Glaucoma

Question 1

What is glaucoma?

-what is a risk factor?

Answer 1

A group of diseases characterised by progressive optic nerve damage and visual field loss.
Raised intra-ocular pressure is a prominent risk factor

Question 2

What is the pathogenesis of glaucoma?

Answer 2

• Usually blockage to aqueous outflow
• Raised intra-ocular pressure
• Damage and loss of retinal nerve fibres at optic disc
• Visual field loss

Question 3

What are the signs of glaucoma?

Answer 3

Raised intra-ocular pressure
characteristic field defects
Optic disc cupping

Question 4

What is included in the diagnosis and management of glaucoma?

Answer 4

IOP- tonometry
Fields - perimetry
optic nerve/disc - clinical examination

Question 5

What changes to the optic disc is seen in glaucoma?

Answer 5

• increased cupping
• fewer nerves course through optic disc
• Cup: disk ratio > 0.4-0.7

-vertical thinning and notching of neural rim
(Neural rim= space between inner cup and surrounding disc, and normal rims follow ISNT rule)

Haemorrhage at disc

Disc vessels displaced nasally

Optic atrophy – optic disc becomes pale as damage progresses

Question 6

What is the ISNT rule for optic discs

Answer 6

Inferior rim Thickest
Superior rim
Nasal rim
Temporal rim Thinnest

In glaucoma this is lost

Question 7

What is the classic visual field loss in glaucoma?

Answer 7

• Central vision typically SPARED e.g. late stage patients may have 20/20 central vision but peripheral blindness
• Arcuate scotoma

Question 8

For primary open angle glaucoma:

-how does this present?

Answer 8

No symptoms till late
a disease of signs
needs to be screened for
Most detected by optometrist at routine examination

Question 9

What are the risk factors for primary open angle glaucoma?

Answer 9

Age
raised intraocular pressure
Afro-Carribean origin
Family history

Question 10

What is the aim of treatment for primary open angle glaucoma?

Answer 10

Lower IOP to a level that prevents further nerve damage

Target IOP varies between patients

Question 11

What is the first line medical treatment for primary open angle glaucoma?

Answer 11

Prostaglandin analogues (Bimatoprost 300micrograms/mL, every evening)

• increase uveoscleral outflow
• make iris vessels more leakyBeta blockers (Timoptol, laevobutanol)
  -Reduce aqueous secretion
  Systemic side effects -reduced by shutting eyes for a few minutes
  -Few topical side effects

Carbonic anhydrase inhibitors and systemic drugs (Acetazolamide PO or IV, 0.25-1g daily)

• Very effective at lowering IOP
• BUT systemic side effects – Parasthesia, peri-oral tingling, renal calculi
• Short term use only
• can use topical but local irritation and much less effective (no systemic side effects)

Sympathomimetics (adrenaline, propine, alphagan)
Increase outflow
dilate pupil
local irritation, hyperaemia
cardiovascular side effects
long term use reduces the success of surgery

Parasympathomimetics/ Miotics (Pilocarpine Hydrochloride 0.5%, topical eye drops, up to four applications daily, adrenaline, propine, alphagan)
Increase outflow
few systemic side effects
Many local side effects
pupil constriction - pain, dimming of vision, problems at night

Question 12

What is the usual order of treatment for primary open angle glaucoma

Answer 12

Prostaglandin
B-blocker
Trusopt/alphagan
surgery

Question 13

What surgery is used for primary open angle glaucoma?

Answer 13

Trabeculectomy

Question 14

What are the pros and cons of surgery?

Answer 14

Surgery more effective
Better compliance

But intra-ocular surgery
Increases progression of cataract

Question 15

What can cause secondary open angle glaucoma?

Answer 15

Blood
Uveitis
Lens protein
Pseudo-exfoliation

Question 16

Acute closed angle glaucoma:

• what is this?
• who usually suffers this?

Answer 16

Hypermetropes (long-sighted)
Closure of the angle by iris causes sudden rise in IOP
Disease of symptoms

Question 17

What are the symptoms of acute angle closure glaucoma?

Answer 17

Pain 
Nausea + vomiting
Reduced vision
Hazy cornea
Fixed mid-dilated pupil

Question 18

What is the treatment for acute angle closure glaucoma?

Answer 18

Reduce IOP medically
Peripheral iridotomy – surgical or laser

Beta blockers (Timolol 0.5% single dose)

  Steroids (Prednisolone 1% one dose every 15 minutes for an hour, followed by hourly doses)

  Apraclonidine 0.5-1% single dose

  Natural lens: Pilocarpine 1-2% single drop an hour after treatment commenced

  No natural lens: Phenylephrine 2.5% single drop

  Acetazolamide given IV (500mg over 10 minutes), with further 250mg slow-release tablet after an hour

  If no response, systemic hyperosmotics used (glycerol PO 1 gm/kg of 50% solution in lemon juice or mannitol 20% solution IV 1-1.5 gm/kg)

  Systemic analgesia

  Anti-emetics

Question 19

What is the normal range for intraocular pressure?

Answer 19

10-21