Clinical Pathology of the Eye Flashcards
what is the main pathology of the lens
cataracts
what are cataracts
opacifications within the lens
usually age related by has multiple causes
what is the main cause of cataracts
degenerative changes in the fibres of the lens due to UV exposure
what are some less common causes of cataracts
hypertension smoking post op and trauma metabolic disorders genetic diabetes
what is glaucoma
abnormal increase in the pressure in the eye (intraocular pressure)
causes of increase intraocular pressure
too much aqueous humour being produced
the aqueous humour not being properly drained
where does aqueous humour normally drain
through the trabecular meshwork into the canal of schlem
what is open angled glaucoma
most common cause
poor drainage between the trabecular meshwork or canal of schlem leads to increase IOP which then damages the optic disc and nerve
what is primary closed angle glaucoma
when the drainage through the meshwork if fine but the fluid can’t get to the meshwork
fluid can’t pass over the iris into the anterior chamber properly
Acute and site threatening
how do you treat open angle glaucoma
pharmacological therapy aimed at widening the canal
how do you treat closed angle glaucoma
medical emergency
use a laser to make a hole in the iris and allow the fluid to drain (peripheral iridotomy)
what is ‘cupping’ of the optic disc
when raised IOP damages the optic disc and nerve, so the edges of the disc become rolled up and the centre becomes depressed
what is papilloedema
swelling of the optic disc/nerve as a result of increased intracranial pressure
what is conjunctivitis
inflammation of the conjunctiva - usually viral but can be bacterial or allergic
symptoms of conjunctivitis
swelling, redness, pain and heat of the conjunctiva
what is the different between episcleritis and scleritis
both inflammation of the sclera however scleritis is more rare and severe and episcleritis is most superficial and self limiting
scleritis symptoms
pain on movement
associated with underlying autoimmune aetiology
what is ARMD
age related macular degeneration
difference between wet and dry ARMD
Dry- no significant vascular proliferation
wet- vascular proliferation
what is drusen
by-product seen in ARMD - proteins, lipid and inflammatory mediators
What is wet ARMD
Neovascularisation in choroid mediated by VEGF
the new vessels are fragile and leaky so are more likely to result in vision loss
treatment for wet ARMD
anti-VEGF injections
what effect does hyperglycaemia have on the eye
leads to changes to osmotic pressure in the anterior chamber of the eye (this cause blurred vision)
what affect does hyperglycaemia have on the pupils
Argyll Roberston pupil
-pupil accommodates but doesn’t reaction (no constriction or dilation but can focus near/far)
how can diabetes cause cataracts
increased sugar content in lens leads to the conversion of glucose to sorbitol (this leads to altered osmotic gradients with swelling and fibre disruption)
how can diabetes cause glaucoma
causes Rubeotic glaucoma - new vessel formation obstructions the angle (also seen in severe vensous occlusion)
what is diabetic retinopathy
complex mechanisms leading to poor function of vessels
leaky vessels and small aneurysms form
if severe new vessel formation occurs leading to oedema
if the macular is affected the visual loss is worse
what arteries can be occluded to cause sight loss
carotids, central retinal artery
what veins are occluded to cause sight loss
central venous occlusion
which form of vasculitis can lead to sight loss
giant cell vasculitis
what cancers are seen in the eye
BCC
SCC
Melanoma
Retinal melanoma
