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12 Cards in this Set
- Front
- Back
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Tropicamide
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(Mydriacyl®)
Muscarinic antagonist 6 hr duration. |
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What two types of drugs can cause mydriasis?
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An α1 agonist or a muscarinic receptor antagonist.
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What is cycloplegia?
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The state of having your pupils dilated (mydriasis) and accommodation inhibited (you want to be able to focus on far objects)
Imagine that you are a rabbit being chased by a wolf. You want to have dilated pupils so you can see in the forest, and you want to have your lens focused on distant objects so that you can find a hole to run into. (SNS stimulation) |
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Cyclopentolate
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(Cyclogyl®)
Muscarinic antagonist 12 - 24 hr duration |
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Why isn't atropine used in the opthalmic examination?
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The antimuscarinic effects would last weeks.
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What can be administered to counteract the effects of muscarinic antagonists used during the opthalmic exam?
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Pilocarpine, a muscarinic agonist. Will competitively compete with tropicamide at the iris sphincter.
BUT pilocarpine will not affect the ciliary muscle --> accommodation NOT restored. |
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What are the nature of the effects on the eye when phenylephrine is used in the opthalmic examination?
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Phenylephrine acts as an α1 agonist and contracts the radial muscle. Phenylephrine has NO EFFECT on the ciliary muscle, and thus does not cause inhibition of accommodation.
Phenylephrine is not so effective in producing mydriasis in patients with dark irides (phenylephrine binds nonspecifically to the dark pigment) May also cause peripheral vasoconstriction. |
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Dapiprazole
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(Rev-Eyes®)
α adrenergic antagonist that can reverse phenylephrine induced mydriasis. |
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What is anisocoria?
What is the first thing to check in the evaluation of anisocoria? |
Unequal pupil sizes.
Check to see if it is more marked in the darkness or in the light. Greater in darkness --> smaller pupil may be lacking SNS stimulation. Greater in light --> larger pupil may be lacking PSNS stimulation. |
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Hydroxyamphetamine
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(Paredrine®)
- Causes release of NE from the presynaptic side of adrenergic synapses. - Used to determine if Horner's is pre or postganglionic. - If put into eye and the eye dilates, it indicates that the post-ganglionic fibers are working fine and that the problem is in the preganglionic fibers. - If the eye doesn't dilate, then the problem is post-ganglionic. |
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How can you test for SNS denervation supersensitivity in the eye?
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The normal eye is responsive to 1% phenylephrine.
The denervated (post-ganglionic Horner's) eye may dilate when given 0.1% phenylephrine. Normal eyes and pre-ganglionic Horner's eyes would not be affected. |
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How can you test for PSNS denervation supersensitivity in the eye?
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The normal eye will constrict if given 1% pilocarpine.
If the patient has a post-ganglionic PSNS lesion (Adie's pupil), their eyes will constrict with a 0.1% pilocarpine solution. |
