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18 Cards in this Set
- Front
- Back
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iris sphincter muscle
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innervated by cholinergic fibers to muscarinic M3 receptors
Agonists at M3 receptors cause pupil constriction (miosis) Antagonists at M3 receptors cause pupil dilation (mydriasis) |
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radial muscle
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innervated by adrenergic biers to a1 receptors
Agonists at a1 receptors cause pupil dilation (mydriasis) |
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Cholinomimetic Parasympathomimetic
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Cause constriction (miosis)
Examples: Carbachol Pilocarpine |
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Cholinesterase Inhibitor Anticholinesterase Agents
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Cause Constriction (Miosis)
Examples: Organophosphates (pesticiddes) Echothiophate Physostigmine |
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Cholinergic Antagonist Parasympatholytic
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Causes Dilation (Mydriasis)
Examples: Cyclopentolate Atropine Scopolamine |
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Sympathomimetic
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Causes Dilation (mydriassi)
Example: Phenylephrine |
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Production of Aqueous Humor and Intraocular pressure
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Ciliary process-- produce aqueous humor
Posterior Chamber -- aqueous humor flows from this chamber through the pupil in anterior chamber Canal of Schlemm -- reabsorbs aqueous humor |
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Increased Introcular pressure
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If the angle b/t the iris and cornea narrows, drainage slows and intraocular pressure rises.
This is aggravated by mydriasis b/c the iris contracts toward that angle (narrow angle glaucoma) --which impedes outflow |
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Treatment of Open -Angle Glaucoma
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1. Limit aqueous humor production
2. maintain uveascleral flow |
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Ciliary epithelium
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Has a2 and B2 adrenergic receptors
It is involved in aqueous humor production |
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ciliary muscle
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M3 cholinergic receptors
involved in accomodation |
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Cholinomimetics
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Pilocarpine
Carbachol Acetylcholine Action- ciliary muscle contraction = open trabecular network Effect - increase drainage via canal of Schlemm |
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Anticholinersterase
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Echothiophate
Physostigmine Action- ciliary muscle contraction = open trabecular network Effect-- increase drainage via canal of Schlemm |
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Timolol
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B Adrenergic receptor Antagonists
Effect- lessen aqueous humor secretion from ciliary epithelium |
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Betaxolo
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B1 selective -- cardioselective.
Less risk for asthamtic patients Effect- lessen aqueous humor secretion from ciliary epithelium |
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Apraclonidine
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a2 adrenergic receptor agonist (pre-synaptic)
Effect- lessen aqueous humor secretion from ciliary epithelium |
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Acetazolamide and Dorzolamide
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Carbonic anhydrase inhibiton
Effect- lessen aqueous humor secretion from ciliary epithelium |
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Latanaprost
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Prostaglandin F receptor agonists (FP agonists)
Effect -- Increase drainage via canal of Schlemm 2 Possible Mechanisms are: 1. relaxation of the ciliary muscles = enough space for the aqueous humor to go towards the uveosclearal space 2. remodeling the extra cellular matrix of the ciliary muscle -- enzymattically mediated lysis of the intramuscular connective tissue Side effects: darkinging of the iris, lengthening and thickening of the eyelashes, intraocular inflammation, macular edema |
