Ocular Pharmacology Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Ocular Pharmacology. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Ocular Pharmacology Indian Medical PG Question 1: Anti-glaucoma drug that acts by increasing uveoscleral outflow is
- A. Dorzolamide
- B. Latanoprost (Correct Answer)
- C. Pilocarpine
- D. Timolol
Ocular Pharmacology Explanation: ***Latanoprost***
- **Latanoprost** is a **prostaglandin F2α analog** that effectively lowers intraocular pressure by significantly increasing **uveoscleral outflow**.
- It works by remodeling the extracellular matrix in the ciliary body and sclera, which facilitates the drainage of aqueous humor through the uveoscleral pathway.
*Dorzolamide*
- **Dorzolamide** is a **topical carbonic anhydrase inhibitor** that reduces the production of aqueous humor, thus lowering intraocular pressure.
- It does not directly affect the uveoscleral outflow pathway.
*Pilocarpine*
- **Pilocarpine** is a **cholinergic agonist** that primarily works by increasing the **trabecular outflow** of aqueous humor through contraction of the ciliary muscle [1].
- It does not significantly influence the uveoscleral outflow pathway.
*Timolol*
- **Timolol** is a **beta-adrenergic blocker** that reduces aqueous humor production by the ciliary body [1].
- Its mechanism of action involves decreasing the formation, rather than increasing the outflow, of aqueous humor [1].
Ocular Pharmacology Indian Medical PG Question 2: Atropine is the drug of choice in –
- A. Chorioretinitis
- B. Lens induced glaucoma
- C. Iridocyclitis (Correct Answer)
- D. Closed angle glaucoma
Ocular Pharmacology Explanation: ***Iridocyclitis***
- Atropine is a **potent cycloplegic and mydriatic agent** often used in iridocyclitis to **relax the ciliary body muscles** and prevent the formation of posterior synechiae.
- Its **long-acting effect** helps in reducing pain, inflammation, and preventing complications such as iris bombe by keeping the pupil dilated.
*Chorioretinitis*
- This condition primarily affects the **choroid and retina**, and while inflammation may be present, systemic or topical **corticosteroids** are typically the primary treatment.
- Atropine is not indicated as a primary treatment for the inflammation itself in chorioretinitis, as its main action is on the iris and ciliary body.
*Lens induced glaucoma*
- The definitive treatment for lens-induced glaucoma, such as **phacomorphic glaucoma** or **phacolytic glaucoma**, is surgical removal of the cataractous lens.
- Atropine would cause mydriasis, which can paradoxically worsen some forms of glaucoma by blocking the drainage angle, especially in cases of angle closure [1] [2].
*Closed angle glaucoma*
- Atropine, being a mydriatic, would **dilate the pupil** and potentially exacerbate closed-angle glaucoma by further **crowding the anterior chamber angle** and blocking aqueous humor outflow [3].
- The focus in closed-angle glaucoma is to constrict the pupil (with miotics like pilocarpine) and reduce intraocular pressure.
Ocular Pharmacology Indian Medical PG Question 3: What is the best drug for open-angle glaucoma?
- A. Latanoprost (Correct Answer)
- B. Pilocarpine
- C. Physostigmine
- D. Apraclonidine
Ocular Pharmacology Explanation: Latanoprost
- Latanoprost is a prostaglandin analog and is often considered a first-line treatment for open-angle glaucoma due to its efficacy in reducing intraocular pressure (IOP) and its once-daily dosing.
- It works by increasing the outflow of aqueous humor through the uveoscleral pathway, thereby lowering IOP.
Pilocarpine
- Pilocarpine is a cholinergic agonist that causes miosis and ciliary muscle contraction [3], increasing the outflow of aqueous humor through the trabecular meshwork [4].
- While effective, its side effects (e.g., accommodative spasm, miosis) [1] and more frequent dosing make it generally a second-line or third-line agent for long-term management compared to prostaglandins.
Physostigmine
- Physostigmine is an acetylcholinesterase inhibitor that indirectly increases acetylcholine, mimicking cholinergic stimulation.
- Although it can lower IOP, it is generally not used for open-angle glaucoma due to significant side effects and the availability of safer, more effective alternatives [1].
Apraclonidine
- Apraclonidine is an alpha-2 adrenergic agonist [2] used primarily for short-term control of IOP, especially before or after ocular surgery, or as an adjunct therapy.
- Its efficacy as a long-term monotherapy for open-angle glaucoma is limited by tachyphylaxis and potential for significant systemic side effects with chronic use.
Ocular Pharmacology Indian Medical PG Question 4: Which among the following is the drug of choice for iridocyclitis?
- A. Corticosteroids (anti-inflammatory) (Correct Answer)
- B. Pilocarpine (miotic agent)
- C. Atropine (mydriatic agent)
- D. Timolol (beta-blocker)
Ocular Pharmacology Explanation: ***Corticosteroids (anti-inflammatory)***
- **Corticosteroids** are the drug of choice for iridocyclitis as they effectively suppress the **inflammation** within the iris and ciliary body.
- They work by reducing the influx of inflammatory cells and inhibiting the production of inflammatory mediators, thereby alleviating pain, redness, and preventing complications like **posterior synechiae**.
*Atropine (mydriatic agent)*
- **Atropine** is a **mydriatic** (pupil-dilating) and cycloplegic agent used in iridocyclitis, but it is not the primary anti-inflammatory treatment.
- Its role is to prevent the formation of **posterior synechiae** (adhesions between the iris and lens) and to relieve ciliary spasm, which reduces pain.
*Pilocarpine (miotic agent)*
- **Pilocarpine** is a **miotic** agent, meaning it constricts the pupil.
- Pupil constriction is contraindicated in iridocyclitis as it can worsen pain and promote the formation of **posterior synechiae**.
*Timolol (beta-blocker)*
- **Timolol** is a **beta-blocker** primarily used to lower intraocular pressure in conditions like glaucoma.
- While glaucoma can sometimes be a complication of severe iridocyclitis, timolol does not address the underlying **inflammation** of the iris and ciliary body, which is the primary pathology.
Ocular Pharmacology Indian Medical PG Question 5: Choose the correct options regarding the route of administration and bioavailability.
A- Intravenous =1
B- 0.75< Oral <1
C-0.75 <IM ≤ 1
D- 0.75<SC ≤ 1
IM - Intramuscular
SC- Subcutaneous
- A. A and D
- B. A and C
- C. A, C, D (Correct Answer)
- D. A, B, D
Ocular Pharmacology Explanation: ***A, C, D***
- Intravenous (IV) administration has **100% bioavailability** because the drug enters the systemic circulation directly, bypassing any absorption barriers.
- Intramuscular (IM) and subcutaneous (SC) routes generally have **high bioavailability**, often between 75% and 100%, as drugs are absorbed directly into the bloodstream without first-pass metabolism.
*A and D*
- While options A and D are correct, this choice is incomplete as option C is also a correct statement regarding bioavailability.
- IM administration typically results in high systemic bioavailability, similar to SC, making its exclusion here incorrect.
*A and C*
- While options A and C are correct, this choice is incomplete as option D is also a correct statement regarding bioavailability.
- Subcutaneous administration also generally results in high bioavailability, as absorption tends to be complete.
*A, B, D*
- While options A and D are correct, option B is typically incorrect for oral bioavailability.
- Oral bioavailability of many drugs is often less than 0.75 (75%) due to factors like **first-pass metabolism** and incomplete absorption in the gastrointestinal tract.
Ocular Pharmacology Indian Medical PG Question 6: Injection of muscarinic agonist in conjunctival sac will lead to all of the following except
- A. Miosis
- B. Conjunctival and uveal hyperemia
- C. Decreased secretion from ciliary epithelium (Correct Answer)
- D. Ciliary spasm
Ocular Pharmacology Explanation: ***Decreased secretion from ciliary epithelium***
- Muscarinic agonists **do NOT significantly decrease** aqueous humor secretion from the ciliary epithelium.
- The primary mechanism for reducing intraocular pressure with drugs like **pilocarpine** is by **increasing outflow** of aqueous humor through the trabecular meshwork via contraction of the ciliary muscle, NOT by decreasing production.
- Therefore, "decreased secretion from ciliary epithelium" is the correct answer to this "EXCEPT" question—it does NOT occur with muscarinic agonists.
*Miosis*
- Muscarinic agonists cause the **pupillary sphincter muscle** (which has M3 receptors) to contract, leading to **pupil constriction** (miosis).
- This effect opens the trabecular meshwork and facilitates aqueous humor drainage.
*Conjunctival and uveal hyperemia*
- Muscarinic agonists cause **vasodilation** in the conjunctival and uveal blood vessels, leading to increased blood flow and **redness** (hyperemia).
- This is a common side effect associated with topical application of cholinergic drugs to the eye.
*Ciliary spasm*
- Muscarinic agonists stimulate the **ciliary muscle** (which has M3 receptors), causing it to contract.
- This contraction leads to **accommodation spasm**, resulting in blurred distance vision and brow ache, which is a common adverse effect in younger patients.
Ocular Pharmacology Indian Medical PG Question 7: Drug of choice for open angle glaucoma:
- A. Acetazolamide
- B. Latanoprost (Correct Answer)
- C. Brimonidine
- D. Timolol
Ocular Pharmacology Explanation: ***Latanoprost***
- **Prostaglandin F2α analogs** like latanoprost are generally considered **first-line therapy** for open-angle glaucoma due to their efficacy and once-daily dosing.
- They work by **increasing uveoscleral outflow** of aqueous humor, thereby lowering intraocular pressure (IOP).
*Acetazolamide*
- **Acetazolamide** is a **carbonic anhydrase inhibitor** that reduces aqueous humor production.
- It is typically used for **acute angle-closure glaucoma** or when initial treatments fail, often due to systemic side effects with long-term use.
*Timolol*
- **Timolol** is a **non-selective beta-blocker** that reduces aqueous humor production.
- While effective, it is often a second-line agent or used in combination due to potential systemic side effects like **bronchospasm** and **bradycardia**.
*Brimonidine*
- **Brimonidine** is an **alpha-2 adrenergic agonist** that reduces aqueous humor production and increases uveoscleral outflow.
- It is typically used as a second-line agent or in combination therapy due to potential side effects like **ocular pruritus** and **allergic conjunctivitis**.
Ocular Pharmacology Indian Medical PG Question 8: In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?
- A. Procaine
- B. Cocaine
- C. Prilocaine (Correct Answer)
- D. Tetracaine
Ocular Pharmacology Explanation: **Local anesthetics are classified into two chemical groups: esters (aminoesters) and amides. Allergies to esters typically do not cross-react with amides.**
***Prilocaine***
- **Prilocaine** is an **amide-type local anesthetic**, and allergies to **aminoesters** typically do not cross-react with **amides**.
- It is a safe alternative in patients with a known allergy to **ester-type local anesthetics**.
*Cocaine*
- **Cocaine** is an **ester-type local anesthetic**, sharing a similar chemical structure with **aminoesters**.
- Patients allergic to **aminoesters** are likely to experience a **cross-reaction** with **cocaine**.
*Procaine*
- **Procaine** is a classic **ester-type local anesthetic** (an aminoester).
- An allergy to aminoesters directly implies an allergy to **procaine** due to its chemical classification.
*Tetracaine*
- **Tetracaine** is also an **ester-type local anesthetic** (an aminoester).
- It is contraindicated in patients with an allergy to **aminoesters** due to the high risk of **allergic reaction**.
Ocular Pharmacology Indian Medical PG Question 9: Which of the following is a specific sign of albinism?
- A. Iris transillumination (Correct Answer)
- B. Sensitivity to light (photophobia)
- C. Involuntary eye movements (nystagmus)
- D. Decreased visual acuity
Ocular Pharmacology Explanation: ***Iris transillumination***
- This is a highly **specific sign** of albinism, resulting from the severe reduction or absence of pigment in the iris.
- When light shines through the pupil, it passes through the unpigmented iris, creating a visible red reflex, indicating the lack of pigment that normally blocks the light.
*Sensitivity to light (photophobia)*
- While common in albinism due to the lack of pigment in the iris and retina allowing more light to enter the eye, **photophobia is not specific** to albinism.
- It can be a symptom of various other ocular conditions like uveitis, corneal abrasions, or migraines.
*Involuntary eye movements (nystagmus)*
- **Nystagmus is frequently associated with albinism** due to foveal hypoplasia and impaired visual development but is **not specific**.
- It can also be caused by neurological disorders, inner ear problems, or other ocular conditions.
*Decreased visual acuity*
- **Reduced vision is a characteristic feature of albinism** resulting from foveal hypoplasia and abnormal optic nerve pathways, but it is **not specific** to the condition.
- Numerous eye conditions, such as refractive errors, cataracts, and retinal diseases, can lead to decreased visual acuity.
Ocular Pharmacology Indian Medical PG Question 10: 1% atropine is given in uveitis to:
- A. Cause miosis and prevent formation of posterior synechiae
- B. Cause mydriasis and prevent formation of anterior synechiae
- C. Cause mydriasis and prevent formation of posterior synechiae (Correct Answer)
- D. Reduce inflammation and relieve pain
Ocular Pharmacology Explanation: ***Cause mydriasis and prevent formation of posterior synechiae***
- **Atropine** is a **cycloplegic** and mydriatic agent used in uveitis to dilate the pupil, which helps to separate the iris from the lens.
- This dilation is crucial in preventing the formation of **posterior synechiae** (adhesions between the iris and the anterior lens capsule), which can lead to complications such as pupil distortion, secondary glaucoma, and cataracts.
*Cause miosis and prevent formation of posterior synechiae*
- **Atropine** causes **mydriasis** (pupil dilation), not miosis (pupil constriction).
- Miosis would increase the risk of posterior synechiae formation by bringing the iris and lens closer together.
*Cause mydriasis and prevent formation of anterior synechiae*
- **Anterior synechiae** are adhesions between the iris and the cornea, which are less commonly affected by atropine in uveitis compared to posterior synechiae.
- While atropine causes mydriasis, its primary role in preventing synechiae formation in uveitis is directed at **posterior synechiae**.
*Reduce inflammation and relieve pain*
- While **atropine** can indirectly relieve pain by reducing **ciliary spasm** (a component of uveitic pain), its primary mechanism of action is not to reduce inflammation.
- **Corticosteroids** are the main treatment for reducing inflammation in uveitis.
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