Glaucoma Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Glaucoma. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Glaucoma Indian Medical PG Question 1: A 75-year-old patient presents with deterioration of vision. On examination, the pupillary reflex is observed to be sluggish, and the intraocular pressure is normal. Optic disc evaluation shows a large and deep cup and paracentral scotomas. What is the most likely diagnosis?
- A. Primary Narrow angle glaucoma
- B. Normal Tension Glaucoma (Correct Answer)
- C. Neovascular Glaucoma
- D. Absolute Glaucoma
Glaucoma Explanation: **Explanation:**
The diagnosis is **Normal Tension Glaucoma (NTG)**, a variant of Primary Open-Angle Glaucoma (POAG). The key to this question lies in the triad of **normal intraocular pressure (IOP)**, characteristic **glaucomatous optic disc changes** (large, deep cup), and corresponding **visual field defects** (paracentral scotomas).
**Why Option B is Correct:**
In NTG, glaucomatous damage occurs despite IOP remaining consistently within the statistically normal range (≤21 mmHg). It is often associated with vascular dysregulation or systemic hypotension. The presence of a **sluggish pupillary reflex** indicates an Afferent Pupillary Defect (APD) due to advanced optic nerve damage. **Paracentral scotomas** are classically deeper and closer to the fixation point in NTG compared to high-tension POAG.
**Why Other Options are Incorrect:**
* **A. Primary Narrow Angle Glaucoma:** Typically presents with episodes of high IOP, ocular pain, and a shallow anterior chamber.
* **C. Neovascular Glaucoma:** A secondary glaucoma characterized by very high IOP and rubeosis iridis (new vessels on the iris), usually following retinal ischemia.
* **D. Absolute Glaucoma:** The final stage of any uncontrolled glaucoma where the eye is blind (No PL), the pupil is fixed/dilated, and IOP is usually very high.
**NEET-PG High-Yield Pearls:**
* **Drance Hemorrhage:** Flame-shaped disc margin hemorrhages are more common in NTG than in POAG.
* **Risk Factors:** NTG is frequently associated with Raynaud’s phenomenon, migraines, and nocturnal systemic hypotension.
* **Differential:** Always rule out "burnt-out" glaucoma or neurological compression of the optic nerve before diagnosing NTG.
* **Treatment Goal:** Even though IOP is "normal," the mainstay of treatment is still lowering the IOP by 30% from the baseline.
Glaucoma Indian Medical PG Question 2: What is the area of the cornea indented by a Goldmann applanation tonometer when measuring intraocular pressure?
- A. 3.66 mm
- B. 3.6 mm
- C. 3.0 mm
- D. 3.06 mm (Correct Answer)
Glaucoma Explanation: ### Explanation
The Goldmann Applanation Tonometer (GAT) is the "gold standard" for measuring intraocular pressure (IOP). It is based on the **Imbert-Fick Principle**, which states that for a thin-walled, perfectly spherical container, the pressure ($P$) inside is equal to the force ($F$) required to flatten a specific area ($A$), expressed as $P = F/A$.
**Why 3.06 mm is the correct answer:**
In the human eye, the Imbert-Fick principle is affected by two opposing forces: **corneal rigidity** (which resists indentation) and the **surface tension of the tear film** (which pulls the tonometer toward the cornea).
* At an applanation diameter of exactly **3.06 mm**, these two forces cancel each other out.
* Furthermore, at this specific diameter, the numerical value of the force applied (in grams) multiplied by 10 gives the IOP directly in mmHg (e.g., 2g = 20 mmHg). This simplifies the clinical measurement significantly.
**Analysis of Incorrect Options:**
* **3.0 mm:** While close, this is a rounding error. The mathematical precision required to balance the tear film capillary attraction and corneal stiffness is specifically 3.06 mm.
* **3.6 mm & 3.66 mm:** These values are distractors. They do not satisfy the mathematical requirement to negate corneal resistance or provide the 1:10 conversion ratio used in the GAT biprism.
**High-Yield Clinical Pearls for NEET-PG:**
* **Standard Central Corneal Thickness (CCT):** GAT is most accurate at a CCT of **520–540 µm**.
* **CCT Variations:** Thicker corneas give falsely high IOP readings; thinner corneas (or post-LASIK eyes) give falsely low readings.
* **Fluorescein:** Sodium fluorescein is used to visualize the "Mires." The inner edges of the two semicircles must just touch for an accurate reading.
* **Disinfection:** The tonometer head should be cleaned with 70% isopropyl alcohol or 3% $H_2O_2$ to prevent transmission of infections like Epidemic Keratoconjunctivitis (EKC) or HIV.
Glaucoma Indian Medical PG Question 3: "Iris bombe" occurs due to
- A. Adherent Glaucoma
- B. Anterior Synechiae
- C. Posterior Synechiae
- D. Ring synechiae (Correct Answer)
Glaucoma Explanation: ### Explanation
**Iris bombe** is a clinical condition where the iris is bowed forward (convexity) due to the accumulation of aqueous humor in the posterior chamber.
**1. Why Ring Synechiae is Correct:**
The underlying mechanism is **seclusio pupillae**. This occurs when **ring synechiae** (360-degree posterior synechiae) form, creating a complete circular adhesion between the pupillary margin of the iris and the anterior capsule of the lens. This adhesion blocks the flow of aqueous humor from the posterior chamber to the anterior chamber through the pupil. The resulting pressure buildup in the posterior chamber pushes the peripheral iris forward, creating the characteristic "bombe" appearance. This can lead to secondary angle-closure glaucoma.
**2. Why Other Options are Incorrect:**
* **Adherent Leucoma:** This is a vascularized corneal opacity with the iris incarcerated in the scar. While it involves iris adhesion to the cornea, it does not typically cause the circumferential pupillary block required for iris bombe.
* **Anterior Synechiae:** These are adhesions between the iris and the cornea/iridocorneal angle (Peripheral Anterior Synechiae - PAS). These are a *consequence* of iris bombe or chronic inflammation, not the primary cause of the bombe itself.
* **Posterior Synechiae:** This refers to any adhesion between the iris and the lens. While iris bombe requires posterior synechiae, it specifically requires them to be circumferential (**Ring Synechiae**). Isolated or focal posterior synechiae do not block aqueous flow completely.
**3. NEET-PG High-Yield Pearls:**
* **Treatment of Choice:** Laser Peripheral Iridotomy (LPI) to bypass the pupillary block.
* **Sequence of Events:** Iridocyclitis → Seclusio pupillae (Ring synechiae) → Iris bombe → Secondary angle-closure glaucoma.
* **Festooned Pupil:** Irregularly shaped pupil seen after using mydriatics in an eye with focal posterior synechiae.
Glaucoma Indian Medical PG Question 4: Intractable secondary glaucoma is seen in which of the following conditions?
- A. Diffuse iris melanoma (Correct Answer)
- B. Nodular iris melanoma
- C. Melanocytic deposits in the anterior part of the iris
- D. Melanocyte proliferation in posterior uveal tissue
Glaucoma Explanation: **Explanation:**
**1. Why Diffuse Iris Melanoma is Correct:**
Diffuse iris melanoma is a specific variant of uveal melanoma characterized by a flat, infiltrative growth pattern rather than a discrete mass. It typically presents with **progressive heterochromia iridis** (the affected eye becomes darker). The "intractable" secondary glaucoma occurs because the neoplastic cells directly infiltrate and replace the **trabecular meshwork** circumferentially. This leads to a mechanical obstruction of aqueous outflow that is often resistant to conventional medical therapy, frequently necessitating enucleation.
**2. Why the Other Options are Incorrect:**
* **Nodular Iris Melanoma:** These are discrete, localized masses. While they can cause glaucoma through pigment dispersion or angle crowding, they do not involve the entire trabecular meshwork as extensively or aggressively as the diffuse type.
* **Melanocytic deposits (Anterior Iris):** These are typically benign (e.g., iris freckles or nevi). While they change the iris color, they do not proliferate or invade the drainage angle to cause intractable pressure elevation.
* **Melanocyte proliferation in posterior uveal tissue:** This refers to ciliary body or choroidal melanomas. While these can cause secondary glaucoma (via neovascularization or forward displacement of the lens-iris diaphragm), the specific clinical association with diffuse, intractable infiltration of the angle is a hallmark of the **diffuse iris** variant.
**Clinical Pearls for NEET-PG:**
* **Classic Triad of Diffuse Iris Melanoma:** Acquired heterochromia, unilateral glaucoma, and absence of a discrete iris mass.
* **Ring Melanoma:** A subset of diffuse melanoma that grows circumferentially around the iridocorneal angle.
* **Management:** Unlike nodular melanoma (which may be observed or locally excised), diffuse iris melanoma with intractable glaucoma usually requires **enucleation** due to the high risk of extraocular extension through the aqueous drainage pathways.
Glaucoma Indian Medical PG Question 5: A 56-year-old female presents with acute narrow-angle glaucoma, characterized by severe eye pain that radiates. In what distribution does this pain typically spread?
- A. Ophthalmic nerve
- B. Trigeminal nerve (Correct Answer)
- C. Facial nerve
- D. Optic nerve
Glaucoma Explanation: **Explanation:**
**1. Why the Trigeminal Nerve is Correct:**
The pain in acute narrow-angle glaucoma is primarily mediated by the **Trigeminal nerve (Cranial Nerve V)**. Specifically, the ciliary body and iris are densely innervated by the **long and short ciliary nerves**, which are branches of the **Ophthalmic division (V1)** of the trigeminal nerve. When intraocular pressure (IOP) rises acutely, it causes mechanical stretching and ischemia of these nerve endings. This results in severe, throbbing pain that often radiates beyond the eye to the forehead, temple, and even the teeth, following the sensory distribution of the trigeminal nerve.
**2. Why the Other Options are Incorrect:**
* **Ophthalmic Nerve (Option A):** While the ophthalmic nerve (V1) is the specific branch involved, the question asks for the broader nerve distribution. In medical examinations, if both a specific branch and the parent cranial nerve are listed, the broader nerve (Trigeminal) is often the preferred answer to describe the general radiating pattern (which can sometimes involve V2/Maxillary distribution, such as referred toothache).
* **Facial Nerve (Option C):** The facial nerve (CN VII) is primarily a motor nerve responsible for muscles of facial expression and the orbicularis oculi. It does not carry the sensory fibers responsible for glaucoma pain.
* **Optic Nerve (Option D):** The optic nerve (CN II) is a purely sensory nerve for **vision**. It does not have pain receptors; damage to the optic nerve in glaucoma leads to vision loss (cupping), not the sensation of pain.
**Clinical Pearls for NEET-PG:**
* **Vagal Stimulation:** Severe pain in acute glaucoma can stimulate the Vagus nerve (via the oculocardiac reflex), leading to systemic symptoms like **nausea, vomiting, and bradycardia**, which may mimic an acute abdominal emergency.
* **Classic Triad:** Clouding of the cornea, a mid-dilated non-reactive pupil, and a "stony hard" eye on palpation.
* **Drug of Choice:** Immediate management involves IV Mannitol (to reduce IOP) and topical Pilocarpine (once IOP drops below 40-50 mmHg) to pull the iris away from the angle.
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