Tonometry 3% Flashcards
What principle is the application tonometry based on?
Imbert-Fick Principle
What is the Imbert-Fick principle?
The pressure inside a thin-walled sphere=the force necessary to flatten its surface divided by the area of flattening.
What is the formula for Imbert-Fick Prinicplr?
P=F/A
P= Pressure
F=Force
A=Area
In applanation tonometry pressure is determined by the amount of weight required to flatten the cornea _____mm
3.06mm
______and ______are factored into formula for Goldmann applanation principle.
K rigidity
Surface tension
Tip of Goldmann is designed to minimize ______pull from tear film and _____push from K.
Inward
Outward
This form of tonometry is very accurate, has minimal effect from repeats measurements.
Goldmann
Goldmann applanation principle formula is based on _______mcm thick K
550
_________used for thinner and thicker K’s
Namograms
What are the advantages of Goldmann?
Most accurate, reproducible
What is the most accurate tonometry test?
Goldmann
What are the disadvantages to Goldmann?
Requires training, subjective to breath holding, tight collars, and pressure on the globe, not portable, requires anesthetic, poor technique can cause K injury
The following products/procedures for disinfection will _________the tip causing it to _______: alcohol, Acetone, UV radiation, Sterilization, immersion in fluid for more than 1 hour, storing at temp greater than 60C
Degrade
Fail
What do you clean the tip of Goldmann with?
Hydrogen peroxide
Never leave the Goldmann tip in hydrogen peroxide for more than _______minutes
10
70% Isopropyl Alcohol will _____the probes of Goldmann and if not _____properly can cause marked pain and anterior uveitis.
Destroy
Dried
A side view of the Tonometry probe-set the axis to _____degrees.
180
*If pt has_______cyl position the probe on Goldmann with the red line at the corresponding minus cyl axis of K astig
Greater than or equal to 3D
Where should the drum be set when starting Goldmann?
at 10
Each mark on the drum of Goldman tip represents…..
2 mm Hg
When doing Goldmann the light source should be place at what degree?
60-65 degrees
When doing Goldmann what should the light setting be?
Use wide open diffuse illumination, bright illumination, the cobalt blue filter and 10 or 12x magnification
When doing Goldmann you should approach the cornea with your _______
naked eye
When doing Goldmann you should look through the ______when you are almost on the cornea.
oculars
What are the steps in doing Goldmann once you have got it lined up, lights and magnification adjusted and you are now looking through the oculars?
Judge mire thickness, Adjust alignment of mires horizontally and vertically, check for proper forward pressure on the eye “the sweet spot”, measure IOP.
*In Goldmann, If mires are too thick what should you do?
Have pt blot closed eyes with tissue
In Goldmann if mires are too thin what should you do?
Add more dye.
In Goldmann, if mires are too_______ the pressure will be overestimated.
Fat
In Goldmann, If the mires are too ______ the IOP will be underestimated.
thin
What should you do if mires are too thick when doing Goldmann?
Pull the slit lamp back, dry off the end of the prism tip , have pt blot closed eyes, start over.
*What is the likely cause of mires being too fat when doing Goldmann?
lashes in contact with the probe, too much Fluress ore excessive tearing
How should you hold lids when doing Goldmann?
By pressing on the orbital rim, do not put pressure on the globe itself.
What is the usual variation in IOP over a 24 hour period?
3-5 mmHg
*What time of day is the highest IOP reading?
Approx 6am
Pressure spikes that are ____ are diagnostic.
> 5mmHg
What should you do for your CL pt to do if you have done Goldmann?
Soft: Irrigate eyes with sterile irrigating solution to remove all fluorescein. Advise pt not to wear their CL for at least 1 hour, lenses will absorb Fluorescein turning them yellow.
Hard: Advise pt not to wear their lenses as long as they normally would. Topical anesthetics soften K epithelium makin an abrasion more likely.
