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Introduction to Eye Disease - Year 2 > Glaucoma 1 > Flashcards

Flashcards in Glaucoma 1 Deck (29)
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1
Q

What is glaucoma?

A

“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]

2
Q

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

A
3
Q

What are the three types of primary glaucoma?

A
4
Q

Define prevalence

A

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

5
Q

What is the prevalence of glaucoma?

A

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

6
Q

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

A

–High IOP – modifiable risk factor +++

–Myopia

–Corneal thickness

7
Q

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

A

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

–Race – African ethnicity - 4x more risk

–Gender ? Men more than women

–Family history - 6.7%

8
Q

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

A

–Diabetes (3.3%)

–Potential link to Migraines/Vasospasms

9
Q

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

A

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]

10
Q

Do all pxs with glaucoma have raised IOP?

A

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]

11
Q

What factors affect the value of IOP?

A

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

–Central corneal thickness CCT

12
Q

How does Central Corneal Thickness affect IOP measurements?

A

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

A thick CCT will cause an overestimation of IOP

13
Q

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

A
14
Q

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

A

A ratio >0.6 is suspicious or

>0.15 change in C/D ratio over time

15
Q

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

A

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).

16
Q

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

A

True

17
Q

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

A

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

18
Q

How do glaucomatous haemorrhages at the disk appear?

A
19
Q

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

A

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

20
Q

What does the abbreviation NRR stand for?

A

Neuro-retinal rim

21
Q

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

A

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.

22
Q

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

A

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.

23
Q

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

A

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

24
Q

What visual defects are characteristic of glaucoma?

A

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]

25
Q

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

A

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
26
Q

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

A

True

27
Q

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

A
28
Q

What is the prevalence of Ocular Hypertension (OHT)?

A

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

29
Q

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

A