Glaucoma Flashcards
what is glaucoma?
It is a group of ocular disorders characterised by increased intraocular pressure
What are the two types of glaucoma?
- Open angle
- Closed angle glaucoma
Describe open and closed angle glaucoma/
- Open angle - occur in more than 70% of the glaucoma cases
- chronic condition that has no symptoms until visual impairemnts start to occur
Closed angle - More severe, can lead to nerve damage
- usually diagnosed during surgery
Impairement in aqueous humour outflow can result in an increase in intraocular presssure. TRUE OR FALSE?
TRUE
What can occur when IOP is increased?
- Leads to nerve damage
- Loss of peripheral vision
- and eventually blindness
How is aqueuous humour produced and drained?
- Aqueous humor is produced by the non-pigmented ciliray body (cilia)
- This then flows behind the lens and throught the pupil via the trabecular mesh work to be drained out via the canal of schlemm
What are the two routes of aqueous humor drainage and how much in terms of percentage is drained from each?
- Via the canal of schlemm (conventional - 90%)
- Via Uveoscleral outflow - this allows for drainage without passign through the trabecular network (aletrantive 10%)
what are the two types of cilia epithilia?
- Darker inner layer - pigmented epthilia
- Outer layer - non-prigmented epithilia
How much aqueous humor is produced?
- 3mL of aqueous humor is produced per day with coninus ultrafiltration from aterial blood and active secretion
Aqueous humor passes from posterior to anterior chamber via the pupils. TRUE OR FALSE?
TRUE
What is the normal IOP?
- 10-20mm Hg - this inceases in glaucoma
What is IOP determined by?
- Rate of aquoeus humor production
- rate of aquoeus humor drainage
Increased IOP causes damage to the retina and optic nerve. TRUE OR FALSE?
TRUE
What occurs in closed angle (angle glaucoma)?
- Iris presses forwards
- Adheres to the trabecular network (closing the angle)
- This prevents outflow of aqueous humor
- Leading to acute but large increase in IOP
- Leads to rapid nerve damage
- Eventually blindness
Wat occurs in open angle glaucoma?
- It is most common amongst patients
- Not many structural changes observed
- Angle is usually the same but the outflow of aqueous humor is reduced i.e due to blockage in trabecular meshwork, canal of schlemm or vein draining the eye
- IOP is not as increased compared to cloased angle but can cause nerve damage over time
Visual impairement caused prior diagnosis is usually unlikely to be treated/ restored. TRUE OR FALSE?
TRUE
The angle in closed between the iris and the cornea. TRUE OR FALSE?
TRUE
IOP is increased by altered AH production and outflow . TRUE OR FALSE?
TRUE
What are the treatment options for treating open angle glaucoma?
- Increase AH outflow via Prostaglandins via the uveoscelral path
- Decreased AH production by ciliary body with B2 anatagonists, a2 agonists an carboni anhydrase inhibitors
What are the treatment options for closed angle glaucoma?
- Managment of Increased IOP by manitol
- Miotics - increase outflow of AH via the trabecular meshwork
- Prostangladins to increase outflow of AH via uvescleral
- Surgery to reduce pressure betweenthe anteror and psoterior chambers
Give an example of Prostangladins F2a analgue?
- Latanoprost - increases outfflow through uvescleral pathway
- Better efficacy and fewer systemic side effects
Water is osmotically pumped into the aquoes humor via the Na+/K+ ATPase. TRUE OR FLASE?
TRUE
Na+ and Cl- balance is restored from stroma via antiports in the pigmented epithlial cells. TRUE OR FLASE?
TRUE
The electrochemical balance is maintained by the xports of H+ and HCO3- produced by carbonic anhydrase. TRUE OR FALSE?
TRUE
Increased cAMP does not increase AH production. TRUE OR FALSE?
FALSE
B-andrenergic activation increases cAMP production. therefore B-andrenergic antagonists will reduce AH production. TRUE OR FLASE?
TRUE
A-andrehergic decreases cAMP activation. Therefore A-andrenergic agonist will reduce AH production. TRUE OR FALSE?
TRUE
A-andrenergic agonist indirectly reduces AH production by reducing B-adrenergic production. TRUE OR FALSE?
TRUE
B- receptors in the eye are primarily B2. true or false?
true
B2 receptors regulate AH production by ciliary body and they decrease blood flow to the eye therefore decreasing the fluid available for AH production (e.g timolol). TRUE OR FLASE?
TRUE
B antagonists are contradincated with asthma ptients and patients with heart failure. TRUE or FALSE?
TRUE
Provide an example of a a2 agonist drug?
Brimonidine
How do a2 agonist work (mechanism of action)?
What are the two mechanisms of action?
- pre-synaptic membrane inhibit NA release (Sympathetic Nervous System)
- activation of a2 receptors direcrly inhibits the formatio of AH prouction
Carbonic anhydrases inhibiotrs are mostly used in open angle glaucoma. TRUE IR FALSE?
TRUE
Brinzolamide is most commonly used carbonic anhydrase inhibitors as it is given topically. TRUE OR FALSE?
TRUE
Drug interactions with carbonic anhydrase inhibitors with digoxin. TRUE OR FALSE?
TRUE
Drugs that cause hypokaleamia are contranidicated in patients receiving digoxin including acetazolamide. TRUE OR FALSE?
TRUE
Miotics for closed angle glaucoma opens drainage channels. TRUE OR FALSE?
TRUE
Mannitol for closed angle glaucoma reduces fluid secretion into the eye. TRUE OR FALSE?
TRUE
