Lecture 3 Stuff Flashcards
What is aqueous humor?
A watery substance that nourishes the lens and cornea. It is formed and secreted by the ciliary processes. On the ciliary body, carbonic anhydrase, alpha and beta adrenergic receptors, and sodium and potassium activated ATPases are present and appear to be involved in the pathway of aqueous humor. Aqueous humor is secreted into the posterior chamber of the eye creating pressure that then pushed the aqueous humor between the iris and lens and through the pupil into the anterior chamber of the eye.
Aqueous humor in the anterior chamber drains the eye via what routes?
- Filtration though the trabecular meshwork (conventional outflow)to the Schlemm canal (80 to 85%)
- Through the ciliary body and the suprachoroidal space (uveoscleral outflow or unconventional outflow).
What is glaucoma’s statistics?
It is the 2nd leading cause of blindness and is 6 times more likely in African Americans.
What are the risk factors for glaucoma?
IOP Older age Family history of glaucoma Genetic mutations African ancestry or Latino/ Hispanic ethnicity Low ocular perfusion pressures Type 2 DM Myopia thinner central cornea
What is the normal IOP?
21 mmHg
What are the two types of open angle glaucoma(60 to 70 percent of glaucoma)?
Primary:
Most common type of glaucoma
With or without increased IOP
Vision loss is typically the 1st sign
Secondary:
Known eye disorder altering normal fluid flow.
What are the two types of closed angle glaucoma?
Chronic:
less than 5 percent of all glaucoma’s
Mechanical blockage of trabecular meshwork by peripheral iris.
Acute:
Medical emergency
IOPs greater than 40 percent
What is the first sign of glaucoma?
visual field loss (IOP can be increased or normal)
vision loss is associated with increasing IOP
The increased IOP in all types of glaucoma results from?
decreased facility for aqueous humor outflow through the trabecular meshwork
What causes closed angle glaucoma?
The angle formed by the cornea and iris closes, preventing the aqueous humor from draining normally. Partial or complete blockage occurs intermittently resulting in fluctuations between symptoms and no symptoms.
What are the signs and symptoms closed angle glaucoma?
Can cause acute elevations in IOP greater than 40 mmHg. Cloudy, edematous cornea, ocular pain, or discomfort, nausea, vomiting, abdominal pain, and sudden onset of visual disturbance (often in low light)
What is the goal of therapy of open angle glaucoma?
A target IOP of 20 to 30 percent reduction from baseline is recommended. The main goals of therapy include reduction of IOP to preserve vision, prevent functional vision loss, and slow/stop the progression of optic nerve damage, while minimizing adverse effects associated with therapy.
What are the first line agents for glaucoma?
beta blockers or prostaglandin analogs
if contradiction then brimonidine
if contradiction again then topical CAI
What if there is no response to first line agents for glaucoma?
Switch to alternative first-line agent if no response.
Add second first-line agent if partial response.
What is the treatment for closed angle glaucoma?
1st line = Iridectomy
may use pharmacologic therapy as an adjunct or prior to surgery to reduce IOP
Treatment of an acute attack generally involves pilocarpine, hyerosmotic agents, and a secretory inhibitor (Beta blocker, alpha 2 agonist, prostaglandin analog, or topical or systemic CAI)
What are the glaucoma clinical pearls?
Instilling more than one drop at a time does not improve response.
Monocular use of medication is suggested for initial administration to assess efficacy and tolerance.
Initial IOP response does not predict long-term response.
Ideally, only one drop of a single medication should be instilled in the eye at any given time. If a patient is on more than one eye drop, they should be administered at least 5 to 10 minutes apart to allow for complete absorption of each eye drop.
If compliance is an issue, consider oral therapy.
It is important to teach patients proper eye drop instillation technique.
How much glaucoma medication passes through the nasolacrimal canal into systemic circulation?
about 80 percent
Why should you close eyelid and punctual occlusion and for how long?
Significantly decreases the systemic absorption and other things….
Recommended amount of time is 2 to 5 minutes.
What are the colors of the caps on the glaucoma agents?
Prostaglandins are Turquoise
Beta-blockers are yellow or blue(low dose)
adrenergic agonists are purple
carbonic anhydrase inhibitors are orange
parasympathomimetic agents - Miotics are green
What are the prostaglandin analogs MOA?
increased aqueous humor uveoscleral outflow and to a lesser extent trabecular outflow.
What are the side effects of prostaglandin analogs?
Conjunctival hyperemia Eyelash growth Ocular pruritus iris color change (3-12 months) Periocular hyperpigmentation (panda eyes, reversible)
What are the contraindications to prostaglandin analogs?
Macular edema
History of herpetic keratits (herpes simplex virus 1 or 2) - it can make the virus spread
Which prostaglandin is preservative-free solution?
tafluprost (Zioptan)
How often are prostaglandins dosed?
1 drop every night
What is the strength of the latisse and lumigan?
latisse 0.03 percent
Lumigan 0.01 percent
What are the prostaglandin agents, strengths included?
latanoprost (Xalatan) - 0.005 percent
bimatoprost (Lumigan) - 0.01 percent
travoprost (Travatan Z) - 0.004 percent
tafluprost (Zioptan) - 0.0015 percent
What are the side effects of beta-blockers?
Stinging/burning bronchospasm (nonselective) bradycardia depression impotence decrease in blood pressure
What are the contraindications to beta blockers?
COPD (nonselective) Asthma (nonselective) bradycardia hypotension greater than first degree heart block
What beta blocker glaucoma drops come in a suspension?
betaxolol comes in a generic solution and brand suspension
