Diseases of the Retina Practice Questions

Q: All of the following are seen in retinitis pigmentosa except?

Prominent retinal vessels. **Explanation:** Retinitis Pigmentosa (RP) is a hereditary dystrophy primarily affecting the rod photoreceptors. The classic clinical presentation is characterized by a "triad" of signs, and understanding the pathophysiology of these signs is key to identifying the correct answer. **Why "Prominent retinal vessels" is the correct answer:** In RP, there is progressive atrophy of the retinal tissue and a decrease in metabolic demand. This leads to **marked attenuation (narrowing)** of the retinal arterioles, not prominence. The vessels often appear thread-like or "wiry" as the disease progresses. **Analysis of Incorrect Options:** * **Ring scotoma:** This is the characteristic visual field defect in RP. It begins as a series of isolated scotomas in the mid-periphery (corresponding to the maximum density of rods) which eventually coalesce to form a partial or complete ring. * **Pigmentation around the retinal veins:** As photoreceptors die, the Retinal Pigment Epithelium (RPE) migrates into the sensory retina. This pigment typically accumulates in the perivascular spaces (especially around the veins), forming the classic **"bone-spicule"** appearance. * **Pale disc:** Chronic retinal degeneration leads to consecutive optic atrophy. The disc takes on a characteristic **"waxy pallor"** appearance due to glial proliferation over the optic nerve head. **NEET-PG High-Yield Pearls:** * **Classic Triad:** 1. Bone-spicule pigmentation, 2. Attenuated retinal arterioles, 3. Waxy disc pallor. * **Earliest Symptom:** Nyctalopia (night blindness). * **ERG Findings:** The Electroretinogram (ERG) is the most sensitive test; it shows a reduced "a" and "b" wave amplitude even before fundus changes appear (eventually becoming "extinguished"). * **Inheritance:** Most common is Autosomal Recessive; most severe is X-linked Recessive.

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

Hypertensive retinopathy. ***Hypertensive retinopathy*** - Characterized by **arteriovenous (AV) nipping**, **flame-shaped hemorrhages**, **cotton wool spots**, and **hard exudates** in a patient with systemic hypertension. - Progressive changes include **silver wiring** and **copper wiring** of arterioles, with **papilledema** in severe cases (Keith-Wagener-Barker Grade IV). *Diabetic retinopathy* - Features **microaneurysms**, **dot and blot hemorrhages**, and **neovascularization** in advanced stages, typically without AV nipping. - Associated with **diabetic maculopathy** and **proliferative changes** like fibrovascular proliferation, not seen in pure hypertensive changes. *Optic atrophy* - Presents with **pale optic disc** due to loss of nerve fibers, without retinal vascular changes or hemorrhages. - Associated with **visual field defects** and **reduced visual acuity**, but lacks the characteristic vascular abnormalities of hypertensive retinopathy. *Central retinal vein occlusion* - Shows **severe retinal hemorrhages** in all four quadrants, **cotton wool spots**, and **optic disc swelling** with a "blood and thunder" appearance. - Typically unilateral with **tortuous and dilated retinal veins**, unlike the bilateral arterial changes seen in hypertensive retinopathy.

Q: Which of the following is NOT a recognized test for assessing macular function?

Retinogram. **Explanation:** The assessment of macular function is crucial, especially when a cataract obscures the view of the fundus. The goal is to determine the visual potential of the macula before surgery. **Why Retinogram (Electroretinogram/ERG) is the correct answer:** A **Retinogram (ERG)** measures the mass electrical response of the entire retina to a light stimulus. It is primarily used to assess the health of the outer retinal layers (photoreceptors). Because it represents a global response, a standard ERG can remain normal even if there is localized macular degeneration. Therefore, it is **not** a specific test for macular function. (Note: *Multifocal ERG* can assess the macula, but a general "retinogram" does not). **Analysis of Incorrect Options:** * **Two-point discrimination:** This tests the ability of the macula to distinguish two points of light as separate entities. It is a simple bedside test for central visual acuity. * **Maddox rod:** While primarily used for muscle imbalance, in the context of macular function (specifically the "Maddox rod test for projection"), it checks if the patient can perceive the orientation and position of the red line, indicating intact central/paracentral retinal function. * **Laser interferometry:** This is a sophisticated test that bypasses media opacities (like cataracts) to project interference fringes directly onto the retina, allowing for an objective measurement of potential macular visual acuity. **High-Yield Clinical Pearls for NEET-PG:** * **Other Macular Function Tests:** Entoptic visualization (Purkinje images), Photo-stress test (recovery time), Amsler Grid, and the Potential Acuity Meter (PAM). * **Photo-stress test:** Normal recovery time is <30 seconds; prolonged recovery indicates macular disease rather than optic nerve disease. * **EOG (Electro-oculogram):** Specifically measures the health of the **Retinal Pigment Epithelium (RPE)**.

Q: GNAQ mutations are seen in which of the following conditions?

Uveal melanoma. **Explanation:** **Uveal Melanoma** is the most common primary intraocular malignancy in adults. The correct answer is **Option B** because approximately **80-90%** of uveal melanomas harbor mutually exclusive mutations in the **GNAQ** or **GNA11** genes. These genes encode alpha subunits of heterotrimeric G proteins. Mutations lead to the constitutive activation of the MAPK (mitogen-activated protein kinase) pathway, driving oncogenesis independently of UV radiation—a key distinction from cutaneous melanoma. **Analysis of Options:** * **Malignant Melanoma (Cutaneous):** While "malignant melanoma" often refers to the skin subtype, it is genetically distinct from uveal melanoma. Cutaneous melanomas typically involve **BRAF (V600E)**, NRAS, or KIT mutations and are strongly linked to UV exposure. GNAQ mutations are exceptionally rare here. * **Medulloepithelioma:** This is a rare intraocular tumor arising from the primitive medullary epithelium of the ciliary body (usually in children). It is associated with **DICER1** mutations, not GNAQ. * **All the above:** Incorrect, as the mutation is highly specific to the uveal subtype within this list. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** GNAQ/GNA11 are early "driver" mutations. Late-stage progression and metastasis (especially to the **liver**) are associated with **BAP1** (BRCA1-associated protein 1) mutations on Chromosome 3 (Monosomy 3). * **Diagnosis:** Characterized by a "collar-stud" or **mushroom-shaped** appearance on B-scan ultrasonography. * **Associated Condition:** Patients with **Nevus of Ota** (Oculodermal Melanocytosis) have an increased risk of developing uveal melanoma and also frequently harbor GNAQ mutations.

Q: All of the following are true about the electroretinogram (ERG) except:

Flash ERG is good for the detection of macular diseases.. The **Electroretinogram (ERG)** is a clinical test that records the mass electrical response of the entire retina to a light stimulus. ### Why Option D is the Correct Answer (The "Except" Statement) **Flash ERG (Full-field ERG)** measures the summed electrical activity of the **entire retina**. Because the macula represents only a tiny fraction (approx. 2%) of the total retinal area, a localized macular lesion will not significantly alter the global response. Therefore, Flash ERG remains normal in early or localized macular diseases. To detect macular dysfunction, **Pattern ERG (pERG)** or **Multifocal ERG (mfERG)** must be used. ### Analysis of Other Options * **Option A:** ERG measures the action potential generated by the **neurosensory retina** in response to light, specifically the layers between the pigment epithelium and the ganglion cells. * **Option B:** The **a-wave** is the first negative deflection. It represents the hyperpolarization of the **photoreceptors** (rods and cones) in response to light. * **Option C:** The **b-wave** is the large positive deflection following the a-wave. It is generated by the **Muller cells and Bipolar cells**. It is the most clinically significant component of the ERG. ### High-Yield Clinical Pearls for NEET-PG * **c-wave:** Represents the Retinal Pigment Epithelium (RPE). * **Early Sign of Siderosis Bulbi:** An increase in the a-wave amplitude followed by a decrease in the b-wave. * **Negative ERG (Normal a-wave, absent/reduced b-wave):** Seen in Central Retinal Artery Occlusion (CRAO), Congenital Stationary Night Blindness, and Quinine toxicity. * **Extinguished ERG (Flat):** Seen in advanced Retinitis Pigmentosa, Total Retinal Detachment, and Pan-retinal Photocoagulation.

Q: Which of the following conditions is best investigated using angiography?

Central serous retinopathy. **Explanation:** **Central Serous Retinal Detachment (CSR)** is the correct answer because it is a vascular/exudative condition characterized by a localized detachment of the neurosensory retina due to leakage from the Choriocapillaris through a defect in the Retinal Pigment Epithelium (RPE). **Fluorescein Angiography (FFA)** is the gold standard for diagnosing CSR, as it identifies the specific site of leakage. Classic patterns include the **"Smokestack appearance"** (due to convection currents) or the more common **"Ink-blot appearance."** **Why the other options are incorrect:** * **Posterior Vitreous Detachment (PVD):** This is a structural change where the vitreous gel separates from the retina. It is diagnosed clinically via slit-lamp biomicroscopy (looking for a **Weiss ring**) or B-scan ultrasonography. Angiography has no role as there is no vascular leakage. * **Rhegmatogenous Retinal Detachment (RRD):** This is caused by a physical break/hole in the retina. Diagnosis is made through indirect ophthalmoscopy and scleral depression to locate the break. Angiography is not indicated. * **Retinoschisis:** This involves a splitting of the retinal layers (usually at the outer plexiform layer). It is a structural anatomical defect best differentiated from retinal detachment using clinical examination or **Optical Coherence Tomography (OCT)**, not angiography. **NEET-PG High-Yield Pearls:** * **CSR Risk Factors:** Type A personality, steroid use, pregnancy, and stress. * **CSR Treatment:** Most cases are self-limiting (observe for 3–4 months). If persistent, consider laser photocoagulation or PDT. * **Investigation of Choice:** While FFA shows the leak, **OCT** is the best non-invasive tool to monitor subretinal fluid resolution.

Q: A "white centered retinal haemorrhage" is seen in which of the following conditions?

All of the above. The clinical finding described is a **Roth spot**. A Roth spot is a retinal hemorrhage with a central white or pale spot. Historically, the white center was thought to be an abscess, but it is now understood to be a **fibrin-platelet thrombus** at the site of capillary rupture. ### **Explanation of Options** * **Subacute Bacterial Endocarditis (SBE):** Classically associated with Roth spots due to septic emboli causing capillary damage and subsequent hemorrhage. * **Leukaemia:** A very common cause where the white center often represents a cluster of malignant white blood cells or localized anemia/thrombocytopenia leading to fragile vessels. * **Diabetes Mellitus:** While less common than microaneurysms, Roth spots can occur in diabetic retinopathy due to capillary fragility and localized ischemia. Since all three conditions (along with others like severe anemia and hypertension) can manifest with these lesions, **Option D (All of the above)** is the correct answer. ### **High-Yield Clinical Pearls for NEET-PG** * **Pathophysiology:** The white center represents **fibrin-platelet plug** formation following a rupture of the retinal capillary wall. * **Differential Diagnosis (Mnemonic: "LASH"):** * **L**eukaemia * **A**nemia (Severe) * **S**BE (Subacute Bacterial Endocarditis) * **H**ypertension / **H**IV * **Other Causes:** Carbon monoxide poisoning, Preeclampsia, and Scurvy. * **Key Distinction:** Roth spots are **not pathognomonic** for SBE; they are a non-specific sign of blood dyscrasias or vascular injury.

Question 1

All of the following are seen in retinitis pigmentosa except?

Accepted Answer

Prominent retinal vessels

Answer

Ring scotoma

Answer

Pigmentation around the retinal veins

Answer

Pale disc

Question 2

What is the diagnosis based on the following fundus examination?

Accepted Answer

Hypertensive retinopathy

Answer

Diabetic retinopathy

Answer

Optic atrophy

Answer

Central retinal vein occlusion

Question 3

Which of the following is NOT a recognized test for assessing macular function?

Accepted Answer

Retinogram

Answer

Two-point discrimination

Answer

Maddox rod

Answer

Laser interferometry

Question 4

GNAQ mutations are seen in which of the following conditions?

Accepted Answer

Uveal melanoma

Answer

Malignant melanoma

Answer

Medulloepithelioma

Answer

All the above

Question 5

All of the following are true about the electroretinogram (ERG) except:

Accepted Answer

Flash ERG is good for the detection of macular diseases.

Answer

Measures the potential difference of the neurosensory layer of the retina.

Answer

The negative a-wave is produced by the hyperpolarization of the photoreceptors.

Answer

The positive b-wave is due to the bipolar and Muller's cells.

Question 6

Which of the following conditions is best investigated using angiography?

Accepted Answer

Central serous retinopathy

Answer

Posterior vitreous detachment

Answer

Rhegmatogenous retinal detachment

Answer

Retinoschisis

Question 7

All of the following are true about retinoblastoma except:

Accepted Answer

Rb1 gene is located on chromosome 13q14.

Answer

It is the commonest cause of intraocular calcification.

Answer

Trilateral retinoblastoma is a combination of bilateral retinoblastoma with pinealoblastoma.

Answer

It is the commonest primary intraocular malignancy of the eye in children.

Question 8

A patient with Coats' disease presents with leukocoria. What condition needs to be differentiated from this?

Accepted Answer

Retinoblastoma

Answer

Retinitis pigmentosa

Answer

Retinal detachment

Answer

Congenital cataract

Question 9

A "white centered retinal haemorrhage" is seen in which of the following conditions?

Accepted Answer

All of the above

Answer

Subacute bacterial endocarditis

Answer

Leukaemia

Answer

Diabetes mellitus

Question 10

Which of the following is NOT a layer of the retina?

Accepted Answer

Bowman's membrane

Answer

Outer limiting membrane

Answer

Retinal pigment epithelium

Answer

Ganglion cell layer

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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