Glaucoma Flashcards
What is glaucoma?
optic nerve damage caused by and increase in intraocular pressure– blockage in aqueous humour trying to escape the eye
What are the two types of glaucoma?
open-angle and close-angle
What is the normal intraocular pressure?
16 mmHg
What is the intraocular pressure from?
resistance to flow through the trabecular meshwork
What is the difference between open-angle and closed-angle glaucoma?
open is chronic and closed is acute
What are the risk factors for open angle glaucoma?
-age
-family history
-black ethnic origin
-near sightedness (myopia)
What is the presentiaton of open-angle?
-asymptomatic– routine screening by optometrist
-gradual loss of peripheral vision (tunnel)
-fluctuating pain
-headaches
-blurred vision
-halos surrounding lights (worse at night)
What is the gold standard for measuring intraocular pressure?
Goldmann applanation tonometry
What is a non-contact tonometry?
-measures pressure
-uses the puff of air
What is the first line treatment for open angle glaucoma?
prostaglandin analogues– latanoprost
-they increase uveoscleral outflow
SE: increase in lash growth and a browning of the iris
What is closed angle glaucoma?
-when the iris bulges forward and blocks the trabecular meshwork– fluid can’t drain
This is an EMERGENCY and needs treatment or will result in a loss of vision
What are the risk factors for closed angle glaucoma?
-increased age
-female
-family history
-Chinese/East Asian ethnic origin
-shallow anterior chamber
What medications are a risk factor for closed angle glaucoma?
-adrenergic medications
-anticholinergic medications
-tricyclic antidepressants
What is the presentation of closed angle glaucoma?
-appear unwell
-blurred vision
-severely painful red eye
-halos around lights
-associated headache, nausea and vomiting
-hazy cornea
-decreased vision
-dilated, fixed size pupil
-eyeball is firm and hard
Management of closed angle glaucoma
-refer for same day assessment by opthalmology
-lie on back
-pilocarpine eye drops
-acetazolamide orally
-analgesia
-antiemetic
How does Pilocarpine eye drops help with closed angle glaucoma?
-causes constriction of the pupil
-ciliary muscle contraction
-this results in drainage of the fluid
What is aqueous humor?
transparent watery fluid that nourishes lens and cornea
-produced by ciliary body
-flows into posterior chamber, through pupil, and into anterior cornea
-drains into scleral venous sinus and is returned to blood
-normally, completely replaced about every 90 minutes
What intraocular pressure (IOP) is considered abnormal? Which requires treatment?
> 21 is abnormal and >30 requires treatment
How is the first line treatment different for open and closed?
first line for open is pharmacological treatment and for closed it is laser surgery (because it’s an emergency)
What screening is done to detect glaucoma?
-measure IOP
-measure drainage angle
-examine optic nerve
-visual field test
What drug classes are used for lowering IOP to treat glaucoma?
1) prostaglandin analogues
2) beta adrenergic antagonists
3) alpha2 adrenergic agonists
4) carbonic anhydrase inhibitors
5) cholinergic agonists
prescribed in this order (first-line is 1)
What does punctual compression do?
delays drainage of drug into the lacrimal duct by pressing the medial eye-nose corner
minimizes absorption of drug into the bloodstream and systemic side effects
What are the side effects of latanoprost?
sensation of foreign body in eye, burning on instillation, iris discolouration, red eyes and thickening/darkening of eyelashes
