Glaucoma Flashcards
def
optic neuropathy associated with increased intraocular pressure
what is the definition of increased intraocular pressure
IOP>21mmHg
aetiology
can be split into primary, secondary and congenital causes
1 primary -acute closed-angle glaucoma -primary opened-angle glaucoma -chronic closed -angle glaucoma 2 secondary -trauma -uveitis -steroids 3 congenital -buphthalmos
what is buphthalmos
congenital disorder which gives enlargement of the eyeball
associated with glaucoma
epi
increases with age
3rd most common cause of blindness worldwide
history
acute closed-angle glaucoma is associated with a painful red eye and impaired vision
primary opened-angle glaucoma is often asymptomatic but there may be peripheral field loss
examination
acute closed-angle glaucoma there is a red eye, hazy cornea, loss of red reflex and fixed + dilated pupil
in primary opened-angle glaucoma there are often no signs
what does a hazy lens and a hazy cornea indicate
hazy lens indicates cataracts
hazy cornea indicates glaucoma (specifically acute closed-angle glaucoma)
what causes visual field loss in glaucoma
increased intraocular pressure compresses and stretches the retinal nerve fibres which leave the optic disk
this causes scotomas and visual field loss
what is a scotoma
partial loss of vision or a blind spot in an otherwise normal visual field
what causes increased intraocular pressure
decreased outflow of aqueous humour due to:
1 obstruction to outflow of aqueous humour due to the iris and cornea sticking together. this closes the iridocorneal angle and trabecular meshwork/canal of schlemm and causes a rapid and severe rise in IOP (ACAG)
2 reduced outflow of aqueous humour through the trabecular meshwork (POAG)
3 blockage of trabecular meshwork by blood or inflammatory cells
what is the pathogenesis of ACAG
there is obstruction to outflow of aqueous humour due to the iris and cornea sticking together
this closes the iridocorneal angle and trabecular meshwork/canal of schlemm
this causes a rapid and severe rise in IOP
what is the pathogenesis of POAG
there is reduced flow of aqueous humour through the trabecular meshwork
investigations
1 goldmann applanation tonometry
-standard examination to measure IOP
-if raised, indicates glaucoma
2 opthalmoscopy
what is normal IOP
15mmHg
