4.2.3 Pharmacology of the Eye Flashcards
Identify the covered structure and the predominant autonomic receptor. For the trabecular meshwork, identify what helps open it to allow for draining of the aqueous humor.
Trabecular meshwork (sweater analogy) - holes in meshwork larger when stretched which occurs when the cilliary muscle is relaxed
Describe the state of the iris, lens, ciliary muscle, and zonular fibers during the two states of accommodation (relaxed and accomodated)
What helps to promote drainage of the aqueous humor?
Accomodation (the ciliary muscle is tightened, which stretches the trabecular meshwork)
Name the locations of the adrenergic receptors in the eye and their type. What happens when stimulated.
Beta adrenergic in ciliary epithelium; stimulation = prod of aqueous humor
Alpha adrenergic in radial (dilator) iris muscle; stimulation = pupil dilation (mydrasis)
Identify the locations of muscarinic receptors in the eye
Sphincter of iris
Ciliary muscle
What is the effect of muscarinic agonists
Miosis (spincter of iris)
Accomodation (ciliary muscle)
Outflow of aqueous humor (pulling of trabecular meshwork by ciliary m)
Stimulate lacrimation (tears)
Endogenous NT that acts as an agonist of muscarinic receptors?
Ach
Direct muscarinic agonist
Carbachol
Indirect muscarinic agonist
Physostigmine (AchE inhibitor)
Muscarinic antagonist
Tropicamide (facilitites opthalmic exam) -> opens pupil
What is the action mediated by alpha adrenergic agonists?
Mydraisis (contraction of radial pupillary dilator)
Direct alpha adrenergic agonist
Phenylephrine
Indirect adrenergic agonist
Cocaine
What is the effect of beta adrenergic agonists? What would be increased as a result?
Ciliary epithelium to promote secreation of aqueous humor; results in increased IOP
Beta adrenergic antagonist
Timolol; inhibits aqueous humor prod -> decrease IOP
What are the two pathophysiologies of glaucoma?
What are some theurapeutic approaches to treating “closed angle” glaucoma?
One muscarinic agonist (carbachol or physostigmine) with alpha adrenergic stimulation (phenylephrine)
If that fails, iridectomy can be performed
What the therapeutic approach to treating “open angle” glaucoma?
Timolol (beta adrenergic antagonist)
What is being shown? What are some possible causes?
Mydriasis -> alpha adrenergic stim
Causes: Phenylephrine (nasal decongestant), cocaine
What is being shown here? What are some possible causes?
Miosis
carbachol or physostigimine (rx of closed angle glaucoma); opioids
What might this girl have if tears aren’t present? How could you test for that?
Horner’s syndrome (loss of sympathetics on the R side) or organophosphate poisoning; Test for Horner’s with cocaine
