6 - Tonometry (Exam 1) Flashcards
What is tonometry?
The measure of tension
What is intraocular pressure determined by?
The balance between the production and elimination of aqueous humor
What are 3 ways to reduce a patient’s IOP?
- Improving aqueous drainage
- Reducing the rate of aqueous production
- Combination of both
What is the normal range of IOP values?
11-22 mmHg
What is the daily variation in normal patients of IOP values?
3-4 mmHg
What is the expected difference in IOP between eyes of one patient?
<3 mmHg
Is IOP directly or indirectly measured by Goldmann applanation? How?
Indirectly
Determine the force necessary to alter corneal contour
What is the diameter of the applanating area of the Goldmann prism?
3.06 mm
What ring width is ideal for Goldmann tonometry?
1/10th of ring diameter
If the tear meniscus produces a ring width that is too wide, how will the IOP measurement be impacted and what can be done to improve accuracy?
Measurement will be too high
Wait for excess tears to clear
If the tear meniscus produces a ring width that is too thin, how will the IOP measurement be impacted and what can be done to improve accuracy?
Measurement will be too low
Add more fluorescein to the eye
How should Goldmann be performed for patients with high astigmatic correction (>3.00D)?
Adjust bi-prism alignment so that it is 43 degrees from the flattest (most hyperopic) corneal meridian
What corneal thickness are Goldmann tonometers calibrated for?
520 microns
What is important to measure on glaucoma/suspect glaucoma patients in addition to IOP?
Central corneal thickness
How does laser refractive surgery impact the measurement from a Goldmann tonometer?
Lowers the reading from the actual value
due to lower resistance to applanation
