Common conditions of the eyes Flashcards
what conditions(s) cause opacification of the eyes and what part does it affect?
cataract - opacification of the lens
corneal degeneration/dystrophie - opacification of the cornea
angle closure glaucoma
what is glaucoma?
raised intraoccqular pressure
what is the triad of symptoms which indicate glaucoma?
raised intraoccqular pressure
vision field defects
optic disc changes on ophthalmoscopy
what are the 2 types of glaucoma?
open angle glaucoma (POAG)
closed angle glaucoma
what does the fundus pictures look like in ophthalmoscopy in someone with glaucoma?
optic disc is cupped , pale and appears unhealthy
how does IOP cause visual defects?
the raised pressure puts pressure on the nerve fibres which lie on the surface of the retina
this results in the nerve fibres dying
because never fibres are dying this puts pressure on the optic nerve head
how is primary open angle glaucoma treated?
eyedrops to decrease IOP - prostaglandin anologues - beta blockers - carbonic anhydrase inhibitors laser trabeculoplasty trabeculotomy surgery
describe the clinical presentation of closed angle glaucoma.
sudden onset
red, painful eye with visual loss
headache (often confused with migraine)
how does closed angle glaucoma result in raised IOP?
suddenly something causes the angle of the anterior chamber to close
therefore this blocks the trabecular meshwork for the aqueous humour to drain into
the pressure therefore builds as it cannot drain
what causes the angle to close in closed angle glaucoma?
functional block in a small eye - lens too big
mid-dilated pupil - periphery of iris crowds around the angle so outflow is obstructed
the iris sticks to pupillary border which causes the iris to dilate anteriorly blocking the angle
how do you treat angle closure glaucoma?
decrease IOP; - IV infusion carbonic anhydrase inhibitors analgesia, antiemetics constrictor eye drops beta blocker eye drops i.e. timolol steroid eye drops iridotomy
what is the difference in the raised IOP of closed and open angle glaucoma?
closed is sudden and acute causing red and painful eye
open is gradual and painless
what is the difference in the drainage of the aqueous humour in open compared to closed angle glaucoma?
in open angle - drainage through trabecular meshwork is obstructed
in closed angle - the peripheral iris is blocking the angle of the anterior chamber so its more sudden
what are he 2 different types of hordeolum/stye’s?
external = infection affecting sebaceous glands of eyelashes internal = infection affecting meibomian glands of tarsal plate
does conjunctivitis cause vision loss?
no, not unless the infection spreads to the cornea
how would you treat bacterial conjunctivitis?
antibacterial eye drops
what may differentiate anterior uveitis from intermediate and posterior?
in anterior uveitis the iris leaks plasma and WBC which can be seen during slit lamp examination as a hazy anterior chamber and cells deposited in the back of the cornea
in anterior uveitis the anterior chamber may settle inferiorly
what is the difference between anterior, intermediate and posterior uveitis?
anterior - inflammation of iris
intermediate - inflammation of ciliary body
posterior - inflammation of choroid
how does posterior uveitis cause blurred vision?
because the choroid sits onto of the retina, infection can easily spread to the retina causing blurred vision
in what condition is the ciliary body inflamed and what does an inflamed ciliary body do?
intermediate uveitis
causes leakage of cells and proteins
what type of cells does anterior uveitis leak?
WBC and plasma cells
what is cataract?
lens opacification
why does cataract develop?
embryological/foetal fibres are never shed - they are compacted in the middle of the lens
due to no blood supply it relies on diffusion for nutrition
the lens absorbs harmful UV rays to protect the retina from harm
this all causes damage to the lens fibres causing opacification
what is the treatment for cataract?
surgery to replace cataract lens with a posterior chamber intra ocular lens (PCIOL)
states some of the features of corneal dystrophies/ degenerations.
bilateral opacifying non-inflammatory mostly genetically determined sometimes they are due to the accumulation of substances within the cornea such as lipase
what is the treatment for corneal degeneration or dystrophies?
corneal transplant
what is the clinical presentation of corneal dystrophies / degeneration?
start in 1st to 4th decade of life
decreased vision
start in 1 corneal layer and spreads
what is the aetiology of corneal ulcer?
bacterial/viral/fungal infection
what is the aetiology of conjunctivitis?
bacterial or viral infection
what are the causes of uveitis?
isolated illness
non-infectious autoimmune causes - presence of HLA-B27 predisposes
infectious i.e. TB
associated with systemic illness i.e. alkalising spondylitis
