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28 Cards in this Set
- Front
- Back
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When is Goldmann tonometry indicated?
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1. on every patient capable of being tested
2. usually after refraction and before dilation 3. after you put in anesthetic/dye |
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What are two methods to prepare the eye for tonometry? (explain what the drops are and what's in them)
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1. Fluress (benoxinate/fluorescein)
2. proparacaine with fluorescein strip |
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How is aqueous formed and describe its flow pathway/elimination?
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formation - non-pigmented epithelium in the ciliary body pumps Na+ into the aqueous creating an osmotic gradient, H20 follows
elimination - trabecular meshwork (canal of Schlemm) to uveo-scleral pathway |
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How long does it take for aqueous to turnover?
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100 minutes
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Trace the pressure gradient of aqueous from posterior to anterior structures?
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Post chamber - 17mmHg
Ant chamber - 15 Trabecular meshwork - 15-4 Episcleral veins - 4-1 |
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What are three main functions of aqueous?
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1. Maintain shape (structural integrity)
2. Supply nutrients (to cornea, lens, TM) 3. Remove metabolic by-products of (cornea, lens) |
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What is ocular hypertension?
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IOP greater thqn 21mmHG but with no sign of glaucomatous optic nerve head damage
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What is hypotony?
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abnormally low IOP (<7mmHG)
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List situations which may cause transient flucuations in IOP?
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diurnal variation (5-6 and less)
respiration heartbeat valsalva posture exercise |
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List long term influences on IOP?
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-IOP higher with increasing age
but greater with females than males -myopes tend to have higher IOP |
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List three situations that can cause a physiologic IOP increase?
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1. increased aqueous production
2, increased resistance to outflow (from trauma) 3. Blockage of the drainage? |
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Give some examples of things that can cause a blockage of the aqueous drainage system?
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1. narrow angle
2. pigmetned angle 3. angle neovascularization |
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What the difference between applaanation and indentation tonometry?
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applanation - flattens cornea
indentation - indents cornea |
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Give examples of applanation and indentation tonometry?
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app - Goldmann, Perkins, Tonopin, McKay-Marg, Tonomat
indent - SCHIOTZ! |
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What the hell is Fick-Lambert law?
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pressure in a sphere of liquid in a thin membrane is equal to the counter pressure needed to flatten the cornea (applanation technique)
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What the diameter of Goldmann probe and why is it advantageous?
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3.06mm
small size negates surface tension and corneal bending forces |
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What are the three acceptable ways to clean the Goldmann probe?
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1. 15 min in 70% alcohol, tissue dry
2. 10 min in 3% H2O2, tissue dry 3. 15 min in 10%bleach, tissue dry (it doesn't say it but rinse well with saline, yo!) |
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What's the appropriate magnification for the slit lamp for G. tonometry?
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10-16x
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Looking through the slit lamp at the mires, which direction do you need to move if one semi-circle is larger than the other one?
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Move toward the larger one!
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If your mires are overlapping too much what do you need to do with your pressure dial?
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Dial out pressure - you've got too much force dialed in!
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If your mires are lined up correctly but are too thick, how will this affect your resultant reading? How can you correct this?
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This will over estimate IOP. Blot the eye and make sure lids aren't touching probe. If there too thin, this will under estimate - so put another drop in or use dye strip.
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How might the mires appear if you're applying way too much force?
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Very small mires and far apart and don't change much with changes of the dial....ease up, man.
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How do you record your tonometry resuls in the patients file...?
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- actual measurement of right and left eye
- time of day - apprehension level |
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Say the patients cornea is 565um thick. How would you adjust your reading?
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- thinner corneas give falsely lower readings
- Add/subtract 1mmHG for every 20um change in cornea thickness from 545um. - thus, 565um is 20 thicker, so subtract 1mmhg from your reading |
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Your patient has high astigmatism (>4D), how do you adjust your procedure to measure IOP correctly?
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If >4D, turn probe so it is aligned 45 degrees away from the flattest meridian.
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When performing tonometry your patient's mires seem to pulsate. What's up with this?
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Patient's forehead is probably not firmly secured
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How do you calibrate for Goldmann tonometry?
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Hard to show without picture, but put probe in holder and lower it, set calibration tool to 20 or 60mmHG, then turn dial till the probe shifts slightly, note reading, turn dial opposite direction till probe shifts back, note reading
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How often should you calibrate your slit lamp for Goldmann tonometry?
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once a month, return to manufacturer if out of calibration.....
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