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Advanced Optometry Exam 2 > Tonometry 1 > Flashcards

Tonometry 1 Flashcards

1
Q

Circulation of aqueous delivers ___ to and removes ____ from ____.

A

Delivers oxygen and nutrients and removes waste from posterior cornea, lens and anterior vitreous (avascular structures)

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2
Q

Hypotony

A

Very low IOP <5mmHg

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3
Q

Very low IOP could be due to

A

Post surgery wound leaks

CB disease

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4
Q

Low IOP can lead to (hypotony)

A

Corneal decompensation, macular edema, choroidal effusions, etc

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5
Q

Acute elevation of IOP can be due to

A

Acute decline in aqueous outflow

Angle closure, inflammation, neovascularization

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6
Q

Acute elevation of IOP can lead to

A

Insufficient perfusion of ONH and subsequent optic atrophy (ischemic optic neuropathy)

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7
Q

Chronic elevation of IOP is

A

Slow gradual rise of IOP, compensatory mechanisms have time to operate avoiding the symptoms of acute IOP elevation

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8
Q

Chronic IOP elevation is almost always a consequence of

A

Decreased aqueous outflow facility

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9
Q

Chronic elevation of IOP is usually idiopathic but may also occur secondary to

A

Pigment deposition, exfoliation syndrome, etc

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10
Q

During chronic elevation of IOP ___ arises in susceptible individuals

A

Optic neuropathy

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11
Q

IOP is important in an eye exam because of

A 
Screen for glaucoma 
Future comparison in glaucoma pts 
Detect wound leak in post op/trauma 
Rule out acute glaucoma 
Detect drug reactions for corticosteroids 
Monitor glaucoma therapy
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12
Q

Any attempt of measuring IOP will often change it by

A

causing an artificial rise in pressure

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13
Q

Gold standard of measuring IOP due to historical reasons

A

Goldman

Not because its less subjected to influences

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14
Q

Measured IOP is influence by

A

Biochemical properties like corneal rigidity, thickness and hysteresis

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15
Q

IOP is highly variable and its measurement is subject to

A

Considerable error

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16
Q

IOP is dynamic meaning

A

It’s constantly changing and each reading is at best a snapshot of the IOP in that moment

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17
Q

A change in about 3mmHg is considered

A

Clinically significant, smaller changes are likely to be noise or measurement error

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18
Q

Time of day, cardiac cycle and body position can

A

Change IOP

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19
Q

IOP is highest at what time of the day?

A

Early morning

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20
Q

IOP is increased during what part of the cardiac cycle?

A

Systole

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21
Q

IOP increases during what body position

A

When position is changed from upright to recumbent

head down position

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22
Q

IOP changing during changing body positions is believed to be due to

A

Episcleral venous pressure

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23
Q

The variability (difference) between IOPs in the same eye during different visits is ____ than the variability of IOP of R & L eyes in one visit

A

Greater

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24
Q

What is monocular treatment trial

A

Since the correlations of IOP between eyes is so strong. One eyes may serve as a control when starting glaucoma medication

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25
Q

What is a safe IOP

A

There is no IOP considered safe or unsafe

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26
Q

Target pressure is

A

A presumed safe IOP that is a certain amount less than IOP at glaucoma damage has occurred

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27
Q

A difference of more than 3mmH is considered ___ and is a risk factor for ___

A

Asymmetric

Glaucoma

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28
Q

Prevalence of asymmetry of IOPs between eyes _____ with age.

A

Increases

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29
Q

Each additional 1mmHg increase of IPA asymmetry between eyes is associated with _% increase of ____

A

21% of risk for development of glaucoma

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30
Q

Ocular pulse amplitude means _____. Which results from ___.

A

IOP increase during systole and decreases during diastole. Results from volume change in the blood entering the eye that occurs during systole

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31
Q

Normal ocular pulse amplitude is

A

3mmHg with <0.5 mmHg difference between eyes

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32
Q

Because of OPA, ____ is required to record and compensate for the pulse

A

Continuous Tonometry over several pulse cycles

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33
Q

During higher IOP, OPA usually

A

Increases

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34
Q

IOP will increase in __ position, largely due to elevation of ____

A

Supine

Elevation of episcleral venous pressure

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35
Q

IOP will increase ___ when changing from standing/ sitting straigh to supine position

A

2-4 mmHg

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36
Q

IOP will _____ when the body is upside down

A

Increase (2-3X)

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37
Q

Even though aqueous production decreases during night time, there is decreased outflow and increased episcleral venous pressure counteracting and causing

A

Overall increase in nocturnal IOP

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38
Q

Pressure is usually highest during __ and lowest in ___.

A

3-5 am

Lowest at 7-9 PM evening

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39
Q

The observed nocturnal rise in IOP is part of the reason why IOP is elevated during

A

IOP elevation while laying down

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40
Q

Diurnal IOP variation can still occur even in absence of

A

Postural effect

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41
Q

Diurnal IOP variation is due to various physiological reasons including

A

Ocular perfusion pressures, hormones, outflow facility during sleep

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42
Q

Large diurnal variation is suggestive of

A

Glaucoma

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43
Q

Normal diurnal amplitudes is

A

<5mm Hg

44
Q

IOP measure in supine position will more closely approximate the nocturnal peak than

A

IOP measured in sitting position

45
Q

Medication that ___ diurnal variation may be more effective in slowing down glaucoma

A

Dampen (decrease)

46
Q

When measuring IOPs in glaucoma patients/ glaucoma treatment try to measure at the same time of the day

A

To minimize inter day variation

47
Q

What is serial Tonometry

A

When IOPs are measured every 2hrs over a single 24hr period

Requires sleep lab or hospitalization

48
Q

Water drinking test is used for

A

Evaluating diurnal variation in IOPs

49
Q

Whats a positive/negative Water drinking test

A

An increase of 8-10 mmHg after rapid ingestion of a quart of water strongly suggests glaucoma. A negative test does not rule it out

50
Q

Rapid ingestion of water causes fluid to move into the intraocular space, an abnormal outflow facility impairs its egress

A

Resulting in an increase in IOP

51
Q

IOP undergoes rhythmic oscillations

A

Arterial pulse and respiratory cycle

52
Q

BP effect on IOP

A

IOP is usually immune to small changes in BP

Large swings in BP will cause transient shift in IOP in same direction

53
Q

Elevation of EVP will

A

Raise IOP at a 1:1 ratio

54
Q

Valsalva maneuver

A

Forced expiration against a closed glottis like coughing, chicking, vomiting, wind instruments, weightlifting

55
Q

Valsalva maneuver can raise venous pressure and decreases arterial blood pressure which causes

A

Acute distinction of choroidal and orbital veins and increase in IOP of 10-20 mmHg

56
Q

External pressure on eye effect on IOP

A

Initially it will raise IOP

After releasing, the pressure will be even lower than before the pressure was initially applied

57
Q

Tomography effect

A

External pressure accelerates rate of aqueous outflow

58
Q

What will happen if you repeat Tonometry a lot

A

Lower IOP

59
Q

Forced eyelid closure affect on IOP

A

Increase iop 50 mmHg or more

60
Q

Eyelid closure is a form of

A

External pressure

61
Q

Normal blink

A

5-10mmHg transient rise in IOP

62
Q

Voluntary fissure widening is a type of

A

External pressure
About 2mmHg rise in IOP
Can be avoided w careful lid retraction

63
Q

In western countries IOP has a

A

Gradual upward trend with increasing age

64
Q

In eastern countries

A

There will be a gradual downward trend of IOP with age

65
Q

Regular excessive can affect IOP

A

Longer term lowering of IOP (about 4 mm Hg )

66
Q

Hyper osmolarity affect on IOP

A

Rapidly draws fluid out of eye, lowering IOP (treatment of acute glaucoma)

67
Q

Hypoosmolariy

A

Fluid enters the eye, raising IOP (water drinking test)

68
Q

Systemic acidosis

A

Inhibit production of aqueous humor

Carbonic a hydrate inhibitors

69
Q

IOP does not define glaucoma but it is the only risk factor

A

Amenable to treatment

70
Q

What IOP pressure should be considered suspect

A

> 22mm Hg

71
Q

Direct, intracameral pressure measurement of IOP

A

Manometry

72
Q

Only method capable of recording the true intraocular pressure

A

Manometry

73
Q

Simplest, least expensive, and least accurate method of measuring IOP

A

Digital palpitation

74
Q

May be the only feasible method in patients unwilling or unable to undergo other forms of Tonometry

A

Digital palpitation

75
Q

Transcorneal tonometry can be influenced can be influenced by

A

CCT and other corneal biochemical factors

76
Q

Corneal biochemical factors may be affected by

A

Age, lasik and corneal disease ( keratoconus, Fuchs)

77
Q

Greater CCT may lead to

A

Over estimation of IOP, degree of effect is variable (not a linear relationship)

78
Q

General precautions of Tonometry

A

Poor patient cooperation, disinfect reusable probes, warn patients regarding air puff, irregular cornea and high astigmatism, caution with epithelial lesions and CL

79
Q

gravity provides a known force on a weighted metal plunger. The lower the iop the farther into the cornea the plunger sinks and the higher scale reading

A

Schiotz Tonometry

80
Q

The relative resistance an eye offers to expansion for a given rise in IOP is known as

A

Scleral rigidity

81
Q

Does schiotz tonometry require anesthetia

A

Yes

82
Q

Patient is supine, anesthetized, the Tono meter is lowered onto the core an until the full weight of the instrument is resting on the eye. Conversion chart is used to derive IOP

A

Schiotz Tonometry

83
Q

The onset of the pressure of phosphene is

A

Correlated to IOP

84
Q

Increasing pressure externally on the eye, a point of visual sensations is induced described as an eclipse of dark circle surrounded by a bright halo

A

Pressure phosphene Tonometry

85
Q

Where is the phosphene Tonometer placed

A

Superonasal globe over the upper eyelid while the eye is looking inferno temporally

86
Q

Does pressure phosphene tonometry require anesthetics

A

No

87
Q

Provue(phosphene) tonometry is designed for

A

Home use

88
Q

One of the newest forms of tonometry

A

Impact bound

89
Q

Ballistic devices that measure the return bounce of an object after impacting the eye

A

Impact bound tonometry

90
Q

Two types of impact rebound tonometry currently on the market

A

iCARE - transcorneal

Diatom- trans palpebral

91
Q

iCARE can be used in

A

Upright and supine positions

92
Q

Does iCARE require anesthetic

A

No

93
Q

Sic reliable readings are obtained and the instrument will generate an average and discard unreliable readings

A

I care

94
Q

Correlation between RBT and GAT

A

Good both equally affected by CCT

95
Q

Tonometry that does not require a smooth regular cornea

A

I care

96
Q

Can be performed over SCL

A

ICARE

97
Q

Analyzes the declaration of a free falling metal rode after impacting the eyelid

A

Diaton Tonometry

98
Q

Position used for diaton tonometry

A

Supine and eyes in downward gaze

99
Q

Does diaton require anesthetics

A

No

100
Q

Diaton is placed on

A

The upper lid margin

101
Q

After 3 reliable reading the instrument calculates average

A

Diaton tonometry

102
Q

Diaton relation with GAT

A

Poor agreement

103
Q

Diaton relation with corneal biomechanics

A

Not affected because it is trans palpebral

104
Q

Diaton has risks of false negatives because

A

It underestimates GAT at higher IOPs

105
Q

Position for diaton

A

Supine or which fully extended neck

Advanced Optometry Exam 2 (4 decks)

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