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Respiratory Diseases & Dermatology > PT9: Ocular Pharmacology > Flashcards

PT9: Ocular Pharmacology Flashcards

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Dermatology Board Prep flashcards
1
Q

what are the features of the iris smooth muscle

A

radial (dilator), sphincteric (constrictor)

regulate pupil size and the amount of light reaching retina

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2
Q

what is the function of the ciliary muscle in the eye

A

changes refractive index of lens, accommodation

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3
Q

what parts of the eye are smooth muscle

A

iris, ciliary

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4
Q

what do cranial parasympathetic axons in the iris do

A

innervate the ciliary ganglion (back of the eye)

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5
Q

what do postganglionic fibers do in the iris

A

innervate the sphincteric constrictor smooth muscle

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6
Q

what does high basal tone mean

A

small pupils at rest

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7
Q

what causes pupil constriction

A

contraction of sphincteric constrictor smooth muscle

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8
Q

what causes pupil dilation

A

contraction of radial dilator smooth muscle

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9
Q

what is the smooth muscle response to bright light

A

miosis

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10
Q

what is the smooth muscle response to low light

A

mydriasis

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11
Q

what is consensual pupil response

A

response in one eye will stimulate same response in the other

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12
Q

what is the parasympathetic tone

A

increase in miosis, ACh acts on M3 muscarinic receptors

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13
Q

what is the sympathetic tone

A

mydriasis, NA acts on alpha1 adrenoceptors

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14
Q

what do alpha 1 adrenoreceptors agonists cause

A

mydriasis

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15
Q

what do alpha 1 adrenoreceptor antagonists cause

A

miosis

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16
Q

what is the autonomic action of the eye

A

calcium/calmodulin binds to myosin light chain kenase (MLCK) which uses ATP to phosphorykate myosin cross bridges; phosphorylated cross bridges bind to actin which produces tension

17
Q

what are two examples of muscarinic antagonists in the eye

A

mydriatics and cycloplegics

18
Q

what do mydriatics do

A

block constrictor muscle which causes pupillary dilation

19
Q

what do cycloplegics do

A

paralyse ciliary muscle which blocks accommodation

20
Q

what are the uses of muscarinic antagonists

A

anterior uveitis (inflammation), ocular examination, amblyopia (lazy eye)

21
Q

what causes glaucoma

A

damaged optic nerve, usually a consequence of raised intra-ocular pressure

22
Q

what determines intraocular pressure

A

determined by rate of formation and rate of drainage of aqueous humour
AH produced by ciliary body epithelium

23
Q

what is the purpose of aqueous humour

A

maintains intraocular pressure, provides nutrients to the cornea, lens etc, released into posterior chamber

24
Q

how does drainage occur in the eye

A

through trabecular meshwork and canal of Schlemm

25
Q

what is aqueous humour formation stimulated by

A

beta agonists

26
Q

what is aqueous humour formulation inhibited by

A

alpha agonists

27
Q

what are the three inhibitors of aqueous humour formation

A

alpha1 agonists
alpha2 agonists
beta adrenoreceptor antagonists

28
Q

what do alpha 1 agonists do

A

vasoconstrictors that reduce blood supply to ciliary body

29
Q

what do alpha 2 agonists do

A

reduce cAMP

directly inhibits aqueous humour formation and reduce NA release from sympathetic fibres

30
Q

what do adrenoreceptor agonists do

A

reduce aqueous humour production

31
Q

what does aqueous humour formation require

A

active transport of HCO3- out of the ciliary body

carbonic anhydrase catalyses which then dissociates to HCO3-

32
Q

what do carbonic anhydrase inhibitors do

A

decrease intracellular bicarbonate; decrease carbonic anhydrase which impairs aqueous humour secretion

33
Q

what are the steps of circulation of aqueous humour

A

AH produced by ciliary body, AH flows from the posterior chamber through the iris into the anterior chamber, trabecular meshwork (canal of Schlemm and into vein), uveoscleral outflow

34
Q

what does drug therapy do in glaucoma

A

improves drainage of aqueous humour through trabecular network, useful in raised and normal pressure glaucoma (miotics make pupil smaller, muscarinic agonists (carbachol, pilocarpine, ACh)
improved drainage through uveoscleral outflow, prostaglandin analogues, latanoprost PGF2alpha analogue

35
Q

what is closed-angle glaucoma

A

angle between iris and cornea is narrowed, blocks flow of aqueous humour from posterior to anterior chamber, onset can be sudden and result in rapid irreversible damage

36
Q

what is the emergency treatment for closed-angle glaucoma

A

relieves intra-ocular pressure

increase blood osmolarity; water out of vitreous humour to decrease volume of VH and intra-ocular pressure

37
Q

what are three treatment for glaucoms

A

laser trabeculoplasty, surgical scleral flap, laser iridectomy

38
Q

what is age-related macular degeneration

A

‘dry’ AMD is geographic atrophy with no successful treatments
‘wet’ AMD is neovascular and has a rapid onset

Respiratory Diseases & Dermatology (34 decks)

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