11 Questions
What is the effect of sympathomimetic agents on aqueous humor?
Decrease production and increase outflow
What is the mechanism of action of Carbonic Anhydrase Inhibitors?
Decrease aqueous humor production and increase outflow
What is the effect of Prostaglandin Agonists on aqueous humor outflow?
Increase outflow through the uveoscleral pathway
What is the effect of Mydriatic Cycloplegic Agents on the eye?
Dilate the pupil and decrease accommodation
What is the indication for Anti-inflammatory Agents, such as NSAIDs, in ophthalmic use?
To treat postoperative inflammation
What is a potential side effect of long-term use of Corticosteroids in the eye?
Glaucoma, cataract, and thinning of the cornea
What is the main pathway for aqueous humor outflow in the eye?
Trabecular pathway
What is the effect of beta blockers on aqueous humor production in glaucoma treatment?
Reduce the production of aqueous humor
What is the effect of cholinergic agents, such as pilocarpine, on the iris?
Cause miosis
What is the results of excessive production of aqueous humor or diminished ocular fluid outflow?
Glaucoma
Why is betaxolol (selective beta-1) preferred over timolol (non-selective beta blocker) in patients with pulmonary disease?
Because of its selective beta-1 blocking effect
Study Notes
Glaucoma and Ocular Pharmacology
Aqueous Humor Outflow
- Two pathways for outflow:
- Trabecular pathway: through trabecular meshwork → Schlem's canal → aqueous vein
- Uveoscleral pathway: diffusion through intercellular spaces of the ciliary body
Glaucoma
- Characterized by excessive production of aqueous humor or diminished ocular fluid outflow
- Associated with increased intraocular pressure (IOP)
- Can lead to blindness if left untreated
Drugs Used for Glaucoma
Beta Blockers
- Reduce production of aqueous humor → reducing IOP
- Examples:
- Betaxolol (selective beta-1 blocker)
- Timolol (non-selective blocker)
- Betaxolol is suitable for patients with pulmonary disease due to its selective beta-1 blocking effect
Cholinergic Agents
- Pilocarpine:
- Contraction of the sphincter muscle of the iris → miosis
Sympathomimetic Agents
- Dipivefrin:
- Converted to adrenaline by enzyme hydrolysis in the eye
- Decreases aqueous humor production and increases outflow
- Action mediated by alpha-receptors
- Apraclonidine:
- Selective alpha-2 agonist (derived from clonidine)
Carbonic Anhydrase Inhibitors
- Dorzolamide:
- Decreases aqueous humor production → increases outflow
Prostaglandin Agonists
- Latanoprost:
- Increases aqueous humor outflow through the uveoscleral pathway → reduced IOP
Mydriatic Cycloplegic Agents
- Tropicamide:
- Anticholinergic agent
- Blocks muscarinic receptors → mydriasis and cycloplegia
- Can increase IOP
- Indications:
- Mydriasis to facilitate eye examination
- Pre- and postoperative use in intraocular surgery
Anti-inflammatory Agents
- NSAIDs (e.g., diclofenac):
- Available topically for ophthalmic use
- Indicated to treat postoperative inflammation after cataract extraction or corneal surgery
- Corticosteroids (e.g., prednisolone):
- Available topically alone or in combination with antibiotics
- Indicated to treat allergic and inflammatory conditions of the eye
- Can cause glaucoma, cataract, and thinning of the cornea
This quiz covers the basics of glaucoma, its causes, and medications used to treat it. It also explores the anatomy of the eye, particularly the aqueous humor outflow pathways. Test your knowledge of pharmacology and ocular health!
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