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CVSOH BVSc4 > Ophth - Special senses pharmacology > Flashcards

Ophth - Special senses pharmacology Flashcards

1
Q

What are some inherent ocular defences?

A

Lacrimal functional unit
Internal ocular homeostasis

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2
Q

What is the name for increased tearing?

A

Epiphora

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3
Q

What is the nmae for increased blinking?

A

Blepharospasm

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4
Q

What is the function of the functional lacrimal unit?

A

Physical and chemical barrier to infectious agents

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5
Q

What makes up the functional lacrimal unit?

A

Normal eyelids
Normal tear film
Corneal epithelium
Functional tear drainage
Conjunctival associated lymphoid tissue

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6
Q

What is conjunctival associated lymphoid tissue?

A

Very diffuse lymph gland under epithelium
Recruits immune cells with chemical mediators to remove foreign substances by WBCs

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7
Q

What makes up the ocular surface response?

A

Epiphora
Mucoid discharge
Purulent discharge
Blepharospasm

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8
Q

What is the function of internal ocular homeostasis?

A

Maintains the clarity of ocular media (aqueous and vitreous humour) for vision

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9
Q

What helps to maintain the internal ocular homeostasis?

A

Blood ocular barrier
immune priveliged site
Intraocular pressure maintained locally

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10
Q

What is the blood ocular barrier?

A

Second line physical and chemical barrier - tight junctions that act as a filter to keep drugs and infectious agents out of eye

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11
Q

What does it mean that the eye is an immune privileged site?

A

No immune cells are in the eye as they can damage the eye
There is no lymphatic drainage

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12
Q

What is the general rule for treating the eye with drugs?

A

Surface and anterior segment - topical drugs needed
Posterior segment - systemic drugs needed

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13
Q

What are the barriers to topical penetration?

A

Tear dilution
Blinking
Lacrimal drainage
Permeability of tissues - cornea, conjunctiva, sclera

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14
Q

What is the best pH for drugs used in the eye?

A

pH 7.4 - same as normal tears so non-irritant
Between 4.5 and 9 for comfort

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15
Q

What are the two main routes of penetration?

A

Transcellular - across the corneal epithelial cell
Paracellular - between individual cells

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16
Q

What is the structure of the cornea? What are the layers?

A

Corneal epithelium - lipophilic barrier
Corneal stroma - hyprophilic
Descemet’s membrane (endothelium) - lipophilic barrier

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17
Q

What is required for a drug to be able to go the transcellular route for topical eye treatment?

A

Lipophilic-hydrophilic balance of the drug

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18
Q

What is required for a drug to be able to go the paracellular route for topical eye treatment?

A

Small molecular weight - to pass between the tight junctions

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19
Q

What is an example of a drug that go via the transcellular route?

A

Chloramphenicol

20
Q

How do topical solutions for eye treatment work?

A

Treat the ocular surface without needing to penetrate deeply

21
Q

What is an example of an optical topical solution?

A

Prednisolone sulphate

22
Q

How can you improve topical penetration?

A

Combine drugs with organic salts
Add preservatives that disrupt the corneal epithelial barrier
Use suspension

23
Q

How do topical suspensions aid with drug absorption?

A

They improve tear retention by micronizing the particles to prevent irritation

24
Q

Why are topical ointments good for drug retention and absorption?

A

Have a lipophilic character so are retained in the tearfilm

25
Q

What is the topical dose/drop volume to use

A

1 drop! Palpebral fissure can hold max 25/30 ul

26
Q

How often do you need to give topical eye treatments?

A

As often as possible - 1 drop cleared in 10 mins
Wait 10 mins in between applications of different drops or will dilute each other

27
Q

What order should you put different eye treatments in?

A

Aqueous drop>suspension>gel>ointment

28
Q

What periocular injections can you give?

A

Subconjunctival injection - for absrobing across the sclera
Retrobulbar injection - for removing an eye

29
Q

When do you use sustained release implants in eyes?

A

For immun emediated conditions

30
Q

What do systemic medications need to penetrate the eye?

A

Lipid solubility
Low molecular weight molecules
Protein binding

31
Q

What are the most commonly used systemic drugs for eyes?

A

Chloramphenicol, doxycycline

32
Q

What anti-inflammatory drugs are used for eyes?

A

Corticosteroids
NSAIDs

33
Q

What are the contraindications for corticosteroids?

A

Dont use in infections - immunosuppressive
Dont use in corneal ulceration

34
Q

What are the antiglaucoma drugs?

A

Prostaglandin analogues
Carbonic anhydrase inhibitors
Beta blockers

35
Q

How do prostaglandin analogues act as anti-glaucoma drugs?

A

The increase the outflow of aqueous humour so reduce the pressure in the eye

36
Q

When do prostaglandin analogues not work to prevent glaucoma?

A

In cats

37
Q

What is a side effect of prostaglandin analogues as anti-glaucoma drugs?

A

Cause a profound myosis - small pupil

38
Q

How do carbonic anhydrase
inhibitors and beta blockers act as anti-glaucoma drugs?

A

They decrease aqueous humour production

39
Q

What are the two main mydriatic drugs?

A

Atropine
Tropicamide

40
Q

What are the features of atropine and when should it be used?

A

Atropine has a slower onset but longer duration
So use for clinical indication to dilate the pupil eg. spasming
Tastes bitter

41
Q

When should you not use atropine?

A

In glaucoma or keratoconjunctivitis secca cases

42
Q

What are the main features of tropicamide and when should it be used?

A

Rapid onset, quicker wear off
Reduces tears in cats

43
Q

What local anaesthetics can be used in the eye?

A

Proxymetacaine

44
Q

What should you use for tear replacement?

A

Hyaluronic acid (clinitas) - holds water well, good lubricant
Lipid based substitutes
Aqueous based substitutes

45
Q

What are anti-collagenases used for in the eyes?

A

They stop the cornea melting from collagenase enzymes produced by bacteria

46
Q

What are the best anti-collagenases?

A

Serum and plasma from the patients own blood
Acetylcysteine
Tetracyclines

CVSOH BVSc4 (86 decks)

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