Glaucoma Flashcards
(46 cards)
what produces aqueous fluid
ciliary bodies
where is aqueous fluid secreted + how
posterior chamber, 50% diffusion, 50% active secretion
how does aqueous fluid drain from the anterior chamber
via trabecular meshwork, into the canals of schlemm, then to the collecting channels into the venous system
what is aqueous used for
maintain IOP for eye shape, as well as providing nutrition to the cornea and removing waste
what is the average IOP
15.5
whats the normal range of IOP
10-21 mmHg
what is progressive open angle glaucoma
chronic increase in IOP leading to a loss of retina/nerve fibres + optic disc cupping, causing peripheral vision loss which may progress to total blindness
what is the most common type of glaucoma
progressive open angle glaucoma
what are risk factors of progressive open angle glaucoma
increased intraocular pressure FHx (most important) myopia afrocaribbean diabetes `
what % of people >40 and >75 have progressive open angle glaucoma
1% >40 ,5% >75
what is seen on fundoscopy when looking at an eye with progressive open angle glaucoma
optic disc atrophy (border blurring)
cupping (increased cup to disc ratio)
what is acute angle closure glaucoma
acute increased pressure causing pain, blurred vision , corneal odema, red eye and a fixed, mid-dilated pupil
what is the pathology of acute angle closure glaucoma
lens increases with age and pushes iris closer to the trabecular meshwork, at a critical point the iris blocks off the drainage causing a blockage and rapid rise in intraocular pressure
why may acute angle closure glaucoma be helped by going to bed
causes the pupil to constrict, causing iris to be pulled away from sides of eye, decreasing the blockage and allowing drainage - this means symptoms may be present for weeks before a full attack occurs
why may acute angle closure glaucoma be helped by going to bed
causes the pupil to constrict, causing iris to be pulled away from sides of eye, decreasing the blockage and allowing drainage - this means symptoms may be present for weeks before a full attack occurs
how do you treat acute angle closure glaucoma
pilocarpine/acetazolamide to shrink pupil
IV Diamox and mannitol
BILATERAL laser iridotomy or trabeculotomy allows drainage - bilateral = preventative
what is rubeotic glaucoma
complication of central retinal vein occlusion or diabetic retinopathy, where neovascularisation near the iris causes occlusion of the trabecular network causing rapid increase in IOP
what are the symptoms of rubeotic glaucoma
pain decreased VA red eye corneal odema rubeosis (neovascularisation of the iris - looks like a red ring) pupil distortion
how does each untreated IOP over the threshold relate to prognosis for vision
IOP >30 = blind in 3 years
IOP 25-30 = blind in 6 years
IOP 21-25 = blind in 15 years
how are visual fields mapped + which is more common now
Goldmann perimetry or automated perimetry (automated more common now)
how does goldmann perimetry work
hollow white bowl is placed in front of patient and lights of varying size and intensity are presented and the patient must say if they can see it
these are then mapped on a diagram
how does automated perimetry work
similar to goldmann perimetery i that they look at a blank screen with a light on it but the machine moves the lights automatically and the machine has a button to press when the light is seen, this then automatically maps the visual field
what eye drops are available for glaucoma treatment
prostaglandin analogues - latenoprost beta blockers carbonic anhydrase inhibitors - dozolamide alpha-agonists - brimonidine cholinergic - pilocarpine
which medical treatments for glaucoma cause decreased aqueous production
beta blockers
carbonic anhydrase inhibitors
alpha-agonists (partially)
