Diseases of the Retina Practice Questions

Q: What is the characteristic appearance of the fundus in retinitis pigmentosa?

Jet-black spots with a pale-waxy disc. **Explanation:** Retinitis Pigmentosa (RP) is a hereditary dystrophy primarily affecting the rod photoreceptors and the retinal pigment epithelium (RPE). The characteristic fundus appearance is defined by a classic **clinical triad**: 1. **Bony Spicule Pigmentation:** These are "jet-black" spots caused by the migration of pigment from the RPE into the sensory retina. They typically cluster around the mid-peripheral retinal vessels. 2. **Arteriolar Attenuation:** The retinal blood vessels become markedly thin and thread-like. 3. **Waxy Pallor of the Disc:** This is due to consecutive optic atrophy resulting from the degeneration of retinal ganglion cells and glial proliferation. **Analysis of Options:** * **Option A (White spots with a red disc):** This is not seen in RP. White spots are more characteristic of conditions like *Retinitis Punctata Albescens* or *Fundus Albipunctatus*. * **Option C (No pigmentation):** While a variant called *RP sine pigmento* exists where pigmentation is absent, it is not the "characteristic" textbook appearance. * **Option D (Dilatation of arterioles):** Incorrect; RP is characterized by severe **narrowing** (attenuation) of arterioles, not dilatation. **High-Yield Clinical Pearls for NEET-PG:** * **Earliest Symptom:** Nyctalopia (Night blindness) due to rod dysfunction. * **Visual Field:** Characteristically shows a **Ring Scotoma**, which may progress to "Tubular Vision." * **ERG Findings:** The Electroretinogram (ERG) is **subnormal or extinguished** (flat) even in early stages. * **Inheritance:** Most common is Autosomal Recessive; most severe is X-linked Recessive. * **Associated Syndrome:** **Usher Syndrome** (RP + Sensorineural hearing loss) is a frequent exam topic.

Q: Angioid streaks are seen in which of the following conditions?

All of the above. **Explanation:** **Angioid streaks** are irregular, jagged, radiating lines deep to the retina that resemble blood vessels. They represent **linear crack-like dehiscences (breaks) in a thickened, calcified, and brittle Bruch’s membrane.** **Why "All of the above" is correct:** The underlying pathophysiology involves any condition that causes mineralization or structural weakness of the elastic lamina of Bruch’s membrane. * **Pseudoxanthoma elasticum (PXE):** This is the most common systemic association (Grönblad-Strandberg syndrome). It involves a mutation in the ABCC6 gene leading to fragmentation of elastic fibers. * **Paget’s disease of bone:** Chronic bone remodeling leads to hypercalcemia and subsequent metastatic calcification of Bruch’s membrane, making it prone to cracks. * **Old age (Senile Elastosis):** Age-related degenerative changes and calcification of the elastic tissue in the eye can lead to the formation of these streaks, even in the absence of systemic disease. **Clinical Pearls & High-Yield Facts for NEET-PG:** To remember the systemic associations, use the mnemonic **"PEPSI"**: * **P** – **P**seudoxanthoma elasticum (Most common) * **E** – **E**hlers-Danlos syndrome * **P** – **P**aget’s disease of bone * **S** – **S**ickle cell anemia (and other hemoglobinopathies like Thalassemia) * **I** – **I**diopathic **Key Diagnostic Features:** * **Appearance:** Reddish-brown or grey streaks radiating from the peripapillary area (around the optic disc). * **Complication:** The most vision-threatening complication is **Choroidal Neovascularization (CNVM)**, which can lead to subretinal hemorrhage and scarring. * **Peau d'orange:** A speckled "orange peel" appearance of the retinal pigment epithelium is often seen temporal to the macula, frequently preceding the appearance of the streaks.

Q: What is the recommended treatment for CMV retinitis in an AIDS patient?

Valganciclovir. **Explanation:** **CMV Retinitis** is the most common opportunistic ocular infection in patients with AIDS, typically occurring when the CD4+ T-cell count falls below **50 cells/mm³**. It is characterized by a "pizza-pie" or "cheese and ketchup" fundus appearance due to retinal necrosis and hemorrhage. **Why Valganciclovir is correct:** The mainstay of treatment for CMV retinitis is anti-CMV agents that inhibit viral DNA polymerase. **Valganciclovir** (an oral prodrug of Ganciclovir) is the preferred treatment because it offers high oral bioavailability, achieving plasma levels comparable to intravenous Ganciclovir. It is used for both induction and maintenance therapy, significantly reducing the pill burden and the need for indwelling catheters. **Why the other options are incorrect:** * **Amantadine:** An antiviral used primarily for Influenza A and Parkinson’s disease; it has no activity against CMV. * **Fludarabine:** A purine analog chemotherapy agent used in the treatment of chronic lymphocytic leukemia (CLL), not an antiviral. * **Oseltamivir:** A neuraminidase inhibitor used specifically for the treatment and prophylaxis of Influenza A and B. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Oral Valganciclovir is the first-line treatment. For sight-threatening lesions (near the macula or optic nerve), **Intravitreal Ganciclovir or Foscarnet** may be added. * **Alternative Agents:** Foscarnet and Cidofovir (used if there is resistance or systemic toxicity). * **Side Effects:** Ganciclovir/Valganciclovir can cause **bone marrow suppression** (neutropenia), while Foscarnet is notably **nephrotoxic**. * **HAART:** Initiation of Highly Active Antiretroviral Therapy is crucial for long-term management to restore immune function.

Q: What is the standard treatment regimen for retinoblastoma?

Carboplatin + Etoposide + Vincristine. **Explanation:** The standard of care for chemoreduction in Retinoblastoma is the **CEV regimen**, which consists of **Carboplatin, Etoposide, and Vincristine**. **Why Option B is Correct:** Chemoreduction is primarily used to shrink the tumor size to allow for focal consolidation therapies (like cryotherapy or laser photocoagulation) and to avoid enucleation or external beam radiotherapy (EBRT). * **Carboplatin:** An alkylating agent that is the backbone of the treatment; it has better ocular penetration and lower nephrotoxicity compared to Cisplatin. * **Etoposide:** A topoisomerase II inhibitor. * **Vincristine:** A microtubule inhibitor. This combination is highly effective in treating intraocular retinoblastoma while minimizing long-term systemic side effects. **Why Other Options are Incorrect:** * **Option A:** Cisplatin is generally avoided in pediatric ocular cases due to high risk of ototoxicity and nephrotoxicity. Vinblastine is typically used in lymphomas/histiocytosis, not retinoblastoma. * **Option C & D:** Cyclophosphamide was historically used but has been largely replaced in standard protocols due to the high risk of inducing secondary malignancies (like bladder cancer or leukemia) and its potential for causing infertility. Doxorubicin is cardiotoxic and not part of the primary intraocular management. **High-Yield Clinical Pearls for NEET-PG:** * **Most common intraocular malignancy** in children. * **RB1 Gene:** Located on Chromosome **13q14**. * **Knudson’s Two-Hit Hypothesis:** Explains the genetic basis (hereditary vs. sporadic). * **Clinical Sign:** Leukocoria (white pupillary reflex) is the most common presentation. * **Histopathology:** Look for **Flexner-Wintersteiner rosettes** (pathognomonic) and Homer-Wright rosettes. * **Calcification:** Presence of intraocular calcification on CT scan is a hallmark diagnostic feature.

Q: All except one are tests for macular functions?

Retinal electroretinogram. **Explanation:** The **Retinal Electroretinogram (ERG)** is the correct answer because it is a measure of the **generalized** electrical activity of the entire retina, primarily the photoreceptors and inner retinal layers. In cases of isolated macular disease, the standard ERG remains **normal** because the macula represents only a tiny fraction (approx. 2%) of the total retinal area. To specifically test macular function via electrophysiology, a *Multifocal ERG (mfERG)* or *Pattern ERG (pERG)* is required. **Analysis of other options (Macular Function Tests):** * **Laser Interferometry:** A subjective test used to assess **potential visual acuity** (retinal acuity) behind a cataract. It bypasses optical opacities to project interference fringes directly onto the macula. * **Two-point Discrimination:** This is the physiological basis of **visual acuity**. The macula (specifically the fovea) has the highest cone density, allowing the eye to distinguish two close points as separate entities. * **Maddox Rod Test:** While primarily used for squint (phorias/tropias), in the context of macular function, it is used to assess **macular projection**. If a patient can accurately perceive the orientation and position of the red line, it indicates functioning macular receptors. **NEET-PG High-Yield Pearls:** * **Clinical Macular Tests:** Amsler Grid (metamorphopsia), Photostress test (recovery time >50-60s indicates macular disease), and Color vision (Ishihara). * **EOG (Electro-oculogram):** Measures the standing potential between the cornea and retina; it is the gold standard for **Best Disease**. * **ERG Components:** 'a' wave (photoreceptors), 'b' wave (Müller & Bipolar cells). ERG is extinguished in **Retinitis Pigmentosa**.

Q: What is the area of highest visual resolution in the retina?

Foveola centralis. ### Explanation **Correct Answer: B. Foveola centralis** The **foveola centralis** is the area of highest visual resolution (visual acuity) because it contains the highest density of cone photoreceptors in the entire retina. Anatomically, it is a 0.35 mm diameter depression located at the center of the fovea. To maximize resolution, all internal layers of the retina (including the ganglion cell layer and plexiform layers) are displaced laterally, allowing light to fall directly onto the cones without scattering. Furthermore, in this region, each cone synapses with a single bipolar cell and a single ganglion cell (a 1:1 ratio), ensuring minimal convergence and maximal spatial resolution. **Why other options are incorrect:** * **A. Macula lutea:** This is a larger area (approx. 5.5 mm) responsible for central vision. While it contains the fovea and foveola, the macula as a whole does not have the same peak density of cones or the specialized "one-to-one" neural circuitry found specifically in the foveola. * **C. Blind spot:** This corresponds to the **Optic Disc**, where the optic nerve exits the eye. It contains no photoreceptors (rods or cones) and therefore has zero visual resolution. **High-Yield Clinical Pearls for NEET-PG:** * **Foveola Anatomy:** It is the thinnest part of the retina and contains **only cones** (no rods). * **Blood Supply:** The foveola is avascular (Foveal Avascular Zone - FAZ) and relies on the underlying choriocapillaris for nutrition. * **Henle’s Layer:** The axons of the photoreceptors in the foveal region are oriented obliquely and are known as Henle’s fiber layer; this is where yellow exudates accumulate in a "star" pattern (e.g., in hypertensive retinopathy). * **Macular Pigments:** The yellow color of the macula is due to carotenoid pigments (**Lutein and Zeaxanthin**), which protect the retina from UV damage.

Q: Macular edema is caused by all of the following mechanisms EXCEPT:

None of the above. **Explanation:** The correct answer is **None of the above** because all the listed mechanisms (microaneurysms, capillary dilatation, and neovascularization) are classic pathological causes of macular edema. **Underlying Medical Concept:** Macular edema occurs due to the breakdown of the **Blood-Retinal Barrier (BRB)**. When the tight junctions of the retinal vascular endothelium are compromised, fluid, proteins, and lipids leak into the extracellular space of the neurosensory retina, particularly within the outer plexiform and inner nuclear layers. * **Microaneurysms (Option A):** These are the earliest clinical signs of diabetic retinopathy. They are thin-walled focal outpouchings of capillaries that are highly permeable. Leakage from these microaneurysms is a primary cause of focal macular edema. * **Capillary Dilatation (Option B):** Chronic hypoxia leads to the release of vasoproliferative factors (like VEGF), causing telangiectatic changes and dilatation of existing capillaries. These dilated vessels are "leaky," contributing to diffuse macular edema. * **Neovascularization (Option C):** New vessels formed in response to ischemia (as seen in Proliferative Diabetic Retinopathy or Wet AMD) lack a mature endothelial structure and tight junctions. They are inherently fragile and prone to significant leakage and exudation. **Clinical Pearls for NEET-PG:** * **Cystoid Macular Edema (CME):** Characterized by a "Flower-petal" appearance on Fundus Fluorescein Angiography (FFA) due to fluid accumulation in Henle’s layer (outer plexiform layer). * **Irvine-Gass Syndrome:** A specific type of CME occurring after cataract surgery. * **Gold Standard Investigation:** Optical Coherence Tomography (OCT) is the most sensitive tool to quantify macular thickness, while FFA is used to identify the source of leakage. * **Drug-induced CME:** Can be caused by Latanoprost, Epinephrine, and Nicotinic acid.

Question 1

A cherry red spot at the macula is seen in all of the following conditions except?

Accepted Answer

Letterer-Siwe disease

Answer

Tay-Sach's disease

Answer

Niemann-Pick disease

Answer

Commotio retinae

Question 2

What is the characteristic appearance of the fundus in retinitis pigmentosa?

Accepted Answer

Jet-black spots with a pale-waxy disc

Answer

White spots with a red disc

Answer

No pigmentation

Answer

Dilatation of arterioles

Question 3

Angioid streaks are seen in which of the following conditions?

Accepted Answer

All of the above

Answer

Pseudoxanthoma elasticum

Answer

Paget's disease

Answer

Old age

Question 4

A cherry red spot is seen in which of the following conditions?

Accepted Answer

Metachromatic leukodystrophy

Answer

Retinitis pigmentosa

Answer

Retinopathy of prematurity

Answer

Central retinal vein occlusion

Question 5

What is the recommended treatment for CMV retinitis in an AIDS patient?

Accepted Answer

Valganciclovir

Answer

Amantadine

Answer

Fludrabine

Answer

Oseltamivir

Question 6

Which method is used to visualize the periphery of the retina?

Accepted Answer

Indirect binocular ophthalmoscopy

Answer

Direct ophthalmoscopy

Answer

Anterior segment lens

Answer

Goldman's three-mirror contact lens

Question 7

What is the standard treatment regimen for retinoblastoma?

Accepted Answer

Carboplatin + Etoposide + Vincristine

Answer

5-Fluorouracil + Cisplatin + Vinblastine

Answer

Cyclophosphamide + Etoposide + Vincristine

Answer

Cyclophosphamide + Doxorubicin + Etoposide

Question 8

All except one are tests for macular functions?

Accepted Answer

Retinal electroretinogram

Answer

Laser interferometry

Answer

Two-point discrimination

Answer

Maddox rod test

Question 9

What is the area of highest visual resolution in the retina?

Accepted Answer

Foveola centralis

Answer

Macula lutea

Answer

Blind spot

Answer

None of the above

Question 10

Macular edema is caused by all of the following mechanisms EXCEPT:

Accepted Answer

None of the above

Answer

Microaneurysms

Answer

Capillary dilatation

Answer

Neovascularization

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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