Eye 2

Question 1

cannabinoids: effect for glaucoma? but?

Answer 1

lowers IOP probably by relaxing trabecular meshwork. no significant advantage over other drugs.

Question 2

anandamine: what? aka?

Answer 2

endogenous cannabinoid ligand, aka arachidonylethanolamine

Question 3

anandamine: what receptors? transduction mechanism?

Answer 3

CB1 and CB2 receptors. CB1: couple to Gi (inhibit calcium influx, activate GIRK channels = hyperpolarization; so reduce transmitter release)

Question 4

atropine: effects?

Answer 4

muscarinic blocker = pupil dilation. can’t cry. blurry vision.

Question 5

cocaine test for ___ syndrome? normally causes?

Answer 5

horner’s syndrome. normally: pupil dilation

Question 6

cocaine test: if there is what damage, what effect?

Answer 6

if there is unilateral damage to sympathetic nerves or a brainstem stroke, pupil on affected side doesn’t dilate

Question 7

normal vs. abnormal pupil in room light? bright light? dark room?

Answer 7

room light: both normal. bright light: both constricted. dark room: normally dilated, horner’s syndrome doesn’t dilate.

Question 8

horner’s syndrome: what is normal? what is affected?

Answer 8

parasympathetic function normal (pupils constrict in bright light). pupil dilation affected.

Question 9

horner’s syndrome characterized by interruption of _________? what 3 neurons?

Answer 9

oculosympathetic nerve pathway somewhere between hypothalamus and eye. hypothalamus to SC. sympathetic preganglionic neuron. sympathetic post ganglionic neuron.

Question 10

if cocaine doesn’t work, then lesion is? then use what to check what neuron?

Answer 10

lesion can be in any of the three neurons. use amphetamine to check neuron 3.

Question 11

amphetamine: neuron intact = what effect? why?

Answer 11

3rd neuron normal = pupil dilation. NA will be released regardless of sympathetic outflow to neuron 3, doesn’t matter about neuron 1/2 condition.

Question 12

cocaine: what effects? requires?

Answer 12

inhibits NA/DA reuptake = sympathomimetic. requires ongoing neuronal activity for effect.

Question 13

amphetamine: substrate for? effects?

Answer 13

catecholamine transporter. will release NA/DA from vesicles in terminals, will reverse uptake system so transporter pumps out NA/DA. overall: amphetamines release NA/DA in absence of ongoing nerve activity

Question 14

sequence: cocaine test options? amphetamine test options?

Answer 14

cocaine test: no dilation is pathologic. then to amphetamine test. no dilation = 3rd neuron lesion, dilation = 1/2 neuron lesion.

Question 15

summary: alpha adrenoreceptor agonists 2 effects for eye?

Answer 15

lower IOP by decreasing blood flow to ciliary body. mydriasis (iris radial muscle constriction = dilation)

Question 16

summary: 3 effects of muscarinic agonists on eye?

Answer 16

miosis (contract iris sphincter = pupil constriction). myopia (contract ciliary muscle = near vision). lower IOP (ciliar muscle contraction = tension on trabecular meshwork = aqueous humour goes out)

Question 17

summary - beta adrenoreceptor antagonists: effect on eye?

Answer 17

lowers IOP, because it blocks beta-adrenergic facilitation of humour production by ciliary body

Question 18

atropine used to dilate pupil for ocular exam: untoward effects?

Answer 18

blurry vision, can’t focus eyes. increased IOP.