Glaucoma Flashcards
Definition of glaucoma?
Group of disorders characterized by progressive damage to the optic nerve, which manifests as visual field loss, and which is usually (but not always) accompanied by raised intra-ocular pressure
Normal IOP?
10-21mmHg
Cup-disc ratio which should prompt suspicion of glaucoma?
0.8
Clinical assessment of patient with suspected glaucoma? (3)
Tonometry (measures IOP)
Optic disc assessment
Visual field assessment
Risk factors for primary open-angle glaucoma? (5)
Age Family history Race (more common in afro-caribbeans) Ocular hypertension Myopia
How does open-angle glaucoma present?
Usually asymptomatic until severe and permanent damage has occurred
What is gonioscopy?
Technique used to measure the angle between cornea and iris
Two mechanisms of medical treatment for glaucoma?
Reduction of aqeous production
Increased aqueous outflow
Drug classes which reduce production of aqueous?
Topical beta blockers
Carbonic anhydrase inhibitors
Drug classes which increase aqueous outflow?
Parasympathomimetic (e.g. pilocarpine)
Prostaglandin analogues e.g. latanoprost
What is the exact mechanism of pilocarpine in glaucoma treatment?
Activates cholinergic receptors, opening up the trabecular meshwork and enabling drainage of aqueous humour
Adverse effect of latanoprost?
Brown pigmentation of the iris
Underlying pathophysiology of acute angle closure glaucoma?
Build-up of aqueous in the posterior chamber exerts pressure on the iris, pushing it forward onto the peripheral cornea, thus blocking off the angle where trabcular meshwork/Schlemm’s canal drains
Symptoms/signs of acute angle closure glaucoma? (5)
Severe pain Red eye Hazy cornea Mid-dilated pupil Blurred vision
How is acute angle closure glaucoma managed?
Medical treatment to lower IOP
Followed by surgery (iridectomy or iridotomy)
