Trachte

Question 1

mydriasis

Answer 1

pupil dilation

caused by sympathetic innervation

3 muscles: pupillary dilator (alpha₁ receptor) constriction and superior tarsal constriction; ciliary muscle (beta₂ receptor) relaxation

Question 2

miosis

Answer 2

pupil constriction

parasympathetic response

2 muscles: ciliary muscle contraction, pupillary sphincter contraction

All work through muscarinic receptors

(also…Enhance drainage of aqueous humor (trabecular meshwork & canal of Schlemm))

Question 3

agonist

Answer 3

An agonist is a chemical that binds to a receptor and activates the receptor to produce a biological response.

Whereas an agonist causes an action, an antagonist blocks the action of the agonist and an inverse agonist causes an action opposite to that of the agonist.

Question 4

antagonist

Answer 4

. Whereas an agonist causes an action, an antagonist blocks the action of the agonist (and an inverse agonist causes an action opposite to that of the agonist.)

Question 5

aqueous humor production

Answer 5

Sympathetic

Enhance aqueous humor formation (ß receptors)
Inhibit aqueous humor formation (alpha₂ receptors)

**Parasympathetic **

Enhance drainage of aqueous humor (trabecular meshwork & canal of Schlemm) via muscarinic receptors

Question 6

Drugs promoting mydriasis

Answer 6

A. sympathetic activation or B. inhibition of the parasympathetic pathway!!

A = phenylephrine,_ _epinephrine, amphetamine (promotes NE release from postganglionic cell) or cocaine (blocks Na+ dependent NE reuptake transporter)

B= Inhibitors of parasympathetic nervous system (Atropine—muscarinic antagonist. Literally translates as “pretty women”)

Question 7

alpha₁ adrenergic stimulants

Answer 7

**mydriatics **

PHENYLEPHRINE (selective) (mydrifrin) is a drug used in eye drops to dilate pupil. Also reverses ptosis in Horner’s Syndrome.

Epinephrine (Epitrate) 0.5 to 2% solution to treat glaucoma (nonselective!!!)– promotes humor outflow and inhibits formation

Question 8

No eye response to cocaine or amphetamine means what?

Answer 8

postganglionic Horner’s Syndrome

Question 9

Agents releaseing NE

Answer 9

**nicotine **

amphetamine – reverses axoplasmic pump

hydroxyamphetamine (0.1% solution) used to diagnose post-ganglionic nerve damage vs. a defect prior to the postganglionic nerve

no reaction means postganglionic nerve defect

response to amphetamine indicates normal post-ganglionic nerve

Question 10

If eye responds to pilocarpine with miosis, then problem…

Answer 10

is with the nerve (third nerve palsy)

pilocarpine is a muscarinic agonist

Question 11

If eye does not respond to pilocarpine, then problem…

Answer 11

is with the eye itself (Atropinic mydriasis)

pilocarpine is a muscarinic agonist

Question 12

Drugs producing miosis

Answer 12

Nicotine activates parasympathetic nerves

Muscarinic agonists such as Pilocarpine (Pilocar), acetylcholine (Miochol)

Pilocarpine used as 2% solution
1% solution to differentiate IIIrd nerve palsy from “Atropinic” mydriasis

If pilocarpine is active (produces miosis) then the defect must be in the nerve.

Question 13

Agents preventing acetylcholine degradation…

Answer 13

increase in ACh will cause miosis… pupil constriction… via parasympathetic activation (sort of)

Physostigmine (Isopto eserine), Ecothiophate (phospholine iodide), demecarium (Humorsol), isofluorophate (floropryl)

Question 14

Norepinephrine depleting agents…

Answer 14

cause miosis

NE release from postganglionic terminal on smooth muscle prevented

Reserpine – not normally used for eye treatment, but can have ocular side effects.

Question 15

Drugs for Treatment of Glaucoma

Answer 15

ß Blockers: Timolol (Timoptic); Betaxolol (Betoptic); Carteolol (Ocupress); Levobunolol (Betagan); Metipranolol (Optipranolol)- they decrease aqueous humor formation

Muscarinic Receptor Agonists-
Pilocarpine (Pilocar)- enhances aqueous humor drainage through trabecular meshwork & canal of Schlemm

Anticholinesterases-
Physostigmine (Isopto eserine), Ecothiophate (Phospholine iodide)- enhances aqueous humor drainage through trabecular meshwork & canal of Schlemm

Question 16

Ptosis and treatment

Answer 16

drooping of the upper eyelid due to paralysis or disease,

Characteristic of sympathetic nerve disruption;
Superior tarsalis muscle holds eyelid open

Myasthenia gravis
Botulinism
Occulomotor palsy
Muscular Dystrophy

treate wth botulinum toxin (inhibits acetylcholine release)

Question 17

Summary

Mydriatic Agents

Answer 17

alpha₁ agonist, Phenylephrine
Muscarinic antagonist, Atropine
Agents releasing norepinephine, Amphetamine
Agents preventing norepinephrine uptake into the nerve (Cocaine)

These can all precipitate closed angle gluacoma

Question 18

Summary

Miotic Agents

Answer 18

Muscarinic agonist (Pilocarpine, Acetylcholine)
a₁ adrenergic antagonists (Terazosin)
Anticholinesterases (Physostigmine)
Nicotine

Question 19

Treatments for Glaucoma

Answer 19

Agents enhancing aqueous humor outflow (by trabecular meshwork and Canal of Schlemm)
Muscarinic agonists (pilocarpine)
Prostaglandins (Latanaprost)
Epinephrine

Agents suppressing aqueous humor production (by ciliary processes)
ß adrenergic antagonists (Timolol)
a₂ adrenergic agonists (Aproclonidine)
Carbonic anhydrase inhibitors (Acetazolamide)