic hypertension
• CVS disease
• Diabetes

Question 9

what is the pathophysiology of chronic open angle glaucoma?

Answer 9

The trabecular meshwork appears normal but structurally and functionally offers an increased resistance to the outflow of aqueous.
This results in elevated ocular pressure

Question 10

what is the cause of the obstruction in chronic open angle glaucoma?

Answer 10

o Thickening of the trabecular lamellae which reduces pore size
o Reduction in the number of lining trabecular cells

Question 11

how does reduced blood flow in open angle glaucoma cause nerve loss to the optic head?

Answer 11

o Stretching
o Vascular compromise
o Alteration of glutamate transmitter pathways

Question 12

what are the clinical features of the chronic open angle glaucoma?

Answer 12

• Elevated pressure
• Optic disc changes – increased cupping, vertical thinning and notching of neural rim, haemorrhage at disc , atrophy as damage progresses
• Visual loss – peripheral, central spared

Question 13

what is the medical management of chronic open angle glaucoma?

Answer 13

o Topical B blockers
o Prostaglandin analogues
o Carbonic anhydrase inhibitors, alpha agonists

Question 14

what is the surgical management of chronic open angle glaucoma?

Answer 14

o Trabeculectomy
o Plastic tube
o Laser procedure

Question 15

acute angle glaucoma is a…

Answer 15

medical emergency

Question 16

what are the risk factors of acute angle glaucoma?

Answer 16

shallow eyes, hypermetropia, a short eye, older age, presence of cataracts, small cornea, antidepressants, anticholinergics, thick glasses, steroids

Question 17

what are the primary causes of acute angle glaucoma?

Answer 17

pupillary block, plateau iris configuration

Question 18

what are the secondary causes of acute angle glaucoma?

Answer 18

phaemorphic, ciliochondrial expansion, lens subluxatoon, uveitis

Question 19

what are the clinical features of acute angle glaucoma?

Answer 19

• Acute onset
• Painful
• Reduced visual acuity
• Coloured haloes around bright lights
• Headache, nausea, vomiting
• Red conjunctiva, cloudy cornea
• Pale optic disc
• Eye stony hard – blot
• Pupil mid dilated
• ICP>40

Question 20

what is the management of acute angle glaucoma?

Answer 20

• Reduce pressure with medication then surgical iridotomy
• Medical – acetazolamide + timolol then brimodine
• Surgery – laser

Question 21

what are the two mechanisms of acute angle glaucoma?

Answer 21

Pupillary block

Closure of outflow angle in

Question 22

what is the pathophysiology of pupillary block in acute angle glaucoma?

Answer 22

o The lens pushes up against the back of iris blocking flow of aqueous humour through the pupil
o This resistance to aqueous flow produces a pressure-gradient across the iris
o Iris and lens are forced to move anteriorly
o Forward movement closes the irido-corneal angle and blocks the trabecular meshwork
o This causes build up of the aqueous fluid = RAPID RISE in eye pressure

Question 23

what is the pathophysiology of closure of outflow angle in acute angle glaucoma?

Answer 23

o Hyperopic eyes which have naturally shallow anterior chambers
o When the pupil dilates the iris gets thicker and the irido-corneal angle becomes smaller and is more likely to close spontaneously