Interpretation of Goldmann Tonometry

Question 1

If you need to move the mires towards each other do you increase or decrease drum pressure? (Move dial towards you or away from you)

Answer 1

• Increase drum pressure (turn dial away from you)

Question 2

If you see full mires that are off center, where do you move joystick?
- If mire patterns are too large what do you do?

Answer 2

• Move joystick towards center of larger mire

- If too large, move joystick away from cornea (too much pressure on eye)

Question 3

If lashes are caught between probe and cornea what do you do?

Answer 3

• Remove probe and reapplanate

Question 4

What can cause thick mires and does it overestimate/underestimate IOP readings?
What is the desirable mire width to applanation area ratio?

Answer 4

• Too much NaFl in tear film results in overestimation of IOP
• Desirable mire width is 1:10 of applanation area

Question 5

For systole/ diastole pulsations, what are two methods to measure IOP?

Answer 5

1) Take highest IOP reading

2) Take the average IOP reading

Question 6

Significant WTR astigmatism will underestimate/overestimate IOP?
- Signifant ATR astigmatism will underestimate/overestimate IOP?

Answer 6

• WTR underestimates IOP (less area applanated)

- ATR overestimates IOP

Question 7

What is the error if you take a Goldmann reading without compensating for astigmatism? (WTR cyl and corneal cyl)

Answer 7

• 1 mmHg error for ever 4D of WTR cyl

- 0.53 mmHg error for ever 1D of corneal cyl

Question 8

Can Goldmann tonometry compensate for irregular astigmatism? (YES/NO)

Answer 8

• No

Question 9

How will poor illumination affect the mire pattern and the IOP reading?

Answer 9

• Probe less bright, will make mires thinner than actually are
• Will underestimate IOP