Glaucoma Practice Questions

Q: What is the normal range for intraocular pressure?

10 - 21 mm Hg. **Explanation:** **1. Why Option C is Correct:** Intraocular pressure (IOP) is determined by the dynamic balance between the production of aqueous humor by the ciliary body and its drainage through the trabecular meshwork and uveoscleral pathways. In the general population, IOP follows a Gaussian (normal) distribution curve. The statistically defined normal range is **10 to 21 mm Hg**. This range represents the mean (approximately 15.5 mm Hg) plus or minus two standard deviations. **2. Why Other Options are Incorrect:** * **Option A (7 - 14 mm Hg):** This range is too low. While some individuals naturally have low IOP, setting the upper limit at 14 would misclassify a large portion of the healthy population as having ocular hypertension. * **Option B (2.1 - 6 mm Hg):** These values represent **Hypotony**. IOP below 5-6 mm Hg can lead to phthisis bulbi, macular edema, and corneal decompensation. * **Option D (16 - 32 mm Hg):** Values consistently above 21 mm Hg are classified as **Ocular Hypertension**. While not everyone with an IOP >21 mm Hg has glaucoma, they are at a significantly higher risk for optic nerve damage. **3. NEET-PG High-Yield Clinical Pearls:** * **Goldmann Applanation Tonometry (GAT):** The "Gold Standard" for measuring IOP. It is based on the **Imbert-Fick Law**. * **Diurnal Variation:** IOP is not constant; it is typically highest in the early morning. A variation of **3–6 mm Hg** is normal; >8 mm Hg is suggestive of glaucoma. * **Central Corneal Thickness (CCT):** A thin cornea leads to an underestimation of IOP, while a thick cornea leads to an overestimation. * **Glaucoma Definition:** Remember, glaucoma is a progressive optic neuropathy; it is **not** defined solely by high IOP, though IOP is the only modifiable risk factor.

Q: Which tonometer is used for the irregular surface of the cornea?

Mackey-Marg tonometer. The **Mackey-Marg tonometer** is the instrument of choice for measuring intraocular pressure (IOP) in eyes with **irregular, scarred, or edematous corneas**. ### Why Mackey-Marg is Correct The underlying principle is **Electronic Applanation**. Unlike the Goldmann Applanation Tonometer (GAT), which requires a perfectly smooth, thin, and regular corneal surface to create a precise meniscus, the Mackey-Marg uses a small central transducer (plunger) surrounded by a guard ring. The guard ring flattens the surrounding irregular cornea, while the central transducer measures the pressure. This design minimizes the errors caused by corneal surface irregularities, scarring, or the presence of a therapeutic bandage contact lens. ### Explanation of Incorrect Options * **Rebound Tonometer (e.g., Icare):** Uses a small disposable probe that bounces off the cornea. While it doesn't require anesthesia, it is sensitive to corneal thickness and is not specifically designed for highly irregular surfaces. * **Dreger’s Tonometer:** This is a handheld version of the Goldmann tonometer. It operates on the same principle as GAT and is therefore unsuitable for irregular corneas. * **Maklakov Tonometer:** An early form of applanation tonometry using a weighted metal cylinder. It is highly dependent on corneal curvature and surface integrity, making it inaccurate for irregular surfaces. ### NEET-PG High-Yield Pearls * **Goldmann Applanation Tonometry (GAT):** The current **Gold Standard** for IOP measurement. * **Pneumotonometry:** Another excellent option for irregular corneas or when a bandage contact lens is in situ. * **Tono-Pen:** A portable electronic tonometer based on the Mackey-Marg principle; it is the most commonly used clinical tool for scarred or irregular corneas today. * **Schiotz Tonometer:** An indentation tonometer; it is contraindicated in cases of corneal ulcers or suspected globe perforation.

Q: Coloured haloes are found in all except:

Uveitis. **Explanation:** Coloured haloes are a visual phenomenon caused by the diffraction of light into its spectral components. This occurs when there is either **corneal edema** (fluid between epithelial cells) or **lenticular opacities**. **Why Uveitis is the correct answer:** In Uveitis, the vision is typically blurred due to inflammatory cells and "flare" in the anterior chamber. However, it does **not** typically cause the specific diffraction pattern required for coloured haloes unless secondary glaucoma develops. In fact, the presence of inflammatory debris often scatters light randomly rather than diffracting it into distinct rings. **Analysis of Incorrect Options:** * **Acute Angle-Closure Glaucoma:** This is the classic cause. Sudden, high intraocular pressure (IOP) leads to corneal edema. The edematous corneal epithelium acts as a diffraction grating, creating haloes where the blue ring is innermost and the red ring is outermost. * **Cataract (Immature Senile):** In early stages of cataract, irregular refractive indices in the crystalline lens (water clefts) cause diffraction of light, leading to "lenticular haloes." * **Pigmentary Glaucoma:** Like other forms of glaucoma with high IOP spikes, it can cause transient corneal edema and subsequent haloes. **Clinical Pearls for NEET-PG:** 1. **Fincham’s Test:** Used to differentiate Glaucomatous (corneal) haloes from Cataractous (lenticular) haloes. When a stenopeic slit is passed across the pupil, glaucomatous haloes remain intact, whereas cataractous haloes break into segments. 2. **Order of Colors:** In corneal haloes, the **Blue** ring is internal and **Red** is external (mnemonic: **B**lue is **B**efore). 3. **Other causes:** Mucus on the cornea (conjunctivitis) can also cause haloes, but these disappear after blinking or washing the eye.

Q: What is the cause of decreased aqueous outflow in primary open-angle glaucoma in a diabetic patient?

Block in the trabecular meshwork. **Explanation:** In **Primary Open-Angle Glaucoma (POAG)**, the anterior chamber angle remains anatomically "open," but there is a functional resistance to aqueous humor drainage. The primary site of this resistance is the **trabecular meshwork (TM)**, specifically the juxtacanalicular portion. **1. Why "Block in the trabecular meshwork" is correct:** In POAG, pathological changes occur in the TM, including basement membrane thickening, loss of trabecular cells, and increased deposition of extracellular matrix (glycosaminoglycans). This creates a "clogging" effect that increases resistance to outflow, leading to elevated Intraocular Pressure (IOP). In diabetic patients, the risk of POAG is higher due to potential metabolic alterations in the TM cells, further exacerbating this blockage. **2. Why other options are incorrect:** * **Block in episcleral veins:** This occurs in conditions like Sturge-Weber syndrome or carotid-cavernous fistulas, leading to *secondary* glaucoma, not POAG. * **Lens:** The lens is the culprit in *Phacomorphic* or *Phacolytic* glaucoma (secondary angle-closure or open-angle), but not in POAG. * **Infection:** While inflammation (Uveitis) can cause secondary glaucoma, POAG is a chronic, non-inflammatory degenerative condition. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of resistance in POAG:** Juxtacanalicular trabecular meshwork. * **Risk Factors for POAG:** Age >40, Myopia, Diabetes Mellitus, Family History, and African-American race. * **Diagnosis:** Requires the triad of elevated IOP (usually >21 mmHg), characteristic optic disc cupping, and corresponding visual field defects (e.g., Bjerrum’s scotoma). * **First-line treatment:** Prostaglandin analogues (e.g., Latanoprost) which increase uveoscleral outflow.

Q: A 64-year-old woman is diagnosed with chronic simple (open angle) glaucoma. Which of the following is the most appropriate medication for this condition?

Timolol. **Explanation:** **Primary Open Angle Glaucoma (POAG)** is characterized by a progressive optic neuropathy with associated visual field defects, typically driven by elevated intraocular pressure (IOP). The primary goal of treatment is to lower IOP to a "target pressure" to prevent further axonal damage. **Why Timolol is the Correct Answer:** **Timolol** is a non-selective **Beta-blocker** and has historically been the first-line medical therapy for POAG (though Prostaglandin analogues are now often preferred, Timolol remains a gold-standard choice in exams). It works by **decreasing the production of aqueous humor** from the ciliary body epithelium. It is effective, well-tolerated ocularly, and administered twice daily. **Analysis of Incorrect Options:** * **A. Brimonidine:** An alpha-2 agonist. While used in glaucoma, it is generally a second-line agent due to a high incidence of follicular conjunctivitis and systemic side effects like drowsiness. * **B. Tropicamide:** A short-acting mydriatic and cycloplegic. It is **contraindicated** in patients predisposed to angle-closure glaucoma as it can precipitate an acute attack. It has no role in lowering IOP. * **D. Hypromellose:** An artificial tear substitute used for dry eye syndrome. It has no effect on intraocular pressure. **NEET-PG High-Yield Pearls:** * **Mechanism of Action:** Timolol reduces aqueous production; Latanoprost (Prostaglandin) increases uveoscleral outflow. * **Contraindications:** Avoid Timolol in patients with **Bronchial Asthma**, COPD, or heart block (due to systemic absorption via the nasolacrimal duct). * **Side Effect:** To minimize systemic absorption of Timolol, advise patients to perform **punctal occlusion** after instillation. * **Drug of Choice (DOC):** Currently, **Latanoprost** (Prostaglandin analogue) is considered the overall DOC for POAG due to superior efficacy and once-daily dosing.

Q: What is the most common cause of glaucoma with elevated intraocular pressure and optic nerve damage present in only one eye?

Blunt trauma. **Explanation:** The key to this question lies in the **unilateral** presentation of glaucoma. When a patient presents with elevated intraocular pressure (IOP) and optic nerve damage in only one eye, the clinician must look for secondary causes that are localized rather than systemic or genetic. **1. Why Blunt Trauma is Correct:** Blunt trauma is the most common cause of unilateral secondary glaucoma. It leads to elevated IOP through several mechanisms: * **Acute phase:** Hyphema (blood in the anterior chamber) or inflammatory debris clogging the trabecular meshwork. * **Late phase:** **Angle recession**, where the longitudinal and circular muscles of the ciliary body tear. This leads to scarring of the trabecular meshwork months or years after the initial injury, resulting in unilateral chronic glaucoma. **2. Analysis of Incorrect Options:** * **Sturge-Weber Syndrome:** While it can cause unilateral glaucoma (due to elevated episcleral venous pressure), it is a rare neurocutaneous syndrome. Trauma is statistically much more common. * **Pseudoexfoliation (PEX) Syndrome:** PEX is a systemic condition. Although it often presents asymmetrically, it is pathologically a **bilateral** disease. * **Axenfeld-Rieger Syndrome:** This is a spectrum of **bilateral**, congenital anterior segment dysgenesis. It is hereditary (Autosomal Dominant) and typically affects both eyes. **Clinical Pearls for NEET-PG:** * **Angle Recession Glaucoma:** Suspect this in any patient with unilateral glaucoma and a history of trauma. Gonioscopy will show a "widened ciliary body band." * **10-10-10 Rule:** In trauma cases, 10% of patients with >180° of angle recession develop glaucoma 10 years later. * **Vossius Ring:** A circular ring of pigment on the anterior lens capsule is a pathognomonic sign of previous blunt trauma.

Q: Which of the following is NOT a feature of congenital glaucoma?

Shallow anterior chamber. In congenital glaucoma (Buphthalmos), the primary pathology is a developmental defect in the trabecular meshwork (trabeculodysgenesis) that leads to increased intraocular pressure (IOP) in an infant's eye. **Why "Shallow Anterior Chamber" is the correct answer:** In congenital glaucoma, the eye is highly distensible. The increased IOP causes the entire globe to enlarge (Buphthalmos). As the cornea and sclera stretch, the **anterior chamber becomes characteristically deep**, not shallow. A shallow anterior chamber is typically a feature of primary angle-closure glaucoma in adults, where the eye is anatomically small (hypermetropic). **Explanation of other options:** * **Haab’s Striae:** These are horizontal or curvilinear breaks in the Descemet’s membrane caused by the stretching of the cornea. They are a hallmark clinical sign. * **Blue Sclera:** The sclera in infants is thin. When it stretches due to high IOP, the underlying uveal tissue (choroid) shows through, giving the sclera a bluish appearance. * **Corneal Edema:** This is often the first sign noticed by parents. High IOP causes fluid to enter the corneal stroma and epithelium, leading to cloudiness, photophobia, and lacrimation. **High-Yield Clinical Pearls for NEET-PG:** * **Triad of Symptoms:** Photophobia, Blepharospasm, and Lacrimation (Epiphora). * **Corneal Diameter:** Diagnosis is suspected if the diameter is >12 mm before age 1. * **Management:** The treatment is primarily **surgical**. The procedures of choice are **Goniotomy** (if the cornea is clear) or **Trabeculotomy** (if the cornea is hazy). * **Barkan’s Membrane:** A controversial persistent embryonic tissue layer that may cover the trabecular meshwork.

Q: Comment on the diagnosis?

Buphthalmos. ***Buphthalmos*** - **Enlarged globe and cornea** in a child is pathognomonic of **congenital glaucoma**, causing the characteristic "ox-eye" appearance. - Results from **increased intraocular pressure** during early development when the sclera is still pliable and can stretch. *Retinoblastoma* - Typically presents with **leukocoria** (white pupillary reflex) rather than globe enlargement. - Most common **intraocular malignancy** in children but doesn't cause corneal or globe enlargement. *Esotropia* - Characterized by **inward deviation** of one or both eyes, not globe enlargement. - A form of **strabismus** with normal globe size and corneal dimensions. *Anterior uveitis* - Presents with **ciliary injection**, **photophobia**, and **decreased vision** without globe enlargement. - Inflammatory condition affecting the **iris and ciliary body**, not associated with corneal or scleral changes.

Q: A patient presents with a miotic pupil of size 2 mm in diameter. The intraocular pressure (IOP) is 25 mm Hg. The cornea is hazy. The anterior chamber is shallow in the fellow eye. What is the most probable diagnosis?

Acute anterior uveitis. ### Explanation The key to solving this clinical scenario lies in the **pupillary findings**. **1. Why Acute Anterior Uveitis is correct:** In **Acute Anterior Uveitis**, the hallmark pupillary finding is a **miotic (constricted) pupil**, caused by iris sphincter spasm and the presence of inflammatory mediators. While uveitis typically presents with low IOP (due to ciliary body exhaustion), it can present with **elevated IOP** (Hypertensive Uveitis) if inflammatory debris or cells clog the trabecular meshwork. The "hazy cornea" is due to inflammatory keratic precipitates or mild edema. **2. Why the other options are incorrect:** * **Acute Congestive Glaucoma (ACG):** This is the most common distractor. While ACG presents with high IOP, a hazy cornea, and a shallow AC, the pupil is characteristically **vertically oval and semi-dilated (4–6 mm)**, not miotic. * **Chronic Simple Glaucoma (POAG):** This is a painless, chronic condition. It typically presents with a clear cornea, normal AC depth, and no acute pupillary changes. * **Endophthalmitis:** While this presents with a hazy cornea and high/low IOP, it is usually a post-surgical or traumatic complication characterized by severe pain, loss of vision, and a **hypopyon**; it does not specifically present with a 2 mm miotic pupil as a defining feature. **Clinical Pearls for NEET-PG:** * **The "Golden Rule" for Pupils:** * Miotic pupil + High IOP = Hypertensive Uveitis. * Mid-dilated/Oval pupil + High IOP = Acute Angle Closure Glaucoma. * **Shallow AC in the fellow eye:** This indicates a "predisposing eye" for angle closure, but the pupillary size (2 mm) remains the pathognomonic sign that points away from ACG in this specific question. * **Management Tip:** In uveitis, we use **Mydriatics** (Atropine) to break synechiae and relieve pain; in ACG, we use **Miotics** (Pilocarpine) to open the angle. Using the wrong one can worsen the condition.

Question 1

Iris bombe is due to which of the following?

Accepted Answer

Ring synechiae

Answer

Segmental posterior synechiae

Answer

Total posterior synechiae

Answer

Anterior synechiae

Question 2

What is the normal range for intraocular pressure?

Accepted Answer

10 - 21 mm Hg

Answer

7 - 14 mm Hg

Answer

2.1 - 6 mm Hg

Answer

16 - 32 mm Hg

Question 3

Which tonometer is used for the irregular surface of the cornea?

Accepted Answer

Mackey-Marg tonometer

Answer

Rebound tonometer

Answer

Dreger's tonometer

Answer

Maklakov tonometer

Question 4

Coloured haloes are found in all except:

Accepted Answer

Uveitis

Answer

Pigmentary glaucoma

Answer

Acute-angle-closure glaucoma

Answer

Cataract

Question 5

What is the cause of decreased aqueous outflow in primary open-angle glaucoma in a diabetic patient?

Accepted Answer

Block in the trabecular meshwork

Answer

Block in episcleral veins

Answer

Lens

Answer

Infection

Question 6

A 64-year-old woman is diagnosed with chronic simple (open angle) glaucoma. Which of the following is the most appropriate medication for this condition?

Accepted Answer

Timolol

Answer

Brimonidine

Answer

Tropicamide

Answer

Hypromellose

Question 7

What is the most common cause of glaucoma with elevated intraocular pressure and optic nerve damage present in only one eye?

Accepted Answer

Blunt trauma

Answer

Sturge-Weber syndrome

Answer

Pseudoexfoliation syndrome

Answer

Axenfeld-Rieger syndrome

Question 8

Which of the following is NOT a feature of congenital glaucoma?

Accepted Answer

Shallow anterior chamber

Answer

Haab's striae

Answer

Blue sclera

Answer

Corneal edema

Question 9

Comment on the diagnosis?

Accepted Answer

Buphthalmos

Answer

Retinoblastoma

Answer

Esotropia

Answer

Anterior uveitis

Question 10

A patient presents with a miotic pupil of size 2 mm in diameter. The intraocular pressure (IOP) is 25 mm Hg. The cornea is hazy. The anterior chamber is shallow in the fellow eye. What is the most probable diagnosis?

Accepted Answer

Acute anterior uveitis

Answer

Acute congestive glaucoma

Answer

Chronic simple glaucoma

Answer

Endophthalmitis

Glaucoma — MCQs

Glaucoma — MCQs

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