Ophthalmic Pharmacology Practice Questions

Q: Which of the following drugs possesses similar cycloplegic action and is a more potent mydriatic than atropine?

Hyoscine. **Explanation:** The correct answer is **Hyoscine (Scopolamine)**. **Why Hyoscine is the correct answer:** Hyoscine is a belladonna alkaloid that acts as a competitive antagonist at muscarinic receptors. In terms of ocular potency, it is significantly more potent than atropine on a weight-for-weight basis. While it produces a **similar degree of cycloplegia** (paralysis of the ciliary muscle), it is a **more potent mydriatic** (pupillary dilator) than atropine. Its duration of action (3–7 days) is shorter than that of atropine (7–10 days), making it a useful alternative when a potent but slightly shorter-acting cycloplegic is required. **Analysis of Incorrect Options:** * **Tropicamide:** This is the shortest-acting mydriatic (duration 4–6 hours). While it is excellent for fundus examination, its cycloplegic action is much weaker and shorter than atropine. * **Homatropine:** A semi-synthetic derivative that is 10 times less potent than atropine. It has a shorter duration of action (1–3 days) and is primarily used in the treatment of anterior uveitis to prevent synechiae without the prolonged blurriness of atropine. **High-Yield Clinical Pearls for NEET-PG:** * **Potency Order:** Hyoscine > Atropine > Homatropine. * **Duration of Action (Cycloplegia):** Atropine (7–10 days) > Hyoscine (3–7 days) > Homatropine (1–3 days) > Cyclopentolate (24 hours) > Tropicamide (6 hours). * **Drug of Choice:** Atropine is the drug of choice for refraction in children <5 years (due to strong accommodation), while Homatropine/Cyclopentolate is preferred for older children. * **Side Effect:** Systemic absorption of atropine in children can lead to "Atropine flushing," fever, and tachycardia.

Q: Pilocarpine is the drug of choice in which type of glaucoma?

Acute angle closure glaucoma. **Explanation:** **Pilocarpine** is a direct-acting parasympathomimetic (cholinergic agonist) that acts on the muscarinic receptors (M3) of the iris sphincter muscle and the ciliary body. **Why it is the drug of choice for Acute Angle Closure Glaucoma (AACG):** In AACG, the primary goal is to pull the peripheral iris away from the trabecular meshwork to open the drainage angle. Pilocarpine causes **miosis** (pupillary constriction), which physically stretches the iris, thinning it and pulling it out of the angle. This restores the outflow of aqueous humor and rapidly lowers intraocular pressure (IOP). *Note:* In clinical practice, it is typically administered once the IOP has been slightly lowered by systemic agents (like Acetazolamide), as the iris sphincter is often ischemic and non-responsive when IOP is >40-50 mmHg. **Why other options are incorrect:** * **Open Angle Glaucoma:** While Pilocarpine can lower IOP by increasing trabecular outflow, it is no longer a first-line treatment due to side effects like miosis (causing night blindness) and accommodative spasms (brow ache). Prostaglandin analogues and Beta-blockers are preferred. * **Pigmentary Glaucoma:** This is a subtype of open-angle glaucoma. While miotics can reduce iris-zonule friction, they are rarely the "drug of choice" compared to modern medical or laser therapies. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mechanism in AACG:** Miosis → Mechanical opening of the angle. 2. **Side Effects:** Accommodative spasm (pseudomyopia), brow ache, and retinal detachment (due to ciliary body contraction pulling on the retina). 3. **Contraindication:** It should **never** be used in **Uveitic Glaucoma** or Malignant Glaucoma, as it can worsen inflammation and promote posterior synechiae formation. 4. **Pre-Laser:** It is routinely used before Peripheral Iridotomy (LPI) to thin the iris, making the procedure easier.

Q: Latanoprost (a prostaglandin F2 alpha analogue) is used for the treatment of which of the following conditions?

Treating glaucoma. **Explanation:** **Latanoprost** is a synthetic **Prostaglandin F2α (PGF2α) analogue** and is currently considered the first-line medical therapy for Primary Open-Angle Glaucoma (POAG). **1. Why Option D is Correct:** Latanoprost acts as a selective agonist at the **FP receptors** in the eye. Its primary mechanism of action is increasing the **uveoscleral outflow** of aqueous humor (the non-conventional pathway). By enhancing the drainage of fluid through the ciliary muscle into the suprachoroidal space, it effectively lowers intraocular pressure (IOP). **2. Why Other Options are Incorrect:** * **Option A:** Maintaining the patency of the ductus arteriosus is achieved using **Alprostadil (PGE1)**. Conversely, NSAIDs like Indomethacin are used to close a patent ductus. * **Option B:** Pulmonary hypertension is managed using prostacyclin (PGI2) analogues like **Epoprostenol, Treprostinil, or Iloprost**. * **Option C:** Gastric mucosa protection (especially in NSAID-induced ulcers) is the role of **Misoprostol (PGE1 analogue)**. **3. High-Yield Clinical Pearls for NEET-PG:** * **Dosing:** It is administered as a **once-daily** drop (usually at night), which ensures better patient compliance compared to beta-blockers. * **Side Effects (Highly Tested):** * **Increased iris pigmentation:** Permanent darkening of the iris (brown discoloration). * **Hypertrichosis:** Increased length, thickness, and number of eyelashes (trichomegaly). * **Cystoid Macular Edema (CME):** Should be avoided in aphakic or pseudophakic patients. * **Prostaglandin-associated periorbitopathy:** Loss of periorbital fat. * **Contraindication:** Active intraocular inflammation (Uveitis), as prostaglandins are pro-inflammatory mediators.

Question 1

Which of the following drugs possesses similar cycloplegic action and is a more potent mydriatic than atropine?

Accepted Answer

Hyoscine

Answer

Tropicamide

Answer

Homatropine

Answer

All of the above

Question 2

Pilocarpine is the drug of choice in which type of glaucoma?

Accepted Answer

Acute angle closure glaucoma

Answer

Open angle glaucoma

Answer

Pigmentary glaucoma

Answer

None of the above

Question 3

In atropine instillation, all are seen except:

Accepted Answer

Increased water content to tear

Answer

Dilated pupil

Answer

Paralysis of accommodation

Answer

Decreased water content to tear

Question 4

Latanoprost (a prostaglandin F2 alpha analogue) is used for the treatment of which of the following conditions?

Accepted Answer

Treating glaucoma

Answer

Maintaining the patency of the ductus arteriosus

Answer

Managing pulmonary hypertension

Answer

Protecting the gastric mucosa

Question 5

For refraction in a hypermetropic child, which is the best drug?

Accepted Answer

Atropine ointment

Answer

Phenylephrine

Answer

Atropine drops

Answer

Homatropine

Ophthalmic Pharmacology — MCQs

Ophthalmic Pharmacology — MCQs

On this page

Practice by Chapter

Want unlimited practice?