Glaucoma — MCQs

Glaucoma Indian Medical PG Practice Questions and MCQs

Question 11: Pilocarpine eye drops act as

A. Directly acting mydriatic
B. Directly acting miotic (Correct Answer)
C. Indirectly acting miotic
D. Indirectly acting mydriatic

Explanation: **Explanation:** Pilocarpine is a tertiary amine alkaloid that acts as a **parasympathomimetic** agent. It is classified as a **directly acting miotic** because it binds directly to and stimulates the **muscarinic (M3) receptors** located on the sphincter pupillae muscle of the iris and the ciliary muscle. * **Why Option B is correct:** By directly stimulating M3 receptors, Pilocarpine causes the sphincter pupillae to contract, leading to pupillary constriction (**miosis**). It also causes the ciliary muscle to contract, which increases the outflow of aqueous humor through the trabecular meshwork, making it useful in treating glaucoma. * **Why Option C is incorrect:** Indirectly acting miotics (e.g., Physostigmine, Echothiophate) do not bind to receptors directly; instead, they inhibit the enzyme **acetylcholinesterase**, thereby increasing the concentration of endogenous acetylcholine at the neuromuscular junction. * **Why Options A & D are incorrect:** Mydriatics (like Atropine or Phenylephrine) cause pupillary dilation. Pilocarpine causes constriction, which is the physiological opposite. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism in Glaucoma:** In Angle-Closure Glaucoma, Pilocarpine pulls the peripheral iris away from the trabecular meshwork, opening the angle. * **Drug of Choice:** It is the drug of choice for the immediate management of **Acute Angle-Closure Glaucoma** (pre-operatively). * **Side Effects:** Common side effects include **brow ache** (due to ciliary muscle spasm), induced myopia, and retinal detachment (rare). * **Contraindication:** It should be avoided in young patients (due to accommodative spasm) and patients with secondary glaucomas like uveitic glaucoma.

Question 12: Which of the following is NOT true concerning Rieger's syndrome?

A. Autosomal dominant inheritance (Correct Answer)
B. Glaucoma
C. Possible presence of facial, dental, and osseous defects
D. Spectrum of Axenfeld's anomaly and marked abnormal development of the iris mesoderm

Explanation: **Explanation:** Rieger’s syndrome is part of the **Axenfeld-Rieger Syndrome (ARS)** spectrum, a group of anterior segment dysgenesis disorders. **Why Option A is the correct answer (The "NOT true" statement):** The question is slightly tricky in its framing. In standard medical literature, Rieger’s syndrome **is** inherited in an **Autosomal Dominant (AD)** fashion (linked to PITX2 and FOXC1 genes). However, in the context of this specific MCQ format often seen in PG exams, if Option A is marked as the "incorrect" statement, it usually implies a technicality regarding its classification or a distractor. *Note: In clinical reality, AD is the correct inheritance; if the key identifies this as the answer, it suggests the question may be testing a specific subtype or is a flawed recall.* **Analysis of other options:** * **Option B (Glaucoma):** This is a hallmark feature. Approximately 50% of patients develop glaucoma due to associated angle underdevelopment (trabeculodysgenesis). * **Option C (Systemic defects):** Rieger’s **Syndrome** is specifically distinguished from Rieger’s **Anomaly** by the presence of systemic findings, including dental (hypodontia, microdontia), facial (maxillary hypoplasia, telecanthus), and umbilical (redundant periumbilical skin) defects. * **Option D (Spectrum/Iris defects):** It represents a progression of Axenfeld’s anomaly (posterior embryotoxon + iris strands) with additional marked iris stromal atrophy, corectopia (displaced pupil), and polycoria (multiple pupils). **High-Yield Clinical Pearls for NEET-PG:** * **Posterior Embryotoxon:** An anteriorly displaced Schwalbe’s line; the earliest sign of the spectrum. * **Axenfeld Anomaly:** Posterior embryotoxon + peripheral iris strands attaching to it. * **Rieger Anomaly:** Axenfeld anomaly + Iris hypoplasia + Corectopia. * **Rieger Syndrome:** Rieger anomaly + Systemic defects (Dental/Skeletal/Umbilical). * **Gene Associations:** PITX2 (4q25) and FOXC1 (6p25).

Question 13: Which investigation is commonly performed during an ophthalmological examination?

A. Pachymetry
B. Tonometry (Correct Answer)
C. Biometry
D. LASER interferometry

Explanation: **Explanation:** **Tonometry** is the correct answer because it is the standard clinical procedure used to measure **Intraocular Pressure (IOP)**. Since elevated IOP is the only modifiable risk factor for glaucoma, tonometry is a fundamental component of every routine ophthalmological examination. The "Gold Standard" for this measurement is **Goldmann Applanation Tonometry (GAT)**, which works on the Imbert-Fick principle. **Analysis of Incorrect Options:** * **Pachymetry (A):** This measures **corneal thickness**. While crucial in glaucoma management (as central corneal thickness affects the accuracy of IOP readings), it is a specialized test rather than a routine screening tool for all patients. * **Biometry (C):** This involves measuring the axial length of the eye and corneal curvature (keratometry). It is primarily used to calculate the **Intraocular Lens (IOL) power** before cataract surgery. * **LASER Interferometry (D):** This is a technique used to assess **potential visual acuity** (retinal function) behind an opaque medium, such as a dense cataract, to predict post-operative vision. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Tonometry:** Goldmann Applanation Tonometry (GAT). * **Schiotz Tonometry:** An indentation tonometer; it is portable but affected by scleral rigidity. * **Imbert-Fick Principle:** States that for a thin-walled sphere, the pressure (P) inside is equal to the force (F) required to flatten a surface area (A); $P = F/A$. * **Normal IOP:** 10–21 mmHg. Diurnal variation of $>5$ mmHg is suspicious of glaucoma.

Question 14: A 60-year-old woman presents with eye pain. Her intraocular pressure is 22 mm Hg in the right eye and 25 mm Hg in the left eye. What is the most likely cause of her eye pain?

A. Decreased hydraulic resistance of the trabecular meshwork
B. Decreased production of aqueous humor
C. Increased hydraulic resistance of the trabecular meshwork (Correct Answer)
D. Increased production of aqueous humor

Explanation: **Explanation:** The patient presents with elevated intraocular pressure (IOP) (normal range: 10–21 mm Hg), which is the hallmark of glaucoma. In the vast majority of primary glaucoma cases, the elevation in IOP is not due to an overproduction of fluid, but rather a **failure in the drainage mechanism.** **Why Option C is Correct:** The primary site of resistance to aqueous outflow in the conventional pathway is the **juxtacanalicular trabecular meshwork** and Schlemm’s canal. In conditions like Primary Open Angle Glaucoma (POAG), pathological changes (such as deposition of extracellular matrix or loss of trabecular cells) lead to **increased hydraulic resistance**. This resistance prevents aqueous humor from exiting the eye at a normal rate, leading to a buildup of pressure. **Why Other Options are Incorrect:** * **Options A & B:** Decreased resistance or decreased production would lead to **hypotony** (low IOP), not the elevated levels seen in this patient. * **Option D:** While it seems logical that "more fluid equals more pressure," **increased production** of aqueous humor is almost never the primary cause of clinical glaucoma. The ciliary body production rate remains relatively constant; the pathology lies in the "clogged" drain (the meshwork). **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for IOP:** Goldmann Applanation Tonometry (GAT). * **Most common site of resistance:** Juxtacanalicular trabecular meshwork. * **Normal Aqueous Production:** ~2–2.5 µL/min. * **Drainage Pathways:** 90% via the Trabecular (conventional) pathway; 10% via the Uveoscleral (unconventional) pathway. * **Drug Link:** Prostaglandin analogs (Latanoprost) increase uveoscleral outflow, while Beta-blockers (Timolol) decrease aqueous production.

Question 15: Which of the following substances is found in higher concentration in aqueous humor compared to plasma?

A. Protein
B. Urea
C. Lactate (Correct Answer)
D. Glucose

Explanation: **Explanation:** The composition of aqueous humor is meticulously regulated by the ciliary body through diffusion, ultrafiltration, and active secretion. While aqueous humor is essentially an ultrafiltrate of plasma, its concentrations of specific solutes differ significantly due to the metabolic demands of the avascular lens and cornea. **Why Lactate is the Correct Answer:** Aqueous humor contains a **higher concentration of Lactate** (and Ascorbate) compared to plasma. This is primarily due to the **anaerobic glycolysis** occurring in the lens and the corneal epithelium. Since these structures are avascular, they metabolize glucose into lactate, which is then excreted into the aqueous humor, leading to a relative excess compared to systemic circulation. **Analysis of Incorrect Options:** * **Protein (A):** Aqueous humor is significantly **protein-poor** (approx. 0.02 g/dL vs. 7 g/dL in plasma). This is crucial for maintaining optical clarity and the Blood-Aqueous Barrier. * **Urea (B):** Urea levels are slightly **lower** in the aqueous humor compared to plasma. * **Glucose (C):** Glucose levels are roughly **20-30% lower** in the aqueous than in plasma because it is actively consumed by the lens and cornea for energy. **High-Yield NEET-PG Pearls:** * **Ascorbate (Vitamin C):** Found in concentrations **15–20 times higher** in aqueous than plasma; it acts as a potent antioxidant protecting against UV damage. * **Chloride & Bicarbonate:** These ions are also found in higher concentrations in the aqueous humor due to active transport by the ciliary epithelium. * **Specific Gravity:** Aqueous humor has a specific gravity of 1.002–1.004. * **pH:** Slightly more acidic than plasma (pH ~7.2).

Question 16: Neovascular glaucoma is caused by which of the following conditions?

A. Central retinal vein occlusion (CRVO)
B. Central retinal artery occlusion (CRAO)
C. Diabetes mellitus
D. All of the above (Correct Answer)

Explanation: **Explanation:** Neovascular Glaucoma (NVG) is a secondary glaucoma caused by the formation of new, fragile blood vessels (neovascularization) on the iris (**Rubeosis Iridis**) and in the iridocorneal angle. **The Underlying Mechanism:** The common denominator in all these conditions is **retinal ischemia**. When the retina is deprived of oxygen, it releases pro-angiogenic factors, most notably **Vascular Endothelial Growth Factor (VEGF)**. VEGF diffuses into the anterior segment, stimulating the growth of new vessels. These vessels, along with an associated fibrovascular membrane, physically block the trabecular meshwork (initially causing open-angle glaucoma) and eventually contract, pulling the iris forward to cause **secondary angle-closure glaucoma**. **Analysis of Options:** * **Central Retinal Vein Occlusion (CRVO):** Specifically the **ischemic type**, it is a leading cause of NVG. It is classically known as **"100-day glaucoma"** because NVG typically develops about three months after the occlusive event. * **Diabetes Mellitus:** Proliferative Diabetic Retinopathy (PDR) is the most common cause of NVG worldwide. Chronic ischemia from damaged retinal capillaries triggers massive VEGF release. * **Central Retinal Artery Occlusion (CRAO):** While less common than CRVO, approximately 15-20% of CRAO cases develop NVG due to profound retinal hypoxia. **Clinical Pearls for NEET-PG:** * **Most common cause:** Proliferative Diabetic Retinopathy. * **Most common cause of unilateral NVG:** Ischemic CRVO. * **Management:** The mainstay of treatment is **Pan-retinal Photocoagulation (PRP)** to reduce the ischemic drive, often combined with **Anti-VEGF injections** (e.g., Ranibizumab or Bevacizumab) to regress the new vessels. * **Clinical Sign:** Look for "Rubeosis Iridis" (new vessels at the pupillary margin) as the earliest sign.

Question 17: What is the drug of choice for primary open-angle glaucoma?

A. Beta blockers
B. Prostaglandin analogues (Correct Answer)
C. Alpha agonists
D. Cholinergics

Explanation: **Explanation:** **Prostaglandin Analogues (PGAs)**, such as Latanoprost, Bimatoprost, and Travoprost, are the **first-line drug of choice** for Primary Open-Angle Glaucoma (POAG). Their primary mechanism of action is increasing the **uveoscleral outflow** of aqueous humor. They are preferred because of their superior efficacy in lowering Intraocular Pressure (IOP), long duration of action (allowing for **once-daily dosing**), and lack of systemic side effects compared to other classes. **Analysis of Options:** * **Beta Blockers (e.g., Timolol):** These were previously the first-line treatment. They work by decreasing aqueous production from the ciliary body. However, they are now second-line due to systemic contraindications like bronchial asthma, heart block, and bradycardia. * **Alpha Agonists (e.g., Brimonidine):** These provide a dual mechanism (decreasing production and increasing uveoscleral outflow) but are generally used as adjunctive therapy due to a high incidence of local allergic reactions (follicular conjunctivitis). * **Cholinergics (e.g., Pilocarpine):** These increase trabecular outflow by contracting the ciliary muscle. They are rarely used in POAG today due to side effects like miosis, brow ache, and risk of retinal detachment; they remain the drug of choice for Acute Angle Closure Glaucoma. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects of PGAs:** Increased eyelash growth (trichomegaly), iris hyperpigmentation (permanent), and cystoid macular edema (CME). * **Contraindication:** PGAs should be avoided in patients with active uveitis or a history of herpetic keratitis. * **Most Potent PGA:** Bimatoprost is often cited as having the greatest IOP-lowering effect.

Question 18: What is the primary surgical treatment for congenital glaucoma?

A. Topical medications
B. Trabeculoplasty
C. Trabeculotomy with trabeculectomy (Correct Answer)
D. Cyclocryotherapy

Explanation: **Explanation:** The primary treatment for **Congenital Glaucoma** (Buphthalmos) is surgical, as medical therapy is generally ineffective and serves only as a temporary measure before surgery. The underlying pathology is a developmental defect in the drainage angle (Barkan’s membrane or trabecular dysgenesis), leading to increased intraocular pressure (IOP). **Why Option C is Correct:** **Trabeculotomy with Trabeculectomy (Combined Surgery)** is considered the gold standard in many regions, including India. * **Trabeculotomy** physically breaks the mechanical obstruction (Barkan’s membrane) to restore aqueous outflow into Schlemm’s canal. * **Trabeculectomy** creates an alternative bypass (filtering bleb) for aqueous drainage. Combining these procedures offers a higher success rate and better long-term IOP control compared to either procedure alone. **Why Other Options are Incorrect:** * **A. Topical medications:** These are only used as a bridge to surgery to clear corneal edema. They do not address the anatomical defect. * **B. Trabeculoplasty:** Laser trabeculoplasty (ALT/SLT) is used in adult open-angle glaucoma; it is ineffective in congenital cases due to the presence of structural dysgenesis. * **D. Cyclocryotherapy:** This is a destructive procedure (ciliary body ablation) reserved for refractory or end-stage cases where conventional surgery has failed. **High-Yield Clinical Pearls for NEET-PG:** * **Goniotomy:** The procedure of choice if the **cornea is clear**. It involves an internal incision of the trabecular meshwork. * **Trabeculotomy:** The procedure of choice if the **cornea is hazy/cloudy**, as it is performed via an external approach and does not require a clear view of the angle. * **Classic Triad:** Epiphora (tearing), Photophobia, and Blepharospasm. * **Haab’s Striae:** Horizontal breaks in Descemet’s membrane, a pathognomonic sign.

Question 19: Miotics are used in the treatment of which condition?

A. Open angle glaucoma
B. Angle closure glaucoma (Correct Answer)
C. After cataract
D. Posterior uveitis

Explanation: **Explanation:** **Miotics** (such as Pilocarpine) are primarily used in the management of **Angle Closure Glaucoma**. The underlying mechanism involves the contraction of the sphincter pupillae muscle, which causes miosis (pupillary constriction). This action pulls the peripheral iris away from the trabecular meshwork, physically opening the drainage angle and allowing the aqueous humor to reach the outflow channels. In acute attacks, pilocarpine also helps to thin the iris, making it easier for a Peripheral Iridotomy (PI) to be performed later. **Analysis of Incorrect Options:** * **Open Angle Glaucoma:** While miotics were historically used, they are no longer first-line treatments due to side effects (e.g., brow ache, accommodative spasm, and decreased night vision). Prostaglandin analogues and Beta-blockers are preferred. * **After Cataract (PCO):** This is a membrane opacity behind an IOL treated with YAG laser capsulotomy; miotics have no therapeutic role here. * **Posterior Uveitis:** Miotics are strictly **contraindicated** in uveitis. They promote the formation of posterior synechiae (adhesions between the iris and lens) and increase inflammation by breaking the blood-aqueous barrier. Mydriatics (like Atropine) are used instead to provide rest to the ciliary body and prevent synechiae. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Pilocarpine is the miotic of choice, but it is ineffective if Intraocular Pressure (IOP) is >40-50 mmHg because the iris sphincter becomes ischemic and non-responsive. * **Pre-Laser Use:** Miotics are used before YAG PI to stretch the iris, making it thinner and easier to penetrate. * **Side Effect:** A serious but rare side effect of miotics is **Retinal Detachment**, caused by the forward pull on the vitreous base during ciliary muscle contraction.

Question 20: Which of the following is true about primary angle closure glaucoma?

A. It is more common in females.
B. It is characterized by a shallow anterior chamber.
C. A shorter corneal diameter is a predisposing factor.
D. All of the above. (Correct Answer)

Explanation: Primary Angle Closure Glaucoma (PACG) is a condition where the peripheral iris obstructs the trabecular meshwork, leading to increased intraocular pressure. It is primarily a disease of "small eyes" with crowded anterior segments. **Explanation of Options:** * **Option A (Gender):** PACG is significantly more common in **females** (ratio approx. 3:1). This is attributed to the fact that women generally have shallower anterior chambers and shorter axial lengths compared to men. * **Option B (Anterior Chamber Depth):** A **shallow anterior chamber** (axial depth <2.5 mm) is the hallmark anatomical predisposition. This crowding increases the likelihood of pupillary block and subsequent iridocorneal contact. * **Option C (Corneal Diameter):** A **shorter corneal diameter** (microcornea) and a smaller eyeball (short axial length/hypermetropia) result in a disproportionately large lens relative to the small anterior segment, predisposing the eye to angle closure. Since all three anatomical and demographic factors are classic features of PACG, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Refractive Error:** PACG is associated with **Hypermetropia** (small eyes), whereas Primary Open Angle Glaucoma (POAG) is associated with Myopia. * **The Lens:** As age increases, the lens grows in thickness (phakomorphic component), further shallowing the anterior chamber. * **Provocative Factors:** Mydriasis (pupillary dilation) can trigger an acute attack; hence, drugs like atropine are contraindicated. * **Gold Standard Treatment:** **Laser Peripheral Iridotomy (LPI)** is the definitive management to bypass pupillary block.

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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