Glaucoma Practice Questions

Q: 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?

Normal Tension Glaucoma. ***Normal Tension Glaucoma*** - Characterized by **glaucomatous optic nerve damage** (large, deep cup) and **visual field defects** (paracentral scotomas) despite having **normal intraocular pressure** (≤21 mmHg). - Frequently associated with **vascular factors** like nocturnal hypotension or migraines, and often presents with a **sluggish pupillary reflex** due to progressive optic nerve atrophy. *Primary Narrow angle glaucoma* - Typically presents with **sudden ocular pain**, halos around lights, and **shallow anterior chambers**, which are not described here. - Intraocular pressure is usually **significantly elevated** during acute episodes, unlike the normal pressure seen in this patient. *Neovascular Glaucoma* - A secondary glaucoma characterized by **rubeosis iridis** (new vessel formation on the iris) and very **high intraocular pressure**. - Usually occurs following major ischemic events like **Central Retinal Vein Occlusion** or proliferative diabetic retinopathy. *Absolute Glaucoma* - Represents the **end-stage** of any uncontrolled glaucoma where the eye has **no light perception** (PL negative). - The eye is typically **stony hard** due to very high pressure, and the pupil is completely **fixed and dilated** rather than just sluggish.

Q: What is the area of the cornea indented by a Goldmann applanation tonometer when measuring intraocular pressure?

3.06 mm. ### 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.

Q: Pilocarpine is the drug of choice in which type of glaucoma?

Acute angle closure glaucoma. **Explanation:** **Pilocarpine** is a direct-acting parasympathomimetic (cholinergic agonist) that acts on the muscarinic receptors (M3) of the iris sphincter muscle and the ciliary body. **Why it is the drug of choice for Acute Angle Closure Glaucoma (AACG):** In AACG, the primary goal is to pull the peripheral iris away from the trabecular meshwork to open the drainage angle. Pilocarpine causes **miosis** (pupillary constriction), which physically stretches the iris, thinning it and pulling it out of the angle. This restores the outflow of aqueous humor and rapidly lowers intraocular pressure (IOP). *Note:* In clinical practice, it is typically administered once the IOP has been slightly lowered by systemic agents (like Acetazolamide), as the iris sphincter is often ischemic and non-responsive when IOP is >40-50 mmHg. **Why other options are incorrect:** * **Open Angle Glaucoma:** While Pilocarpine can lower IOP by increasing trabecular outflow, it is no longer a first-line treatment due to side effects like miosis (causing night blindness) and accommodative spasms (brow ache). Prostaglandin analogues and Beta-blockers are preferred. * **Pigmentary Glaucoma:** This is a subtype of open-angle glaucoma. While miotics can reduce iris-zonule friction, they are rarely the "drug of choice" compared to modern medical or laser therapies. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mechanism in AACG:** Miosis → Mechanical opening of the angle. 2. **Side Effects:** Accommodative spasm (pseudomyopia), brow ache, and retinal detachment (due to ciliary body contraction pulling on the retina). 3. **Contraindication:** It should **never** be used in **Uveitic Glaucoma** or Malignant Glaucoma, as it can worsen inflammation and promote posterior synechiae formation. 4. **Pre-Laser:** It is routinely used before Peripheral Iridotomy (LPI) to thin the iris, making the procedure easier.

Q: What is the normal aqueous production rate?

2 ml/min. **Explanation:** The correct answer is **2 µl/min** (Note: The options provided in the prompt contain a unit error; the physiological rate is measured in microliters, not milliliters). **1. Underlying Medical Concept:** Aqueous humor is produced by the **ciliary processes** of the non-pigmented ciliary epithelium in the posterior chamber. It is formed through three mechanisms: active secretion (80%), ultrafiltration, and simple diffusion. In a healthy adult eye, the average rate of aqueous production is approximately **2.0 to 2.5 µl/min**. This rate follows a **circadian rhythm**, being highest in the morning and significantly lower (about 50%) during sleep. **2. Analysis of Options:** * **2 µl/min (Correct):** This matches the physiological baseline required to maintain a stable Intraocular Pressure (IOP) between 10-21 mmHg. * **5 µl/min (Incorrect):** This rate is pathologically high. Such a high production rate, or a failure in drainage at this rate, would lead to a rapid and severe increase in IOP (Ocular Hypertension/Glaucoma). * **Milliliter (ml) vs. Microliter (µl):** It is crucial to note that the total volume of the anterior chamber is only about 0.25 ml. A production rate of 2 **ml**/min would be impossible as it would replace the entire volume of the eye multiple times per minute. **3. High-Yield Clinical Pearls for NEET-PG:** * **Total Volume:** The total volume of aqueous humor is approx. **0.3 ml** (0.25ml in the anterior chamber, 0.06ml in the posterior chamber). * **Turnover Rate:** Approximately 1% of the anterior chamber volume is replaced every minute. * **Drainage:** 90% occurs via the **Trabecular (conventional) pathway** and 10% via the **Uveoscleral (unconventional) pathway**. * **Drug Correlation:** Beta-blockers (Timolol) and Carbonic Anhydrase Inhibitors (Dorzolamide) work by **decreasing** this production rate.

Q: Coloured halos are seen in all, except?

Mucopurulent conjunctivitis. **Explanation:** The phenomenon of **colored halos** occurs due to the diffraction of light as it passes through an edematous cornea or accumulated debris. **Why Mucopurulent Conjunctivitis is the correct answer:** In mucopurulent conjunctivitis, colored halos are **not** a true clinical feature. While patients may complain of blurred vision or "halos" due to mucus flakes/discharge over the cornea, these disappear immediately upon **blinking** or washing the eyes (Fincham’s Test negative). Therefore, they are considered "false halos." **Analysis of Incorrect Options:** * **Glaucoma (Acute Congestive):** This is the most classic cause. High intraocular pressure leads to **corneal edema**. The fluid droplets in the epithelium act as prisms, splitting white light into spectral colors (Fincham’s Test positive). * **Acute Anterior Uveitis:** While less common than in glaucoma, inflammatory cells and protein (flare) in the aqueous humor or mild secondary corneal edema can occasionally cause light diffraction. * **Tetracycline:** Certain drugs, including Tetracycline and Amiodarone, can cause **corneal deposits** (cornea verticillata) or lens changes that result in the perception of colored halos. **NEET-PG High-Yield Pearls:** 1. **Fincham’s Test:** Used to differentiate Glaucomatous halos from Cataractous halos. * Passing a stenopaic slit across the pupil: If halos persist and break into segments, it is **Cataract** (lenticular). If the halo remains intact but diminishes in intensity, it is **Glaucoma** (corneal). 2. **Differential Diagnosis of Colored Halos:** * **Corneal Edema:** Acute Glaucoma, Bullous Keratopathy. * **Lens Changes:** Early stages of Immature Senile Cataract. * **Deposits:** Pigmentary dispersion syndrome, certain drugs. 3. **Key Distinguisher:** Halos in conjunctivitis are cleared by blinking; halos in glaucoma are not.

Q: What is the diagnosis based on the following fundus examination findings?

Acute glaucoma. ***Acute glaucoma*** - Fundus examination typically shows a **hyperemic and edematous optic disc** with **dilated retinal veins** due to acute increase in intraocular pressure. - The **cup-to-disc ratio** may appear reduced due to disc swelling, and **flame-shaped hemorrhages** may be present around the disc. *Diabetic retinopathy* - Characterized by **microaneurysms**, **dot-blot hemorrhages**, **hard exudates**, and **cotton wool spots** distributed throughout the retina. - Advanced stages show **neovascularization** and **fibrovascular proliferation**, not acute disc changes. *Optic atrophy* - Presents with a **pale, white optic disc** with **sharp, well-defined margins** and **thin retinal vessels**. - There is **absence of disc swelling** and the fundus appears relatively normal except for disc pallor. *Optic disc drusen* - Shows **irregular, lumpy disc margins** with **pseudopapilledema** appearance and may have **calcific deposits** visible on the disc. - The disc appears **elevated** but without true edema, and **spontaneous venous pulsations** are typically preserved.

Question 1

A mother brings her 18-month-old son to the paediatrician after noticing a white glow in his right eye in flash photographs over the past two months. There is no family history of eye disease. The child appears otherwise well and is reaching developmental milestones. The finding in the right eye is shown in Image 1. Which of the following is the most appropriate immediate next step in management?

Accepted Answer

A. Urgent referral to an ophthalmologist for examination under anaesthesia and ocular imaging

Answer

B. Reassurance and review in six months as the finding is likely a benign light reflex artefact

Answer

C. Prescription of occlusion therapy to the fellow eye to treat presumed amblyopia

Answer

D. Referral for audiological assessment to exclude a syndromic neurodevelopmental disorder

Question 2

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?

Accepted Answer

Normal Tension Glaucoma

Answer

Primary Narrow angle glaucoma

Answer

Neovascular Glaucoma

Answer

Absolute Glaucoma

Question 3

What is the area of the cornea indented by a Goldmann applanation tonometer when measuring intraocular pressure?

Accepted Answer

3.06 mm

Answer

3.66 mm

Answer

3.6 mm

Answer

3.0 mm

Question 4

Intractable secondary glaucoma is seen in which of the following conditions?

Accepted Answer

Diffuse iris melanoma

Answer

Nodular iris melanoma

Answer

Melanocytic deposits in the anterior part of the iris

Answer

Melanocyte proliferation in posterior uveal tissue

Question 5

Pilocarpine is the drug of choice in which type of glaucoma?

Accepted Answer

Acute angle closure glaucoma

Answer

Open angle glaucoma

Answer

Pigmentary glaucoma

Answer

None of the above

Question 6

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?

Accepted Answer

Trigeminal nerve

Answer

Ophthalmic nerve

Answer

Facial nerve

Answer

Optic nerve

Question 7

What is the normal aqueous production rate?

Accepted Answer

2 ml/min

Answer

5 ml/min

Answer

5 ml/min

Question 8

Which of the following is NOT an early sign of glaucoma?

Accepted Answer

Horizontal cup enlargement

Answer

Nerve fiber atrophy

Answer

Peripheral halo

Answer

Vertical cup enlargement

Question 9

Coloured halos are seen in all, except?

Accepted Answer

Mucopurulent conjunctivitis

Answer

Acute anterior uveitis

Answer

Tetracycline

Answer

Glaucoma

Question 10

What is the diagnosis based on the following fundus examination findings?

Accepted Answer

Acute glaucoma

Answer

Diabetic retinopathy

Answer

Optic atrophy

Answer

Optic disc drusen

Glaucoma — MCQs

Glaucoma — MCQs

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