Opthalmology Flashcards
what is the macula?
it is the part of the eye that is involved in central vision (i.e. seeing what is directly in front of you)
what is the foveola centralis?
small depression within the neurosensory retina where visual acuity is the highest.
located within the macula
What are the types of AMD?
wet and dry
dry: takes years, due to deposition of various metabolites; 90% cases - more common
wet: takes weeks to months, due to neovascularisation growing into subretinal space
causes of pre-senile cataract
steroids (dose and duration dependent)
uveitis (for which steroids are often needed)
DM
high myopia
significant trauma
can also occur in association with Down syndrome and retinitis pigmentosa
what is myopia?
nearsightedness
(struggle seeing what is in the distance)
What are the three main chambers in the eye?
In the anterior segment of the eye
- anterior chamber is form the cornea to the iris
- posterior chamber is the small space between the iris and the lens
in the posterior segment of the eye:
- the vitreous chamber is the space behind the lens
what are the chambers of the eye filled with?
the chambers in the anterior segment of the eye (ant and post chamber) are filled with aqueous humour
the vitreous chamber in the posterior segment of the eye is filled with vitreous humour
describe the journey of aqueous humour in the eye
- produced by the ciliary body
- enters the posterior chamber
- moves to the anterior chamber through a small gap between the iris and lens
- is taken up via the trabecular meshwork
- enters the canal of Schlemm
- is drained into the aqueous veins which are part of the episcleral venous system
Mx of acute closed angle glaucoma
- IV acetazolamide to drop the IOP.
- Also topical agents (eyedrops) to lower the IOP: prostaglandin analogues and if not contraindicated, beta-blocker eyedrops.
- IV mannitol is occasionally required to lower IOP.
- topical steroids if eye inflammed in acute glacuoma
- pilocarpine drops are given to cause miosis (constricted pupils), which helps to unblock the closed drainage angle
- Either that day or after several days, laser peripheral iridotomy to both eyes (as if the acute glaucoma attack occurred in one eye, the other eye is likely to be vulnerable to an attack in future) -> iridotomy should prevent any future attack or recurrence of acute glaucoma
What is mydriasis?
fixed mid dilated pupil
what is miosis
O/E findings in acute angle closure glaucoma
- fixed mid dilated pupil (i.e. mydriasis)
- general corneal haze (rather than specific infiltrates)
- the eye feels rock hard when (gently) palpated, and if measured, intraocular pressure will be markedly raised