2.5 - Drugs for Glaucoma

Question 1

Which structure produces aqueous humour? Where does it secrete it into?

Answer 1

The ciliary body secretes aqueous humor into the posterior chamber of the eye

Question 2

What are the two paths of outflow of aqueous humor?

Answer 2

Main outflow:
Trabecular/conventional - circulates iris, and flows out of pupil into anterior chamber

Nonconventional
uveoscleral - leaves the anterior chamber by diffusing through intercellular spaces among ciliary muscle fibers.

Question 3

Healthy intraocular pressure (IOP) is a result of what?

Answer 3

The equilibrium between aqueous humor production and outflow (or absorption)

Question 4

If aqueous humor outflow from the anterior chamber is impeded, what will happen?

Answer 4

Back pressure will develop, and intraocular pressure (IOP) will rise.

Question 5

What is glaucoma?

Answer 5

Visual field loss secondary to optic nerve damage caused by increased intraocular pressure (IOP).
–> 2nd leading cause of blindness in older North Americans

Question 6

What are the two kinds of glaucoma?

Answer 6

Primary open angle glaucoma (POAG)
–> Increased resistance to outflow through trabecular meshwork

Angle-Closure Glaucoma
–> A closed angle between the iris and lens obstructs trabecular outflow pathway (medical emergency)

Question 7

What are the risk factors for primary open-angle glaucoma (POAG)?

Answer 7

Increased age, being of African descent, high IOP, family history

Question 8

How can drugs reduce IOP?

Answer 8

Improve aqueous humor outflow OR reduce aqueous humor production

Question 9

What are the first line monotherapy drugs for primary open angle glaucoma?

Answer 9

Prostaglandin F2alpha analogs

Question 10

What are some second line adjunctive therapy for primary open angle glaucoma?

Answer 10

–> Beta blockers
–> Alpha 2 agonists
–> Carbonic anhydrase inhibitors
–> PSNS agents (Cholinergic agonists)

Question 11

What percent of topical glaucoma medications might reach systemic circulation and cause adverse effects?

Answer 11

~10%

Question 12

What kind of drugs are latanoprost, travoprost, and bimatoprost?

Answer 12

Prostaglandin F2alpha analogs

Question 13

How do prostaglandins F2alpha analogs such as latanoprost, travoprost, and bimatoprost work?

Answer 13

They lower IOP in glaucoma or ocular HTN by facilitating aqueous humor outflow (mostly uveoscleral outflow)

Question 14

How do beta blockers and prostaglandin F2alpha analogs compare for glaucoma treatment?

Answer 14

the analogs are just as effective as beta blockers, with fewer adverse effects.

Question 15

What are the adverse effects of prostaglandin F2alpha analogs?

Answer 15

–> Darkening of pigmentation of iris and eyelid
–> Thickening/lengthening of the eyelashes

Question 16

What beta blockers are used to treat glaucoma?

Answer 16

Timolol & levobunolol (non-selective)
Betaxolol (B1 selective)

Question 17

Why do beta blockers help with glaucoma?

Answer 17

Lowers IOP by decreasing production of aqueous humor in the ciliary body (mostly through B2 antagonism)

Question 18

What are some systemic adverse effects to beta blockers for glaucoma?

Answer 18

Same as other beta blockers

Question 19

What kinds of drugs are brimonidine and apraclonidine?

Answer 19

A2 agonists used to treat glaucoma

Question 20

How do A2 agonists like brimonidine and apraclonidine treat glaucoma?

Answer 20

Lowers IOP by reducing ocular vasoconstriction, which reduces aqueous humor production in the ciliary body (and may improve aqueous humor outflow)

Question 21

What are the adverse effects of A2 agonists that treat glaucoma, such as brimonidine and apraclonidine?

Answer 21

–> Lowers blood pressure
–> Dizziness
–> Decreased HR
–> Lethargy
–> Fatigue + drowsiness
–> Dry mouth/nose
–> Anxiety
–> Sleep disturbances

Question 22

What kinds of drugs are brinzolamide and dorzolamide?

Answer 22

Carbonic anhydrase inhibitor

Question 23

How do carbonic anhydrase inhibitors such as brinzolamide and dorzolamide work to treat glaucoma?

Answer 23

Inhibits enzyme carbonic anhydrase that facilitates this reaction necessary to aqueous humor production:
CO2 + H2O –> HCO3- + H+
Therefore, reduces IOP by decreasing production of aqueous humor in ciliary body

Question 24

What are some adverse effects of carbonic anhydrase inhibitors used to treat glaucoma, such as brinzolamide, dorzolamide?

Answer 24

–> Ocular stinging
–> Bitter taste
–> Allergic reaction in 10-15% of pts

Question 25

How does angle-closure glaucoma present?

Answer 25

Usually unilateral
–> Red eye, hazy cornea, dilated pupil, dull pain

Question 26

What are some risk factors for angle closure glaucoma?

Answer 26

–> Age
–> Female
–> Being of east Asian or Inuit descent

Question 27

How would you treat angle-closure glaucoma?

Answer 27

With a cholinergic agonist (Pilocarpine or carbachol), or indirectly through an AChE inhibitor (echothiophate)

Question 28

Why might a cholinergic agonist work to treat angle-closure glaucoma?

Answer 28

Contraction of the ciliary muscle improves trabecular outflow (but focuses the lens for accommodation)

Question 29

What are some side effects for parasympathomimetics (such as pilocarpine or echothiophate) used for glaucoma?

Answer 29

–> excessive PSNS effects
–> Possible cataracts with long-term sue