Tono 3

Question 1

Applanation instruments

Answer 1

Goldmann
Perkins
Tonopen (microstrain gauge)

Question 2

Dynamic contour instrument

Answer 2

Pascal

Question 3

Rebound instrument

Answer 3

iCare

Question 4

Indentation instrument

Answer 4

Non contact (puff) , Contact (Shiotz)

Question 5

Pressure phosphene instrument

Answer 5

Proview

Question 6

Transpalpebral instrument

Answer 6

Diaton

Question 7

Tono methods (6)

Answer 7

Applanation (includes microstrain gauge) 
Dynamic Contour 
Rebound
Indentation
Pressure phosphene 
Transpalpebral

Question 8

Indentation method

• Measures what?
• Two types

Answer 8

• Measures amount of force required to indent entire cornea

- Non contact (air puff) or contact (shiotz)

Question 9

Applanation technique

• Measures what?
• Examples

Answer 9

Measures amount of force required to flatten the corneal surface only.
Goldmann, Perkins, tono

Question 10

Tonopen

• method
• useful when
• Measurement affected by what?
• Tends to measure low or high?
• Statistical coefficients
• Measurement range

Answer 10

• Applanation technique with microstrain gauge
• Useful in children, supine patients, gross corneal path
• Affected by central corneal thickness
• Tends to measure high
• 5% is the best, 10%, 20%
• range is 5-80 mmHg (less accurate at higher IOPs)

Can use on peripheral cornea
Consider latex allergies

Question 11

Main differences between ton open and ton open avia

Answer 11

Avia is smaller and averages 10 readings instead of only 3-4.
Larger LCD display
Measurement range is lower: 5-55 mmHg. Pen is 5-80 mmHg.

Question 12

Perkins applanation tono

• Advantages
• Disadvantages
• Pressure range

Answer 12

Advantage: Portable, good for supine patients
Disadvantage: Fixed mag, cannot examine cornea before and after, use anesthetic.
Range: 0-80

Question 13

Dynamic contour tono (pascal)

Answer 13

Slit lamp mounted instrument
Very expensive
Independent of central corneal thickness !!!!!
Measures cardiac cycle
Average reading given with a Q value for quality
Requires several seconds of steady fixation
Range 5-80
calculated and displayed on screen

Question 14

i care rebound tono range and pros/cons

Answer 14

range is 7-50
pros: no anesthesia required
Cons: Can be influenced by CCT, over estimate IOP by 0.6-1.8

• can get i cares at home to measure by self.

Question 15

NCT range

Pros and cons

Answer 15

Range is 0-60
Pros: easy to use, no anesthetic
cons: Less reliable than goldmann. Overestimates. Can be affected by apprehension, keratometry and cardiac cycles.

Question 16

Pressure phosphene tono (PPT)

How do you admin test

Answer 16

Pressure is applied to the patients globe on eyelid by pressing the plunger. Have patient look down and out. Once the pressure in the globe equals the pressure applied by probe, the patient will see a phosphene- circular or arc shaped light.

Question 17

pressure phosphene tono (PPT)
pros/cons
range

Answer 17

pros: good for anyone who can report seeing the phosphene
Cons: Not relibable, must have compliant patient, limited scale
8-40

Question 18

Transpalpebral tono how to admin

Answer 18

Set patient fixation at a 45 degree angle
Position rod on lid and perform 5-6 x then average.
It calculates the eyeballs resistance at cornea and converts to IOP.

Ranges 5-60

Question 19

Corneal hysteresis

What is it and what are the ranges

Answer 19

How well the cornea can absorb energy and dissipate it. Also depends on IOP.

Less than 8mmHg= Risk for glaucoma. K can’t take impact well and ON will likely have same properties.

Medium is 8-12 mmHg

High is 12+ mmHg = good. Less glaucoma risk.