Podcast
Questions and Answers
Which of the following beta-blockers is selective to beta 1 receptors?
Which of the following beta-blockers is selective to beta 1 receptors?
Which type of medication decreases IOP by reducing the amount of aqueous secretion and enhancing aqueous outflow through the uveoscleral route?
Which type of medication decreases IOP by reducing the amount of aqueous secretion and enhancing aqueous outflow through the uveoscleral route?
Which prostaglandin analogue has selective FP receptor agonist activity and lowers IOP by enhancing uveoscleral outflow?
Which prostaglandin analogue has selective FP receptor agonist activity and lowers IOP by enhancing uveoscleral outflow?
What is the primary mechanism of action of unoprostone in lowering IOP?
What is the primary mechanism of action of unoprostone in lowering IOP?
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Which type of medication is used to treat inflammatory eye conditions such as iritis and cyclitis?
Which type of medication is used to treat inflammatory eye conditions such as iritis and cyclitis?
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Which muscle is innervated by the parasympathetic nervous system and constricts the pupil in well-lit areas?
Which muscle is innervated by the parasympathetic nervous system and constricts the pupil in well-lit areas?
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What is the duration of action of tropicamide?
What is the duration of action of tropicamide?
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Which type of medication is used to treat open-angle glaucoma and has a risk of cataract formation as a side effect?
Which type of medication is used to treat open-angle glaucoma and has a risk of cataract formation as a side effect?
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What is the mechanism of action of beta-blockers in reducing IOP?
What is the mechanism of action of beta-blockers in reducing IOP?
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Which type of medication is used to increase aqueous outflow through the trabecular meshwork and uveoscleral pathways?
Which type of medication is used to increase aqueous outflow through the trabecular meshwork and uveoscleral pathways?
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What is the primary function of the trabecular meshwork and Schlemm canal in the eye?
What is the primary function of the trabecular meshwork and Schlemm canal in the eye?
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What is the typical pH of the aqueous humour?
What is the typical pH of the aqueous humour?
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Which of the following is NOT a component of aqueous humour?
Which of the following is NOT a component of aqueous humour?
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What is the main cause of increased intraocular pressure in glaucoma?
What is the main cause of increased intraocular pressure in glaucoma?
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Which type of glaucoma is characterized by a narrow or blocked angle between the iris and cornea?
Which type of glaucoma is characterized by a narrow or blocked angle between the iris and cornea?
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Which medication is used to reduce intraocular pressure by decreasing the production of aqueous humour?
Which medication is used to reduce intraocular pressure by decreasing the production of aqueous humour?
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What is the normal range of intraocular pressure in the eye?
What is the normal range of intraocular pressure in the eye?
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Which type of medication is used to reduce intraocular pressure by increasing the outflow of aqueous humour?
Which type of medication is used to reduce intraocular pressure by increasing the outflow of aqueous humour?
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What is the primary function of the ciliary body in the eye?
What is the primary function of the ciliary body in the eye?
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Which of the following is a characteristic of glaucoma?
Which of the following is a characteristic of glaucoma?
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What is the primary site of aqueous humor drainage in early adulthood?
What is the primary site of aqueous humor drainage in early adulthood?
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What is a characteristic of aqueous humor?
What is a characteristic of aqueous humor?
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What is the mechanism of action of cholinergics in reducing IOP?
What is the mechanism of action of cholinergics in reducing IOP?
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What is the main difference between open-angle and angle-closure glaucoma?
What is the main difference between open-angle and angle-closure glaucoma?
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What is the primary mechanism of action of carbonic anhydrase inhibitors in reducing IOP?
What is the primary mechanism of action of carbonic anhydrase inhibitors in reducing IOP?
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What is the effect of α-adrenergic agonists on IOP?
What is the effect of α-adrenergic agonists on IOP?
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What is the role of the ciliary body in maintaining IOP?
What is the role of the ciliary body in maintaining IOP?
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Which type of medication has a dual mechanism of action, reducing IOP by decreasing aqueous secretion and enhancing aqueous outflow through the uveoscleral route?
Which type of medication has a dual mechanism of action, reducing IOP by decreasing aqueous secretion and enhancing aqueous outflow through the uveoscleral route?
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What is the primary function of the constrictor pupillae muscle?
What is the primary function of the constrictor pupillae muscle?
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What is the effect of prostaglandins on IOP?
What is the effect of prostaglandins on IOP?
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What is a characteristic of glaucoma?
What is a characteristic of glaucoma?
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Which type of medication is used to treat open-angle glaucoma and has a risk of cataract formation as a side effect?
Which type of medication is used to treat open-angle glaucoma and has a risk of cataract formation as a side effect?
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What is the mechanism of action of cholinergic agonists in reducing IOP?
What is the mechanism of action of cholinergic agonists in reducing IOP?
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What is the primary mechanism of action of carbonic anhydrase inhibitors in reducing IOP?
What is the primary mechanism of action of carbonic anhydrase inhibitors in reducing IOP?
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Which type of medication is used to treat mydriasis?
Which type of medication is used to treat mydriasis?
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What is the normal range of intraocular pressure?
What is the normal range of intraocular pressure?
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What is the primary mechanism of action of prostamides in reducing IOP?
What is the primary mechanism of action of prostamides in reducing IOP?
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Which type of medication has selective FP receptor agonist activity and lowers IOP by enhancing uveoscleral outflow?
Which type of medication has selective FP receptor agonist activity and lowers IOP by enhancing uveoscleral outflow?
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What is the primary mechanism of action of beta-blockers in reducing IOP?
What is the primary mechanism of action of beta-blockers in reducing IOP?
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Which type of medication is used to treat angle-closure glaucoma?
Which type of medication is used to treat angle-closure glaucoma?
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Study Notes
Intraocular Pressure (IOP)
- IOP is the fluid pressure inside the eye.
- Normal eye pressure ranges from 12-22 mm Hg, and eye pressure greater than 22 mm Hg is considered higher than normal.
Aqueous Humor Formation and Drainage
- Aqueous humor is produced by the ciliary body.
- Most of the aqueous humor exits the eye at the angle formed by the junction of the iris and cornea.
- It exits primarily via the trabecular meshwork and the Schlemm canal, and to a lesser extent through the ciliary body face entering the uveoscleral pathway.
Composition of Aqueous Humor
- Aqueous humor resembles blood plasma in composition but contains less protein and glucose and more lactic acid and ascorbic acid.
- It also contains amino acids, electrolytes (pH = 7.4, sodium, potassium, calcium, magnesium, chloride, HCO3-, phosphate), and immunoglobulins.
Glaucoma
- Glaucoma is a multi-factorial, complex eye disease with specific characteristics such as optic nerve damage and visual field loss.
- While increased pressure inside the eye (IOP) is usually present, even patients with normal range IOP can develop glaucoma.
Types of Glaucoma
- Open-angle glaucoma and angle-closure glaucoma are the most common forms of glaucoma.
Drug Treatment of Glaucoma
- Reducing IOP in glaucoma patients includes:
- Topical β-adrenergic antagonists (e.g., timolol, betaxolol)
- Carbonic anhydrase inhibitors (e.g., dorzolamide, brinzolamide)
- Cholinergics drug (e.g., pilocarpine)
- α-Adrenergic agonists (e.g., brimonidine)
- Prostaglandins (e.g., latanoprost, travoprost)
- Prostamides (bimatoprost)
Mechanisms of Action for Glaucoma Drugs
- β-Blockers:
- Decrease IOP by blockade of sympathetic nerve endings in the ciliary epithelium, reducing aqueous production.
- Carbonic anhydrase inhibitors:
- Lower IOP by reducing aqueous production.
- Cholinergic agonists:
- Increase aqueous outflow through the trabecular meshwork by ciliary muscle contraction and stimulating the iris sphincter muscle.
- α-Adrenergic agonists:
- Lower IOP by decreasing aqueous secretion and enhancing aqueous outflow through the uveoscleral route.
- Prostaglandins:
- Lower IOP by enhancing uveoscleral outflow.
- Prostamides:
- Lower IOP by increasing outflow of the aqueous humor via the trabecular meshwork and uveoscleral pathways.
Mydriatic Drugs
- Mydriasis is the dilation of the pupil, used during an eye examination to allow visualization of the retina and other structures deep within the eye or to treat inflammatory eye conditions such as iritis and cyclitis.
Iris Innervation
- The iris has two muscles that control light intensity:
- Dilator pupillae, a longitudinal radial muscle that dilates the pupil (mydriasis) in the dark, innervated by the sympathetic nervous system.
- Constrictor pupillae, a circular muscle that constricts the pupil (miosis) in places with good lighting, innervated by the parasympathetic nervous system.
Anticholinergic Drugs
- Atropine:
- Blocks muscarinic receptors in the Constrictor pupillae and causes relaxing of circular muscles (mydriasis).
- Tropicamide and cyclopentolate:
- Used as ophthalmic solutions for mydriasis and cycloplegia, with a shorter duration of action than atropine.
Intraocular Pressure (IOP)
- IOP is the fluid pressure inside the eye.
- Normal eye pressure ranges from 12-22 mm Hg, and eye pressure greater than 22 mm Hg is considered higher than normal.
Aqueous Humor Formation and Drainage
- Aqueous humor is produced by the ciliary body.
- Most of the aqueous humor exits the eye at the angle formed by the junction of the iris and cornea.
- It exits primarily via the trabecular meshwork and the Schlemm canal, and to a lesser extent through the ciliary body face entering the uveoscleral pathway.
Composition of Aqueous Humor
- Aqueous humor resembles blood plasma in composition but contains less protein and glucose and more lactic acid and ascorbic acid.
- It also contains amino acids, electrolytes (pH = 7.4, sodium, potassium, calcium, magnesium, chloride, HCO3-, phosphate), and immunoglobulins.
Glaucoma
- Glaucoma is a multi-factorial, complex eye disease with specific characteristics such as optic nerve damage and visual field loss.
- While increased pressure inside the eye (IOP) is usually present, even patients with normal range IOP can develop glaucoma.
Types of Glaucoma
- Open-angle glaucoma and angle-closure glaucoma are the most common forms of glaucoma.
Drug Treatment of Glaucoma
- Reducing IOP in glaucoma patients includes:
- Topical β-adrenergic antagonists (e.g., timolol, betaxolol)
- Carbonic anhydrase inhibitors (e.g., dorzolamide, brinzolamide)
- Cholinergics drug (e.g., pilocarpine)
- α-Adrenergic agonists (e.g., brimonidine)
- Prostaglandins (e.g., latanoprost, travoprost)
- Prostamides (bimatoprost)
Mechanisms of Action for Glaucoma Drugs
- β-Blockers:
- Decrease IOP by blockade of sympathetic nerve endings in the ciliary epithelium, reducing aqueous production.
- Carbonic anhydrase inhibitors:
- Lower IOP by reducing aqueous production.
- Cholinergic agonists:
- Increase aqueous outflow through the trabecular meshwork by ciliary muscle contraction and stimulating the iris sphincter muscle.
- α-Adrenergic agonists:
- Lower IOP by decreasing aqueous secretion and enhancing aqueous outflow through the uveoscleral route.
- Prostaglandins:
- Lower IOP by enhancing uveoscleral outflow.
- Prostamides:
- Lower IOP by increasing outflow of the aqueous humor via the trabecular meshwork and uveoscleral pathways.
Mydriatic Drugs
- Mydriasis is the dilation of the pupil, used during an eye examination to allow visualization of the retina and other structures deep within the eye or to treat inflammatory eye conditions such as iritis and cyclitis.
Iris Innervation
- The iris has two muscles that control light intensity:
- Dilator pupillae, a longitudinal radial muscle that dilates the pupil (mydriasis) in the dark, innervated by the sympathetic nervous system.
- Constrictor pupillae, a circular muscle that constricts the pupil (miosis) in places with good lighting, innervated by the parasympathetic nervous system.
Anticholinergic Drugs
- Atropine:
- Blocks muscarinic receptors in the Constrictor pupillae and causes relaxing of circular muscles (mydriasis).
- Tropicamide and cyclopentolate:
- Used as ophthalmic solutions for mydriasis and cycloplegia, with a shorter duration of action than atropine.
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Description
Learn about the formation and drainage of aqueous humor in the eye, and its relation to intraocular pressure. Understand how drugs can decrease intraocular pressure and the role of the ciliary body, trabecular meshwork, and Schlemm canal.
