Flashcards in Lec 8 Deck (24)
Where is aq humor produced?
What enzymes control aq humorproduction?
Carbonic anhydrase, Na/K-dependent ATPase
Describe: conventional route of aq humor outflow
aq humor passes through TM into Schlemm's canal. Exits through collector channels into venous system; 70%+ of outflow
Describe: Unconventional route of aq humor outflow
Aq humor passes through uvealscleral pathway: through iris root uveal meshwork and anterior face of ciliary muscle --> through suprachoroidal space and out through slera; 30% or less of outflow
What is the most significant factor in the etiology of increased IOP?
interference with aqueous outflow
T/F: Prostaglandins increase outflow; Carbonic anhydrase inhibit production of aq humor
What % of pts dev glauc despite normal IOP?
What is the diameter of the circular zone of applanation?
What is the area of applanation?
Applanation tonometry has what standard dev of error?
+/- 0.5 mm Hg
What assumptions did Hans Goldmann make when devising his tonometer?
avg corneal thickness of 20 microns, resistance to deformation is cancelled out by surface tension generated when the area applanated has a diameter of 3.06mm
GAT: 1 g of force needed to flatten an an area equal to what? which means the diameter is what?
7.3542 mm^2, 3.06 mm
What are indications for punctal occlusion?
Preg, very young, HTN, when using multiple drops (so pt doesn't taste it), very dark brown eyes
Drops have been instilled. What happens every time a pt blinks?
meds go into the lac canal/sac and increase systemic absorpton
Fluress vs Flurox. Which has benoxinate?
Fluress has benoxinate
What is the wetting agent in Fluress?
How many degrees of separation are between the A & O (or red & white lines) of a tono probe?
K readings: 40 @ 050, 42.50 @ 140. Where would you line up the Red line of the tono probe?
If you see limbal glow, have you made contact with the cornea?
Mires that are too thick will give an artificially ___ IOP. Mires that are too thin will give an artificially ____ IOP.
lateral motion of mires is caused by what phenomenon? When do you "read" the mires?
Pulsating mires; when interlocked at the highest point
What are cautions/contraindications for Contact Tono?
allergy to all anesthetics, pts with recurrent corneal erosion, Bullous keratopathy, Corneal hydrops (Keratoconus), corneal abrasions that aren't healed, signif corneal edema
What doesn't wash out with disinfection, but does wash out with water?
Hep B virus DNA