Non-Contact Tonometry Flashcards Preview

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Flashcards in Non-Contact Tonometry Deck (26):
1

how are blood pressure and IOP related

reduced systemic BP is associated with reduced IOP

2

what is perfusion pressure

the balance between blood pressure and IOP (Diastolic BP- IOP = perfusion pressure)

3

why is ocular perfusion pressure important

important in damaged optic nerves and autoregulation (maintain flow despite perfusion pressure)

4

how is the central venous pressure related to IOP

the central venous pressure is half the IOP (linear relationship)

5

what is the central venous pressure

the amount of blood at the vena cava returning to the heart

6

what are 2 ways central venous pressure can increase

when given too much IV fluid and myocardial infarction

7

what is 1 way central venous pressure can decrease

when there is blood loss

8

what is the triad in glaucoma

increased IOP, optic nerve damage, and visual field loss

9

is an increase in IOP symptomatic

no if it is gradual, yes if it is acute (nausea, halos, and pain)

10

what condition can decrease IOP

phtisis bulbi (shrunken, non-functional eye, usually replaced with a prosthesis)

11

how much change in diurnal variation is suspicious when measuring IOP

more than 4mmHg

12

how much variation is arterial pulse suspicious in IOP measurement

2-4mmHg

13

how much higher are IOP measurements when patient is supine

2-3mmHg (decrease in venous return, increase in episcleral pressure)

14

how can vascular integrity affect IOP measurements

poor perfusion from the carotid will reduce aqueous production on the ipsilateral side

15

how much can exercise reduce IOP measurements

20%

16

how much can external pressure on the globe increase IOP measurements

5-20mmHg (digits or blepharospasm)

17

what 4 medications/drugs can reduce IOP measurements

clonidine, betablockers, marijuana, and alcohol

18

what type of drug can increase IOP measurements

steroids

19

how does trauma/inflammation affect IOP measurements

initial injury shuts down ciliary body- reducing IOP then inflammatory cells clog meshwork- increasing IOP

20

how does corneal hysteresis (elasticity)/thickness affect IOP measurements

thicker corneas may over estimate IOP

21

what amount of IOP are NCT accurate up to

30 mmHg

22

why would you need to take multiple readings on the NCT

one reading may be measured at the height of the ocular pulse

23

what is the standard of care for tonometry

goldmann

24

what is the average IOP in NCT

15.5mmHg (8-23 mmHg range)

25

how much asymmetry is abnormal

2mm

26

what is a normal recording for NCT

OD: 16, 14, 14, mmHg @4:15pm Pulsair NCT