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Cardiovascular, renal and PNS > Ocular pharmacology > Flashcards

Ocular pharmacology Flashcards

1
Q

vitreous humour

A

large space between lens and retina

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2
Q

outer layer of eye

A

sclera

white, connective tissue

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3
Q

choroid

A

darkly pigmented -> absorbs light rays at back of eyeball

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4
Q

coloured part of eye

A

iris

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5
Q

what types of receptors does the retina contain?

A

photoreceptors

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6
Q

smooth muscle in the eye

A

dilator = radial

constrictor = sphincter

^ regulates pupil size + amount of light that enters the eye

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7
Q

what is the ciliary muscle responsible for?

A

changing refractory index of lens / angle at which light enters

accommodation

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8
Q

pupil dilation

A

MYADRIASIS

radial = contracted
sphincter = relaxed

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9
Q

what neurotransmitter is responsible for pupil dilation?

A

NA on α1 adrenoceptor (agonist)

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10
Q

pupil constriction

A

MIOSIS

radial = relaxed
sphincter = contracter

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11
Q

which neurotransmitter is responsible for pupil constriction?

A

Ach on M3 muscarinic receptors (antagonist)

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12
Q

mechanism for radial smooth muscle contraction in pupil dilation

A
  1. NA binds to alpha-1 receptor
  2. activates phospholipase C and protein kinase C
  3. phospholipase C produces DAG and IP3

= increased protein kinase and Ca2+ levels

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13
Q

how does elevated Ca2+ levels then cause muscle contraction?

A

calcium/calmodulin binds to myosin light chain kinase (MLCK)

MLCK uses ATP to phosphorylate myosin cross bridges then bind to actin = tension

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14
Q

mechanism for sphincter smooth muscle contraction in pupil constriction

A

same but Ach binds to M3 receptors at start instead

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15
Q

what happens to the eye in bright light?

A

miosis

parasympathetic

Ach on M3 receptors

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16
Q

what happens to the eye in low light

A

mydriasis

sympathetic (dilator)

M3 antagonist or NA on alpha-1 adrenoceptors

17
Q

effect of Angel’s trumpet on muscle behaviour

A

[contains scopolamine, hyoscyamine + atropine]

act on M3 antagonists

block activation of sphincter muscle

leads to pupil dilation

18
Q

myadriatics

A

block constrictor muscle = pupil dilation

19
Q

cycloplegics

A

paralyse ciliary muscle

block accommodation

20
Q

glaucoma

A

damaged optic nerve due to raised intra-ocular pressure (>21 mmHg)

21
Q

what determines intraocular pressure

A

rate of formation and drainage of aqueous humour

22
Q

aqueous humour

A

produced continuously by ciliary body epithelium

provides nutrients to cornea and lens

released into posterior chamber

23
Q

factors that contribute to glaucoma

A

age

race

diabetes

familial

far/near sight

eye injury

24
Q

circulation of aqueous humour

A

produced in ciliary body

posterior chamber -> iris -> anterior chamber

90% trabecular meshwork (canal of Schelmm and into vein)

10% uveoscleral outflow

25
Q

open angle glaucoma

A

obstruction of drainage through trabecular meshwork + canal of Schlemm

intraocular pressure rises

26
Q

what stimulates aqueous humour formation?

A

β-agonists

27
Q

what inhibits aqueous humour formation?

A

α-agonists

28
Q

types of alpha antagonists

A

[alpha-1]
vasoconstrictors
reduced blood supply to ciliary body

[alpha-2/beta]
reduces cAMP
directly inhibits AH formation
reduces NA release from sympathetic fibres

29
Q

which ion does AH formation depend on?

A

active transport of HCO3- and Na+

30
Q

closed angle glaucoma

A

angle between iris and cornea narrowed

blocks flow of AH from posterior -> anterior chamber

31
Q

symptoms of closed-angle glaucoma

A

severe headache

eye pain

nausea/vomiting

blurred vision

halos around lights

eye redness

32
Q

alternative treatments for closed-angle glaucoma if drugs don’t work

A

laser trabeculosplasty - burn holes in trabecular network (aids drainage)

laser iridectomy - remove small portions of iris

surgical scleral flap
-advanced glaucoma
-relieves intraocular pressure + improves drainage

33
Q

macular degeneration

A

blood leaks from macula (part of retina essential for sharp vision)

34
Q

dry AMD

A

slow onset

no successful treatments

35
Q

wet AMD

A

choroidal neovascularisation
= excessive growth of leaky BV under retina

rapid onset

36
Q

allergy in eye

A

associated with IgE-mediated mast cell degranulation

itchiness and redness

37
Q

treatments for allergic reactions in eye

A

H1 (histamine) receptor antagonists

mast-cell stabilisers

glucocorticoids

Cardiovascular, renal and PNS (16 decks)

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