Ophthalmic Pharmacology — MCQs

Ophthalmic Pharmacology Indian Medical PG Practice Questions and MCQs

Question 91: A patient presented to the casualty with acute bronchial asthma after receiving treatment for glaucoma. What is the probable drug that could have caused this reaction?

A. Timolol (Correct Answer)
B. Betaxolol
C. Latanoprost
D. Anticholinesterase

Explanation: **Explanation:** The patient is experiencing an exacerbation of **bronchial asthma** due to the systemic absorption of a topical glaucoma medication. **1. Why Timolol is the correct answer:** Timolol is a **non-selective beta-blocker** (blocks both $\beta_1$ and $\beta_2$ receptors). When administered as eye drops, it can reach the systemic circulation via the nasolacrimal duct and mucous membranes, bypassing first-pass metabolism. Blocking $\beta_2$ receptors in the bronchial smooth muscle leads to **bronchoconstriction**, which can trigger a life-threatening asthma attack in susceptible individuals. It is strictly contraindicated in patients with asthma or COPD. **2. Why the other options are incorrect:** * **Betaxolol:** This is a **cardioselective ($\beta_1$) blocker**. Because it has minimal effect on $\beta_2$ receptors, it is the safest beta-blocker for glaucoma patients with mild respiratory issues (though still used with caution). * **Latanoprost:** A Prostaglandin F2$\alpha$ analogue. Its primary side effects are local (increased iris pigmentation, eyelash growth, conjunctival hyperemia) and it does not cause bronchospasm. * **Anticholinesterases:** These are miotics (e.g., Echothiophate). While they can cause systemic cholinergic side effects (salivation, bradycardia), they are not the classic or most common cause of acute asthma in a glaucoma clinical scenario compared to non-selective beta-blockers. **Clinical Pearls for NEET-PG:** * **Gold Standard Prevention:** To minimize systemic absorption of any eye drop, advise patients to perform **nasolacrimal occlusion** (pressing the inner corner of the eye) for 2–3 minutes after instillation. * **Drug of Choice:** Prostaglandin analogues (Latanoprost) are currently the first-line treatment for Open Angle Glaucoma. * **Contraindications for Timolol:** Asthma, COPD, 2nd/3rd-degree heart block, and bradycardia.

Question 92: Which of the following drugs is contraindicated in glaucoma?

A. Adrenaline
B. Timolol
C. Atropine (Correct Answer)
D. Pilocarpine

Explanation: **Explanation:** The correct answer is **Atropine**. **Why Atropine is Contraindicated:** Atropine is a potent **parasympatholytic (anticholinergic)** drug. It causes **mydriasis** (dilation of the pupil) and **cycloplegia** (paralysis of the ciliary muscle). In individuals with narrow anterior chamber angles, mydriasis causes the peripheral iris to bunch up and block the trabecular meshwork. This obstructs the outflow of aqueous humor, leading to a rapid rise in intraocular pressure (IOP), which can precipitate an attack of **Acute Angle-Closure Glaucoma**. Additionally, by relaxing the ciliary muscle, it decreases the tension on the scleral spur, further reducing trabecular outflow. **Analysis of Incorrect Options:** * **Adrenaline:** Though rarely used now due to side effects, it was historically used in open-angle glaucoma as it increases uveoscleral outflow and decreases aqueous production. It is avoided in narrow-angle glaucoma but is not as strictly contraindicated as Atropine. * **Timolol:** A non-selective **beta-blocker**, it is a first-line treatment for glaucoma. It works by decreasing the production of aqueous humor from the ciliary body. * **Pilocarpine:** A **miotic (parasympathomimetic)** drug. It is used to treat glaucoma because it causes pupillary constriction and contraction of the ciliary muscle, which opens the trabecular meshwork and enhances aqueous drainage. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for Acute Angle-Closure Glaucoma:** IV Acetazolamide (to lower IOP) and Pilocarpine (once IOP is <30 mmHg). * **Mydriatic of choice for fundus examination in adults:** Tropicamide (shorter duration of action than Atropine). * **Safe Mydriatic in Glaucoma:** Phenylephrine (an alpha-1 agonist) is preferred because it causes mydriasis without cycloplegia, though it must still be used with caution in narrow angles.

Question 93: Which of the following has only a mydriatic action?

A. Tropicamide
B. Homatropine
C. Phenylephrine (Correct Answer)
D. Cyclopentolate

Explanation: **Explanation:** The correct answer is **Phenylephrine** because it is a pure **sympathomimetic** (alpha-1 agonist). It acts directly on the dilator pupillae muscle of the iris to cause **mydriasis (dilation)** without affecting the ciliary muscle. Since the ciliary muscle is responsible for accommodation and is controlled by the parasympathetic system, Phenylephrine does not cause cycloplegia (paralysis of accommodation). **Analysis of Options:** * **Phenylephrine (Option C):** As a sympathomimetic, it produces "active mydriasis." It is the drug of choice when dilation is needed without blurring the patient's near vision. * **Tropicamide, Homatropine, and Cyclopentolate (Options A, B, D):** These are all **parasympatholytics** (antimuscarinics). They block the M3 receptors on both the sphincter pupillae (causing mydriasis) and the ciliary muscle (causing cycloplegia). Therefore, they are classified as **mydriatic-cycloplegics**. **High-Yield Clinical Pearls for NEET-PG:** * **Tropicamide:** Has the fastest onset and shortest duration of action among antimuscarinics, making it the preferred agent for routine fundus examination. * **Atropine:** The most potent cycloplegic with the longest duration (up to 7–10 days). It is the drug of choice for refraction in children under 5 years (due to high ciliary tone) and for treating uveitis. * **Cyclopentolate:** The drug of choice for refraction in children aged 5–15 years. * **Phenylephrine Warning:** It should be used with caution in patients with hypertension or cardiac disease and is contraindicated in patients with narrow-angle glaucoma. It can also be used to differentiate scleritis (vessels don't blanch) from episcleritis (vessels blanch).

Question 94: Which drug is required for dilatation of the pupil in a child with squint?

A. Tropicamide
B. 1% Atropine drop
C. Homatropine
D. 1% Atropine ointment (Correct Answer)

Explanation: **Explanation:** In pediatric ophthalmology, particularly when managing **squint (strabismus)**, it is essential to perform a **cycloplegic refraction**. Children have a very strong accommodative power; therefore, a potent cycloplegic is required to completely paralyze the ciliary muscle to uncover the full refractive error (especially latent hypermetropia), which is often the underlying cause of accommodative esotropia. **Why 1% Atropine Ointment is the Correct Choice:** * **Potency:** Atropine is the most powerful cycloplegic available. In children under 5–7 years, weaker agents like Tropicamide are insufficient to overcome active accommodation. * **Safety (Ointment vs. Drops):** In children, **ointment** is preferred over drops to minimize systemic absorption. Drops can easily drain through the nasolacrimal duct, leading to systemic toxicity (flushing, fever, tachycardia). Ointment stays in the conjunctival sac longer and has a slower, safer absorption rate. **Analysis of Incorrect Options:** * **Tropicamide:** It is a short-acting mydriatic with weak cycloplegic action. It is used for routine fundus examination in adults but is inadequate for squint evaluation in children. * **1% Atropine Drop:** While pharmacologically effective, drops carry a higher risk of systemic toxicity in pediatric patients compared to the ointment formulation. * **Homatropine:** It is moderately potent but less effective than Atropine. It is typically used in older children or cases of anterior uveitis. **Clinical Pearls for NEET-PG:** * **Standard Protocol:** Atropine 1% ointment is usually applied twice daily for **3 days** prior to the refraction (the "3-day Atropine" rule). * **Atropine Toxicity Mnemonic:** "Hot as a hare, red as a beet, dry as a bone, blind as a bat, and mad as a hatter." * **Antidote:** Physostigmine is the specific antidote for atropine poisoning. * **Alternative:** For children aged 7–15, **Cyclopentolate** is often the drug of choice due to a faster onset and shorter duration of action.

Question 95: Which of the following antiglaucoma drugs can cause stenosis of the nasolacrimal duct?

A. Timolol (Correct Answer)
B. Apraclonidine
C. Latanoprost
D. Adrenaline

Explanation: **Explanation:** **Correct Answer: A. Timolol** The correct answer is **Timolol**. Chronic use of certain topical antiglaucoma medications can lead to cicatricial changes in the conjunctiva and the lacrimal drainage system. **Timolol (a non-selective beta-blocker)** and **Echothiophate (a miotic)** are the most commonly implicated agents associated with **nasolacrimal duct (NLD) stenosis** and canalicular obstruction. The underlying mechanism involves drug-induced subepithelial fibrosis and chronic inflammation of the mucosal lining of the lacrimal passages, eventually leading to permanent narrowing or occlusion (secondary acquired lacrimal duct obstruction). **Analysis of Incorrect Options:** * **B. Apraclonidine:** This is an alpha-2 agonist primarily associated with follicular conjunctivitis and eyelid retraction. While it can cause local allergic reactions, it is not a classic cause of NLD stenosis. * **C. Latanoprost:** This prostaglandin analogue is known for causing "Prostaglandin Associated Periorbitopathy" (PAP), which includes deepening of the upper eyelid sulcus, hypertrichosis (increased eyelash growth), and iris hyperpigmentation, but not NLD stenosis. * **D. Adrenaline:** While Adrenaline (and Dipivefrin) can cause the formation of **adrenochrome deposits** (black pigment spots) in the conjunctiva and can rarely cause canalicular blockage due to these deposits, Timolol is the more definitive and classically tested cause of generalized NLD stenosis in this context. **High-Yield Clinical Pearls for NEET-PG:** * **Pilocarpine** and **Phospholine Iodide (Echothiophate)** are also major culprits for punctal and canalicular stenosis. * **Idoxuridine** (antiviral) is another high-yield drug known for causing lacrimal scarring. * To minimize systemic absorption and local side effects of Timolol, patients should be advised to perform **punctal occlusion** for 2 minutes after instillation.

Question 96: Which beta-blocker(s) should be avoided in glaucoma?

A. Pindolol
B. Carvedilol
C. Labetalol
D. All the above (Correct Answer)

Explanation: **Explanation:** The primary goal of beta-blocker therapy in glaucoma is to reduce intraocular pressure (IOP) by decreasing aqueous humor production from the ciliary body. To achieve this, a drug must have potent **Beta-2 antagonist** activity and **lack Intrinsic Sympathomimetic Activity (ISA)**. **Why "All the Above" is Correct:** The drugs listed (Pindolol, Carvedilol, and Labetalol) are avoided in glaucoma management for the following reasons: 1. **Pindolol:** It possesses significant **Intrinsic Sympathomimetic Activity (ISA)**. While it blocks the receptor, it also partially stimulates it. This partial agonism prevents a significant reduction in aqueous secretion, making it ineffective at lowering IOP compared to "pure" antagonists like Timolol. 2. **Carvedilol & Labetalol:** These are **combined Alpha and Beta blockers**. While they block beta receptors, they also cause systemic vasodilation via alpha-1 blockade. When administered topically, they often cause significant **local irritation and conjunctival hyperemia** (redness). Furthermore, their efficacy in lowering IOP does not surpass that of selective or non-selective beta-blockers, and their side effect profile makes them clinically unsuitable for ophthalmic use. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** **Timolol** (Non-selective beta-blocker without ISA) is the most commonly used. * **Cardioselective Option:** **Betaxolol** (Beta-1 selective) is the drug of choice for glaucoma patients with co-existing respiratory issues (e.g., Asthma/COPD), as it has a lower risk of causing bronchospasm. * **Contraindications:** Avoid topical beta-blockers in patients with **Bradycardia, Heart Block, or Overt Cardiac Failure**. * **Side Effect:** Be aware of "masked hypoglycemia" in diabetic patients using systemic or potent topical beta-blockers.

Question 97: Which of the following is NOT used as a local injection for ophthalmic use?

A. Triamcinolone
B. Prednisolone (Correct Answer)
C. Betamethasone
D. Dexamethasone

Explanation: **Explanation:** The correct answer is **Prednisolone (Option B)**. In ophthalmic practice, corticosteroids are administered via various routes depending on the target tissue. **Prednisolone** is highly effective as a topical drop (Prednisolone acetate 1%) for anterior segment inflammation because of its excellent biphasic solubility, which allows it to penetrate the cornea. However, it is **not formulated for local injection** (subconjunctival, sub-Tenon, or intravitreal) because it lacks the necessary pharmacological properties (such as depot formulation or specific pH stability) required for safe and effective intraocular or periocular injection. **Analysis of Incorrect Options:** * **Triamcinolone (Option A):** Commonly used as a **depot injection** (e.g., Triamcinolone acetonide). It is injected into the sub-Tenon space for uveitis or intravitreally to treat macular edema. It is also used to visualize the vitreous during vitrectomy. * **Betamethasone (Option C):** Often used as a **subconjunctival injection** post-operatively to control inflammation. It has a rapid onset and is frequently combined with dexamethasone in clinical practice. * **Dexamethasone (Option D):** Available in both short-acting (sodium phosphate) and long-acting (intravitreal implants like **Ozurdex**) forms. It is a potent steroid used for posterior segment pathologies. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for Anterior Uveitis:** Topical Prednisolone acetate (1%). * **Steroid-Induced Glaucoma:** Most common with topical steroids; least common with systemic steroids. * **Intravitreal Implants:** Dexamethasone (Ozurdex) and Fluocinolone (Iluvien) are the primary steroids used as sustained-release implants. * **Side Effects:** All local steroid injections carry the risk of secondary glaucoma and posterior subcapsular cataracts (PSC).

Question 98: Which direct-acting cholinomimetic agent, known for its lipid solubility, is used in the treatment of glaucoma?

A. Acetylcholine
B. Physostigmine
C. Pilocarpine (Correct Answer)
D. Neostigmine

Explanation: ### Explanation **Correct Option: C. Pilocarpine** Pilocarpine is a **direct-acting cholinomimetic** (parasympathomimetic) alkaloid. It acts primarily on **M3 muscarinic receptors** in the eye, causing contraction of the sphincter pupillae (miosis) and the ciliary muscle. Contraction of the ciliary muscle increases the outflow of aqueous humor through the trabecular meshwork, thereby reducing intraocular pressure (IOP). Crucially, Pilocarpine is a **tertiary amine**, making it **lipid-soluble**, which allows it to penetrate the cornea effectively. **Incorrect Options:** * **A. Acetylcholine:** While it is a direct-acting agonist, it is rapidly degraded by cholinesterases and has very poor corneal penetration. It is used only for rapid miosis during intraocular surgery (e.g., cataract surgery). * **B. Physostigmine:** This is an **indirect-acting** cholinomimetic (acetylcholinesterase inhibitor). Although it is a tertiary amine and lipid-soluble, the question specifically asks for a *direct-acting* agent. * **C. Neostigmine:** This is an **indirect-acting** agent and a **quaternary ammonium** compound. Being polar/lipid-insoluble, it has poor ocular penetration and is not used for glaucoma. **High-Yield NEET-PG Pearls:** * **Drug of Choice (DOC):** Pilocarpine is the DOC for **Acute Angle Closure Glaucoma** (to pull the iris away from the angle), though it is now a second-line agent for Chronic Open Angle Glaucoma. * **Adverse Effects:** Brow ache (due to ciliary spasm), induced myopia, and retinal detachment (rare). * **Ocusert:** A specialized delivery system for Pilocarpine that provides a slow, sustained release over one week.

Question 99: During intraocular lens implantation, corneal endothelial damage can be prevented by the use of which of the following agents?

A. Methyl cellulose
B. Sodium hyaluronate
C. Chondroitin sulfate
D. All of the above (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. All of the above**. These agents belong to a class of drugs known as **Ophthalmic Viscosurgical Devices (OVDs)** or viscoelastics. **Underlying Medical Concept:** The corneal endothelium is a non-regenerative monolayer of cells responsible for maintaining corneal transparency. During intraocular surgeries like cataract extraction and IOL implantation, the endothelium is at high risk of mechanical trauma from surgical instruments, ultrasound energy (phacoemulsification), and the IOL itself. OVDs are used to maintain the anterior chamber depth, provide a physical cushion to protect endothelial cells, and coat surgical instruments/IOLs to reduce friction. **Analysis of Options:** * **Methylcellulose (Hydroxypropyl Methylcellulose - HPMC):** A common dispersive OVD. It is synthetic, non-antigenic, and provides excellent coating properties for the cornea and instruments. * **Sodium Hyaluronate:** A cohesive OVD naturally found in the vitreous humor. It is highly effective at maintaining space and protecting the endothelium due to its high molecular weight and viscosity. * **Chondroitin Sulfate:** Often used in combination with sodium hyaluronate (e.g., Viscoat). It has excellent dispersive properties, adhering to the endothelium to provide a protective shield throughout the procedure. **High-Yield Clinical Pearls for NEET-PG:** * **Classification:** OVDs are classified into **Cohesive** (maintain space, e.g., Sodium Hyaluronate) and **Dispersive** (coat surfaces, e.g., HPMC, Chondroitin Sulfate). * **Complication:** The most common postoperative complication of OVD use is a transient **rise in Intraocular Pressure (IOP)** due to mechanical blockage of the trabecular meshwork if the agent is not thoroughly aspirated. * **Ideal OVD:** Should be transparent, non-toxic, non-pyrogenic, and easily removable from the eye.

Question 100: Which of the following is characteristic of Chloroquine retinopathy?

A. Not associated with other central nervous system reactions
B. Vision loss recovers
C. Progression of retinopathy after cessation of medication (Correct Answer)
D. All of the above

Explanation: **Explanation:** Chloroquine (CQ) and Hydroxychloroquine (HCQ) are known for their affinity for melanin-containing tissues, particularly the **Retinal Pigment Epithelium (RPE)**. **Why Option C is correct:** The hallmark of Chloroquine toxicity is its **long half-life** and its tendency to accumulate in the RPE. Even after the medication is discontinued, the drug remains stored in the ocular tissues for years. This leads to a phenomenon where the retinopathy continues to worsen or progress even after cessation of the drug. This is a critical clinical point for monitoring patients. **Why other options are incorrect:** * **Option A:** Chloroquine is not exclusively retinotoxic. It is associated with various CNS side effects, including headaches, seizures, and even toxic psychosis. It can also cause neuromuscular weakness and ototoxicity. * **Option B:** Chloroquine retinopathy is **irreversible**. Once the classic "Bull’s Eye Maculopathy" (a ring of depigmentation surrounded by a ring of hyperpigmentation) develops, the vision loss is permanent because the damage to the RPE and photoreceptors cannot be undone. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Sign:** The earliest clinical sign is a fine granular pigmentary change in the macula. * **Earliest Functional Change:** Decreased foveal reflex and a **paracentral scotoma** (detected on 10-2 Humphrey Visual Field testing). * **Screening Gold Standard:** SD-OCT (Spectral Domain Optical Coherence Tomography) showing the "Flying Saucer Sign" (loss of the ellipsoid zone in the parafovea). * **Safe Dosage:** To minimize risk, the daily dose should not exceed **2.3 mg/kg** for Chloroquine and **5.0 mg/kg** for Hydroxychloroquine.

Practice by Chapter

Ocular Pharmacokinetics

Practice Questions

Anti-infective Agents

Practice Questions

Anti-inflammatory Drugs

Practice Questions

Antiglaucoma Medications

Practice Questions

Mydriatics and Cycloplegics

Practice Questions

Ocular Lubricants

Practice Questions

Anti-VEGF Agents

Practice Questions

Ocular Diagnostic Agents

Practice Questions

Anesthetics in Ophthalmology

Practice Questions

Preservatives and Their Effects

Practice Questions

Ocular Toxicology

Practice Questions

Novel Drug Delivery Systems

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free