Eye Pharmacology

Question 1

What NT is utilized by the parasympathetic system? How about the sympathetic system?

On what receptors in the case of the eye?

Answer 1

parasympathetic = ACh on muscarinic

sympathetic = NE on alpha and beta

Question 2

What is the sympathetic action on the pupil? How?

Answer 2

Dilates the pupil

activating alpha1 receptors to contract the pupillary dilator muscle

Question 3

What is the sympathetic action on the eyelid? How?

Answer 3

holds it open

activates alpha1 receptor to contract the superior tarsal muscle (smooth muscle)

Question 4

What is the sympathetic action on the lens? How?

Answer 4

It relaxes the ciliary muscle to flatten the lens for far vision

activates beta2 receptors

Question 5

What is the sympathetic action on aqueous humor if activating alpha2 reeptors? beta receptors?

Answer 5

alpha2 = inhibits aqueous humor formatoin

beta = increases aqueous humor formation

Question 6

What will the parasympathetic action be on the lens?

Answer 6

It contracts the ciliary muscle, thus making the lens fatter for near vision

Question 7

What will the parasympathetic action be on the pupil? How?

Answer 7

it will constrict the pupil by activating msucarinic receptors on the pupillary sphincter muscle to contract it

Question 8

What will the parasympathetic action on aqueous humor be?

Answer 8

enhance drainage of the humor thorugh the trabecular meshwork and canal of schlemm

Question 9

Generally speaking, what are the two ways you can cause mydriasis?

Answer 9

mydriasis is pupil dilation!

you can either enhance sympthetics or inhibit parasympathetics

Question 10

What alpha1 adrenergic stimulant is used to dilate the pupil during eye exams?

Answer 10

phenlephrine (mydrifin)

Question 11

Besides dilating the pupil, what can phenylephrine do in theory?

Answer 11

reverse ptosis in Horner’s syndrome

Question 12

What drug will cause mydriasis by inhibiting the parasympathetics?

Answer 12

atropine (a muscarinic antagonist)

Question 13

What effect will epinephrine have on the aqueous humor?

Answer 13

It is an alpha1 stimulant, so it will increase humor outflow and inhibit formation

used as a late-line drug for glaucoma

Question 14

How does cocaine cause pupil dilation?

Answer 14

it blocks the axoplasmic pump, increasing NE iconcentrations in the vicinity of the adrenergic receptors

Question 15

How does amphetamine cause pupil dilation?

Answer 15

It reverses the axoplasmic pump, pumping NE out of the nerve and increasing its concentration near the adreneric receptors

Question 16

If pupils are not equal in size and on is more cosntricted than it should be, how can you pharmacologically distinguish whether the damage is int he eye itself or in the sympathetics?

Answer 16

1. give cocaine, which will dilate the eye if the sympathetics are intact
2. then give amphetamine, which will dilate the eye if the postganglionic nerve is intact

so negative cocaine, positive amphetamine = Horner’s sydnrome with lesion BEFORE the postganglionic nerve

negative cocaine, negative amphetamine = Horner’s syndrome with lesion in the postganglionic

Question 17

As a muscarinic receptor antagonist, atropine will cause dilation of the pupil and what effect on vision?

Answer 17

cycloplegia - inability to accomodate to near vision

Question 18

How can you test nerve vs eye dyxfunction on the parasympathetic side of things?

Answer 18

see if the eye responds to a muscarinic agonist:

if eye reponds to pilocarpin with pupil constriction, then the problem is with the CN3

If the eye does NOT respond to pilocarpine, then the problem is in the eye itself

Question 19

In general, how can you cause miosis?

Answer 19

miosis = pupil dilation

augment the parasympathetics and inhibit the sympathetics

Question 20

How do pilocarpine and acetylcholine cause miosis?

Answer 20

they are muscarinic agonists

Question 21

Besides using a muscarinic agonist, how can you make the muscarinic receptors more likely to fire, thus leading to pupil constriciton?

Answer 21

prevent ACh degradation with physostigmine or Ecothiophate

Question 22

What drug has ocular side effects because it’s an alpha1 receptor antagonist? What effect?

Answer 22

Terazosin - it causes constriction

Question 23

What drug has constriction as a side effect because it depletes norepinephrine?

Answer 23

Reserpine

Question 24

If a patient is exhibiting miosis and you want to treat it pharmacologically, what is the best way to od so?

Answer 24

since they have excessive miosis, their parasympathetic system is overactive

thus you need to treat it with a parasympathetic antagonist like atropine

Question 25

How will beta blockers help with glaucoma?

Answer 25

They block the Beta2 receptors, thus decreases aqueous humor production

Question 26

Which beta blocker is used for glaucoma most often?

Answer 26

timolol

Question 27

How do muscarinic receptor agonists like pilocarpine treat glaucoma?

Answer 27

they enhance drainage

Question 28

How do anticholinesterases like physostigmine and ecothiophate treat glaucoma?

Answer 28

they enhance aqueous humour drainage

Question 29

How do alpha2 agonists like epinephrine treat glaucoma?

Answer 29

increases ouflow and suppresses production

Question 30

How do prostaglandin derivatives treat glaucoma? Which is the most commonly used?

Answer 30

it sill increase outflow

latanoprost is most common

Question 31

How does acetazolamide treat glaucoma?

Answer 31

it blocks carbonic anhydrase, so you don’t get the swap of Cl- for bicarb and thus you have no osmotic force to drive water into the eye for the humor production

Question 32

How can you treat eye probems caused by muscle spasm?

Answer 32

botulinum toxin (botox)

it inhibits ACh release from somatic nerves, relieving the spasms

Question 33

What are the 5 potential causes of ptosis?

Answer 33

Horner syndrome - loss of sympathetic innervation

myasthenia gravis

botulinism

occulomotor palsy

muscular dystropy