Flashcards in 12 Pharm of the Eye Deck (46):
Don't forget picture of eye anatomy in your notes.
Yay, good job looking at it.
constriction[think of cells undergoing meiosis constricting till they split in half]
Consensual pupil response assesses?
What muscle does mydriasis?
-Radial smooth muscle contracts
What happens to sympa/parasympa when mydriasis occurs? (2)
-inhibit para (M3 muscarinic antagonists in iris) [strong dilation]-stimulate sympa (alpha 1 agonists in iris) [weak dilation]
What muscle does miois?
constrictor pupillae contracts
What things happen with sympa/parasympa when miosis occurs? (3)
-stimulate para (M3 muscarinic agonists in iris) [strong contract]-inhibit symmpa (alpha 1 antagonist in iris) [weak contraction]-stimulate (agonist) opioid receptor in the CNS -> "pinhole" pupil [strong contraction]
Of the things that affect refractive power, what are the 2 (of the multiple) ways we need to know?
-air:cornea interface-lens curvature
What suspends the lens?
"suspensory ligaments" (I think these are zonular fibers) attached to ciliary muscle.
When ciliary muscle contracts what happens?
Relaxation of lens -> increased radius -> see close up. (The natural state of the lens is to be round, contraction of ciliary muscle relieves the tension on the zonula fibers. This relief causes the lens to return to the natural round state)
What receptor agonist contracts the ciliary muscle?
Muscarinic agonsits (carbachol & pilocarpine?)
What is cyloplegia?
Blocked accomodation reflex. (muscarinic antagonists, ex atropine)
T/F Ciliary muscle is influenced by sympa?
F. No adrenergic receptors.
What is presbyopia?
lens loses accomodation (flexibility) w/ age[12 diopter accomodation young adult, 1 diopter by age 50]
What secretes aqueous humor?
blood vessels of ciliary body!
What path does aqueous humor take?
thru anterior chamber/pupil, drains to:-trabecular meshwork ->-canal of Schlemm ->-Episcleral vein ->-Uveoscleral outflow
What is carbonic anhydrase?
H2O and CO2 to HCO3 and H+
What decreases aqueous humor production? (3)
-alpha 1 stim. (stimulation) (on blood vessels, reduces blood flow) [same as other vessels!]-alpha2 stim. (on ciliary body)-Carbonic anhydrase inhibitors[see "what increases?" flashcard for 1 more method of decreasing]
How do carbonic anhydrase inhibitors reduce production of aqeous humor?
Reduce HCO3 procution ->active transport of HCO3 & Na is req'd for making the humor.
What increases aqueous humor production?
-B1 stim. (on ciliary body, by epinephrine)[Note antagonist would decrease] [recall B1's are also on the heart]
What is the essential property for an ophthalmic drug?
Eye color (melanin) has what affect on drugs?
Binds some drugs (atropine!) in darker eyes ->slower onset, longer action, tendency to overdose to achieve effect quickly
T/F local application to eye will not affect systemic function?
F. (side effects still possible, though minimized)
Eye drop preservative side effect?
toxic/allergic (benzalkonium chloride!)
T?F local anesthetic for cornea is effective?
How would you detect a corneal lesion?
Fluorescent dye (taken up by injured cells)
For muscarinic antagonist class, what receptor is acted on to produce mydriasis?
-M3 (on iris & ciliary muscle)
How is drug choice determined for creating mydriasis?
Duration & cycloplegia or not
Which class creates mydriasis but not cycloplegia?
Glaucoma is thought of as intraocular pressure over? What is normal?
21 mmHg (normal 12-20)[Note pressure is a result of production minus outflow, so affecting either can help glaucoma]
Open angle glaucoma is a problem with?
Drainage into canal of Schlemm
Which classes help reduce humor production? (3)
Beta antagonists, alpha agonists, carbonic anhydrase inhibitors (diuretic)
Which class increases humor drainage?
Mech. of how B antagonists reduce humor production?
block B1 receptors on ciliary body
Mech. of how alpha agonists reduce humor production?
stim alpha2 on ciliary body &/or alpha1 on ciliary vessels
Mech. of how miotics increase humor drainage?
stim M3 on iris & ciliary body, which may improve uveoscleral outflow
Closed angle glaucoma is?
peripheral iris balloons forward against cornea, reduces flow
Closed angle glaucoma acute treatment? (2)
systemic mannitol/glycerol to up blood osmolarity and thus down intraocular pressure-topical miotic, to tighten iris temporarily
Closed angle glaucoma cure?
YAG laser to create a small hole in iris (iridectomy)
Cautions about closed angle glaucoma?
-No mydriatics or cycloplegics.
What does myasthenia gravis cause in eyes/lids?
fatigue-able, double vision, lid drooping (But pupil is always spared!!)
How can squint & blepharospasm be treated?
botulinum toxin A (relaxes muscle for 3-6 wks) by blocking ACh vesicles from moving to nerve terminal to be released
how is botulinum toxin A administered?
Needle under EMG (electromyography)