Ocular Pharmacology Flashcards
What is the site of aqueous production?
ciliary body
What is the purpose of the trabecular meshwork?
To drain aqueous
What controls lens thickness?
muscular fibers within the ciliary body via tension on the zonules
What is angle closure glaucoma?
Flow of aqueous is prevented from draining into trabecular meshwork by bowing forward of the iris.
What are the three actions involved in near vision?
Thickening of lens
Convergence of eyes
Pupillary constriction
What are three syndromes that have maintained pupillary constriction with near vision but absent light reflex?
Parinaud’s syndrome
Argyll Robertson syndrome
Adie syndrome
What drug blocks muscarinic receptors?
Atropine
What drug blocks nicotinic receptors?
Tubocurarine
Where are muscarinic receptors in the eye?
1) Iris sphincter 2) circular fibers of ciliary muscle (constrict pupil)
3) longitudinal fibers of ciliary muscle (place tension on trabecular meshwork)
3 symptoms of Horner’s syndrome
Ptosis, Miosis, Anhidrosis
What drug do you use to confirm Horner’s diagnosis and how does it work?
Cocaine, blocks reuptake of NE. If sympathetic system intact will cause dilation of pupil.
What drug is used to locate lesion in Horner’s Syndrome?
Paredrine, if pupil dilates lesion is 1st or 2nd order neuron (pre-gang). If pupil does not dilate, lesion is in 3rd order neuron (post-gang).
What are three causes of pupillary dilation related to parasympathetic abnormalities?
Intracranial aneurysm
Aide’s Syndrome
Pharmacologic blockade
How do you separate Aide’s syndrome from intracranial aneurysm?
Give low dose pilocarpine or methacholine (direct parasympathetic agonists).
It should cause constriction due to long term disease causing hypersensitivity (increased receptors). Everyone constricts at high concentration, but Aide’s constrict at low.
Pt with worst headache of life with dilated pupil and limited extraocular movement. Diagnosis?
Intracranial aneurysm.
Parasympathetics travel on CR3 causes dilation and loss of extraocular movements
How would you check to make sure dilation of the eye was not due to pharmacologic blockade produced by cycloplegic?
Give pt 1% pilocarpine- everyones eye should dilate.
Describe Parinaud’s syndrome
Most often in young children
Midbrain tumor
Extensive spread of tumor causes lid retraction, limitation of upward gaze, convergence retraction nystegmus.
Name the characteristics of Argyll Robertson syndrome.
miotic irregular pupils–> do not respond to cycloplegics
pt maintains good visual acuity
CNS involvement w/ syphilis causes ataxia, difficulty walking, nerve pain
What are B-blockers used to treat?
Glaucoma
B-blocker cardiovascular side effects?
Bradycardia, hypotension, syncope, palpitation, CHF
B-blocker respiratory side effects?
broncospasm
B-blocker neurologic side effects?
confusion, depression, fatigue, lightheadedness, hallucinations, memory impairment, sexual dysfunction
Name four non-selective B-blockers used to treat glaucoma.
Timolol, levobunolol, metipranolol, carteolol
Name one B1 selective B-blocker
Betaxolol
What is the mechanism of B-blockers for the treatment of glaucoma?
Reduce intraocular pressure by reducing aqueous production at ciliary process.
What is the mechanism of action for prostaglandin analogs in treatment of glaucoma?
increase uveoscleral outflow
Side effects of prostaglandin analogs?
eyelash growth, change in iris color
When is prostaglandin analog use contraindicated?
Cystoid macular edema and herpes
Name four prostaglandin analogs.
Latanoprast, Travoprost, Bimatoprost, Unoprostone isopyl
What are prostaglandin analogs used to treat?
Glaucoma
Name a Ca channel blocker
Nifedipine
How does Nifedipine work?
increases ocular perfusion at the nerve head
Name three carbonic anhydrase inhibitors.
Dorzolamide, Acetazolamide, Brinzolamide
Side effects of Dorzolamide and Brinzolamide
Red eyes, lid allergies
How do the carbonic anhydrase inhibitors work?
Reduce aqueous production through interference with active transport of Na through Na/K ATPase pump.
What are carbonic anhydrase inhibitors use to treat?
Glaucoma
