Pharmacology and the Eye Flashcards
routes of administration for drugs into the eye
Topical Subconjunctival Subtenons intravitreal intra cameral
what is the cornea made up of
Lipid:water:lipid sandwich - topical drugs need to be able to get through these layers (lipid and water)
what properties is the epithelium of the cornea
hydrophobic and lipophilic
therefore penetrated by lipid soluble drugs
what properties is the stroma of the cornea
lipophobic and hydrophilic
therefore penetrated by water soluble drugs
what happens to the cornea in inflammation
the cells become leaky and move further apart therefore reducing the hydrophobic nature of the epithelium
how can topical steroids be made both hydrophobic and hydrophilic
addition of an alcohol/acetate makes it more hydrophilic so it can get through the epithelium
how can you make sure a topical steroid acts on just the surface of the eye
adding a phosphate makes it more hydrophilic so it can’t get through the epithelium
what are the properties of prednisolone acetate
lipophilic - gets through the epithelium
struggles to get through the stroma but still does as its still a lil bit hydrophilic
what are the properties of prednisolone phosphate
hydrophobic
poor penetration in an uniflamed cornea so used during inflammation or if you want low dose steroids
what is benzalkonium
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
where can systemic absorption occur with topical eye drugs
via the tears into the lacrimal sac and out into the nasopharynx
what is subconjunctival administration
injection into the conjunctiva
what is subtenons administration
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
what is intravitral administration
needle goes through the ciliary body into the back of the eye
what is intracemeral administration
puts drug into back of eye
what drugs are used to treat inflammation
steroids - suppress inflammation, allergy and immune response
topical NSAIDS
Anti-histamines
Mat-cell stabilisers
when are steroids commonly used
post op cataracts
uveitis
prevents corneal graft rejection
Temporal arteritis
what are some local side effects of steroids
cataracts
glaucoma
exacerbation of viral infection
what are some systemic side effects of steroids
gastric ulceration immunosuppression osteoporosis weight gain diabetes Neuropsychiatric effects Cushing's
Aims of glaucoma treatment
aim to slow down by reducing IOP
Drops work by either stopping the production of aqueous humour or opening up the canal of schlem
what do protanoids do (latanoprost)
open up the drain
for glaucoma
what do beta blockers do in glaucoma
stop aqueous humour production
what do carbonic anhydrase inhibitors do
stop aqueous humour production
what do alpha adrenergic agonists do in glaucoma
stop aqueous humour and also open up the drain
what do parasympathomimetic drugs do (pilocarpine) in glaucoma
opens up the drain
how is anti-VEGF delivered
intravitreal injections
v expensive
when are intravitreal antibiotics delivered
Endopthalmitis
when is local anaesthetic used
stops nerve conduction
- foreign body removal
- tonometry
- corneal scraping
- comfort
- cataract surgery
what is the most commonly used diagnostic dye
fluorescein
what is fluorescein used for
shows corneal abrasion dendritic ulcers identifies leaks tonometry diagnosis of nasolacrimal duct obstruction angiography
what are mydriatic drugs and how do they work
pupil dilating drugs
-cause pupil dilation by blocking parasympathetic supply to the spinchter papillae muscle
OR overstimulation of sympathetics
what are the side effects of mydriatic drugs
vision blurring acute glaucoma (rare)
symptoms of acute angle closure glaucoma
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
what are sympathomimetic drugs
drugs which over stimulate the sympathetic nerves causing dilation
some cause paralysis of the ciliary muscle (atropine) however some dont
when should topical steroids NEVER be used
in patients with HERPETIC keratitis
what does an allergy to eyedrops present as
symmetrical redness in each eye and around the eye
what does vigabatrin do
constricts visual fields - can be v painful
anticonvulsant used to treat seizures
what drug cause optic neuropathy
ethambutol (TB drug)
damages the optic nerve
what drug can cause maculopathy
chloroquine and hydropxychoroquine (RA drug)
looks like bulls eye on the macula
