9/13 Pharmacology of Eye - Walworth Flashcards Preview

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Flashcards in 9/13 Pharmacology of Eye - Walworth Deck (9):
1

location of autonomic receptors on particular tissues of eye

muscles that control the diameter of pupil

  • iris dilator: alpha adrenergic → mydriasis
  • iris sphincter: Ach muscarinic → miosis

muscles that control accomodation

  • ciliary muscle: Ach M
  • also puts tension on travecular meshwork to facilitate outflow of aqueous humour

tissue that facilitates secretion of aqueous humour

  • ciliary epithelium: beta adrenergic

2

autonomic control of pupil diameter

spinchter pupillae → constriction

  • PSNS control via muscarinic receptors

dilator pupillae → dilation

  • SNS control via alpha-adrenergic receptors

3

effects of atropine and other antimuscarinic agents of eye

atropine is prototype antimuscarinic agent

  • tertiary amine

scopolamine is closely related

  • both well absorbed from gut, conjunctiva

 

pharmaco effects of antimuscarinic excess:

  • dry as a bone → decreased secretions/salivation
  • blind as a bat → ciliary muscle paralysis (cycloplegia), inability to focus on close objects
  • mad as a hatter → CNS excitation
  • hot as hell → decr ability to sweat
  • red as a beet → cutaneous vasodil
  • full as a flask → urinary retention

4

use of autonomic agents for facilitating ophthalmologic exam

muscarinic receptor antagonists (antimuscarinics)

  • affect: sphincter pupillae m. and ciliary m.

1. tropicamide

  • tertiary amine
  • mydriatic, cycloplegic
  • short duration of action (4-6h...vs 3-7/7-10d for scopolamine/atropine)

 

alpha-agonists

  • affect: dilator pupillae m.

1. phenylephrine

  • facilitates mydriasis for ophtho exam

5

amblyopia

"lazy eye" 

requires extra stimulation to strengthen

 

atropine can be useful!

  • long duration blurring of strong eye to force brain to use/strengthen weak eye

eyepatch might be better...

6

receptors involved in aqueous humour secretion/drainage

 

link to glaucoma

  • beta-adrenergics on ciliary epithelium → secretion of AH
  • M on ciliary muscle → outflow of AH

 

recall: glaucoma is characterized by increased pressure in ant chamber!

  • usually due to partially obstructed AH outflow, but sometimes overproduction

7

mechanism of action of pharma agents used in tx of glaucoma

1. beta-blockers

  • block receptors on ciliary epithelium → drop AH production → drop IOP

2. muscarinic agonists OR cholinesterase inhibitors

  • stim receptors on ciliary m. → increase outflow → drop IOP

8

examples of eye disorders for which pharmaco tx confers benefit

1. age-related macular degen

2. bacterial conjuctivitis

3. dry eyes

4. allergic conjuctivitis

9

special features of eye relevant to pharmaco

1. eye is anatomically isolated

  • relative seclusion from systemic access → unusual PD/PK props

however...

2. lacrimal drainage goes to nose, which is lined by highly vascular mucosal epi

  • topically applied meds that can pass through have direct access to systemic circ

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