Glaucoma — MCQs

Glaucoma Indian Medical PG Practice Questions and MCQs

Question 301: What is the standard in perimetry?

A. Goldman type I
B. Goldman type II
C. Goldman type III (Correct Answer)
D. Goldman type IV

Explanation: In Automated Static Perimetry (the gold standard for diagnosing and monitoring glaucoma), the **Goldmann Size III** stimulus is the universal standard. ### Why Goldman Type III is Correct The Goldmann perimeter uses a standardized system where stimuli vary in size (Roman numerals I-V) and intensity. **Size III** corresponds to a surface area of **4 mm²** (subtending an angle of 0.43°). This size is chosen as the standard because: * It is large enough to be easily perceived by most patients with normal or mildly reduced vision. * It provides a reliable balance between spatial resolution and sensitivity. * Most normative databases (like those used in Humphrey Field Analyzers) are built specifically using Size III stimuli. ### Why Other Options are Incorrect * **Goldman Type I (0.25 mm²):** These are very small stimuli. While useful for detecting subtle defects in patients with excellent visual acuity, they are highly susceptible to "refractive blur" and "scatter," making them less reliable for routine screening. * **Goldman Type II (1 mm²):** Rarely used in modern automated perimetry as a standard. * **Goldman Type IV (16 mm²) & Type V (64 mm²):** These are much larger stimuli. They are reserved for patients with **advanced glaucoma** or **poor vision** (e.g., <6/60) where the standard Size III stimulus is no longer perceived. ### High-Yield Clinical Pearls for NEET-PG 1. **Stimulus Duration:** In automated perimetry, the standard stimulus duration is **200 milliseconds** (0.2 seconds). This is shorter than the latency of voluntary eye movements, preventing the patient from "searching" for the light. 2. **Background Luminance:** The standard background illumination is **31.5 apostilbs (asb)**, which ensures the eye remains in the **photopic** (light-adapted) range. 3. **Weber’s Law:** Perimetry relies on the principle that the eye detects a stimulus based on the contrast between the target and the background. 4. **Apostilbs to Decibels:** Remember that Decibels (dB) are a relative scale; a higher dB value indicates a dimmer stimulus (better sensitivity).

Question 302: Which of the following is true about primary angle closure glaucoma?

A. More common in females
B. Shallow anterior chamber is a risk factor (Correct Answer)
C. Deep anterior chamber is a risk factor
D. Shorter diameter of cornea is a predisposing factor

Explanation: **Explanation:** Primary Angle Closure Glaucoma (PACG) occurs due to the anatomical narrowing of the anterior chamber angle, which obstructs the outflow of aqueous humor. **Why the correct answer is right:** A **shallow anterior chamber** is the hallmark anatomical risk factor for PACG. In eyes with a shallow chamber, the iris is positioned closer to the trabecular meshwork. This proximity increases the likelihood of **iridocorneal contact**, especially during pupillary dilation, leading to a sudden rise in intraocular pressure (IOP). **Analysis of other options:** * **Option A:** While PACG is indeed more common in females (due to smaller ocular dimensions), the question asks for a "true" statement. In many standardized exams, if multiple options are technically true, the **most definitive anatomical risk factor** (shallow AC) is prioritized. However, in most NEET-PG contexts, both A and B are true; if this were a "Multiple True" type, both would be selected. * **Option C:** A deep anterior chamber is a characteristic of **Myopia** and is a risk factor for Primary Open Angle Glaucoma (POAG), not PACG. * **Option D:** While a smaller corneal diameter (microcornea) can be associated with a crowded anterior segment, the more precise predisposing factor is a **short axial length** (Hypermetropia) rather than just the corneal diameter itself. **High-Yield Clinical Pearls for NEET-PG:** * **Anatomical Predispositions:** Hypermetropia (small eyeball), thick lens (aging), and small corneal diameter. * **Demographics:** Elderly (6th–7th decade), Females (F:M = 3:1), and South East Asians. * **Trigger:** Mid-dilated pupil (e.g., watching a movie in a dark theater or using mydriatics). * **Treatment of Choice:** Peripheral Iridotomy (PI) is the definitive management to bypass pupillary block.

Question 303: Which drug is used in refractory glaucoma?

A. Systemic glucocorticoid
B. ACE inhibitor
C. Alpha agonist (Correct Answer)
D. Beta blocker

Explanation: ### Explanation **Correct Option: C (Alpha agonist)** In the context of refractory glaucoma (glaucoma that remains uncontrolled despite conventional medical or surgical therapy), **Apraclonidine** (a selective alpha-2 agonist) is the drug of choice. It is highly effective for the short-term control of intraocular pressure (IOP) spikes, particularly post-laser procedures (like iridotomy or trabeculoplasty) and in cases resistant to other medications. It works by decreasing aqueous humor production and increasing uveoscleral outflow. **Brimonidine** is another alpha-2 agonist used for long-term management due to its neuroprotective properties. **Analysis of Incorrect Options:** * **A. Systemic glucocorticoids:** These are contraindicated in glaucoma. Steroids (topical or systemic) can decrease aqueous outflow through the trabecular meshwork, leading to "steroid-induced glaucoma." * **B. ACE inhibitors:** While systemic ACE inhibitors are used for hypertension, they have no established clinical role in the primary management of refractory glaucoma. * **D. Beta blockers:** While Timolol is a first-line agent for chronic open-angle glaucoma, it is usually the first drug tried. If the glaucoma is labeled "refractory," it implies that standard treatments like beta-blockers have already failed to control the IOP. **NEET-PG High-Yield Pearls:** * **Drug of choice for post-laser IOP spikes:** Apraclonidine. * **Side effect of Apraclonidine:** High incidence of follicular conjunctivitis and "tachyphylaxis" (loss of efficacy over time), which is why it is used for short-term refractory cases. * **Brimonidine:** Can cause "granulomatous uveitis" and is contraindicated in infants due to the risk of CNS depression/apnea. * **First-line for most Glaucomas:** Prostaglandin analogues (Latanoprost) are currently preferred over Beta-blockers due to better efficacy and fewer systemic side effects.

Question 304: Which of the following anatomical changes does NOT predispose to angle closure glaucoma?

A. Small cornea
B. Flat cornea (Correct Answer)
C. Anterior chamber shallower
D. Short axial length of the eyeball

Explanation: **Explanation:** Angle-closure glaucoma (ACG) is primarily a disease of **anatomical crowding**. It occurs in eyes where the structures of the anterior segment are physically cramped, leading to resistance in aqueous outflow. **Why "Flat Cornea" is the correct answer:** A **steep cornea** (increased curvature) is a known risk factor for angle closure because it is often associated with a shallower anterior chamber. Conversely, a **flat cornea** (decreased curvature) typically results in a deeper anterior chamber, which increases the angle width and protects against angle closure. Therefore, a flat cornea is not a predisposing factor. **Analysis of Incorrect Options:** * **Small Cornea:** A smaller corneal diameter (e.g., microcornea) is associated with a crowded anterior segment, pushing the iris closer to the trabecular meshwork. * **Shallow Anterior Chamber:** This is the hallmark anatomical predisposition. A decreased distance between the cornea and the lens iris diaphragm makes it easier for the angle to close, especially during pupillary dilation. * **Short Axial Length:** This is characteristic of **hypermetropic (farsighted) eyes**. In these eyes, the internal structures are "packed" into a smaller globe, leading to a shallow anterior chamber and a relatively large lens, both of which narrow the drainage angle. **High-Yield Clinical Pearls for NEET-PG:** * **The "Typical" Patient:** Elderly, hypermetropic female with a family history of glaucoma. * **Lens Factor:** As age increases, the lens grows in thickness (increased anteroposterior diameter) and moves forward, further shallowing the anterior chamber. * **Precipitating Factor:** Mid-dilated pupil (e.g., in a dark cinema hall or due to mydriatics) is the most common trigger for an acute attack. * **Gold Standard Diagnosis:** Gonioscopy (to visualize the angle structures).

Question 305: Which cells are affected in glaucomatous optic neuropathy?

A. Amacrine cells
B. Bipolar cells
C. Ganglion cells (Correct Answer)
D. Rods and cones

Explanation: **Explanation:** **Glaucomatous Optic Neuropathy (GON)** is characterized by progressive damage to the optic nerve, primarily involving the **Retinal Ganglion Cells (RGCs)** and their axons. 1. **Why Ganglion Cells are correct:** The pathophysiology of glaucoma involves mechanical compression (due to elevated Intraocular Pressure) and vascular ischemia at the lamina cribrosa. This leads to the **apoptosis (programmed cell death)** of Retinal Ganglion Cells. Since the axons of these RGCs converge to form the optic nerve, their loss results in the characteristic "cupping" of the optic disc and corresponding visual field defects. 2. **Why other options are incorrect:** * **Amacrine and Bipolar cells:** These are interneurons located in the inner nuclear layer of the retina. While some secondary degeneration may occur in advanced stages, they are not the primary site of injury in glaucoma. * **Rods and Cones:** These are photoreceptors located in the outermost layer of the retina. They are responsible for converting light into electrical signals. Glaucoma is a disease of the "inner retina" (output neurons), whereas diseases like Retinitis Pigmentosa primarily affect the photoreceptors. **Clinical Pearls for NEET-PG:** * **Earliest Change:** The earliest structural change in glaucoma is often the thinning of the **Retinal Nerve Fiber Layer (RNFL)**, which consists of RGC axons. * **Mechanism of Death:** RGC death in glaucoma occurs via **Apoptosis**, triggered by neurotrophin deprivation and glutamate excitotoxicity. * **Diagnostic Tool:** **Optical Coherence Tomography (OCT)** is used to quantify the loss of the Ganglion Cell Complex (GCC) and RNFL thickness for early diagnosis.

Question 306: A 55-year-old lady presented with sudden onset of severe eye pain and a shallow anterior chamber. What is the treatment of choice?

A. Atropine
B. Intravenous mannitol & Acetazolamide (Correct Answer)
C. Atenolol
D. Intravenous steroids

Explanation: ### Explanation **Diagnosis: Acute Angle-Closure Glaucoma (AACG)** The clinical presentation of sudden onset severe eye pain associated with a shallow anterior chamber in a middle-aged female is a classic description of **Acute Angle-Closure Glaucoma**. This is a medical emergency caused by a rapid rise in intraocular pressure (IOP). **Why Option B is Correct:** The immediate goal of treatment is to **lower the IOP rapidly** to prevent permanent optic nerve damage and clear corneal edema. * **Intravenous Mannitol:** An osmotic diuretic that creates an osmotic gradient, drawing fluid out of the vitreous into the bloodstream, thereby rapidly reducing IOP. * **Acetazolamide:** A carbonic anhydrase inhibitor that reduces the production of aqueous humor. Once the pressure is controlled, the definitive treatment is a Peripheral Iridotomy (PI). **Why Other Options are Incorrect:** * **A. Atropine:** This is a strong mydriatic (dilates the pupil). In AACG, mydriasis further crowds the angle and worsens the pupillary block, potentially exacerbating the condition. It is strictly contraindicated. * **C. Atenolol:** While beta-blockers (like Timolol) are used topically in glaucoma, systemic Atenolol is a cardioselective beta-1 blocker and has no significant role in the emergency management of acute ocular hypertension. * **D. Intravenous Steroids:** These are used for inflammatory conditions (like optic neuritis or uveitis) but do not lower IOP in an acute glaucoma crisis. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for immediate IOP reduction:** IV Mannitol. * **Definitive Treatment:** Laser Peripheral Iridotomy (LPI) – performed on both the affected and the fellow (prophylactic) eye. * **Classic Signs:** "Steamy" or hazy cornea, mid-dilated non-reactive pupil, and a "stony hard" eye on palpation. * **Risk Factors:** Hypermetropia (small eyes), advancing age, and female gender.

Question 307: Which beta-1 selective blocker is used in the management of glaucoma?

A. Levobunolol
B. Timolol
C. Betaxolol (Correct Answer)
D. Carteolol

Explanation: **Explanation:** **Betaxolol** is the correct answer because it is the only **selective beta-1 (β1) adrenergic receptor antagonist** available for topical ophthalmic use. ### Why Betaxolol is Correct: Most topical beta-blockers used in glaucoma are non-selective, meaning they block both β1 (heart) and β2 (lungs) receptors. Betaxolol specifically targets β1 receptors. While it is slightly less potent in lowering intraocular pressure (IOP) compared to timolol, its selectivity makes it the **safest choice for patients with underlying respiratory conditions** like asthma or Chronic Obstructive Pulmonary Disease (COPD), as it minimizes the risk of drug-induced bronchospasm. ### Why Other Options are Incorrect: * **Timolol:** The "gold standard" and most commonly used beta-blocker, but it is **non-selective** (blocks both β1 and β2). It is contraindicated in asthmatics. * **Levobunolol:** A potent **non-selective** beta-blocker with a long duration of action, often used for once-daily dosing. * **Carteolol:** A **non-selective** beta-blocker that possesses **Intrinsic Sympathomimetic Activity (ISA)**. This property may result in fewer bradycardic side effects and is theoretically less likely to adversely affect serum lipid profiles. ### High-Yield Clinical Pearls for NEET-PG: * **Mechanism of Action:** Beta-blockers reduce IOP by **decreasing the production of aqueous humor** from the ciliary body epithelium. * **Neuroprotection:** Betaxolol is often cited for having potential neuroprotective properties (via calcium channel blocking activity), which may benefit the optic nerve beyond just lowering IOP. * **Side Effects:** Always remember the systemic absorption of topical drops. Even selective blockers should be used with caution in patients with severe heart block or heart failure. * **Nasolacrimal Occlusion:** Advise patients to perform punctal occlusion after instillation to reduce systemic absorption and side effects.

Question 308: Glaucomflecken are typically seen in which condition?

A. Open angle glaucoma
B. Uveitis
C. Retinitis pigmentosa
D. Acute angle closure glaucoma (Correct Answer)

Explanation: **Explanation:** **Glaucomflecken** (also known as Vogt’s spots) are a pathognomonic sign of a prior episode of **Acute Angle Closure Glaucoma (AACG)**. They appear as multiple, small, grey-white subcapsular opacities in the anterior lens capsule. **Why the correct answer is right:** During an acute attack of angle-closure glaucoma, the Intraocular Pressure (IOP) rises rapidly and severely (often >50-60 mmHg). This extreme pressure causes mechanical compression and ischemia of the anterior lens epithelium, leading to localized **focal necrosis**. These necrotic cells eventually form the characteristic permanent opacities known as Glaucomflecken. Their presence is a clinical indicator that the patient has suffered a significant acute pressure spike in the past. **Why the incorrect options are wrong:** * **Open Angle Glaucoma:** This is a chronic, progressive condition where IOP rises gradually. It does not cause the sudden, extreme pressure spikes necessary to induce lens epithelial necrosis. * **Uveitis:** While uveitis can cause lens changes (like posterior synechiae or complicated cataracts), it does not produce the specific focal subcapsular spots seen in Glaucomflecken. * **Retinitis Pigmentosa:** This is a retinal dystrophy associated with "bone-spicule" pigmentation and posterior subcapsular cataracts, but not Glaucomflecken. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of AACG Sequelae:** Glaucomflecken, iris atrophy (often sectoral), and a mid-dilated non-reactive pupil. * **Location:** Glaucomflecken are found in the **anterior subcapsular** region of the lens. * **Management:** The definitive treatment for the underlying cause of Glaucomflecken (AACG) is **Laser Peripheral Iridotomy (LPI)**.

Question 309: In indentation tonometry, what is the relationship between scleral rigidity, intraocular pressure, and scale readings?

A. A plunger indents a hard eye more than a soft eye.
B. Lower scale readings are obtained in high intraocular pressure. (Correct Answer)
C. Low scleral rigidity gives a high reading of intraocular pressure.
D. All of the above

Explanation: ### Explanation **1. Why Option B is Correct:** Indentation tonometry (e.g., Schiotz Tonometry) works on the principle that a plunger with a known weight will indent a soft eye more than a hard eye. The scale on the instrument is calibrated such that **greater indentation** (soft eye/low IOP) results in a **higher scale reading** (e.g., 10 units). Conversely, if the IOP is high, the eye is "harder," the plunger indents less, and the pointer moves less, resulting in a **lower scale reading** (e.g., 2 units). Therefore, lower scale readings correlate with higher intraocular pressure. **2. Why Other Options are Incorrect:** * **Option A:** This is physically incorrect. A plunger indents a **soft eye** (low IOP) more than a hard eye. * **Option C:** Low scleral rigidity (e.g., in high myopia) means the eye coat stretches more easily under the weight of the tonometer. This leads to an over-indentation, which produces a high scale reading. On the conversion chart, a high scale reading translates to a **falsely low** IOP estimate. **3. High-Yield Clinical Pearls for NEET-PG:** * **Schiotz Tonometry Principle:** Based on the **Imbert-Fick Law** (though modified for indentation). * **Scleral Rigidity Errors:** * **High Scleral Rigidity** (e.g., hyperopia, long-standing glaucoma): Leads to **falsely high** IOP readings. * **Low Scleral Rigidity** (e.g., high myopia, post-LASIK, keratoconus): Leads to **falsely low** IOP readings. * **Goldmann Applanation Tonometry (GAT):** The current "Gold Standard." It is less affected by scleral rigidity because it displaces a negligible volume of fluid (0.5 mm³). * **Friedenwald Nomogram:** Used to correct for variations in scleral rigidity when using Schiotz tonometry.

Question 310: What is the normal range of intraocular pressure (IOP)?

A. 10 - 15 mmHg
B. 5 - 10 mmHg
C. 11 - 21 mmHg (Correct Answer)
D. 9 - 25 mmHg

Explanation: **Explanation:** The normal range of Intraocular Pressure (IOP) is traditionally defined as **11 to 21 mmHg**. This range is derived from large-scale population studies (like the Framingham Study), where the mean IOP was found to be approximately 15.5 mmHg with a standard deviation (SD) of 2.5 mmHg. In a Gaussian distribution, the "normal" range is calculated as the mean ± 2 SD, which encompasses 95% of the population. * **Why Option C is correct:** 11–21 mmHg is the statistically accepted physiological range. Pressures consistently above 21 mmHg are categorized as **Ocular Hypertension**, while those below 10 mmHg are termed **Ocular Hypotony**. * **Why Options A, B, and D are incorrect:** These ranges do not align with the statistical mean and standard deviation of the general population. Option B (5–10 mmHg) represents hypotony, while Option D (up to 25 mmHg) includes values strongly associated with glaucomatous damage. **Clinical Pearls for NEET-PG:** * **Gold Standard:** Goldmann Applanation Tonometry (GAT) is the gold standard for measuring IOP. * **Diurnal Variation:** IOP is not constant; it is usually highest in the early morning. A variation of **3–6 mmHg** is normal, but a variation **>8 mmHg** is highly suggestive of glaucoma. * **Central Corneal Thickness (CCT):** IOP readings are influenced by CCT. A thin cornea leads to an underestimation of IOP, while a thick cornea leads to an overestimation. * **Glaucoma vs. IOP:** Remember that glaucoma is a progressive optic neuropathy; it can occur even with "normal" IOP (Normal Tension Glaucoma). Conversely, high IOP without disc damage is Ocular Hypertension.

Practice by Chapter

Aqueous Humor Dynamics

Practice Questions

Primary Open-Angle Glaucoma

Practice Questions

Primary Angle-Closure Glaucoma

Practice Questions

Secondary Open-Angle Glaucomas

Practice Questions

Secondary Angle-Closure Glaucomas

Practice Questions

Developmental and Congenital Glaucomas

Practice Questions

Medical Management of Glaucoma

Practice Questions

Laser Therapy in Glaucoma

Practice Questions

Glaucoma Filtration Surgery

Practice Questions

Glaucoma Drainage Devices

Practice Questions

Angle Assessment Techniques

Practice Questions

Visual Field Testing in Glaucoma

Practice Questions

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Glaucoma — MCQs

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