Pharmacology and the Eye

Question 1

routes of administration for drugs into the eye

Answer 1

Topical 
Subconjunctival 
Subtenons 
intravitreal 
intra cameral

Question 2

what is the cornea made up of

Answer 2

Lipid:water:lipid sandwich - topical drugs need to be able to get through these layers (lipid and water)

Question 3

what properties is the epithelium of the cornea

Answer 3

hydrophobic and lipophilic

therefore penetrated by lipid soluble drugs

Question 4

what properties is the stroma of the cornea

Answer 4

lipophobic and hydrophilic

therefore penetrated by water soluble drugs

Question 5

what happens to the cornea in inflammation

Answer 5

the cells become leaky and move further apart therefore reducing the hydrophobic nature of the epithelium

Question 6

how can topical steroids be made both hydrophobic and hydrophilic

Answer 6

addition of an alcohol/acetate makes it more hydrophilic so it can get through the epithelium

Question 7

how can you make sure a topical steroid acts on just the surface of the eye

Answer 7

adding a phosphate makes it more hydrophilic so it can’t get through the epithelium

Question 8

what are the properties of prednisolone acetate

Answer 8

lipophilic - gets through the epithelium

struggles to get through the stroma but still does as its still a lil bit hydrophilic

Question 9

what are the properties of prednisolone phosphate

Answer 9

hydrophobic

poor penetration in an uniflamed cornea so used during inflammation or if you want low dose steroids

Question 10

what is benzalkonium

Answer 10

preservative used in eyedrops to keep the bottle sterile

also aids the penetration of some drugs

strops out the lipid layer of the tear film

Question 11

where can systemic absorption occur with topical eye drugs

Answer 11

via the tears into the lacrimal sac and out into the nasopharynx

Question 12

what is subconjunctival administration

Answer 12

injection into the conjunctiva

Question 13

what is subtenons administration

Answer 13

space through the conjunctiva and through the tendons in the back of the eye

numbs eyes for cataract surgery and can also be used to administer steroids

Question 14

what is intravitral administration

Answer 14

needle goes through the ciliary body into the back of the eye

Question 15

what is intracemeral administration

Answer 15

puts drug into back of eye

Question 16

what drugs are used to treat inflammation

Answer 16

steroids - suppress inflammation, allergy and immune response

topical NSAIDS

Anti-histamines

Mat-cell stabilisers

Question 17

when are steroids commonly used

Answer 17

post op cataracts
uveitis
prevents corneal graft rejection
Temporal arteritis

Question 18

what are some local side effects of steroids

Answer 18

cataracts
glaucoma
exacerbation of viral infection

Question 19

what are some systemic side effects of steroids

Answer 19

gastric ulceration 
immunosuppression 
osteoporosis 
weight gain 
diabetes 
Neuropsychiatric effects 
Cushing's

Question 20

Aims of glaucoma treatment

Answer 20

aim to slow down by reducing IOP

Drops work by either stopping the production of aqueous humour or opening up the canal of schlem

Question 21

what do protanoids do (latanoprost)

Answer 21

open up the drain

for glaucoma

Question 22

what do beta blockers do in glaucoma

Answer 22

stop aqueous humour production

Question 23

what do carbonic anhydrase inhibitors do

Answer 23

stop aqueous humour production

Question 24

what do alpha adrenergic agonists do in glaucoma

Answer 24

stop aqueous humour and also open up the drain

Question 25

what do parasympathomimetic drugs do (pilocarpine) in glaucoma

Answer 25

opens up the drain

Question 26

how is anti-VEGF delivered

Answer 26

intravitreal injections v expensive

Question 27

when are intravitreal antibiotics delivered

Answer 27

Endopthalmitis

Question 28

when is local anaesthetic used

Answer 28

stops nerve conduction - foreign body removal - tonometry - corneal scraping - comfort - cataract surgery

Question 29

what is the most commonly used diagnostic dye

Answer 29

fluorescein

Question 30

what is fluorescein used for

Answer 30

``` shows corneal abrasion dendritic ulcers identifies leaks tonometry diagnosis of nasolacrimal duct obstruction angiography ```

Question 31

what are mydriatic drugs and how do they work

Answer 31

pupil dilating drugs -cause pupil dilation by blocking parasympathetic supply to the spinchter papillae muscle OR overstimulation of sympathetics

Question 32

what are the side effects of mydriatic drugs

Answer 32

``` vision blurring acute glaucoma (rare) ```

Question 33

symptoms of acute angle closure glaucoma

Answer 33

lots of pain sudden onset headache and vomiting red eye and mid dilated pupil which doesn't reaction bc the pressure in eye is too high

Question 34

what are sympathomimetic drugs

Answer 34

drugs which over stimulate the sympathetic nerves causing dilation some cause paralysis of the ciliary muscle (atropine) however some dont

Question 35

when should topical steroids NEVER be used

Answer 35

in patients with HERPETIC keratitis

Question 36

what does an allergy to eyedrops present as

Answer 36

symmetrical redness in each eye and around the eye

Question 37

what does vigabatrin do

Answer 37

constricts visual fields - can be v painful anticonvulsant used to treat seizures

Question 38

what drug cause optic neuropathy

Answer 38

ethambutol (TB drug) damages the optic nerve

Question 39

what drug can cause maculopathy

Answer 39

chloroquine and hydropxychoroquine (RA drug) looks like bulls eye on the macula