Glaucoma Practice Questions

Q: A patient presents with a reddish eye and excessive watering of the left eye, accompanied by a shallow anterior chamber. What is the next best investigation?

Tonometry. ### Explanation The clinical presentation of a **red eye, excessive watering (epiphora), and a shallow anterior chamber** is highly suggestive of **Acute Angle-Closure Glaucoma (AACG)**. In any suspected case of glaucoma, the immediate priority is to confirm the diagnosis by measuring the **Intraocular Pressure (IOP)**. **1. Why Tonometry is the Correct Answer:** Tonometry is the gold standard for measuring IOP. In AACG, the IOP is typically severely elevated (often >40-60 mmHg). Establishing this elevation is the most critical "next step" to initiate emergency management (e.g., IV Mannitol, Acetazolamide) to prevent permanent optic nerve damage. **2. Why Other Options are Incorrect:** * **Gonioscopy:** While essential to visualize the angle and confirm "closure," it is technically difficult to perform during an acute attack due to corneal edema (haze). It is usually performed after the IOP is lowered and the cornea clears. * **Cup-to-disc (C:D) ratio & Ophthalmoscopy:** These assess the optic nerve head for chronic glaucomatous damage. In an acute attack, the priority is the pressure, not the morphology. Furthermore, corneal edema often obscures the view of the fundus during the initial presentation. **Clinical Pearls for NEET-PG:** * **Gold Standard Tonometry:** Goldmann Applanation Tonometry (GAT). * **Classic Triad of AACG:** Sudden ocular pain, "halos" around lights, and a mid-dilated non-reactive pupil. * **Definitive Treatment:** Peripheral Iridotomy (usually YAG laser) once the acute attack is controlled. * **Shallow Anterior Chamber:** Always predisposes a patient to angle closure; avoid mydriatics in such patients.

Q: What is the Amsler sign associated with?

Fuchs heterochromatic iridocyclitis. **Explanation:** **Fuchs Heterochromatic Iridocyclitis (FHI)** is a chronic, typically unilateral, low-grade uveitis. The **Amsler sign** (also known as the Amsler-Verrey sign) refers to the occurrence of **hyphema** (bleeding into the anterior chamber) following a minor trauma, such as a paracentesis or during intraocular surgery (like cataract extraction). The underlying mechanism is the presence of **fragile, fine neovascular vessels** in the angle of the anterior chamber. These filiform vessels bridge the chamber angle and rupture easily when the intraocular pressure (IOP) drops suddenly, leading to characteristic filiform hemorrhages. **Why other options are incorrect:** * **Posner-Schlossman Syndrome (Glaucomatocyclitic Crisis):** Characterized by recurrent episodes of very high IOP with minimal inflammation. It is not associated with angle neovascularization or the Amsler sign. * **Uveal Effusion Syndrome:** Involves idiopathic exudative detachment of the choroid, ciliary body, and retina. It presents with "leopard spot" pigmentary changes, not hyphema upon surgical entry. **High-Yield Clinical Pearls for FHI:** 1. **Triad:** Heterochromia (affected eye is usually lighter), cataract, and small, stellate keratic precipitates (KPs) distributed over the entire corneal endothelium. 2. **No Synechiae:** Unlike most forms of iridocyclitis, FHI typically does **not** form posterior synechiae. 3. **Treatment:** It generally does not respond well to topical steroids; management focuses on complications like glaucoma and cataract.

Q: Trabeculectomy for glaucoma leads to the formation of a channel between which two spaces?

Subconjunctival space and anterior chamber. **Explanation:** Trabeculectomy is the "gold standard" filtering surgery for glaucoma. The primary goal of the procedure is to create a new drainage pathway for aqueous humor to bypass the obstructed trabecular meshwork, thereby lowering intraocular pressure (IOP). **Why Option A is Correct:** During a trabeculectomy, a partial-thickness scleral flap is created, and a small piece of the limbal tissue (including the trabecular meshwork) is removed to create an opening into the **anterior chamber**. The aqueous humor flows through this opening, under the scleral flap, and into the **subconjunctival space**. This results in the formation of a **filtering bleb**, where the fluid is eventually absorbed by the conjunctival capillaries and lymphatics. **Why Other Options are Incorrect:** * **Option B:** A channel between the anterior and posterior chambers is created during a **Peripheral Iridectomy (PI)** or YAG laser iridotomy, used to treat angle-closure glaucoma by equalizing pressure between the two chambers. * **Option C:** This is anatomically incorrect for glaucoma filtration. The posterior chamber is located behind the iris; draining fluid directly from here to the subconjunctival space is not the standard surgical approach for trabeculectomy. **High-Yield Clinical Pearls for NEET-PG:** * **Antimetabolites:** Mitomycin-C (MMC) or 5-Fluorouracil (5-FU) are often applied during surgery to inhibit fibroblast proliferation and prevent bleb scarring (the most common cause of failure). * **Iridectomy:** A "peripheral iridectomy" is always performed during trabeculectomy to prevent the iris from plugging the internal ostium. * **Success Indicator:** The presence of a diffuse, shallow, and minimally vascularized **filtering bleb** indicates a functioning shunt.

Q: Which procedure is being done in the patient?

Indentation tonometry. ***Indentation tonometry*** - Uses the **Schiotz tonometer** which applies a weighted plunger to the cornea, measuring **intraocular pressure** by the degree of corneal indentation. - The instrument consists of a **footplate** that rests on the cornea and a **weighted plunger** that indents the eye, with pressure readings from a scale. *Applanation tonometry* - Uses the **Goldmann applanation tonometer** which flattens a small area of the cornea rather than indenting it. - Considered the **gold standard** for IOP measurement, requiring **fluorescein dye** and a **cobalt blue light** for visualization. *A scan ultrasonography* - An **ultrasonic technique** used to measure **axial length** of the eye and assess intraocular structures. - Primarily used for **biometry** in cataract surgery planning and detecting **posterior segment pathology**, not for pressure measurement. *Keratometry* - Measures the **curvature of the anterior corneal surface** to determine **corneal astigmatism** and **refractive power**. - Used for **contact lens fitting** and **pre-operative assessment** for refractive surgery, not related to intraocular pressure.

Q: What is the main mechanism of action of brimonidine in glaucoma?

Decreased aqueous humor secretion. **Explanation:** **Brimonidine** is a highly selective **alpha-2 (α2) adrenergic agonist**. Its primary mechanism of action in lowering intraocular pressure (IOP) is twofold, but its **initial and main effect** is the **reduction of aqueous humor production** (secretion) from the ciliary body. 1. **Why Option A is correct:** Alpha-2 receptors are located on the ciliary epithelium. Stimulation of these receptors inhibits the enzyme adenylate cyclase, leading to a decrease in cAMP levels. This biochemical pathway results in a significant reduction in the active secretion of aqueous humor. 2. **Why Option C is partially correct but not the "main" mechanism:** Brimonidine is unique because it has a **dual mechanism**. While it primarily decreases production, it also increases **uveoscleral outflow** (via prostaglandin release). However, in the context of standard examinations like NEET-PG, "decreased secretion" is recognized as the primary/initial action. 3. **Why Options B and D are incorrect:** Brimonidine has no significant effect on the trabecular (conventional) outflow pathway (unlike miotics or Rho-kinase inhibitors). It also does not affect vitreous volume (a mechanism associated with hyperosmotic agents like Mannitol). **High-Yield Clinical Pearls for NEET-PG:** * **Neuroprotection:** Brimonidine is the only antiglaucoma medication currently credited with potential neuroprotective properties for the optic nerve. * **Side Effects:** It is notorious for causing **Lid Retraction** and **Allergic Conjunctivitis** (follicular conjunctivitis). * **Contraindication:** It is strictly **contraindicated in infants and children** (under 2 years) as it can cross the blood-brain barrier, causing CNS depression, apnea, and bradycardia.

Q: Laser trabeculoplasty is indicated in which of the following types of glaucoma?

Pseudoexfoliative glaucoma. **Explanation:** **Laser Trabeculoplasty (ALT/SLT)** works by applying laser energy to the trabecular meshwork (TM) to increase aqueous outflow. For this procedure to be effective and safe, the **angle must be open** and the TM must be visible. 1. **Why Pseudoexfoliative Glaucoma (PXG) is correct:** PXG is a type of secondary open-angle glaucoma. In PXG, there is heavy deposition of pigment and fibrillar material within the trabecular meshwork (Sampaolesi line). This increased pigmentation makes the TM an excellent target for laser absorption, often resulting in a **more profound pressure-lowering response** compared to primary open-angle glaucoma. 2. **Why the other options are incorrect:** * **Neovascular Glaucoma (NVG):** This is a secondary closed-angle glaucoma where a fibrovascular membrane pulls the iris over the TM. Laser trabeculoplasty is ineffective because the TM is physically obstructed. * **Chronic Angle Closure Glaucoma (CACG):** In CACG, the angle is narrowed or closed by peripheral anterior synechiae (PAS). If the TM cannot be visualized, trabeculoplasty cannot be performed. * **Uveitic Glaucoma:** This is a relative contraindication. Laser energy can exacerbate intraocular inflammation, potentially leading to a "spike" in IOP or the formation of further synechiae. **High-Yield Clinical Pearls for NEET-PG:** * **Prerequisite:** A clear, open iridocorneal angle (Gonioscopy is mandatory). * **Mechanism:** Argon Laser Trabeculoplasty (ALT) causes mechanical tightening of the TM; Selective Laser Trabeculoplasty (SLT) uses a "cold laser" to stimulate biological remodeling without thermal damage. * **Best Candidates:** Pigmentary glaucoma and Pseudoexfoliative glaucoma (due to high TM pigmentation). * **Common Complication:** Transient post-operative rise in IOP (IOP spike).

Q: The cause of a coloured halo in narrow angle glaucoma is?

Corneal oedema. **Explanation:** In **Narrow-Angle Glaucoma** (specifically Acute Angle Closure), a sudden and severe rise in Intraocular Pressure (IOP) exceeds the pumping capacity of the corneal endothelium. This leads to the accumulation of fluid within the corneal stroma and epithelium, a condition known as **Corneal Oedema**. The oedematous corneal epithelium acts as a **diffraction grating**, breaking up white light into its constituent spectral colors. This optical phenomenon results in the patient seeing "rainbow-colored halos" around lights. **Analysis of Options:** * **Corneal Oedema (Correct):** This is the direct anatomical cause of the diffraction. Specifically, the fluid droplets between epithelial cells act like tiny prisms. * **Increased IOP (Incorrect):** While high IOP is the *triggering event*, it is not the direct optical cause of the halo. The halo is a secondary effect of the resulting oedema. * **Lenticular changes (Incorrect):** While cataracts (lenticular changes) can cause halos, they are typically "dull" and do not resolve with treatment, unlike the vivid halos of glaucoma which disappear once IOP is lowered. * **Lacrimation (Incorrect):** Excessive tearing may cause blurred vision or light scattering, but it does not produce the classic structured colored halos seen in glaucoma. **High-Yield Clinical Pearls for NEET-PG:** 1. **Finchan’s Test:** Used to differentiate glaucomatous halos from cataractous halos. When a stenopaeic slit is passed across the pupil, glaucomatous halos remain intact, whereas cataractous halos break into segments. 2. **Differential Diagnosis:** Colored halos are also seen in **Mucopurulent Conjunctivitis** (due to mucus flakes; these disappear after washing the eyes/blinking). 3. **Management:** The definitive treatment for Narrow-Angle Glaucoma is **Laser Peripheral Iridotomy (LPI)**.

Q: What is the most common cause of neovascular glaucoma?

Diabetes mellitus. **Explanation:** Neovascular Glaucoma (NVG) is a secondary glaucoma caused by retinal ischemia, which triggers the release of **Vascular Endothelial Growth Factor (VEGF)**. This leads to the formation of new vessels (neovascularization) on the iris (rubeosis iridis) and the anterior chamber angle, eventually causing mechanical obstruction of aqueous outflow. **1. Why Diabetes Mellitus is correct:** **Diabetic Retinopathy (specifically PDR)** is the most common cause of NVG worldwide, accounting for approximately **33-50%** of cases. The chronic, widespread retinal ischemia in diabetic patients provides a persistent stimulus for VEGF production. **2. Analysis of Incorrect Options:** * **Central Retinal Vein Occlusion (CRVO):** This is the **second** most common cause. Ischemic CRVO is famously associated with "100-day glaucoma" because NVG typically develops within 3 months of the event. While it is a classic association, statistically, Diabetes is more frequent. * **Central Retinal Artery Occlusion (CRAO):** This is a rare cause of NVG (approx. 1-5% of cases). Since the inner retina is infarcted, there is often insufficient viable tissue to produce sustained VEGF compared to venous stasis or diabetes. * **Eale’s Disease:** While this idiopathic peripheral perivasculitis causes ischemia and neovascularization, it is a much less common cause of NVG compared to systemic metabolic diseases like Diabetes. **Clinical Pearls for NEET-PG:** * **The "100-Day Glaucoma":** Specifically refers to NVG following **Ischemic CRVO**. * **Sequence of NVG:** Rubeosis iridis (at pupillary margin) → Neovascularization of the angle (NVA) → Open-angle stage → **Synechial Angle-closure stage** (contracture of fibrovascular membrane). * **Management Gold Standard:** **Pan-retinal Photocoagulation (PRP)** to reduce the ischemic drive, often combined with Anti-VEGF injections.

Q: What is the most common cause of rubeosis iridis?

Diabetic retinopathy. **Explanation:** **Rubeosis iridis** (neovascularization of the iris) is a serious condition where new, fragile blood vessels form on the iris surface in response to chronic retinal ischemia. **Why Diabetic Retinopathy is Correct:** The underlying mechanism is **retinal hypoxia**, which triggers the release of **Vascular Endothelial Growth Factor (VEGF)**. VEGF diffuses into the anterior segment, stimulating angiogenesis. **Diabetic Retinopathy (DR)**, specifically Proliferative Diabetic Retinopathy (PDR), is the **most common cause** of rubeosis iridis worldwide due to the high prevalence of the disease and the extensive retinal ischemia it induces. **Analysis of Incorrect Options:** * **Central Retinal Artery Occlusion (CRAO):** While CRAO causes ischemia, it is a less common cause of rubeosis (occurring in ~2% of cases) compared to Central Retinal Vein Occlusion (CRVO) or DR. * **Radiation Retinopathy:** This can cause rubeosis due to capillary non-perfusion, but it is a rare clinical entity compared to the systemic burden of diabetes. * **Tumors:** Intraocular tumors like retinoblastoma or melanoma can cause rubeosis via angiogenic factors, but they are statistically infrequent causes. **High-Yield Clinical Pearls for NEET-PG:** 1. **Top 3 Causes:** 1. Diabetic Retinopathy (Most common), 2. Central Retinal Vein Occlusion (CRVO - specifically the ischemic type, often called "100-day glaucoma"), 3. Carotid Artery Occlusive Disease. 2. **Complication:** Rubeosis iridis leads to **Neovascular Glaucoma (NVG)** as the new vessels and associated fibrous membranes pull the iris forward, causing synechial angle closure. 3. **Management:** The mainstay of treatment is **Pan-retinal Photocoagulation (PRP)** to reduce the ischemic drive, often supplemented by anti-VEGF injections.

Question 1

A patient presents with a reddish eye and excessive watering of the left eye, accompanied by a shallow anterior chamber. What is the next best investigation?

Accepted Answer

Tonometry

Answer

Cup-to-disc ratio

Answer

Gonioscopy

Answer

Ophthalmoscopy

Question 2

What is the Amsler sign associated with?

Accepted Answer

Fuchs heterochromatic iridocyclitis

Answer

Posner-Schlossman syndrome

Answer

Uveal effusion syndrome

Answer

None of the above

Question 3

Trabeculectomy for glaucoma leads to the formation of a channel between which two spaces?

Accepted Answer

Subconjunctival space and anterior chamber

Answer

Anterior chamber and posterior chamber

Answer

Subconjunctival space and posterior chamber

Answer

None of the above

Question 4

Which procedure is being done in the patient?

Accepted Answer

Indentation tonometry

Answer

Applanation tonometry

Answer

A scan ultrasonography

Answer

Keratometry

Question 5

What is the main mechanism of action of brimonidine in glaucoma?

Accepted Answer

Decreased aqueous humor secretion

Answer

Increased trabecular outflow

Answer

Increased uveoscleral outflow

Answer

Reduced vitreous volume

Question 6

Laser trabeculoplasty is indicated in which of the following types of glaucoma?

Accepted Answer

Pseudoexfoliative glaucoma

Answer

Neovascular glaucoma

Answer

Chronic angle closure glaucoma

Answer

Uveitic glaucoma

Question 7

The cause of a coloured halo in narrow angle glaucoma is?

Accepted Answer

Corneal oedema

Answer

Increase IOP

Answer

Lenticular changes

Answer

Lacrimation

Question 8

What is the most common cause of neovascular glaucoma?

Accepted Answer

Diabetes mellitus

Answer

Central retinal artery occlusion (CRAO)

Answer

Central retinal vein occlusion (CRVO)

Answer

Eale's disease

Question 9

A patient with open-angle glaucoma and 7 diopters of myopia complains of blurring of vision after administration of pilocarpine. What is the reason for this blurring?

Accepted Answer

Miosis (small pupil)

Answer

Increased myopic asymmetry

Answer

Increased hypermetropic asymmetry

Answer

Increased astigmatism

Question 10

What is the most common cause of rubeosis iridis?

Accepted Answer

Diabetic retinopathy

Answer

Tumor

Answer

Central retinal artery occlusion (CRAO)

Answer

Radiation retinopathy

Glaucoma — MCQs

Glaucoma — MCQs

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