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Block 8 > Clinical: Tonometry And Pachymetry > Flashcards

Clinical: Tonometry And Pachymetry Flashcards

1
Q

Normal range of IOP

A

10-21 mmHg

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2
Q

Diurnal variation

A

Fluctuations that occur during each day

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3
Q

Diurnal variation of IOP of ____________ mmHg is normal

A

3-4 mmHg

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4
Q

What time of the day is IOP highest?

A

In the morning

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5
Q

What time of the day is IOP lowest?

A

In the evening/night

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6
Q

A difference in IOP of > ________ mmHg between the eyes is significant

A

> 4 mmHg

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7
Q

High IOP is a risk factor for __________

A

Glaucoma

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8
Q

Does IOP above 21 mmHg automatically indicate a diagnosis of glaucoma?

A

No but it does raise suspicion

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9
Q

Does IOP being within normal range rule out glaucoma?

A

No

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10
Q

Purpose of Tonometry

A

Measure intraocular pressure

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11
Q

IOP is determined by what?

A

Rate of aqueous production and resistance to outflow

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12
Q

IOP is measured in __________

A

mmHg

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13
Q

Indications for performing Tonometry

A
  • CEE
  • Suspected open angle or acute closed angle glaucoma
  • Monitoring efficacy of IOP lowering drops
  • Ocular trauma without globe rupture
  • Before and after surgical procedures
  • Patients taking steroid meds
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14
Q

Contraindications for performing Tonometry

A
  • Suspected or known globe rupture
  • Active corneal abrasion or ulcer
  • Inability to instill anesthetic due to drug hypersensitivity or patient apprehension
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15
Q

What Tonometry options can be performed without anesthetic?

A

NCT, iCare, Digital Palpation

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16
Q

Precautions for performing Tonometry

A

Infections - viral conjunctivitis, herpetic keratitis, bacterial keratitis

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17
Q

When a patient has an eye infection, which eye should be measured first with tonometry?

A

Unaffected or ‘good eye’

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18
Q

Applanation tonometry instruments/tests

A

Goldmann applanation tonometry

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19
Q

Indentation tonometry instruments/ tests

A

Schiotz tonometer
Tono-pen

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20
Q

Rebound Tonometry instruments/tests

A

iCare

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21
Q

Transpalpebral Tonometry instruments/tests

A

Digital Palpation

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22
Q

With applanation tonometry, the cornea is __________ by the instrument

A

Flattened

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23
Q

With indentation tonometry, the cornea is indented into a ___________ shape by the instrument

A

Reverse cone

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24
Q

Variable force applanation tonometry measures what?

A

The force required to applanate a set area of the corneal surface

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25
Variable area applanation tonometry measures what?
The area of the cornea that is flattened by a specific amount of force
26
The higher the IOP, the greater force that is required to _______________
Compress/flatten the cornea
27
What is the gold standard for measuring IOP?
Goldmann applanation tonometry
28
What two things are required when performing Goldmann Applanation Tonometry?
Anesthesia and a dye
29
What type of applanation tonometry is Goldmann?
Variable force
30
NCT measures IOP how?
Without direct contact of the instrument and eye
31
How is the cornea applanated with NCT?
By a pulse of air increasing force until a set amount of corneal flattening is reached
32
What are some Pros to using NCT to measure IOP?
No anesthetic needed and no contact with the ocular surface
33
Cons to using NCT to measure IOP
Tends to underestimate high IOP and overestimate low IOPs Patients hate this test
34
NCT Procedure
1. Explain the purpose and inform the patient to keep their eyes open and focus on the target and tell them that they may feel a slight puff of air 2. Place the patient in the machine and align the lateral canthus 3. Instrument will automatically take readings when aligned 4. Record the average of 1-3 readings
35
Repeat NCT measurements if there is a __________ mmHg difference between the eyes
3-4 mmHg or greater
36
What type of Tonometry does the Schiotz tonometer perform?
Indentation
37
How does the Schiotz tonometer work?
Weights are stacked onto a probe that depresses the cornea.
38
Pros and Cons for Schiotz Tonometer
Pros - Portable Cons - Patient must be supine and topical anesthetic is needed
39
Tono-Pen is a combination of what types of Tonometry?
Applanation and Indentation
40
Tono-Pen calculates the average of __________ readings
3
41
Pros of Tono-Pen
Good correlation with GAT measurement on normal range IOPs Portable Disposable covers Can be used over contact lenses Good for irregular corneal surfaces Can measure at different locations on the cornea Patient can be in any position
42
Cons of Tono-Pen
Requires Anesthetic Daily Calibration Makes contact with the eye Avoid in Latex allergies
43
iCare is what type of Tonometry?
Rebound indentation
44
With iCare Tonometry, faster rate of deceleration = _________ IOP
Higher
45
With iCare Tonometry, slower rate of deceleration = _________ IOP
Lower IOP
46
Pros of iCare Tonometry
Consistent with Tonopen and NCT No anesthetic needed May be performed over soft contacts
47
Cons of iCare Tonometry
Patient must be sitting up
48
How is IOP measured using Digital Palpation?
Through the eyelid by using your fingers to assess the firmness/softness of the globe
49
Pros of Digital Palpation
No anesthetic needed No equipment necessary Patient can be assessed in any position
50
Cons of Digital Palpation
Least accurate method
51
When performing Tonometry, what should always be recorded?
Method used Eye(s) tested IOP measurement Time performed
52
What are some factors that may affect IOP measurements?
High astigmatism Irregular Cornea Valsalva maneuvers/holding breath Squinting Corneal Thickness
53
Purpose of Pachymetry
Measure corneal thickness, typically central corneal thickness
54
Indications for performing Pachymetry
Glaucoma evaluation Pre-refractive surgeries Corneal Pathologies - edema, dystrophies, endothelial disease Corneal transplants Contact lens wearers
55
Average CCT (central corneal thickness)
550 um
56
Should a patient be anesthetized when performing Ultrasound Pachymetry? Why or why not?
Yes because the instrument makes direct contact with the cornea
57
With Optical Pachymetry, is contact required?
No, non-contact methods
58
Optical Pachymetry methods
Corneal tomography - Pentacam, Orbscan OCT Specular Microscopy
59
Does optical Pachymetry only measure the CCT?
No, measures the entire cornea
60
How can thick corneas affect IOP measurements?
Thick corneas lead to an overestimation of IOP
61
How can thin corneas affect IOP measurements?
Thin corneas lead to an underestimation of IOP
62
What are some conditions that can lead to a thick cornea?
Corneal transplant, edema, naturally thick
63
What are some conditions that can lead to a thin cornea?
Post-Refractive surgery, Keratoconus, Naturally thin
64
It's important to remember the correlation between thickness of cornea and IOP measurements. Why?
Because thinner corneas can lead to an underestimation of IOP by measuring instruments And Thicker corneas can lead to an overestimation of IOP by measuring instruments
65
You perform GAT at 11:35 AM on your patient and find the following: OD: 15 OS: 17. You perform Pachymetry and find the following: OD: 446 OS: 595. What should your adjusted IOP measurements be?
OD: 22 mmHg OS: 13 mmHg
66
What type of Tonometry is Goldmann?
Applanation
67
What type of Tonometry is NCT?
Applanation
68
What type of Tonometry is Schiotz?
Indentation
69
What type of Tonometry is Tono-Pen?
Indentation
70
What type of Tonometry is iCare?
Rebound
71
What type of Tonometry is Digital Palpation?
Transpalpebral
72
Is anesthesia required for Goldmann?
Yes + Dye
73
Is anesthesia required for Non-Contact Tonometry?
No
74
Is anesthesia required for Schiotz Tonometry?
Yes
75
Is anesthesia required for Tono-Pen?
Yes
76
Is anesthesia required for iCare?
No
77
Is anesthesia required for Digital Palpation?
No
78
What position must the patient be in when performing Goldmann?
Sitting up
79
What position must the patient be in when performing Non-Contact Tonometry?
Sitting up
80
What position must the patient be in when performing Schiotz Tonometry?
Supine
81
What position must the patient be in when performing Tono-Pen?
Any
82
What position must the patient be in when performing iCare?
Sitting up
83
What position must the patient be in when performing Digital Palpation?
Any

Block 8 (33 decks)

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