Glaucoma 1

Question 1

What is glaucoma?

Answer 1

“A disease of the optic nerve with characteristic changes in the optic nerve head (optic disc) and typical defects in the visual field with or without raised intraocular pressure.”

[NICE 2017- National Institute for health and Care Excellence]

Question 2

What do we mean when we classify glaucoma as primary or secondary?

Answer 2

Question 3

What are the three types of primary glaucoma?

Answer 3

Question 4

Define prevalence

Answer 4

Prevalence is the number of all cases in a given population at one point in time

Question 5

What is the prevalence of glaucoma?

Answer 5

Main take away: It affects the elderly more than the young.

Question 6

What are the ocular risk factors to Primary Open Angle Glaucoma (POAG)?

Answer 6

–High IOP – modifiable risk factor +++

–Myopia

–Corneal thickness

Question 7

What are demographic and genetic risk factors for Primary Open Angle Glaucoma?

Answer 7

–Age prevalence – over 40yrs: 2%, over 75 years: 10%

–Race – African ethnicity - 4x more risk

–Gender ? Men more than women

–Family history - 6.7%

Question 8

What systemic diseases are risk factors for Primary Open Angle Glaucoma?

Answer 8

–Diabetes (3.3%)

–Potential link to Migraines/Vasospasms

Question 9

How do we detect Primary Open Angle Glaucoma (POAG) and what can make it difficult?

Answer 9

POAG is asymptomatic until end stages of the disease

It may be detected through a triad of tests:

–IOPs

–Optic Disc

–Visual Fields

[Also important to assess angle]

Question 10

Do all pxs with glaucoma have raised IOP?

Answer 10

No- pxs can still have glaucoma without having a raised IOP, although raised IOP is the most important risk factor for glacuoma it is not a criteria for glaucoma.

[–Up to 50% of patients with glaucoma have normal IOP]

Question 11

What factors affect the value of IOP?

Answer 11

–Diurnal variation – i.e. IOP is higher in morning

–Central corneal thickness CCT

Question 12

How does Central Corneal Thickness affect IOP measurements?

Answer 12

–A thin CCT will result in an underestimation of IOP Thin =uNder

A thick CCT will cause an overestimation of IOP

Question 13

When assessing the optic discs in each eye for glaucoma what six things are we looking out for?

Answer 13

Question 14

What is deemed a suspicious for glaucoma in regards to C/D ratio?

Answer 14

A ratio >0.6 is suspicious or

>0.15 change in C/D ratio over time

Question 15

In regards to the neuro-retinal rim, what signs of glaucoma do we look out for in a suspected px?

Answer 15

The neuro-retinal rim should follow the ISNT rule i.e. it should be thickest Inferiorly then superiorly then nasally then temporally. [Glaucoma causes vertical thinning of the neuroretinal rim].

We should also be looking out for any thinning - i.e. where the neuroretinal rim gets thinner, and if that is focal (i.e. only affects one side of the rim) or difuse (thins generally all over).

Question 16

True or False- Larger discs have larger cupping than smaller discs

Answer 16

True

Question 17

True or False-Optic Disc size varies on average between racial groups - largest in Caucasion population

Answer 17

False- Optic Disc size varies on average between racial groups - largest in Afro-Caribbean population

Question 18

How do glaucomatous haemorrhages at the disk appear?

Answer 18

Question 19

What condition can give high IOP readings yet is not glaucoma?

Answer 19

Ocular Hypertension (IOP>21mmHg in the absence of glaucoma) – the prevalence of this is 2.7% - 10%

Question 20

What does the abbreviation NRR stand for?

Answer 20

Neuro-retinal rim

Question 21

How would you use a slit lamp to measure the size of the optic disc?

Answer 21

You would adjust the length of the beam until it is equal to the size of the optic disc - you would then read off the length of the slit lamp beam off the scale.

Question 22

What are we looking for in regards to nerve fibre defects when screening for possible signs of glaucoma?

Answer 22

Any nerve fibre atrophy. This would be a darkened part of the fundus and is best seen with a green filter or red-free photography.

Question 23

What must you bear in mind when assessing the visual field of a px you suspect to have glaucoma?

Answer 23

There may have been considerable nerve fibre death (up to 50%) before the patient has a definite field defect.

–Visual fields are very subjective – variability, need to repeat test to account to fatigue/learning effect

Question 24

What visual defects are characteristic of glaucoma?

Answer 24

A nasal step - early on

An arcuate scotoma - this start of as small scotomas which join together forming that arc.

A larger than normal blind spot.

[At end stage a px is left with tunnel vision]

Question 25

How can we diffrentiate between ocular hypertension (OHT) and the symptoms of glaucoma?

Answer 25

Those with Ocular Hypertension will have:

–Elevated IOP

–IOP >21 mm Hg

–Normal optic discs

–Normal visual fields

–Open anterior chamber angle

Whereas those with glaucoma:

• May or may not have raised IOP
• Abnormal optic disc
• Visual field defects
• Possible closed angle depending on the type of glaucoma

Question 26

True or False-Between 4% and 10% of individuals with OHT will eventually develop glaucoma

Answer 26

True

Question 27

What is the difference between open angle and closed angle glaucoma?

Answer 27

Question 28

What is the prevalence of Ocular Hypertension (OHT)?

Answer 28

–Prevalence of OHT in the adult population is between 2.7%- 10%

Question 29

What is the glaucoma checklist (way of remembering everything to check in a px you suspect of glaucoma)?

Answer 29