Glaucoma Flashcards
What is glaucoma?
condition characterized by optic disc cupping and visual field loss, in which intraocular pressure is sufficiently raised to impair optic nerve function
What are the causes of glaucoma?
primary or secondary
- trauma, inflammation, neovascular, or congenital
How can glaucoma be classified?
open angle or closed angle according to appearance of the drainage angle on gonioscopy
When is primary closed angle glaucoma more likely to occur?
occurs in hypermetropic individuals as their eyes are smaller
What are the characteristic features of primary open angle glaucoma (POAG)?
raised IOP >21mmHg
open angle aqueous drainage angle
pathologically cupped optic disc
glaucomatous visual field loss
How is ocular hypertension different to POAG?
IOP is >21 mmHg but a normal optic disc and visual field
What is normal tension glaucoma?
IOP <21 mmHg but there is optic disc cupping and visual field loss
What factors increase prevalence of POAG?
Increasing age Corticosteroid use High myopia Central retinal vein occlusion Diabetes mellitus Family history
Why is it important to reduce IOP ?
IOP is directly proportional with likelihood of disc damage
- raised pressure is sometimes missed because it naturally varies throughout the day
What are the 2 theories for the pathogenesis of POAG affecting eyesight?
1) direct mechanical theory = raised IOP technically damages the optic nerve
2) indirect ischemic theory = raised IPO interferes with microcirculation and the perfusion pressure is too low to compensate
What are the symptoms of POAG?
usually asymptomatic and will never cause pain or reddening of the eye
- Visual loss will begin to occur when the condition is advanced
On examination what clinical features would you expect to see in POAG?
1) usually normal distance visual acuity, raised IOP (Using goldmann application tonometry, this may be false negative if someone has a decreased corneal thickness), and open drainage angle on gonioscopy
2) ophthalmoscopy reveals a pathologically cupped optic disc, cup:disc ratio >0.5 and asymmetrical between eyes, vessels in the disc will be shifted nasally and there may be hemorrhage
What are the complications of glaucoma?
retinal vein occlusion and blindness
How is glaucomatous visual field loss measured?
by Goldmann and Humphrey fields - starts with a nasal step and then may progress to inferior and superior arcuate scotomas, extending out from the normal blind spot
What happens if glaucoma isn’t treated?
if left untreated there will be development of temporal and central islands on top of this, leading to complete blindness
