Glaucoma — MCQs

Glaucoma Indian Medical PG Practice Questions and MCQs

Question 31: A 36-year-old female develops eye pain during a prone dark room test. Which of the following drugs should be avoided?

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

Explanation: ### Explanation **Core Concept: Angle-Closure Glaucoma (ACG)** The **Prone Dark Room Test** is a provocative test used to diagnose **Primary Angle-Closure Susceptibility**. Placing a patient in a prone position in the dark causes the lens to move forward and the pupil to dilate (mydriasis), which crowds the angle of the anterior chamber. If the patient develops eye pain and increased intraocular pressure (IOP) during this test, it indicates a narrow/occludable angle. **Why Atropine is the Correct Answer:** Atropine is a potent **parasympatholytic (mydriatic)** agent. It causes pupillary dilation, which leads to further crowding of the angle and can precipitate a full-blown attack of **Acute Congestive Glaucoma** in a patient with a positive provocative test. Therefore, mydriatics are strictly contraindicated in patients with narrow angles. **Analysis of Incorrect Options:** * **Acetazolamide:** A carbonic anhydrase inhibitor that decreases aqueous humor production. It is used to *lower* IOP in acute glaucoma. * **Pilocarpine:** A miotic (parasympathomimetic) that constricts the pupil, pulling the iris away from the angle. It is a treatment of choice for ACG (after initial IOP reduction). * **Timolol:** A topical beta-blocker that reduces aqueous production. It is a standard treatment to lower IOP and is safe in this context. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for Acute Glaucoma:** IV Mannitol (to rapidly lower IOP) or Acetazolamide. * **Definitive treatment for ACG:** Peripheral Iridotomy (usually via YAG laser). * **Mydriatic of choice for fundus exam in narrow angles:** Phenylephrine (it is easily reversible), but only after assessing the risk. * **Classic Presentation:** "Halos around lights," "steamy cornea," and a "mid-dilated non-reactive pupil."

Question 32: Laser iridotomy is indicated for which type of glaucoma?

A. Primary open-angle glaucoma (POAG)
B. Primary angle-closure glaucoma (PACG) (Correct Answer)
C. Congenital glaucoma
D. Secondary angle-closure glaucoma

Explanation: **Explanation:** **1. Why Primary Angle-Closure Glaucoma (PACG) is correct:** The fundamental mechanism in PACG is **pupillary block**, where the iris is in close contact with the lens, obstructing the flow of aqueous humor from the posterior to the anterior chamber. This leads to increased pressure in the posterior chamber, causing the iris to bulge forward (**iris bombe**) and mechanically block the trabecular meshwork. **Laser Peripheral Iridotomy (LPI)** creates a small hole in the peripheral iris, providing an alternative pathway for aqueous flow. This equalizes the pressure between the chambers, flattens the iris, and opens the drainage angle. It is the definitive treatment for PACG. **2. Why other options are incorrect:** * **Primary Open-Angle Glaucoma (POAG):** The angle is already open; the resistance to outflow is within the trabecular meshwork itself. LPI has no role here. Treatment involves medical therapy or Laser Trabeculoplasty. * **Congenital Glaucoma:** This is caused by a structural abnormality (dysgenesis) of the angle (Barkan’s membrane). The primary treatment is surgical, specifically **Goniotomy** or **Trabeculotomy**. * **Secondary Angle-Closure Glaucoma:** While LPI may be used in specific subtypes (like seclusio pupillae), it is not the standard indication for all secondary closures (e.g., neovascular glaucoma), where the underlying cause must be addressed. **3. Clinical Pearls for NEET-PG:** * **Prophylaxis:** LPI is also indicated in the fellow eye of a patient with an acute attack of PACG, as there is a 50-75% risk of a similar attack in the other eye. * **YAG Laser:** The Nd:YAG laser is the most common instrument used for performing iridotomy. * **Complication:** A common transient complication of LPI is a spike in intraocular pressure (IOP) and hyphema.

Question 33: A person with glaucoma should not receive which of the following?

A. Sedatives
B. Vasoconstrictors
C. Antisialogogues (Correct Answer)
D. Local anaesthetics

Explanation: ### Explanation **Correct Answer: C. Antisialogogues** **Why Antisialogogues?** Antisialogogues (such as **Atropine, Scopolamine, and Glycopyrrolate**) are drugs used to decrease salivary secretions, typically as pre-anesthetic medication. These drugs are **Anticholinergics** (muscarinic antagonists). * **Mechanism:** They cause **mydriasis** (dilation of the pupil) and **cycloplegia** (paralysis of the ciliary muscle). * **The Glaucoma Link:** In patients with **Angle-Closure Glaucoma**, mydriasis causes the peripheral iris to bunch up and block the trabecular meshwork (the drainage angle). This leads to a sudden, acute rise in intraocular pressure (IOP), potentially precipitating an attack of acute congestive glaucoma. **Analysis of Incorrect Options:** * **A. Sedatives:** Most sedatives (like Benzodiazepines) do not significantly affect pupil size or aqueous humor dynamics and are generally safe in glaucoma. * **B. Vasoconstrictors:** Systemic vasoconstrictors (like Adrenaline) are sometimes used cautiously; however, they do not carry the same high risk of angle closure as potent anticholinergics. In fact, some sympathomimetics were historically used to *lower* IOP. * **D. Local Anaesthetics:** These agents (like Lignocaine) act by blocking sodium channels and do not influence the autonomic control of the pupil or aqueous outflow. **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindication:** Mydriatics/Anticholinergics are strictly contraindicated in **Primary Angle-Closure Glaucoma (PACG)**. * **Open-Angle Glaucoma (POAG):** Systemic anticholinergics are generally considered safe in POAG because the drainage angle is already wide. * **Drug of Choice for Acute Attack:** Intravenous **Mannitol** (osmotic diuretic) and topical **Pilocarpine** (miotic) once IOP is lowered. * **Safe Alternative:** If an antisialogogue is mandatory, **Glycopyrrolate** is often preferred over Atropine as it crosses the blood-brain/blood-ocular barrier less readily, though caution is still required.

Question 34: What is the sickle-shaped extension of the blind spot known as?

A. Down's sign
B. Bjerrum's sign
C. Seidel's sign (Correct Answer)
D. Baring of blind spot

Explanation: ### Explanation In glaucoma, visual field defects follow a specific progression based on the anatomy of the retinal nerve fiber layer (RNFL). **Why Seidel’s Sign is Correct:** **Seidel’s sign** represents an early glaucomatous field defect. It is a **sickle-shaped extension** of the physiological blind spot, caused by the involvement of the arcuate nerve fibers (specifically the small-diameter fibers). It typically starts at the upper or lower pole of the blind spot and curves around the fixation point, following the path of the arcuate fibers. **Analysis of Incorrect Options:** * **Down’s Sign:** This is not a recognized term in glaucomatous perimetry. * **Bjerrum’s Sign (Arcuate Scotoma):** This is a more advanced stage where the Seidel’s scotoma extends further to meet the horizontal raphe. It forms a complete arc-shaped defect (usually between 10° and 20° from fixation). * **Baring of Blind Spot:** This occurs when an island of vision is lost, making the blind spot appear "open" to the outside of the visual field. While common in glaucoma, it is considered **non-specific** and can occur in normal individuals. **High-Yield Clinical Pearls for NEET-PG:** 1. **Sequence of Defects:** Ischaemic (Paracentral) scotoma → Seidel’s sign → Bjerrum’s scotoma → Double arcuate (Ring) scotoma → Roenne’s nasal step → Tubular vision → Temporal island. 2. **Bjerrum’s Area:** The area of the retina between 10° and 20° from the fixation point where early glaucomatous damage is most frequently detected. 3. **Gold Standard:** Automated Perimetry (specifically the Humphrey Field Analyzer) is the gold standard for monitoring these defects.

Question 35: A 78-year-old male presents with a chief complaint of diminution of vision in both eyes. Intraocular pressure (IOP) in both eyes is 24 mm Hg, and an inferior notch is seen in the optic nerve head. Visual fields reveal a paracentral scotoma. What is the drug of choice?

A. Latanoprost (Correct Answer)
B. Timolol
C. Carbonic anhydrase inhibitor
D. Brimonidine

Explanation: **Explanation:** The clinical presentation of elevated intraocular pressure (24 mm Hg), characteristic optic disc changes (inferior notch), and corresponding visual field defects (paracentral scotoma) confirms a diagnosis of **Primary Open-Angle Glaucoma (POAG)**. **1. Why Latanoprost is the Correct Answer:** **Prostalgandin Analogues (PGAs)** like Latanoprost are the **first-line drug of choice** for POAG. They work by increasing the **uveoscleral outflow** of aqueous humor. They are preferred because of their superior efficacy in lowering IOP (25-35%), once-daily dosing (improving compliance), and lack of systemic side effects compared to beta-blockers. **2. Analysis of Incorrect Options:** * **Timolol (Beta-blocker):** Previously the first-line treatment, it is now considered second-line. It works by decreasing aqueous production. It is often contraindicated in elderly patients with potential systemic comorbidities like asthma, COPD, or heart block. * **Carbonic Anhydrase Inhibitors (e.g., Dorzolamide):** These are less potent than PGAs and are typically used as adjunctive therapy rather than monotherapy. * **Brimonidine (Alpha-2 Agonist):** Primarily used as an add-on therapy. While it has potential neuroprotective properties, it has a high incidence of local allergic reactions. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of PGAs:** Increase uveoscleral outflow (the "alternative" pathway). * **Side Effects of PGAs:** Increased iris pigmentation (heterochromia), hypertrichosis (thickening of eyelashes), and deepening of the sulcus. * **Early Field Defect:** Small islands of vision loss like the **paracentral scotoma** or **Siedel’s scotoma** are early signs; the **Arcuate (Bjerrum) scotoma** is the most classic. * **ISNT Rule:** In a healthy disc, the Neuroretinal Rim width follows Inferior > Superior > Nasal > Temporal. Notching (as seen in this patient) indicates a violation of this rule.

Question 36: Intractable glaucoma characteristically occurs due to which one of the following?

A. Diffuse iris melanoma (Correct Answer)
B. Anterior iris melanocyte proliferation
C. Posterior uveal melanocyte proliferation
D. Lens enlargement

Explanation: **Explanation:** **Diffuse iris melanoma** is a rare but classic cause of **intractable secondary open-angle glaucoma**. Unlike nodular melanomas, the diffuse variant spreads as a flat, infiltrating sheet across the iris surface. The primary mechanism for glaucoma is the direct infiltration and replacement of the **trabecular meshwork (TM)** by malignant melanocytes or pigment-laden macrophages. This leads to a progressive, severe increase in intraocular pressure (IOP) that is often refractory to medical therapy, hence the term "intractable." **Analysis of Options:** * **A. Diffuse iris melanoma (Correct):** Characterized by heterochromia iridis and progressive glaucoma due to TM infiltration. * **B. Anterior iris melanocyte proliferation:** While this occurs in conditions like Iris Nevus Syndrome (Cogan-Reese), it is not the "characteristic" cause of intractable glaucoma in the context of malignant transformation. * **C. Posterior uveal melanocyte proliferation:** This refers to choroidal or ciliary body melanomas. While they can cause glaucoma (via neovascularization or angle closure), they do not typically present with the diffuse TM infiltration seen in iris melanoma. * **D. Lens enlargement:** This causes **Phacomorphic glaucoma** (secondary angle-closure). While serious, it is usually reversible with lens extraction and is not the classic association for "intractable" pigmentary-related glaucoma. **High-Yield Clinical Pearls for NEET-PG:** * **Heterochromia Iridis:** The most common presenting sign of diffuse iris melanoma (the affected eye becomes darker). * **Ring Melanoma:** A variant of diffuse melanoma that involves the entire circumference of the angle. * **Management:** Intractable glaucoma in the presence of a suspected diffuse iris melanoma often necessitates **enucleation**, as filtering surgeries (like trabeculectomy) are contraindicated due to the risk of extraocular tumor seeding.

Question 37: Phacolytic glaucoma commonly arises from which type of cataract?

A. Late mature cataract
B. Immature cataract
C. Hypermature cataract (Correct Answer)
D. Intumescent cataract

Explanation: **Explanation:** **Phacolytic glaucoma** is a type of secondary open-angle glaucoma caused by the leakage of high-molecular-weight lens proteins through the capsule of a **hypermature cataract** (Morgagnian or sclerotic). These proteins leak into the aqueous humor and are subsequently engulfed by macrophages. These protein-laden macrophages, along with the proteins themselves, physically obstruct the trabecular meshwork, leading to a sudden and severe rise in intraocular pressure (IOP). **Analysis of Options:** * **Hypermature Cataract (Correct):** The lens capsule becomes thin and leaky in the hypermature stage, allowing the liquefied cortex to escape. This is the essential prerequisite for phacolytic glaucoma. * **Late Mature Cataract:** While the lens is fully opaque, the capsule remains intact and the cortex has not yet liquefied to the point of significant protein leakage. * **Immature Cataract:** The lens is only partially opaque, and the capsule is healthy and non-leaky. * **Intumescent Cataract:** This is a swollen lens that can cause **Phacomorphic glaucoma** (a secondary *closed-angle* glaucoma) due to pupillary block, rather than the protein-leakage mechanism of phacolytic glaucoma. **Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Sudden onset of pain, redness, and "halos" with a milky-white lens and deep anterior chamber (distinguishing it from the shallow AC in phacomorphic glaucoma). * **Aqueous Tap:** Microscopy of the aqueous humor reveals characteristic **eosinophilic material** and **large macrophages** (Lederhosen cells) swollen with lens material. * **Definitive Treatment:** Urgent reduction of IOP using hyperosmotics (Mannitol) and topical medications, followed by **Extracapsular Cataract Extraction (ECCE)** or Phacoemulsification.

Question 38: An indentation tonometer is based on the principle that a plunger indents more in which type of eye?

A. Soft eye (Correct Answer)
B. Hard eye
C. Equal indentation in soft and hard eyes
D. None of the above

Explanation: **Explanation:** The principle of **Indentation Tonometry** (most commonly represented by the **Schiotz Tonometer**) is based on the physical relationship between internal pressure and the deformability of a sphere. 1. **Why Option A is Correct:** In a **soft eye** (low intraocular pressure), the globe offers less resistance to external force. Therefore, a plunger of a fixed weight will sink deeper into the cornea, creating a larger indentation. The Schiotz tonometer measures this depth of indentation; a higher scale reading indicates a deeper indentation, which correlates to a lower IOP. 2. **Why Option B is Incorrect:** In a **hard eye** (high intraocular pressure), the internal tension makes the cornea more rigid and resistant to deformation. Consequently, the plunger indents the eye **less**. 3. **Why Option C is Incorrect:** Indentation is inversely proportional to the intraocular pressure. If indentation were equal, the device would have no diagnostic utility in measuring pressure variations. **High-Yield Clinical Pearls for NEET-PG:** * **Imbert-Fick Law:** This is the principle for **Applanation Tonometry** (Goldmann), which states that pressure is equal to the force required to flatten a specific area ($P = F/A$). * **Schiotz vs. Goldmann:** Schiotz is an indentation tonometer (portable but less accurate), while Goldmann is an applanation tonometer (the **Gold Standard**). * **Scleral Rigidity:** A major drawback of Schiotz tonometry is that it is influenced by scleral rigidity. In conditions like high myopia (low rigidity), Schiotz may give a falsely low IOP reading. * **Formula:** $P_0$ (actual IOP) is derived using the Friedenwald Nomogram based on the plunger weight and scale reading.

Question 39: Which of the following findings is most helpful in the diagnosis of open-angle glaucoma?

A. Cupping of the optic disc (Correct Answer)
B. Depth of the anterior chamber
C. Visual acuity and refractive error
D. Angle of the anterior chamber

Explanation: **Explanation:** The diagnosis of **Primary Open-Angle Glaucoma (POAG)** relies on a triad of findings: raised intraocular pressure (IOP), characteristic optic disc changes, and corresponding visual field defects. Among the options provided, **cupping of the optic disc** is the most definitive clinical sign of glaucomatous structural damage. 1. **Why Option A is correct:** Glaucoma is essentially an optic neuropathy. Increased IOP or vascular insufficiency leads to the death of retinal ganglion cells, resulting in the enlargement of the "cup" relative to the "disc" (increased Cup-Disc Ratio). Findings like vertical expansion of the cup, thinning of the neuroretinal rim, and **Bayoneting sign** are hallmark diagnostic features that confirm structural damage. 2. **Why other options are incorrect:** * **Option B & D:** The depth and angle of the anterior chamber are used to **classify** the type of glaucoma (Open vs. Angle-closure) via gonioscopy, but they do not diagnose the presence of the disease itself. In POAG, the angle is characteristically normal and open. * **Option C:** Visual acuity often remains 6/6 (normal) until the very advanced stages of POAG, as peripheral vision is lost first. Refractive error (like high myopia) is a risk factor but not a diagnostic finding. **High-Yield Clinical Pearls for NEET-PG:** * **ISNT Rule:** In a normal disc, the thickness of the neuroretinal rim follows the order Inferior > Superior > Nasal > Temporal. Glaucoma often breaks this rule (Inferior/Superior thinning occurs first). * **Goldmann Applanation Tonometry:** The gold standard for measuring IOP. * **Humphrey Visual Field (HVF) Analysis:** The standard for detecting functional damage (e.g., Arcuate/Bjerrum scotoma). * **Early Sign:** The earliest clinical sign of POAG is often an increase in IOP, but the earliest structural sign is often **RNFL (Retinal Nerve Fiber Layer) thinning** on OCT.

Question 40: Which of the following drugs is NOT used topically for the treatment of open-angle glaucoma?

A. Latanoprost
B. Brimonidine
C. Acetazolamide (Correct Answer)
D. Dorzolamide

Explanation: **Explanation:** The correct answer is **Acetazolamide** because it is a potent systemic Carbonic Anhydrase Inhibitor (CAI) administered **orally or intravenously**, not topically. While it effectively reduces intraocular pressure (IOP) by decreasing aqueous humor production, its poor lipid solubility and high ionization at physiological pH prevent it from achieving therapeutic concentrations in the eye when applied as a drop. **Analysis of Options:** * **Latanoprost (Option A):** A Prostaglandin F2α analog. It is the first-line **topical** treatment for open-angle glaucoma, acting by increasing uveoscleral outflow. * **Brimonidine (Option B):** A selective Alpha-2 agonist used **topically**. It has a dual mechanism: decreasing aqueous production and increasing uveoscleral outflow. It also possesses potential neuroprotective properties. * **Dorzolamide (Option D):** A **topical** Carbonic Anhydrase Inhibitor. Unlike acetazolamide, it was specifically designed to penetrate the cornea, allowing for local inhibition of carbonic anhydrase in the ciliary body without the systemic side effects of oral therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Acetazolamide Side Effects:** Paresthesia (most common), metabolic acidosis, hypokalemia, and renal stones. It is contraindicated in patients with sulfonamide allergies. * **Drug of Choice:** Prostaglandin analogs (e.g., Latanoprost) are the current DOC for Primary Open Angle Glaucoma (POAG) due to once-daily dosing and high efficacy. * **Acute Congestive Glaucoma:** Intravenous Mannitol and oral/IV Acetazolamide are the mainstays for rapid IOP reduction. * **Brimonidine Caution:** It is contraindicated in children under 2 years of age due to the risk of CNS depression and apnea.

Practice by Chapter

Aqueous Humor Dynamics

Practice Questions

Primary Open-Angle Glaucoma

Practice Questions

Primary Angle-Closure Glaucoma

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Secondary Open-Angle Glaucomas

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Secondary Angle-Closure Glaucomas

Practice Questions

Developmental and Congenital Glaucomas

Practice Questions

Medical Management of Glaucoma

Practice Questions

Laser Therapy in Glaucoma

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Glaucoma Filtration Surgery

Practice Questions

Glaucoma Drainage Devices

Practice Questions

Angle Assessment Techniques

Practice Questions

Visual Field Testing in Glaucoma

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Glaucoma — MCQs

Glaucoma — MCQs

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