Exam 1 Flashcards
What are the Imbert-Fick law assumptions in Goldman tonometry?
The cornea is infinitely thin, perfectly elastic, and perfectly flexible. These of course are false but the law is only an approximation
What is the actual equation of of forces in Goldman?
Capillary Tear Attraction + Applanation Force = IOP + Corneal Elasticity
We assume capillary attraction and corneal elasticity are negligible, leaving us with…
Applanation force = IOP
What is the diameter applanated in Goldman?
2.8-3.5mm, averaging 3.06mm
How do you disinfect a Goldman probe as per CDC?
3% H2O2 or 1:10-1:00 dilution bleach for 10 minutes
However, many doctors use 70% isopropyl alcohol and let it air dry
Either way, rinse with saline
What should you do if you patient has astigmatism? (Goldman)
You only care if it’s 4D of corneal toricity or more. If it is, line the patient’s minus cyl axis with the red mark on the probe holder
What can you see from outside the slitlamp to know you’ve made contact with GAT?
The limbus will glow! Cool!
If the mires are too thin, your reading will be….
… too low
If the mires are too thick, your reading will be….
…. too high
What are normal, borderline, and abnormal IOP readings?
Normal: 10-21mmHg
Borderline: 21-24mmHg
Abnormal: 24+mmHg
What are normal and abnormal diurnal variations in IOP?
Normal: 4-6mmHg
Borderline: 6-9mmHg
Abnormal: >9
What are normal and abnormal differences in IOP between OD and OS?
Normal: 2-3mmHg
Borderline: 4-6mmHg
Abnormal: >6
What indicates a repeat after 2 measurements (GAT)?
Difference of 2mmHg between eyes, or between readings on same eye
How does pinning the upper lid cause an error in overestimating IOP?
If you do it wrong and pin it to the globe! Don’t do that!
What’s the deal with pregnancy and GAT?
Flurox is category C
