Glaucoma treatment
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- What are the types of glaucoma?
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Open angle--most common
Narrow angle - What is open angle glaucoma (OAG)?
- Histological change in trabecular meshwork that slows outflow of aqueous humor --> increases amount of aqueous humor in eye --> increases introcular pressure
- What can be done to treat OAG?
- Decrease aqueous humor production (turn off tap) and increase aqueous humor outflow (unclog the drain)
- What non-selective beta blockers are used for OAG?
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Timolol
Carteolol
Levobunolol - What beta 1 selective blockers used for OAG?
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Betaxolol
Levobetaxolol - What is the MOA of beta blockers in OAG?
- Beta blockers --> decrease aqueous humor production by the ciliary body --> decreases IOP (20-30%)
- What direct acting adrenomimetics are used for OAG?
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Epinephrine--A and B
Dipivefrin --A and B
Brimonidine--A2
Apraclonidine--A2 - How does Brimonidine work on OAG?
- A2 on ciliary epithelium --> decrease aqueous humor production --> decrease intraocular pressure (IOP)
- How does EPI work on OAG?
- EPI --> B2 on endothelial cells of trabecular meshwork --> increases outflow of aqueous humor --> decrease IOP
- What cholinomimetics used for glaucoma?
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Muscarinic agonists--Pilocarpine and Carbachol
Reversible AChE inhibitors--Physostigmine
Irreversible AChE inhibitors--Echothiophate - How does a cholinomimetic work on OAG?
- Pilocarpine --> contracts ciliary muscle --> pulls on trabecular meshwork --> opens "holes" --> increases ouflow of aqueous humor
- Treatment of OAG with Epinephrine...
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Increases outflow and decreases production --> no blurred vision
Less effective - Treatment of OAG with Brimonidine and Betaxolol...
- Decreased production --> no blurred vision
- Treatment of OAG with Pilocarpine...
- Increased outflow --> blurred vision (affects ciliary muscle)
- Why do you get blurred vision with Pilocarpine and not betaxolol?
- Pilocarpine activates M receptors on the ciliary muscle
- What is the first choice treatment in OAG?
- Beta blockers
- What are the alternative tx choices for OAG?
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Epinephrine
Cholinomimetics:
Pilocarpine (first)
Carbachol
Physostigmine
Echothiophate (last) - What is the advantage of using a beta blocker (betaxolol) over pilocarpine for treating OAG?
- Less side effects and no effect on the lens (doesnt move ciliary muscle)
- What topical carbonic anhyddrase inhibitors are used for OAG?
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Brinzolamide
Dorzolamide - What prostaglandins are used in OAG?
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Latanoprost
Travoprost
Bimatoprost - How does marijuana affect glaucoma?
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Lowers IOP by about 24%
Does not work topically
MOA unknown
Cannabinoid receptors found--retina, ciliary body, and iris - What is the potential problem with marijuana and glaucoma?
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DOA only 3-3.5 hours and the goal is to maintain a continuous lowering of IOP
dont know if interferes with other glaucoma meds - What is narrow angle glaucoma (NAG)?
- There is a structural defect in the eye that causes a narrow angle between the iris and the cornea.
- When do attacks of NAG occur?
- When the pupil is dilated --> obstructs the outflow of aqueous humor through the trabecular meshwork
- What would happen if outflow through the trabecular is blocked?
- Attack of NAG --> IOP can increase from 15 mmHG to 40-60 mm Hg --> can cause blindness
- How does Pilocarpine treat NAG?
- Pilocarpine --> contract the iris sphincter smooth muscle --> induce miosis --> pulls the iris away from the trabecular meshwork --> increase outflow of aqueous humor --> decrease IOP
- Will pilocarpine be used chronically for the treatment of NAG?
- No, it is used to reduce pressure during an acute attack. Chronic treatment or cure is iridectomy.
- What are the alternative tx for NAG attaks?
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Carbachol
Physostigmine
Echothiophate
Decreasing aqueous humor production with other drugs (beta blockers) may be helpful but takes too long - How does cholinomimetics work on NAG?
- Pilocarpine --> NAG --> contract iris sphincter muscle --> move iris out of the way --> increase outflow