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17 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Side effects: Mydriasis. stinging, and non-suitability for closed angle glaucoma.
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Epinephrine: Alpha agonist like epinephrine causes vasoconstriction and decrease humor formation. Why can't you use it in narrow angle?
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The problem is that in narrow angle, our issue is the space between the iris and the trabecular network. If you do something that increases tone in the trabecular network, you will compound things and end up with two glaucomas.
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No side effects but not helpful in narrow anlge.
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Brimonidine: more selective alpha agonist and does not cause the other sympathetic side effects of epinephrine
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You open the trabecular network by constricting the pupil, this is a muscarinic response! Adrenergics will contribute to mydriasis which could compound your glaucoma
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Explain Closed angle glaucoma.
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The angle just tells you where the problem is. It is not neccessarily even the cause of the increased pressure! In closed angle, pre-existing pressure and factors leads to the trabecular network contacting the iris. This aposition forms a closed anlge.
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I
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Iris and trabecular network come intocontact. What does this Cause?
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Narrow Angle. How do you treat?
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Cholinomimetics like Pilocarpine phyostigmine echothiophate
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Explain Open Angle Glaucoma
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Pressure is pre-existing: In open angle glaucoma the problem is not obstructive at the level of the trabecular network (the angle/door is open!). So where is the problem?
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The problem in open angle is in the communication between the posterior and anterior chambers. Usually the tone of the ciliary body is the drug target. When the ciliary muscle contracts, it opens the trabecular network and tends to cause miosis. You should get accomodation at the same time as the lense is also getting tugged on.
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What is the angle of the eye(of Louie)? this is the angle between the irsis and trabecular network/cornea
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If the angle is closed, so too is the trabecular network. Thats why they call it closed! This obstructs the canal of schlem. The open position is the normal position! So if there is glaucoma and the door is open, then the problem must be elsewhere.
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What is the function of the ciliary body?
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It communicates with the autonomic nervous system nuclei like Edinger Westphal, It controls accomodation via the cilliary spindles, the concentric muscle of the iris grow out of it. Stimulation of the cilliary body causes
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2/3 of the near response. Constriction and accomodation. Lense and Iris action.
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Describe the cilliary body.
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It is really a big concentric muscle with two attachments(or two muscles; constrictor pupillae and cilliary muscle). The lense's power increases when it is allowed to round up. Constriction of the cilliary body causes the fibers conecting to the lense to relax. At the same time, constriction of the iris muscle causes miosis. In either case, muscle constriction leads to the concentric muscle moving to the middle, filling the circle.
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Innervation of the cilliary body
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Both Parasympathetic and Sympathetic. CNIII, CNV1(opthalmic branch). Cervical Ganglion Sympathetics (B2). The ciliary ganglion is actually a CN V1 structure. Recall also that the cotton to cornea test is for CN V.
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What drugs besides the alpha agonists decrease humor?
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Diuretics, beta blockers
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What is the mechanism of Acetazolamide
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It is a diurtetic that inhibits carbonic anydrase and causes decreased humor production. Does it have side effects?
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No side effects, can help eith open or closed door problems.
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What is the mechanism of the cholinomimetic drugs in the eye
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The increase outflow by contracting the ciliary muscle: this increases flow through the spindles. Contraction also affects the sphinchter pupilae so this can open the door. Side effects
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Cyclospasm: loss of far vision because the spindles stay relaxed(muscle stays contracted). Miosis of course
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Pilocarpine, Physostigmine. What are their side-effects
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Cyclospasm and miosis. these are cholinomimetics
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Timolol, carteol, betaxolol
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These are beta blocker and the affect production of humor negatively.
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Action of sympathetic drugs in general
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Decrease humor production in ciliary body via alpha agonism or beta antagonism
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In general the action of the cholinergic drugs is what?
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They increase outflow by stimulating miosis and spindle body relaxation.
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What is the wildcard drug for glaucoma?
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LatanoPROST. It is a prostaglandin analoug and it also increases outflow. It has a side effect. What is it?
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A person with glaucoma comes to the outpatient clinic because of changes in her eye. Her complaint is not about dryness, myopia, or night blindness, or light sensitivity. What is her problem? Change in coloration. LatanoProst causes change in iris pigmentation.
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