Glaucoma Pharmacology Flashcards
What are strong risk factors for getting glaucoma?
- high IOP
- aging (>40 y)
- family history - first degree relative
- race (blacks 4x)
- optic disc appearance
- corneal thickness >0.5 mm
What are the possible risk factors for getting glaucoma?
- high myopia (near sightedness)
- diabetes
- hypertension
- eye injury/surgery
What are the other risk factors that are possible for getting glaucoma?
- history of steroid use
- sleep apnea
- gender = male
What is the basic pathophysiology of experiencing glaucoma?
- when the axons going to the eye die off
- the axon plasma flows within the structures get cut off- nothing going to the eye
- the vasculature within the eyes gets pinched off and stops the blood flow from being carried to the rain
- when pressure within the eye increases, then there is a cut off of messengers from going outside of the eye
What is the upper limit of normal for IOP?
- 21 mm Hg is the upper limit of normal
- some are safe at 22-30 mm Hg
- some may have damage at < 21 mm Hg
What ethnic groups have a high rate of closed angle glaucoma?
- inuit of the north and Chinese or east indian groups
What is normal IOP?
- 10-21 mm Hg
Pressure within the eye is due to a pressure balance of ________. What produces this?
aqueous humor (AH) - ciliary body
What helps with drainage of IOP from the eye?
- trabecular meshwork
- canal of schlemm (80%)
- uveoscleral outflow (20%)
Open angle glaucoma is primarily a defect in what?
- primary a defect in decreased drainage
- tx: drainage and/or humour production
Closed angle glaucoma is primarily a defect of what?
- ballooning of the iris, aqueous humour flow is:
- increased pressure
- in an emergency situation acute drug treatment followed by surgery
What are the 2 main approaches to treating glaucoma?
- decrease production of AH
(receptors on ciliary body, carbonic anhydrase) - increase drainage
(trabecular meshwork and canal of scheme, uveoscleral outflow and surgical intervention)
For drugs to penetrate the epithelial layer, the drug should be ____
hydrophobic
For drugs to penetrate the stroma, the drug should be _____
hydrophilic
For drugs to penetrate the epithelial layer or the endothelial layer, the drug should be _____
hydrophobic
What should patients be counselled to do to stop the drug from getting into the systemic circulation?
- should always counsel the patient on how to compress the teat ducts- then this way you will stop the drug from going systemic
What is an example of a parasympathetic drug (miotics)?
- pilocarpine (receptor agonists), carbachol (receptor agonists)
- the peripheral vision starts to decrease to start off
What are common symptoms when the IOP gets over 60 mm of Hg?
- N/V, cramping, the person can see halos, the iris becomes unresponsive and will not move
- these attacks can occur intermittently or can occur all the time
- over time the person will need to receive treatment for this in order to stop the progression - will make a surgical tunnel going out tot he sclera, creating a bleb that drains fluid all the time
- can also use lasers to punch holes in the eyes to drain fluid
What are the most common SE of pilocarpine?
- increased outflow of aqueous humour pilocarpine for OAG and CAG
- poor night vision, blurred vision and aching
- loss of accompodative spasm with pilocarpine
- brow ache (this clears after about 2 weeks)
- contraindicated with miosis (this is undesirable)
Avoid strong miotics in _______
retinal detachment
What are some of the main SE of miotics?
GI, salivation
Why is nasolacrimal occlusion so important in drugs that are miotics?
- they can cause heart block, cramping and salivation
- if you decrease the amount of blood you get into the systemic circulation then you decrease the SE profile
What is a common complication of closed angle glaucoma?
- floppy iris
What is the MOA of epinephrine?
- improves outflow (uveoscleral and TM)
- acts on the alpha and beta adrenoreceptors in the ciliary body
- increased outflow (yet mydriasis) but may actually increase the aqueous humour production
- avoid in CAG