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Ophthalmology > 2.3: Ocular Pharmacology > Flashcards

2.3: Ocular Pharmacology Flashcards

1
Q

Name four routes of specifically for ocular drugs?

A

Topical

Subconjunctival

Subtenons

Intravitreal

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2
Q

Topical application lets the drug work in two places - where?

A

Act on the surface of the eye

Penetrate through the cornea to act on the deeper layers

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3
Q

Describe the composition of the cornea?

A

Lipid sandwich:

  • Lipid epithelium
  • Fluid layer (Stroma)
  • Lipid tear film

Stroma makes up most of the cornea

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4
Q

Describe how drugs can pass through the cornea?

A

Low molecule weight drugs can pass through (small).

Large drugs must be either lipid or water soluble to pass through

Lipid soluble drugs are able to penetrate epithelium

Water soluble drugs are able to penetrate stroma

Some drugs are lipophilic and hydrophilic

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5
Q

Give an example of a drug that is lipophilic and hydrophilic that is used in eyes?

A

Chloramephenicol

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6
Q

Describe the affect of inflammation on the absorption of topical applications?

A

Occular surface inflammation can limit the hydrophobic nature of the endothelium

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7
Q

Describe the affect of the lipid layer (of the tear film) on drug penetration?

A

The lipid layer of the tear film may impede drug penetration

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8
Q

What limits hydrophobic drugs?

A

Stroma

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9
Q

What limits hydrophilic drugs?

A

Lipid Layer (Epithelium)

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10
Q

Are topical steroids hydrophobic or hydrophillic? Why?

A

They require both hydrophobic and hydrophilic ability

They are altered depending on what they are required for

Eg: Can penetrate the cornea or remain on surface

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11
Q

Describe a hydrophobic steroid?

A

Prednisolone Acetate

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12
Q

Describe a hydrophilic steroid?

A

Prednisolone Phosphate

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13
Q

How do you make a steroid hydrophilic?

A

Add phosphate

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14
Q

How do you make a steroid hydrophobic?

A

Add acetate or alcohol

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15
Q

Describe Prednisolone Acetate?

A

Hydrophobic Steroid

Used in un-inflamed eye

Is absorbed into the eye

If cornea is normal, a large amount of prednisolone acetate will get into the eye

Used post-operatively

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16
Q

Describe Prednisolone Phosphate?

A

Hydrophillic steroid

Used in inflamed eye

Poor penetration

Sits on the surface of the eye - very little drug penetrates into the actual eye

Used for corneal disease

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17
Q

Describe how to enhance corneal penetration?

A

Breaking up the lipid layer increases penetration

Benzalkonium is a preservative used in eye drops that helps to break the lipid layer and increase corneal penetration

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18
Q

Describe the job of Benzalkonium?

A
  1. Preservative in eye drops (prevents bacterial soup)
  2. Increases corneal penetration by punching holes
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19
Q

Describe Bimatoprost? What happened?

A

Drug used to lower Intra-ocular pressure in glaucoma

High dose of drug, low dose of preservative

Led to red eye

Swapped now to lower dose of drug but higher dose of preservative - allows for corneal penetration but no red eye

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20
Q

Describe systemic absorption of topical drugs?

A

Excess eye drops can result in systemic absorption at nasopharynx

  • Tears pumped out of lacrimal sac rapidly
  • Drops can be washed into nasopharynx
  • Explains bad taste
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21
Q

How can the systemic absorption of topical drugs be limited?

A

Punctal occlusion

Pressing down on the puncta when administering topical drugs causes excess to wash down face as tears

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22
Q

Describe subconjunctival route of administration?

A

Injection directly into the space between conjunctiva and sclera

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23
Q

Steroids can be given topically - what is another (preferred) method of administration?

A

Subconjunctival Injection

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24
Q

Describe Subtenons route of administration?

A

Injection directly behind the eye into Tenon’s capsule/Sub tenon’s space

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25
Q

Describe intravitreal route of administration? Two uses?

A

Injection directly into the eye.

This is done very commonly

Used in steroids and delivering anti-VEGF for wet macular degeneration

26
Q

Two common treatments for eye infections?

A

Chloramphenicol

Ofloxacin

27
Q

What is Ofloxacin used for?

A

Eye infections

28
Q

Common treatments for eye inflammation? For allergic eye inflammation?

A

Steroids Topical

NSAIDs

Anti Histamines

Mast Cell Stabilizers

29
Q

Action of steroids?

A

Suppress inflammation, allergy and the immune system

30
Q

Three uses of topical steroids?

A

Cataracts (post-op)

Uveitis

To prevent corneal graft rejection

31
Q

Why are steroids used in cataracts post-op?

A

Cataract surgery always results in inflammation

Steroids needed to reduce inflammation

32
Q

What is uveitis?

A

The uvea is composed of the choroid, iris and ciliary body Uveitis is inflammation of any of these parts

33
Q

Why is Iritis painful? Worse on light exposure?

A

Iris is a muscle and inflammation of any muscle is sore when you move it

When light is shone on the eye, iris constricts (painful)

34
Q

Local side effects of steroids?

A

Cataracts

Glaucoma

Exacerbation of viral infection

35
Q

Systemic side effects of steroids?

A

Gastric Ulcers

Immunosupression

Osteoporosis

Weight Gain

Diabetes

36
Q

What is temporal arteritis?

A

This is inflammation of the muscular arteries

Can present with symptoms of headache and visual symptoms

37
Q

Describe a classic presentation of temporal arteritis?

A

Jaw pain

Fine when you start eating but gets worse (cramp)

Also bit of a headache over temporal area

New onset

38
Q

Treatment for temporal arteritis?

A

Systemic Steroids

39
Q

What is anterior ischaemic neuropathy?

A

This is loss/damage to vision due to damage to the optic nerve due to lack of blood supply

40
Q

What does the retina look like in anterior ischaemic neuropathy?

A

Poorly defined contour

Odd coloured - some pink bits

Hard to visualise cup

Many haemorrhages

41
Q

Name some steroids used in eye treatment?

A

Prednisolone

FML

Dexamethasone

42
Q

What is glaucoma?

Risk factor?

Progression?

Is any part retained?

A

This is a group of eye diseases that cause damage to the optic nerve and vision loss

Normal death of optic nerve occurs with ageing however in glaucoma this is sped up

Only modifiable risk factor for glaucoma is raised intraocular pressure

Chronic disease that progresses slowly

Central part is always retained

43
Q

Describe how people notice glaucoma?

A

Often not noticed by patients

Screened for

Often unaware they are missing the edges of their visual field as the brain compensates

44
Q

First line treatment for glaucoma?

A

Prostaglandin analogue - Latanoprost

45
Q

Other treatments for glaucoma?

A

Beta Blockers

Alpha Agonists

Carbonic Anhydrase Inhibitors

Parasympathomimetic

46
Q

Describe the pros and cons of intravitreal injection?

A

Allows you to get drugs where they are needed (can’t get there from systemic system due to blood/retina barrier)

Can be toxic to retina

47
Q

What is Endophthalmitis?

Classic story?

A

Inflammation of the globe

Often caused by surgery

Classic: Cataract surgery on tuesday, blind on thursday

48
Q

Treatment for Endophthalmitis?

A

Lots and lots of antibiotics

Only way to save vision

In some cases, vision cannot be saved (infection is too virulent)

49
Q

What is wet macular degeneration?

A

This is the development of abnormal blood vessels underneath the macula

This causes leakage of blood and fluid that is toxic to the retina and leads to damage

50
Q

Treatment for wet macular degeneration?

A

Anti-VGEF treatment by intravitreal injection

51
Q

Describe local anaesthetic drops? Use in ophthalmology? Drawback (why can’t be used long term?)

A

Blocks sodium channels and impedes nerve conduction

Can be used for:

  • Foreign Body Removal
  • Corneal Scrapes
  • Tonometry (Intra-ocular pressure measurement
  • Comfort (when examining patient)

Slows healing

52
Q

Describe fluorescein?

Use in ophthalmology?

A

Used as a stain

Uses:

  • Shows corneal abrasions
  • Used in tonometry (for IOP)
  • Helps to diagnose nasolacrimal duct obstruction
  • Angiography
53
Q

What are Mydriatics?

Examples?

Side effects?

A

These cause pupil dilation by blocking parasympathetic

Eg: Tropicamide, Cylopentolate

Blurring of eye vision, acute glaucoma (so rare!)

54
Q

Giving mydriatics can lead to one rare, acute side effect

What is this?

Sign of this?

A

Acute Glaucoma

Headache

55
Q

What are Sympathomimetics? Examples

A

These act on the sympathetic system to dilate the pupil

Eg: Phenylephrine, Atropine

56
Q

Why don’t systemic antibiotics work on eyes?

A

They are prevented from reaching the eye due to the retinal/blood barrier

57
Q

Concern about steroids for eye treatments?

A

Can lead to cataracts

58
Q

Concern for ethambutol (used in TB) in regards to eyes?

A

Can lead to optic neuropathy

59
Q

Concern about chloroquine?

A

Causes bulls-eye maculopathy

Not used anymore

60
Q

Concerns about hydrochloroquine?

A

Seems to cause macular problems

Depends on dose

Close monitoring needed

61
Q

What is this photo of? Caused by what drug?

A

Corneal Verticillata Caused by Amiodarone

Ophthalmology (19 decks)

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