Pharmacology

Question 1

how do topical agents work?

Answer 1

can act on the surface

can penetrate the cornea

Question 2

2 types of topical agent?

Answer 2

drops

ointment

Question 3

describe the layers of the cornea

Answer 3

lipid:water:lipid sandwich

90% of the cornea is water

Question 4

how does the structure of the cornea relate to cornea penetrating drugs?

Answer 4

epithelium is lipophilic/hydrophobic and stroma is lipophobic and hydrophilic
therefore
to penetrate epithelium, drug must be lipid soluble
to penetrate stroma, drug must be water soluble

Question 5

give an example of a type of drug which penetrates cornea?

Answer 5

LMW drugs

chloramphenicol has lipophilic and hydrophilic properties to can penetrate

Question 6

what can influence drug penetration in the cornea?

Answer 6

ocular surface inflammation (can reduce hydrophobic nature of endothelium)
lipid layer of tear film can impede penetration
hydrophillic drugs limited by epithelium
hydrophobic drugs limited by stroma

Question 7

what area of the eye limits absorption of hydrophilic drugs?

Answer 7

epithelium

Question 8

what are of the eye limits absorption of hydrophobic drugs?

Answer 8

stroma

Question 9

describe the features of prednisolone acetate?

Answer 9

hydrophobic
good penetration of uninflamed cornea
used post op in cataract surgeery

Question 10

what are the features of prednisolone phosphate?

Answer 10

hydrophilic
poor penetration in uninflamed cornea
used for cornea disease or when want low dose steroid
more used in surface inflammation

Question 11

what is benzylkonium?

Answer 11

type of ammonia which destroys bacteria which can culture in eye drops
keeps bottle of drops sterile

Question 12

how does benzalkonium work?

Answer 12

disrupts lipid layer of tera film

aids penetration of some drugs

Question 13

give an example of a glaucoma drug and 2 side effects?

Answer 13

bimatoprost

lack of benzalkonium can cause red eyes and darkening around eyes

Question 14

how are topical drugs systemically absorbed?

Answer 14

tears are pumped out of lacrimal sac rapidly
excess gains systemic absorption at nasopharynx
limited by punctal occlusion

Question 15

give 2 non-topical routes of administration

Answer 15

subconjunctival

subtenons

Question 16

give 2 types of ocular injection

Answer 16

intravitreal (into the back of the eye)

intracameral (into the front of the eye)

Question 17

name 4 anti-inflammatory agents used in the eye

Answer 17

steroids
topical NSAIDs
anti-histamines
mast cell stabilisers

Question 18

what do steroids do and what 3 conditions are the used in?

Answer 18

suppress inflammation, allergy and immune response
used topically in
- post op cataract
- uveitis
- to prevent corneal graft rejection

Question 19

what can indicate a corneal graft rejection?

Answer 19

vessels approaching the cornea
vision blurred
white line appears in the cornea

Question 20

how does temporal arteritis relate to the eye?

Answer 20

can cause vague visual symptoms

can lead to blindness

Question 21

how is temporal arteritis managed?

Answer 21

systemic steroids

Question 22

non-pressure related cause of optic disc swelling?

Answer 22

anterior ischaemic neuropathy

loss of blood supply to the optic nerve

Question 23

name 3 local side effects of steroids

Answer 23

cataract
glaucoma
exacerbation of viral infection

Question 24

name 6 systemic side effects of steroids?

Answer 24

gastric ulcer
immunosuppression
osteoporosis
weight gain (moon face)
diabetes
neuropsychiatric effects

Question 25

4 strengths of steroid?

Answer 25

FML (weak) Predsol (prednisolone phosphate) = moderate betamethasone = potent dexamethasone/prednisolone acetate = very potent

Question 26

when might NSAIDs be used in the eye?

Answer 26

can be used for pain relief in post laser eye surgery or in conreal abrasion (in place of local anaesthetic which can reduce healing)

Question 27

what is glaucoma?

Answer 27

group of dieases characterised by progressive optic neuropathy resulting in characteristic field defects

Question 28

what is the only modifiable risk factor in glaucoma?

Answer 28

raised intra-ocular pressure

Question 29

features of glaucoma?

Answer 29

usually asymptomatic unless in late stage chronic disease usually slowly progressive

Question 30

how does the optic disc change in glaucoma?

Answer 30

cup increases in size as the number of nerve fibres surrounding the cup decreases so it occupies the space can impact vessels

Question 31

characteristic visual field of glaucoma?

Answer 31

tunnel vision | brain only sees central vision but brain fills in the periphery with what it thinks is there

Question 32

how do glaucoma drops work?

Answer 32

either close the tap or open the drain for aqueous humor

Question 33

name 5 common glaucoma medications

Answer 33

prostanoids (latanoprost/xalatan) = most common beta blockers carbonic anhydrase inhibitors ("...zolamide") alpha2 adrenergic agonist (brimonidine/alphagan) parasympathomimetic (Pilocarpine)

Question 34

how does intravitreal administration work?

Answer 34

delivers effective concentration of drug at target site instantly but many drugs are toxic to retina

Question 35

what is intravitreal administration for?

Answer 35

used as method of administration of antibiotics in endopthalmitis used to deliver intra-ocular steroids anti VEGF delivery

Question 36

sign of endopthalmitis?

Answer 36

hypopyon

Question 37

how does local anaesthetic work?

Answer 37

blocks sodium channels and impedes nerve conduction

Question 38

name 5 uses for local anaesthetic in the eye

Answer 38

``` FB removal tonometry (IOP measurement) corneal scraping comfort cataract surgery ```

Question 39

what is the most commonly used diagnostic dye and in what 6 cases may it be used?

Answer 39

fluorescein - shows corneal abrasion - dendritic ulcer - indentify leaks - tonometry - diagnosing nasolacrimal duct obstruction - angiography

Question 40

what are mydriatics?

Answer 40

cause pupil dilation by blocking parasympathetic supply to the iris e. g - tropicamide - cyclopentolate

Question 41

name 2 side effects of mydriatics

Answer 41

blurring (cycloplegia) - stop the lens from focusing | AACG

Question 42

signs of acute angle closure glaucoma?

Answer 42

sudden onset headache vomiting pupil mid-dilated red sclera

Question 43

what are sympathomimetics?

Answer 43

another class of pupil dilators

Question 44

how do sympathomimetics work and name a side effect

Answer 44

acts on sympathetic system causes pupil to dilate some can cause cycloplegia (e.g atropine) some don't cause cycloplegia (phenylephrine)

Question 45

in what condition must steroid never be given?

Answer 45

herpetic keratitis

Question 46

name a drug which can cause irreversible constriction of visual fields?

Answer 46

vigabatrin (anti convulsant)

Question 47

name a drug which can cause cataract

Answer 47

steroids

Question 48

name a drug which can cause optic neuropathy

Answer 48

ethambutol (for TB)

Question 49

name a drug which can cause maculopathy

Answer 49

chloroquine (hydroxychloroquine can cause if an accumulated dose)

Question 50

what drug can cause vortex keratopathy?

Answer 50

amiodarone