Week 2.06 Gluacoma

Question 1

Definition of glaucoma

Answer 1

Group of eye diseases that damage the optic nerve
Progressive optic neuropathies - degeneration of retinal ganglion cells

Question 2

Open angle glaucoma

Answer 2

Primary - absence of an identifiable cause
High IOP (POAG)
Normal IOP (normal tension glaucoma NTG)

Secondary - occurs as a side effect to another underlying condition/treatment - damage to trabecular mesh work - steroid use

Question 3

Closed angle glaucoma

Answer 3

Primary - in absence of identifiable cause (except for size of angle) - hyperopes have smaller angles

Secondary - glaucoma that occurs as a side effect to another underlying condition - trabecular mesh work, advanced cataract - as the IOL is thickening that can cause ant chamber angle to narrow

Question 4

When would we suspect glaucoma

Answer 4

When we see signs of damage at the optic nerve and or visual field damage

Question 5

What is ocular hypertension

Answer 5

Consistently or recurrently elevated IOP (greater than 21mmHg) with no clinical evidence of optic nerve damage or visual field defect

(As soon as there is any change to optic disc suspect glaucoma)

Question 6

Is OHT a risk for developing COAG

Answer 6

Yes

Question 7

Chronic open angle glaucoma can also be called

Answer 7

Primary open angle glaucoma

Question 8

Who is certified as severely sight impaired

Answer 8

Group 1: ppl who have VA worse than 3/60 snellen
Group 2: ppl who are 3/60 snellen or better but worse than 6/60 snellen who also have contraction of their visual field
Group 3: 6/60 snellen or better who have significant contracted field of vision which is functionally impairing the person

Question 9

What are the two main theories of glaucoma

Answer 9

Mechanical
Vasogenic - good vessels and circulation

Question 10

Mechanical theory of glaucoma

Answer 10

Increased resistance to aqueous outflow through trabecular mesh work leads to increased IOP
Connective tissues of ONH constantly subject to IOP related stress

Mechanical failure of
- laminated cribrosa
- scleras canal wall
- peripapillary sclera

Question 11

Vasogenic theory of glaucoma

Answer 11

• damage caused by compromise of tiny blood vessels at ONH
• reduction in blood pressure at ONH similar effect to increased IOP

Question 12

What happens to the prevalence of glaucoma with age

Answer 12

• Prevalence increases with age
• > 60yrs SIX times more likely than <60

Question 13

Are men or women more likely to have glaucoma

Answer 13

Men more likely to have POAG

Question 14

What does myopia have to do with glaucoma

Answer 14

o Low myopia (-1.00D to -3.00D) – 2x risk
o Moderate-high myopia (>-3.00D) – 3x risk
o Possible bias as increased visit frequency – due to increase in rx, broken glasses etc

Question 15

FH and glaucoma

Answer 15

o Definite genetic link
o 13-50% POAG are familial
Biggest risk is if siblings have glaucoma

Question 16

GH and glaucoma

Answer 16

o Diabetes
- 1.5x risk for POAG
- Increased susceptibility of the optic nerve fibres
- Common risk factors

Question 17

What are the NICE guidelines for the tests before referring glaucoma

Answer 17

Need to offer all the tests:
1. VF full/supra-threshold
2. Optic nerve assessment and fundus examination using stereoscopic slit lamp and OCT
3. IOP using Goldman-type tonometry
4. Peripheral ant chamber and depth assessment using gonioscopy

Question 18

What are the guidelines for referring glaucoma then

Answer 18

Optic nerve head damage on stereoscopic slit lamp bimicroscopy
Visual field defect consistent with glaucoma
IOP is 24mmHg or more using Goldman-type tonometry

Question 19

Why measure CCT

Answer 19

Thicker CCT provides greater resistant to GAT thus ELAVATING IOP measurement to more than actual
Thinner CCT provides less resistance to GAT thus REDUCING IOP measurement

Question 20

Which corneas thick or thin are more risk of underestimating

Answer 20

So thinner corneas more at risk as ur underestimating the pressure. The pressure is actually higher than the measurement

Question 21

How to measure CCT

Answer 21

Ultrasound - small transducer contact cornea, good resolution and precision
Optical - attachment to SL, observer dependent

Question 22

What do we mean by optic nerve head damage

Answer 22

Increase in C/D ratio
Increase in cup depth
Asymmetry of C/D ratio
Loss of NNR (notching)
Bayoneting

Question 23

What are the typical visual field defects for glaucoma

Answer 23

Paracentral scotomas
Actuate scotomas
Nasal steps
Temporal wedges

Question 24

On a VF test how can u tell left or right eye

Answer 24

Blind spot is usually nasal in real life
On VF chart it is inverted so is on the temporal side

Question 25

What does paracentral scotoma look like

Answer 25

Near the centre of the visual field there will be darker areas

Question 26

What does arcuate defect look like

Answer 26

Connects to blind spot looks like half the bottom has gone black

Question 27

What are the two main types if management for glaucoma

Answer 27

Surgical - SLT Medical

Question 28

What does the management of glaucoma try to do

Answer 28

Reduce IOP Prevent optic nerve damage Preserve vision

Question 29

Selective laser trabeculoplasty

Answer 29

YAG laser Targets melanin rich cells in trabecular mesh work Surrounding tissue left intact and unharmed Cell activity increased to improve drainage of fluid in the eye

Question 30

Prostaglandin analogues

Answer 30

Latanoprost 1x at night Increase uveoscleral outflow More potent than b blockers

Question 31

Beta blockers

Answer 31

Timolol 2x day Reduce IOP by reducing aqueous secretion Dry eye

Question 32

Carbonic anhydrase inhibitors

Answer 32

Dorzolamide 3 x Reduce aqueous secretion

Question 33

Why would anyone use a miotic

Answer 33

Pilocarpine 4x day Improve trabecular outflow

Question 34

What trabeculectomy

Answer 34

Produce a fistula to allow aqueous to drain into subconjucntival space Seen as a ‘filtration bleb’

Question 35

Iridotomy

Answer 35

helps for narrow angle, iris bulging forward making narrow angle so if you punch a hole in the iris it stops the pressure of the iris pushing forward

Question 36

What’s the definition of primary angle closure glaucoma

Answer 36

Condition in which elevation of IOP occurs as a result of obstruction of aqueous outflow by partial or compete closure of the angle by the peripheral iris

Question 37

What is the risk of getting primary closed angle glaucoma

Answer 37

60yrs old F-M 4:1

Question 38

Acute closed angle glaucoma

Answer 38

Angle is closed Intense eye pain Corneal oedema, blurred vision, haloes IOP significantly raised Circumlimbal redness Headache Nausea and vomiting

Question 39

Chronic closed angle glaucoma

Answer 39

Angles are narrow and capable of closure Symptoms are vague and often intermittent Occur when angle is narrower - pupil is larger low light Haloes Headache Redness Blurred vision Ache in eye