Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Assessment of Ocular Health > Week 5: IOP > Flashcards

Week 5: IOP Flashcards

1
Q

What is IOP?

A

The dynamic fluid force within the eye that reflects a balance between aqueous production and aqueous outflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What factors determined IOPs?

A

○ Rate of aqueous secretion
○ Resistance to aqueous outflow
○ Level of episcleral venous pressure

Difference in pressure between the arteries entering the tissue and the veins leaving it

Higher venous pressure reduces outflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is normal IOPs?

A

Mean IOP = 15.5+/- 3.0mmHg

But can range between 10 - 21 mmHg

Difference between eye <3 - 5 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What effects IOPs results?

A

Diurnal variation - 3 - 5 mmHg

Sitting to supine: Increases 2 -4 mmHg

Arterial Pulse oscillation: 2 - 4 mmHg

Heart rate, blood pressure, age, weight, ocular pathology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do we detect and manage anomalous IOP?

A

Ocular hypertension
○ Defined by the Ocular Hypertension Treatment study (OHTS) as IOP 24 - 32 mmHg
○ Monitored and managed by Optoms

Ocular Hypotension
○ Low IOP <6mmHg
This is often associated with corneal edema, retinal edema, chorioretinal folds and choroidal detachment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What causes Ocular Hypertension?

A

Excessive Production

Impaired outflow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why is measuring IOP important?

A

Elevated IOP may damage ocular structure

○ Especially nerve fibre layer at the optic disc, leading to loss of sight

However, individual susceptibility varies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Is IOP a Glaucoma Test?

A

Not exactly, normal IOP doesn’t mean the patient doesn’t have glaucoma, and high IOPs Is not a diagnosis of glaucoma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Glaucoma?

A

is “an optic neuropathy characterised by classic optic nerve heard changes and corresponding visual field changes for which IOP is the only known modifiable risk factor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is included in Glaucoma Assessement?

A
  • Functional tests

- objective measures sujc as IOPs, visual assessment of the health of the optic nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

List the 6 types of Tonometry?

A

Applanation, Non-contact, rebound, electronic indentation, indentation and Implantable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the types of Applanation tonometry?

A

Biomicroscope mounted (Goldmann Applanation Tonometry (GAT) )

Hand held (Perkins Tonometry)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is a type of non-contact tonometry?

A

Pneumatic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is a type of rebound tonometry?

A

iCare

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is a type of Electronic indentation tonometry?

A

tonopen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a type of indentation tonometry?

A

Shiotz

17
Q

What is contraindication of tonometry?

A
  • Active infection/inflammation (or use disposable prism if available)
    • Significant corneal abrasions/erosions
    • Significant epithelial basement membrane dystrophy
    • Lacerated or perforated globes
    • Hyphaemia
      Known sensitivity to anaesthetics
18
Q

What errors can be made with mires?

A
  • Incorrect amount of fluorescein
    • Incorrect calibration
    • Pressure on the globe
    • Central corneal thickness
    • Corneal oedema
    • Astigmatism
    • Wide pulse pressure
    • Patient comfort
      If the mires too thin = falsely high IOP
      If the mires are too thick = falsely low IOP
19
Q

What are the advantage of Goldmann Applanation Tonometry?

A

Considered the Gold Standard

Accurate

High Degree of Repeatability

20
Q

What are the disadvantage of Goldmann Applanation tonometry?

A

Risk of cross infection (disposable prisms)

Mires more difficult to visualise as light intensity varies with battery power

Non portable

Patient must sit behind biomicroscope

Ocular rigidity affects applanation
Age, ocular disease, high myopia, eye surgery

High rigidity over estimates

Low rigidity under estimates
21
Q

What are the advantage of Rebound tonometry?

A

Well tolerated and safe

No anaesthetic required

Reasonably accurate

Extremely fast

Contamination risk low as probes are disposable

Objective test

Portable, uninvasive (children, disabled people)

Small cornea are required (can avoid scarring, distortin)

22
Q

What are the disadvantage of Rebound Tonometry?

A

Does not balance pulsatile variation ( 6 readings required)

23
Q

What test is designed to check the diurnal varition of IOP?

A

Water Drinking Test

It assesses the eyes ability to increase aqueous outflow in response to increased production.

A rise in IOP of 6-8mmHg or 30% from baseline is considered positive.

 Physiology
 Not fully known
 Episcleral venous pressure doubles in 10 minutes following WDT
 20% increase in choroidal expansion

24
Q

Why is Goldmann the gold standard for tonometry?

A

Goldmann applanation tonometry is the gold standard.
 Best for accuracy, reliability, repeatability.
 Repeatability of successive readings is ± 2.2 to 2.5mmHg 1

Assessment of Ocular Health (11 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions