Acute Glaucoma
Glaucoma is where there's optic nerve damage due to a rise in intra-ocular pressure, which is caused by a blockage in the drainage of aqueous humour. In Acute glaucoma, the iris bulges forward and seals off the trabecular meshwork from the anterior chamber, therefore preventing the drainage of aqueous humour, therefore leading to a quick increase in pressure. This pressure then builds up in the posterior chamber, therefore worsening the angle closure. This is an emergency, as it can lead to permanent loss of vision.
Risk factors:
Age
Female
FHx
Anti-muscarinics, Adrenergics, Anticholinergics, TCAs
Presentation
Severely painful red eye
Blurred vision
Halos around lights
Headache, N+V
Worse at night as the pupil dilates and closes the angle further - For this reason, it's important to avoid giving mydriatics (pupil dilator) before examining the eyes
O/E - FIXED dilated pupil, Decreased visual acuity
Management
Conservative - Lie patient flat on their back (relieves pressure)
The mainstay of treatment is:
Pilocarpine eyedrops (2% if blue, 4% if brown) - This is a muscarinic agonist, causing ciliary muscle contraction and pupil constriction
This pulls the iris away from the trabecular network, leading to more efficient aqueous drainage
Acetazolamide 500mg PO/IV - This is a Carbonic Anhydrase inhibitor to decrease production of aqueous humour
Timolol eyedrops B-blocker to decrease production of aqueous humour
The definitive management option is Iridotomy, which is where a hole is made into the iris to allow aqueous humour to flow from the posterior chamber into the anterior chamber, therefore opening the angle and relieving pressure from the iris onto the cornea.