Ophthalmic Pharmacology — MCQs

Ophthalmic Pharmacology Indian Medical PG Practice Questions and MCQs

Question 171: Which mydriatic is used in a 3-year-old child for refraction?

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

Explanation: **Explanation:** In pediatric ophthalmology, the gold standard for cycloplegic refraction in children under 5–7 years of age (especially those with strabismus or high hypermetropia) is **Atropine**. This is because children have a very strong ciliary muscle tone (high accommodative power) that must be completely paralyzed to reveal the true refractive error. **Why 1% Atropine Ointment is the Correct Choice:** 1. **Potency:** Atropine is the most potent cycloplegic available, ensuring total paralysis of accommodation. 2. **Safety (Ointment vs. Drops):** In young children, **ointment** is preferred over drops to minimize systemic absorption. Drops can easily drain through the nasolacrimal duct into the highly vascular nasal mucosa, leading to systemic toxicity (Atropine poisoning). Ointment stays in the conjunctival sac longer and has a slower, safer absorption rate. **Analysis of Incorrect Options:** * **1% Atropine Drops:** While chemically effective, they carry a high risk of systemic side effects in toddlers (tachycardia, flushing, fever, and dry mouth) due to rapid nasolacrimal absorption. * **1% Homatropine Drops:** This is a weaker cycloplegic with a shorter duration. It is generally used in older children or for treating anterior uveitis, but it is insufficient for initial refraction in a 3-year-old. * **1% Tropicamide Drops:** This is the shortest-acting mydriatic. While excellent for adult fundus examinations, it provides inadequate cycloplegia for pediatric refraction. **Clinical Pearls for NEET-PG:** * **Standard Regimen:** Atropine 1% ointment is typically applied twice daily for 3 days prior to the refraction ("Atropine 3-day habit"). * **Cycloplegic of Choice by Age:** * < 5 years: Atropine (Ointment preferred). * 5–12 years: Cyclopentolate. * > 12 years/Adults: Homatropine or Tropicamide. * **Antidote:** In case of Atropine toxicity, the specific antidote is **Physostigmine**.

Question 172: Which drug can cause macular toxicity when administered intravitreally?

A. Gentamicin (Correct Answer)
B. Vancomycin
C. Dexamethasone
D. Ceftazidime

Explanation: **Explanation:** **Gentamicin (Option A)** is a potent aminoglycoside antibiotic often used for endophthalmitis. However, it is notorious for causing **dose-dependent macular toxicity** (Aminoglycoside Maculopathy). The underlying mechanism involves the drug's direct toxic effect on the retinal pigment epithelium (RPE) and photoreceptors, leading to **retinal vascular occlusion** (macular infarction). Clinically, this presents as a "cherry-red spot" and permanent vision loss. Due to this narrow therapeutic index, its intravitreal use has largely been replaced by safer alternatives like Amikacin or Ceftazidime. **Why other options are incorrect:** * **Vancomycin (Option B):** It is the gold standard for Gram-positive coverage in endophthalmitis. While it is generally safe for the macula, it is rarely associated with **HORV** (Hemorrhagic Occlusive Retinal Vasculitis), a delayed hypersensitivity reaction, rather than direct dose-dependent toxicity. * **Dexamethasone (Option C):** This is a corticosteroid used to reduce inflammation. Its primary ocular side effects are cataract formation and increased intraocular pressure (steroid-induced glaucoma), not macular toxicity. * **Ceftazidime (Option D):** A third-generation cephalosporin used for Gram-negative coverage. It is significantly less toxic to the retina than Gentamicin and is currently the preferred drug for intravitreal injection in suspected endophthalmitis. **High-Yield Clinical Pearls for NEET-PG:** * **Aminoglycoside Toxicity:** Gentamicin > Tobramycin > Amikacin (Amikacin is the least vestibulotoxic/retinotoxic). * **Classic Sign:** Macular infarction with "pruning" of retinal vessels. * **Standard Endophthalmitis Cocktail:** Intravitreal Vancomycin (1mg/0.1ml) + Ceftazidime (2.25mg/0.1ml).

Question 173: Which of the following drugs used to treat glaucoma is contraindicated in patients with urine retention?

A. Disopyramide (Correct Answer)
B. Flecainide
C. Lidocaine
D. Tocainide

Explanation: **Explanation:** The correct answer is **Disopyramide**. **1. Why Disopyramide is correct:** Disopyramide is a Class IA antiarrhythmic agent. While primarily used for cardiac arrhythmias, it possesses significant **anticholinergic (atropine-like) side effects**. In the eye, anticholinergics cause mydriasis (pupillary dilation), which can precipitate **acute angle-closure glaucoma** in predisposed individuals. Systemically, its potent anticholinergic action leads to smooth muscle relaxation in the bladder neck and prostate, causing **urinary retention**. Therefore, it is contraindicated in patients with pre-existing urinary retention (e.g., BPH) and should be used with extreme caution in patients with glaucoma. **2. Why the other options are incorrect:** * **Flecainide (Class IC):** This drug primarily blocks sodium channels with minimal effect on the autonomic nervous system. It does not possess significant anticholinergic properties and does not typically affect urinary outflow or intraocular pressure. * **Lidocaine (Class IB):** Used as a local anesthetic and antiarrhythmic, lidocaine has no anticholinergic activity. It is safe for patients with glaucoma and urinary retention. * **Tocainide (Class IB):** Similar to lidocaine, it lacks anticholinergic effects and does not pose a risk for urinary retention or glaucoma exacerbation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Anticholinergic Toxidrome:** Remember the mnemonic "Blind as a bat (mydriasis/glaucoma), Mad as a hatter (delirium), Red as a beet (flushing), Hot as a hare (hyperthermia), and **Dry as a bone (urinary retention/dry mouth)**." * **Glaucoma Contraindications:** Always look for drugs with "antimuscarinic" or "anticholinergic" profiles (e.g., Atropine, TCAs, First-generation antihistamines, and Disopyramide). * **Disopyramide Unique Property:** Among all antiarrhythmics, Disopyramide has the **strongest negative inotropic effect** and the **most prominent anticholinergic profile**.

Question 174: Which of the following drugs can cause pigment deposition on the cornea?

A. Chloroquine
B. Digoxin (Correct Answer)
C. Ranitidine
D. Amiodarone

Explanation: **Explanation:** The correct answer is **Digoxin**. While many drugs affect the eye, Digoxin is specifically associated with the deposition of fine, dust-like granules on the corneal endothelium. This occurs due to the drug's systemic accumulation, though it rarely affects visual acuity. More famously, Digoxin toxicity causes **Xanthopsia** (yellow-tinted vision) and "snowy" vision due to its inhibitory effect on the Na+/K+ ATPase pump in the retina (photoreceptors). **Analysis of Options:** * **A. Chloroquine:** This drug primarily causes **Vortex Keratopathy** (Cornea Verticillata), which consists of whorl-like epithelial deposits, not generalized pigment deposition. Its most serious side effect is "Bull’s eye maculopathy." * **C. Ranitidine:** This H2-receptor antagonist has no significant documented ocular side effects or corneal deposition patterns relevant to clinical practice or the NEET-PG syllabus. * **D. Amiodarone:** Like Chloroquine, Amiodarone is a classic cause of **Vortex Keratopathy** (Cornea Verticillata). These are golden-brown microdeposits in the basal epithelium of the cornea, seen in nearly all patients on long-term therapy, but they are distinct from the pigmentary pattern seen with Digoxin. **High-Yield Clinical Pearls for NEET-PG:** * **Cornea Verticillata (Whorl Keratopathy) Mnemonic:** **"CHAI-T"** — **C**hloroquine, **H**ydroxychloroquine, **A**miodarone, **I**ndomethacin, and **T**amoxifen (also seen in Fabry’s disease). * **Chlorpromazine:** A high-yield differential for pigment deposition; it causes stellate (star-shaped) opacities on the **anterior lens capsule** and brownish deposits on the corneal endothelium. * **Epinephrine:** Can cause black pigment deposits (adrenochrome) in the conjunctiva.

Question 175: Which of the following statements is NOT true regarding atropine?

A. Used as an eye ointment
B. Used in refraction in children less than 5 years old
C. Fast acting (Correct Answer)
D. Experimentally used in the treatment of myopia

Explanation: **Explanation:** Atropine is a potent, non-selective muscarinic antagonist. The correct answer is **C (Fast acting)** because Atropine is actually the **longest-acting** cycloplegic and mydriatic available. It takes approximately 30–60 minutes to achieve maximal effect, and its recovery period can last up to **7–14 days**. In contrast, drugs like Tropicamide are preferred for rapid action (20–30 minutes). **Analysis of Options:** * **A. Used as an eye ointment:** True. In children, Atropine is preferred as a 1% ointment rather than drops to minimize systemic absorption through the nasolacrimal duct, reducing the risk of systemic toxicity (e.g., flushing, fever, tachycardia). * **B. Used in refraction in children < 5 years:** True. Atropine is the "Gold Standard" for cycloplegic refraction in children under 5 (and those with accommodative esotropia) because they have a very strong ciliary muscle that requires a potent agent for complete paralysis. * **D. Experimentally used in myopia:** True. Low-dose Atropine (0.01%) is clinically used to slow the progression of myopia in children by preventing axial elongation of the eyeball. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Blocks M3 receptors in the sphincter pupillae (causing mydriasis) and the ciliary muscle (causing cycloplegia). * **Drug of Choice:** For **Iridocyclitis** (to prevent posterior synechiae and provide pain relief by resting the ciliary muscle). * **Contraindication:** Absolute contraindication in **Primary Angle Closure Glaucoma (PACG)**. * **Antidote:** Physostigmine is used for atropine poisoning.

Question 176: Topical sodium cromoglycate is useful in the treatment of which of the following conditions?

A. Trachoma
B. Anterior uveitis
C. Phlyctenular conjunctivitis
D. Vernal keratoconjunctivitis (Correct Answer)

Explanation: **Explanation:** **Sodium Cromoglycate** is a **mast cell stabilizer**. It works by preventing the degranulation of sensitized mast cells, thereby inhibiting the release of inflammatory mediators like histamine and leukotrienes. **Why Vernal Keratoconjunctivitis (VKC) is correct:** VKC is a Type I (IgE-mediated) hypersensitivity reaction. Since mast cell degranulation is the primary trigger for the itching and inflammation seen in VKC, sodium cromoglycate is highly effective as a prophylactic agent. It is often used as a long-term maintenance therapy to reduce the frequency of acute exacerbations. **Analysis of Incorrect Options:** * **Trachoma:** This is a chronic infectious keratoconjunctivitis caused by *Chlamydia trachomatis*. Treatment requires antibiotics (e.g., Azithromycin). * **Anterior Uveitis:** This is an intraocular inflammation. Management requires topical steroids to control inflammation and cycloplegics (like Atropine) to prevent synechiae and relieve ciliary spasm. * **Phlyctenular Conjunctivitis:** This is a Type IV (delayed) hypersensitivity reaction to endogenous microbial proteins (most commonly Tubercular or Staphylococcal). It is treated with topical steroids and addressing the underlying cause. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Sodium cromoglycate acts by blocking calcium channels, preventing the influx of calcium necessary for mast cell degranulation. * **Lag Period:** It is not effective for acute relief; it takes **5–10 days** to achieve therapeutic effects. * **VKC Triad:** Look for "Cobblestone" papillae, Horner-Trantas dots, and Shield ulcers in clinical vignettes. * **Other Mast Cell Stabilizers:** Nedocromil, Lodoxamide. * **Dual Action Agents:** Olopatadine and Ketotifen (both antihistaminic and mast cell stabilizing) are now preferred for faster symptomatic relief.

Question 177: Which of the following clinical trials is used to measure the response of a drug in non-infectious uveitis?

A. Luminate (Correct Answer)
B. CATT
C. ETDRS
D. AREDS

Explanation: **Explanation:** The **Luminate trial** (specifically the Luminate study program) evaluated the efficacy and safety of **Intravitreal Fluocinolone Acetonide (YUTIQ)** in patients with chronic, non-infectious uveitis affecting the posterior segment. This trial was pivotal in demonstrating that a sustained-release corticosteroid implant could significantly reduce the rate of uveitis recurrence and improve visual acuity over a 36-month period. **Analysis of Incorrect Options:** * **CATT (Comparison of Age-related Macular Degeneration Treatments Trials):** A landmark study that compared the efficacy of **Ranibizumab** (Lucentis) vs. **Bevacizumab** (Avastin) for the treatment of neovascular (wet) AMD. It concluded that both drugs were highly effective and had similar outcomes. * **ETDRS (Early Treatment Diabetic Retinopathy Study):** This trial established the gold standard for managing diabetic retinopathy. It defined "Clinically Significant Macular Edema" (CSME) and validated the use of **laser photocoagulation** and aspirin in diabetic patients. * **AREDS (Age-Related Eye Disease Study):** This trial evaluated the effect of high-dose **antioxidant vitamins and minerals** (Vitamin C, E, Beta-carotene, Zinc) on the progression of AMD and cataracts. (Note: AREDS2 later replaced Beta-carotene with Lutein/Zeaxanthin). **High-Yield Clinical Pearls for NEET-PG:** * **Non-infectious uveitis** is primarily managed with corticosteroids (topical, periocular, or intravitreal implants like Ozurdex or Retisert/Yutiq). * **MUST KNOW Trials:** * **SCORE:** Steroids vs. Laser for RVO. * **DRCR.net:** Various protocols for Diabetic Macular Edema (DME). * **HORIZON/ANCHOR:** Ranibizumab for AMD.

Question 178: Which muscarinic agonist is used in the treatment of angle closure glaucoma?

A. Pilocarpine (Correct Answer)
B. Neostigmine
C. Brimonidine
D. Dipivefrine

Explanation: **Explanation:** **Pilocarpine** is the correct answer because it is a direct-acting **muscarinic agonist** (parasympathomimetic). In the management of primary angle-closure glaucoma (PACG), pilocarpine acts on the **sphincter pupillae** muscle to cause miosis. This pull on the iris tissue moves it away from the trabecular meshwork, effectively "opening" the angle and allowing the aqueous humor to drain. It also causes contraction of the ciliary muscle, which further facilitates aqueous outflow. **Analysis of Incorrect Options:** * **Neostigmine:** While it is a parasympathomimetic, it is an *indirect-acting* acetylcholinesterase inhibitor. It is primarily used in Myasthenia Gravis and is not a standard treatment for glaucoma due to poor ocular penetration and systemic side effects. * **Brimonidine:** This is a highly selective **alpha-2 adrenergic agonist**. It works by decreasing aqueous production and increasing uveoscleral outflow, but it is not a muscarinic agonist. * **Dipivefrine:** This is a prodrug of **epinephrine** (sympathomimetic). It is contraindicated in narrow-angle glaucoma because it can cause mydriasis, which may precipitate an acute attack. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** While Pilocarpine is used to break an acute attack, the definitive treatment for PACG is **Laser Peripheral Iridotomy (LPI)**. * **Concentration:** 1–2% Pilocarpine is typically used. Higher concentrations should be avoided as they may cause "vascular congestion," worsening the block. * **Side Effects:** Common side effects include **brow ache** (due to ciliary muscle spasm) and **accommodative myopia**. * **Contraindication:** Pilocarpine is generally avoided in **secondary glaucomas** like uveitic glaucoma, as it can increase the risk of posterior synechiae formation.

Question 179: Which vitamin is used for treating toxic amblyopia?

A. Hydroxycobalamine (Correct Answer)
B. Vitamin B1
C. Vitamin B6
D. Vitamin B3

Explanation: **Explanation:** **Toxic Amblyopia** (specifically tobacco-alcohol amblyopia) is a form of nutritional and toxic optic neuropathy. It is characterized by bilateral, symmetrical visual loss and the presence of **centrocecal scotomas**. **Why Hydroxycobalamine is the Correct Answer:** The underlying pathophysiology involves a deficiency of sulfur-containing amino acids and Vitamin B12, which impairs the detoxification of cyanide (found in tobacco smoke). **Hydroxycobalamine (Vitamin B12b)** is the treatment of choice because it has a high affinity for cyanide. It reacts with cyanide to form **cyanocobalamin**, a non-toxic compound excreted in the urine. Unlike cyanocobalamin, hydroxycobalamine actively scavenges cyanide, making it superior for reversing the optic nerve damage in these patients. **Analysis of Incorrect Options:** * **Vitamin B1 (Thiamine):** While thiamine deficiency causes Beriberi and Wernicke-Korsakoff syndrome (and can contribute to nutritional amblyopia), it does not possess the specific cyanide-binding properties required to treat toxic amblyopia. * **Vitamin B6 (Pyridoxine):** Deficiency is often associated with isoniazid (INH) therapy, leading to peripheral neuropathy, but it is not the primary treatment for toxic optic neuropathy. * **Vitamin B3 (Niacin):** Deficiency leads to Pellagra (Dermatitis, Diarrhea, Dementia). It is not involved in the cyanide detoxification pathway. **High-Yield Clinical Pearls for NEET-PG:** * **Visual Field Defect:** Centrocecal scotoma (a scotoma involving the fixation point and the blind spot). * **Fundus Appearance:** Initially normal; later, temporal pallor of the optic disc may develop. * **Management:** Smoking cessation, alcohol abstinence, and parenteral Hydroxycobalamine (1000 units IM weekly). * **Differential:** Always rule out Leber’s Hereditary Optic Neuropathy (LHON), as tobacco can trigger its onset.

Question 180: Which of the following drugs is not used in the management of glaucoma?

A. Pilocarpine
B. Physostigmine
C. Metoprolol (Correct Answer)
D. Timolol

Explanation: **Explanation:** The correct answer is **Metoprolol (Option C)**. **Why Metoprolol is the correct answer:** In the management of glaucoma, topical beta-blockers are used to decrease the production of aqueous humor from the ciliary body. However, not all beta-blockers are suitable for ophthalmic use. **Metoprolol** is a cardioselective $\beta_1$-blocker primarily used for systemic conditions like hypertension and tachycardia. It is not used topically in glaucoma because it lacks the necessary pharmacokinetic profile for effective intraocular pressure (IOP) reduction compared to established ophthalmic agents. **Analysis of other options:** * **Pilocarpine (Option A):** A direct-acting cholinergic agonist (miotic). It increases aqueous outflow by contracting the ciliary muscle, which opens the trabecular meshwork. It is a classic drug for primary open-angle glaucoma and acute angle-closure glaucoma. * **Physostigmine (Option B):** An indirect-acting cholinergic (anticholinesterase). While less commonly used today due to side effects, it historically serves as a miotic to increase aqueous outflow. * **Timolol (Option D):** A non-selective $\beta$-blocker ($\beta_1 + \beta_2$). It is the "gold standard" first-line topical agent for glaucoma, acting by reducing aqueous secretion from the ciliary epithelium. **High-Yield NEET-PG Pearls:** 1. **Topical Beta-blockers:** **Timolol** (non-selective), **Levobunolol** (most potent), and **Betaxolol** (cardioselective $\beta_1$; safer in patients with mild asthma/COPD). 2. **Mechanism:** Beta-blockers reduce aqueous **production**, whereas Miotics (Pilocarpine) increase **outflow**. 3. **Contraindication:** Avoid non-selective beta-blockers (like Timolol) in patients with **Asthma or Heart Block** due to systemic absorption via the nasolacrimal duct. 4. **Drug of Choice:** Currently, **Prostaglandin analogues** (e.g., Latanoprost) have replaced Timolol as the first-line treatment for most cases of Open Angle Glaucoma.

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