Glaucoma Flashcards
What is glaucoma?
Optic neuropathy that leads to peripheral vision loss
- thinning of the retinal nerve fibre
Neuropathy caused by increased IOP that presses down on optic nerve.
What are the two types of glaucoma?
Open-angle
Angle-closure
What are the two classifications referring to?
Whether the anterior chamber angle (space where the iris means cornea) is opened or narrowed/closed
What is the difference between open-angle or angle-closure glaucoma?
Open-angle= space between the iris and cornea is still opened, fluid draining slowly but still draining. Progressive glaucoma symptoms
Angle-closure= space between iris and cornea is completely closed. Sudden increase in intraocular pressure. May lead to emergency acute attack of glaucoma
Are glaucoma patients usually asymptomatic?
Yes. Symptoms don’t appear unless patient has reached advanced stages in this chronic disease or if it’s an acute attack emergency.
What symptoms would warrant urgent referral?
Eye pain, blurred vision, halos around lights, headache, nausea, vomiting
What is the only modifiable and most important risk factor for glaucoma?
Elevated IOP
What’s another name for elevated IOP?
Ocular hypertension
We are focused on medications that lower IOP, but what other procedures are able to reduce IOP?
Laser or surgical
What are ocular symptoms of glaucoma?
- loss of peripheral vision
- scotoma
- halos around lights
- decreased visual acuity
What are some systemic symptoms associated with glaucoma?
Abdominal pain, nausea and vomiting
What medications could cause or worsen glaucoma?
- Corticosteroids (all routes)
- Drugs with antimuscarinic activity (rare)
- antidepressants, antihistamines, decongestants, antispasmodics - Anticonvulsants
- topiramate associated with angle-closure - Oral contraceptive >3 years associated with open angle
Is screening for elevated IOP helpful for diagnosis of glaucoma?
Lacks adequate sensitivity and specificity
(up to 50% of glaucoma patients have IOP in normal range)
(about 90% of people with elevated IOP do not have glaucoma)
What is normal range of IOP?
<21 mmHg
Is positive family history a risk factor for glaucoma?
Yes
What are risk factors for open-angle glaucoma?
- Elevated IOP
- Advanced age
- Myopia
- Vascular disease such as migraine, hypertension or nocturnal hypotension
- Type 2 diabetes
- Blunt or penetrating trauma
- Previous intraocular surgery
- Previous intraocular inflammation
- Corticosteroid use
- Black, Hispanic or Mexican descent
- Family history of glaucoma
- Sleep apnea
- Obesity
- Smoking
What are risk factors for angle-closure glaucoma?
- Female
- Advanced age
- Hyperopia
The goal of therapy is to use medications to lower IOP. IF patient with glaucoma has IOP in normal range, do we still use medications?
Yes
What are some non-pharm choices for glaucoma?
Lifestyle modifications did not alter outcome.
Aerobic exercise can lower IOP modestly
When does laser or surgical procedures come into play?
If drug therapy is unsuccessful
What is the treatment for acute attack of angle-closure glaucoma?
Laser or surgical iridectomy.
If iridectomy cannot be performed, aggressive medical treatment is required until it can be performed
What are two pathways that aqueous humour could drain from?
Trabecular meshwork and uveoscleral pathway
What are the topical classes to treat open-angle glaucoma?
- Prostaglandin Analogues
- Beta-blockers
- Alpha2-adrenergic agonists
- Carbonic anhydrase inhibitors
Which drug class is often first-line?
Prostaglandin analogues
- slightly more efficacious than beta blockers
- preserve visual field and delay progression
- very few systemic adverse effects
What drugs are within the prostaglandin analogue drug class?
Latanoprost
Travoprost
Latanoprostene bunod
Bimatoprost
How does each of the prostaglandin analogue help treat open-angle glaucoma?
Latanoprost
Travoprost
Latanoprostene bunod
Bimatoprost
Latanoprost and travoprost= lower IOP by increasing outflow of aqueous humor through uveoscleral pathway
Latanoprostene bunod and bimatoprost= increase outflow in both uveoscleral and trabecular meshwork
What are adverse effects of prostaglandin analogues?
Ocular
- darkening of brown colour iris
- lengthening of eye-lashes
- mild conjunctival hyperemia
Is there a preference between prostaglandin analogues?
No
At what time of the day is prostaglandin analogues usually used?
Before bedtime/evening
How long does it take for onset of action of prostaglandin analogues
4 hours
What happens if we do more than one dose of prostaglandin analogues in one day?
Reduces the effectiveness of the drops
What are the storage instructions for latanoprost?
In fridge until opened.
Once opened, can be kept at room temp for 6 weeks.
What agents are part of the beta blocker drug classes?
Betaxolol
Timolol
How do beta blockers help with glaucoma?
Decrease IOP by inhibiting the formation of aqueous humor
Provided visual field protection
Which patient population should we try to avoid beta blockers in?
Patients with:
- asthma
- COPD (CI if severe)
- CI if AV block
- bradycardic (CI if severe)
How do we pick between timolol and betaxolol?
Timolol= non-selective
betaxolol= relatively selective for beta 1 receptor blockade
-> more preferred for those with mild obstructive pulmonary disease
What drugs are in the alpha2-adrenergic agonist class?
Apraclonidine
Brimonidine
How does alpha-2 adrenergic agonists help glaucoma?
Suppresses the formation of aqueous humor
Increase uveoscleral outflow
How do we pick between apraclonidine and brimonidine?
Apraclonidine has limited use due to local allergic reactions
Brimonidine has higher specificity for alpha 2 receptor. Less severe conjunctival hyperemia (red eye)
What are the two different brimonidine formulations?
Brimonidine 0.15% (preserved with urite)
-> slightly lower rate of ocular allergy
Brimonidine 0.2% (preserved with benzalkonium)
What’s the brand names of the two brimonidine?
Alphagan= brimonidine 0.2% preserved with benzalkonium
Alphagan P= brimonidine 0.15% preserved with urite
What are the drugs in the carbonic anhydrase inhibitor class?
-dorzolamide
- brinzolamide
How does carbonic anhydrase inhibitors help glaucoma?
Inhibits an enzyme that is involved in the formation of aqueous humor
How do we pick between dorzolamide and brinzolamide
Brinzolamide is more comfortable to instill. Seem to be as efficacious
When does carbonic anhydrase inhibitors come into play?
Either as adjunctive therapy
OR
Primary treatment if patient has cardiopulmonary contraindication to beta-blockers
What drug is in the cholinergic agonist drug class?
Pilocarpine
How does cholinergic agonists help with glaucoma?
Directly stimulate muscarinic receptors to contract ciliary muscles and increase trabecular outflow
What limits the use of cholinergic agonists?
Poorly tolerated in children and young adults
Ocular side effects like:
- miosis (reduced night vision)
- accommodative spasm (myopia)
- brow ache
- retinal detachment (rare)
What are the benefit of combo products?
- more convenient and improves adherence for patients who need more than one agent
- reduce exposure to preservative
- prevent drug washout
What are the 6 fixed-combo products in Canada?
- Brimonidine/timolol
- Brinzolamide/timolol
- Dorzolamide/timolol
- Latanoprost/timolol
- Travoprost/timolol
- Brimonidine/brinzolamide
What’s the most common preservative in eye drops?
Benzalkoniuim chloride
Does benzalkonium chloride enhance drug penetration into cornea?
Yes, but there is no evidence that they are superior to preservative-free formulations.
Are preservative-free eyedrops safer than those with preservatives?
No, they can still cause some toxic effects
What are concerns with prolonged exposure to this preservative?
Superficial damage to ocular surface and cause symptoms like irritation, dryness, itchiness, and burning
What are some management methods for this preservative concern?
- Travoprost available with ionic buffer preservative (Travatan Z)
- Brimonidine availabe with purite preservative (Alphagan P)
- Some eye drops are available in preservative-free single-dose units
When are oral carbonic anhydrase inhibitors used?
Reserved for emergencies due to significant adverse effects (GI or CNS difficulties, paresthesia, metabolic acidosis or renal lithiasis)
What are the two agents that are oral carbonic anhydrase inhibitors?
Acetazolamide
Methazolamide
What is a reaction we have to watch out for with oral carbonic anhydrase inhibitors?
Sulfa allergy. Not contraindication but should be monitored with caution especially in those with serious reactions (anaphylaxis, Steven-Johnson syndrome)
Is there evidence to support cannabis in glaucoma treatment?
No
Topical glaucoma medications are ______ concentrated to allow adequate intraocular __________.
highly
penetration
How can systemic absorption of these agents be reduced?
Digital occlusion of the nasolacrimal drainage system for several minutes
OR
Close eyelids for 3-5 minutes
How long should patients separate the administration of different eye drops? Why?
5 minutes
To avoid washout of previously administered medication
Can patients use contact lenses if using glaucoma eye drops?
Yes. Soft contact lenses.
Wait at least 15 minutes after each dose before reinserting lenses
Glaucoma patients should use non-prescription ___________ products with caution.
Antihistamine
Rarely causes a problem with open angle glaucoma.
In the rare instance, it can precipitate angle closure glaucoma.
Which patient population needs to be more cautious about this rare incident with antihistamines and glaucoma?
Elderly females who have significant hyperopic
Positive family history of angle closure glaucoma (with no therapeutic or prophylactic iridectomy)
What major drug interaction should we keep in mind with glaucoma eye drops?
Alpha2 adrenergic agonists with MAO inhibitors
What glaucoma eyedrop is first-line and safe for all three trimesters of pregnancy?
Brimonidine
