Ocular Pharmacology — MCQs
Anti-glaucoma drug that acts by increasing uveoscleral outflow is
Atropine is the drug of choice in –
What is the best drug for open-angle glaucoma?
Which among the following is the drug of choice for iridocyclitis?
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
Injection of muscarinic agonist in conjunctival sac will lead to all of the following except
Drug of choice for open angle glaucoma:
In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?
Which of the following is a specific sign of albinism?
1% atropine is given in uveitis to:
Ocular Pharmacology Indian Medical PG Practice Questions and MCQs
Question 1: Anti-glaucoma drug that acts by increasing uveoscleral outflow is
- A. Dorzolamide
- B. Latanoprost (Correct Answer)
- C. Pilocarpine
- D. Timolol
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].
Question 2: Atropine is the drug of choice in –
- A. Chorioretinitis
- B. Lens induced glaucoma
- C. Iridocyclitis (Correct Answer)
- D. Closed angle glaucoma
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.
Question 3: What is the best drug for open-angle glaucoma?
- A. Latanoprost (Correct Answer)
- B. Pilocarpine
- C. Physostigmine
- D. Apraclonidine
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.
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)
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.
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
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.
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
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.
Question 7: Drug of choice for open angle glaucoma:
- A. Acetazolamide
- B. Latanoprost (Correct Answer)
- C. Brimonidine
- D. Timolol
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**.
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
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**.
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
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.
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
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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