Ophthalmic Pharmacology — MCQs

Ophthalmic Pharmacology Indian Medical PG Practice Questions and MCQs

Question 201: Retrobulbar injection of xylocaine blocks all of the following except:

A. 3rd cranial nerve
B. 4th cranial nerve (Correct Answer)
C. 6th cranial nerve
D. Ciliary nerves and ciliary ganglion

Explanation: ***4th cranial nerve*** - The **trochlear nerve (CN IV)** innervates the **superior oblique muscle** and has a unique superior and anterior course in the orbit, making it less accessible to retrobulbar injections. - Its location relative to the muscle cone and globe means a retrobulbar injection, which typically aims to block nerves within the muscle cone, often misses it. *3rd cranial nerve* - The **oculomotor nerve (CN III)** supplies most of the extraocular muscles and travels within the **muscle cone**, where retrobulbar anesthetic is deposited. - It is reliably blocked by a retrobulbar injection, causing akinesia of the muscles it innervates. *6th cranial nerve* - The **abducens nerve (CN VI)** innervates the **lateral rectus muscle** and is located within the **muscle cone**, making it susceptible to retrobulbar block. - Anesthetic diffusion within the cone effectively blocks this nerve, leading to paralysis of the lateral rectus. *Ciliary nerves and ciliary ganglion* - The **short ciliary nerves** and **ciliary ganglion** are located in the retrobulbar space, typically within the muscle cone or close to it. - Anesthetic solution injected retrobulbarly readily diffuses to these structures, blocking sensory input from the cornea and iris, as well as parasympathetic innervation to the pupil and ciliary body.

Question 202: Which route is most preferred for Endophthalmitis treatment?

A. Oral antibiotic
B. Intravenous antibiotic
C. Topical antibiotic
D. Intravitreal antibiotic (Correct Answer)

Explanation: ***Intravitreal antibiotic*** - **Intravitreal injection** directly delivers a high concentration of antibiotics into the **vitreous cavity**, which is essential for treating intraocular infections like endophthalmitis. - This route bypasses protective barriers like the **blood-retinal barrier**, ensuring therapeutic drug levels reach the infection site promptly and effectively. *Oral antibiotic* - **Oral antibiotics** have poor penetration into the **vitreous humor** due to the **blood-retinal barrier**, making them generally ineffective as a sole therapy for endophthalmitis. - They may be used as an adjunct in some cases but cannot achieve the high local concentrations needed to resolve severe intraocular infections. *Intravenous antibiotic* - Similar to oral antibiotics, **intravenous antibiotics** struggle to penetrate the **blood-retinal barrier** adequately to achieve therapeutic concentrations in the vitreous humor for endophthalmitis. - While they can be administered in severe cases, they do not provide the direct, high-dose delivery needed to control the infection within the eye as effectively as intravitreal injections. *Topical antibiotic* - **Topical antibiotics** primarily reach the ocular surface and anterior segment of the eye, with very limited penetration into the **vitreous cavity**. - They are generally ineffective for treating endophthalmitis, which is an infection of the inner eye, and are typically reserved for superficial ocular infections.

Question 203: Drug commonly used in the treatment of iridocyclitis is

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

Explanation: ***Atropine*** - **Atropine** is a potent **cycloplegic** and **mydriatic** agent, effectively paralyzing the ciliary muscles and dilating the pupil. - In **iridocyclitis (anterior uveitis)**, this action helps to **rest the inflamed iris and ciliary body**, prevent posterior synechiae formation, and reduce pain from ciliary spasm. - Atropine is the **drug of choice** for managing acute iridocyclitis due to its long duration of action (7-14 days). *Phenylephrine* - **Phenylephrine** is primarily a **sympathomimetic** drug that causes **mydriasis** (pupil dilation) but has **minimal cycloplegic** (ciliary muscle paralysis) effect. - While it can dilate the pupil, it does not provide the crucial **ciliary body rest** needed to manage inflammation and prevent synechiae in iridocyclitis. *Pilocarpine* - **Pilocarpine** is a **muscarinic agonist** that causes **miosis** (pupil constriction) and **accommodation**. - It would be **contraindicated** in iridocyclitis as it increases ciliary spasm, worsens pain, and promotes posterior synechiae formation. *Timolol* - **Timolol** is a **beta-blocker** used in the treatment of **glaucoma** to reduce intraocular pressure. - It has **no role** in managing inflammation or preventing complications in iridocyclitis.

Question 204: Which drug is generally contraindicated in the management of traumatic hyphema in a patient with sickle cell disease?

A. Timolol
B. Steroids
C. Acetazolamide (Correct Answer)
D. Atropine

Explanation: ***Acetazolamide*** - **Acetazolamide** is a **carbonic anhydrase inhibitor** that is **generally contraindicated** in patients with **sickle cell disease or trait**. - It causes **systemic acidosis** by increasing renal bicarbonate excretion, which lowers blood pH. - **Acidosis promotes sickling** of red blood cells, which can lead to **vaso-occlusion**, increased blood viscosity, and potential complications including **anterior chamber obstruction** and **secondary glaucoma**. - Despite its usefulness in lowering intraocular pressure in other settings, this risk makes it contraindicated in sickle cell patients with hyphema. *Timolol* - **Timolol** is a **beta-blocker** that reduces aqueous humor production and is generally **safe and effective** for reducing **intraocular pressure** in traumatic hyphema. - It does not cause systemic acidosis or affect red blood cell sickling. - Commonly used in hyphema management regardless of sickle cell status. *Steroids* - **Topical or systemic steroids** are often used to reduce **inflammation** and anterior chamber reaction in traumatic hyphema. - They help prevent **secondary hemorrhage** and reduce complications. - They do not contribute to red blood cell sickling or systemic acidosis and are safe in sickle cell disease. *Atropine* - **Atropine** is a **cycloplegic agent** used to paralyze the ciliary body and dilate the pupil, which helps **relieve pain** and prevent **posterior synechiae** in hyphema. - It has no adverse effects related to **sickle cell disease** or red blood cell sickling. - Routinely used in hyphema management.

Question 205: 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.

Question 206: Which of the following drugs is not used in treatment of iridocyclitis:

A. Pilocarpine eye drops
B. Atropine eye ointment
C. Steroid eye drops
D. Timolol eye drops (Correct Answer)

Explanation: ***Timolol eye drops*** - **Timolol** is a **beta-blocker** used to reduce intraocular pressure in **glaucoma** by decreasing aqueous humor production. - It has **no role in iridocyclitis management** as it does not address inflammation, pain, or pupillary abnormalities, which are the key therapeutic targets. - Timolol is simply not part of the treatment protocol for iridocyclitis. *Pilocarpine eye drops* - **Pilocarpine** is a **miotic** agent that constricts the pupil, but it is **contraindicated** in iridocyclitis (not just "not used"). - While not used therapeutically, it's important to distinguish that pilocarpine is actively harmful (increases inflammation and posterior synechiae risk), whereas timolol is simply not indicated. - In the context of this question asking what is "not used in treatment," timolol is the better answer as it's not part of the standard treatment protocol. *Atropine eye ointment* - **Atropine** is a **cycloplegic and mydriatic** agent that is a **cornerstone of iridocyclitis treatment**. - It dilates the pupil and paralyzes the ciliary muscle to prevent and break **posterior synechiae** and relieve pain from ciliary muscle spasm. - By immobilizing the iris and ciliary body, it reduces inflammation and discomfort. *Steroid eye drops* - **Steroid eye drops** (e.g., prednisolone acetate) are **essential for managing iridocyclitis** as they effectively reduce inflammation within the anterior chamber. - They suppress the immune response causing inflammation, thereby alleviating symptoms like redness, pain, and photophobia. - Topical corticosteroids are the mainstay of anti-inflammatory treatment in anterior uveitis.

Question 207: Primary objective of the use of atropine in anterior uveitis

A. Rest to the ciliary muscle (Correct Answer)
B. Helps in preventing posterior synechia formation
C. Increase blood flow
D. Increase supply of antibody

Explanation: ***Rest to the ciliary muscle*** - Atropine is a **cycloplegic** agent that paralyzes the **ciliary muscle**, thereby alleviating pain caused by spasms and inflammation in anterior uveitis. - This **cycloplegia** is the primary therapeutic goal, as it reduces **ciliary spasm** and the associated pain. *Helps in preventing posterior synechia formation (secondary effect)* - While atropine's **mydriatic** action (pupil dilation) helps prevent the formation of **posterior synechiae**, this is a beneficial secondary effect and not its primary objective in alleviating symptoms or pain. - The dilation breaks existing synechiae or prevents new ones from forming by moving the iris away from the lens capsule. *Increase blood flow* - Atropine's primary action is anticholinergic, leading to **cycloplegia** and **mydriasis**, not a direct increase in ocular blood flow. - Increased blood flow is not a targeted therapeutic effect of atropine in acute anterior uveitis. *Increase supply of antibody* - Atropine does not directly influence the immune system or increase the supply of antibodies to the inflamed eye. - Its mechanism of action is limited to blocking muscarinic acetylcholine receptors.

Question 208: Which of the following is a contraindication to topical steroids?

A. Dendritic ulcer (Correct Answer)
B. Herpetic stromal keratitis without epithelial defect
C. Elevated intraocular pressure
D. Non-infectious anterior uveitis

Explanation: ***Dendritic ulcer*** - A **dendritic ulcer** is characteristic of **herpes simplex keratitis**, which is an active viral infection of the cornea. - **Topical steroids** are contraindicated because they can suppress the immune response, leading to viral replication, corneal melt, and potentially severe vision loss or perforation. *Herpetic stromal keratitis without epithelial defect* - In cases of **stromal keratitis**, where the infection is deeper and an intact epithelium is present, topical steroids may be used cautiously in conjunction with antiviral agents to reduce inflammation and scarring. - The primary concern with steroids in herpes simplex keratitis is activating viral replication in the presence of an **epithelial defect**, which is not present here. *Elevated intraocular pressure* - **Elevated intraocular pressure** is a known side effect of topical steroid use, especially with prolonged administration, but it is not an absolute contraindication in itself. - It necessitates careful monitoring and may require concurrent glaucoma treatment, but the primary condition needing steroids may still warrant their use. *Non-infectious anterior uveitis* - **Topical corticosteroids** are the **mainstay of treatment** for non-infectious anterior uveitis to reduce inflammation and prevent complications such as synechiae and vision loss. - The benefits of controlling inflammation in uveitis generally outweigh the risks associated with judicious steroid use.

Question 209: Floppy iris syndrome is associated with usage of

A. 5 alpha reductase inhibitor
B. PDE-5 inhibitor
C. Anticholinergics
D. Selective alpha-adrenergic antagonist (Correct Answer)

Explanation: ***Selective alpha-adrenergic antagonist*** - **Intraoperative Floppy Iris Syndrome (IFIS)** is classically associated with the use of **alpha-1 adrenergic antagonists**, particularly **tamsulosin**. - These drugs cause **flaccidity of the iris** and **prolapse through the incision** during **cataract surgery** by blocking **alpha-1 receptors** in the iris dilator muscle. *5 alpha reductase inhibitor* - These drugs, such as **finasteride** and **dutasteride**, inhibit the conversion of **testosterone to dihydrotestosterone (DHT)**. - They are used to treat **benign prostatic hyperplasia (BPH)** and **androgenetic alopecia** and have no known association with IFIS. *PDE-5 inhibitor* - **Phosphodiesterase-5 (PDE5) inhibitors** like **sildenafil** and **tadalafil** are used to treat **erectile dysfunction**. - While they can cause visual disturbances due to effects on retinal PDE6, they are **not associated with IFIS**. *Anticholinergics* - **Anticholinergic drugs** block the action of **acetylcholine** and are used for various conditions, including **overactive bladder** and **irritable bowel syndrome**. - They tend to cause **mydriasis (pupil dilation)**, but they do **not cause iris floppiness** or IFIS.

Question 210: What is a common side effect of long-term topical steroid use in the eye?

A. Cataract formation (Correct Answer)
B. Dry eye syndrome
C. Allergic conjunctivitis
D. Subconjunctival hemorrhage

Explanation: ***Cataract formation*** - Long-term use of **topical corticosteroids** can lead to the development of **posterior subcapsular cataracts** due to their metabolic effects on lens proteins. - This is a well-established and significant complication, often requiring surgical intervention. - **Note**: The other major sight-threatening complication of long-term topical steroid use is **steroid-induced glaucoma**, which occurs due to increased intraocular pressure from reduced aqueous outflow. *Dry eye syndrome* - While dry eye can be associated with various ocular conditions, it is not a direct or common side effect of **topical steroid use**. - Steroids can sometimes mask inflammation that contributes to dry eye, but they don't typically induce it. *Allergic conjunctivitis* - **Allergic conjunctivitis** is an inflammatory response to an allergen, characterized by itching, redness, and swelling. - Topical steroids are often used to *treat* severe allergic conjunctivitis due to their **anti-inflammatory properties**, not to cause it. *Subconjunctival hemorrhage* - A **subconjunctival hemorrhage** is usually caused by a sudden increase in venous pressure (e.g., coughing, straining) or trauma, leading to bleeding under the conjunctiva. - It is not a common side effect of **topical steroid application**.

Practice by Chapter

Ocular Pharmacokinetics

Practice Questions

Anti-infective Agents

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Anti-inflammatory Drugs

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Antiglaucoma Medications

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Mydriatics and Cycloplegics

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Ocular Lubricants

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Anti-VEGF Agents

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Ocular Diagnostic Agents

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Anesthetics in Ophthalmology

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Preservatives and Their Effects

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Ocular Toxicology

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Novel Drug Delivery Systems

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