Diseases of the Retina — MCQs

Diseases of the Retina Indian Medical PG Practice Questions and MCQs

Question 231: Chorioretinitis in AIDS is caused by which of the following agents?

A. Candida albicans
B. Herpes simplex
C. Toxoplasma
D. Cytomegalovirus (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Cytomegalovirus (CMV)** Cytomegalovirus is the **most common opportunistic ocular infection** in patients with AIDS, typically occurring when the CD4+ T-lymphocyte count falls below **50 cells/mm³**. CMV retinitis is characterized by a full-thickness retinal necrosis and vasculitis. Clinically, it presents in two patterns: 1. **"Pizza-pie" or "Cottage cheese and ketchup" appearance:** Characterized by dense white retinal opacification (necrosis) with associated retinal hemorrhages. 2. **Granular pattern:** Indolent, peripheral lesions with minimal hemorrhage. **Analysis of Incorrect Options:** * **A. Candida albicans:** While it can cause endophthalmitis, it is typically seen in intravenous drug users or patients with long-term indwelling catheters, presenting as "string of pearls" vitreous opacities. * **B. Herpes simplex:** HSV (and VZV) causes **Acute Retinal Necrosis (ARN)**. While it occurs in immunocompromised states, it is less common than CMV in AIDS and progresses much more rapidly with prominent vitritis. * **C. Toxoplasma:** *Toxoplasma gondii* is the most common cause of posterior uveitis in the general population. In AIDS, it causes necrotizing retinitis, but it typically presents as a "headlight in the fog" appearance (due to intense vitritis), which is less common than CMV in this specific demographic. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Intravenous **Ganciclovir** (or Valganciclovir). Foscarnet and Cidofovir are alternatives. * **Immune Recovery Uveitis (IRU):** A paradoxical inflammatory response seen in CMV patients after starting HAART as the CD4 count rises. * **Frosted Branch Angiitis:** A rare clinical sign of CMV retinitis characterized by severe perivascular sheathing. * **Most common cause of blindness in AIDS:** CMV Retinitis.

Question 232: Cattle track appearance in fundoscopy is due to?

A. Central Retinal Artery Occlusion (CRAO) (Correct Answer)
B. Central Retinal Vein Occlusion (CRVO)
C. Retinitis pigmentosa
D. Diabetic retinopathy

Explanation: **Explanation:** **Central Retinal Artery Occlusion (CRAO)** is the correct answer. The "cattle track" or "box-carring" appearance is a pathognomonic sign of CRAO. It occurs due to the fragmentation of the blood column within the retinal arterioles. When the arterial blood flow is severely obstructed, the red blood cells aggregate into segments separated by clear plasma, resembling a line of cattle cars or tracks moving through the vessels. **Analysis of Options:** * **Central Retinal Vein Occlusion (CRVO):** Characterized by a "blood and thunder" fundus, featuring extensive flame-shaped hemorrhages, dilated tortuous veins, and disc edema, rather than arterial segmentation. * **Retinitis Pigmentosa:** Presents with the classic triad of "bony spicule" pigmentation, arteriolar attenuation, and waxy pallor of the optic disc. * **Diabetic Retinopathy:** Features microaneurysms, hard exudates, dot-and-blot hemorrhages, and neovascularization, but does not involve acute segmentation of the blood column. **Clinical Pearls for NEET-PG:** * **Cherry Red Spot:** The most famous sign of CRAO, caused by the contrast between the opaque, edematous perifoveal retina and the underlying red choroid visible through the thin foveola. * **Ocular Emergency:** CRAO is the "stroke of the eye." Irreversible retinal damage occurs within 90–100 minutes. * **Management:** Immediate digital ocular massage, anterior chamber paracentesis, and inhalation of Carbogen (95% $O_2$, 5% $CO_2$) to induce vasodilation and dislodge the embolus. * **Differential for Cherry Red Spot:** Includes Tay-Sachs disease, Niemann-Pick disease, Gaucher disease, and Berlin’s edema (commotio retinae).

Question 233: What is true about Central Retinal Artery Occlusion (CRAO)?

A. Embolism is the main cause.
B. It causes painful loss of vision.
C. "Trucking" of the vessel is a characteristic sign. (Correct Answer)
D. It involves the ophthalmic artery.

Explanation: ### Explanation: Central Retinal Artery Occlusion (CRAO) **Correct Option: C. "Trucking" of the vessel is a characteristic sign.** In CRAO, the sudden cessation of blood flow leads to the fragmentation of the blood column within the retinal arterioles. This phenomenon, where segments of RBCs are separated by clear plasma, is known as **"cattle-trucking"** or **segmentation**. It is a hallmark sign of sluggish or absent blood flow in the retinal circulation. **Analysis of Incorrect Options:** * **A. Embolism is the main cause:** While embolism (from the carotid artery or heart) is a common cause, the **most common cause** of CRAO is actually **atherosclerosis-related thrombosis** occurring at the level of the lamina cribrosa. * **B. It causes painful loss of vision:** CRAO is classic for causing **sudden, painless, unilateral** loss of vision. Painful vision loss is more characteristic of conditions like acute congestive glaucoma or optic neuritis. * **D. It involves the ophthalmic artery:** CRAO specifically involves the **Central Retinal Artery**, which is a branch of the ophthalmic artery. If the ophthalmic artery itself were occluded, the clinical picture would be more severe (e.g., loss of choroidal circulation and absence of a cherry-red spot). **High-Yield Clinical Pearls for NEET-PG:** * **Cherry-Red Spot:** The most famous sign. The fovea appears red because it is thin, allowing the underlying vascular choroid to show through the surrounding pale, edematous retina. * **Cilioretinal Artery:** Present in ~20% of the population; if present, it may spare central vision despite CRAO. * **Management:** It is an ocular emergency. Immediate measures include **ocular massage**, anterior chamber paracentesis, and inhaled carbogen to lower IOP and dislodge the embolus. * **Afferent Pupillary Defect (RAPD):** Always present in the affected eye.

Question 234: A healed patch of chorioretinitis gives rise to:

A. Negative scotoma (Correct Answer)
B. Positive scotoma
C. Both
D. None

Explanation: ### Explanation **1. Why Negative Scotoma is Correct:** A **scotoma** is a localized area of depressed or absent vision within the visual field. A **negative scotoma** is a blind spot that the patient is unaware of; it is only detected during visual field testing (perimetry). In a **healed patch of chorioretinitis**, the active inflammation has subsided, leaving behind a permanent scar. This scar results in the destruction of the overlying photoreceptors and retinal pigment epithelium (RPE). Because the lesion is static and non-active, the brain "fills in" the gap or simply ignores the lack of input from that specific area. Therefore, the patient does not "see" a black spot; rather, they are simply "blind" in that area without subjective awareness. **2. Why the Other Options are Incorrect:** * **Positive Scotoma:** This is a blind spot that the patient **perceives** as a black spot or shadow in their field of vision. It is typically caused by **active** lesions or opacities in front of the retina (e.g., vitreous hemorrhage, active inflammatory exudates, or central serous chorioretinopathy). In active chorioretinitis, the patient may experience a positive scotoma, but once it **heals** into a scar, it becomes a negative scotoma. * **Both/None:** These are incorrect because the clinical distinction between active (positive) and healed (negative) lesions is a fundamental principle in perimetry. **3. High-Yield Clinical Pearls for NEET-PG:** * **Physiological Scotoma:** The "Blind Spot" (Optic Disc) is a classic example of a physiological negative scotoma. * **Chorioretinitis Etiology:** In India, the most common causes are **Tuberculosis** and **Toxoplasmosis**. * **Fundus Appearance:** A healed patch typically appears as a well-defined white area (exposed sclera) with clumps of black pigment (RPE hyperplasia) at the margins. * **Key Distinction:** * **Active lesion** = Positive scotoma (Patient sees a "blur" or "spot"). * **Healed lesion** = Negative scotoma (Patient is unaware until tested).

Question 235: All of the following are features of synchysis scintillans except?

A. Fluid vitreous
B. Spherical cholesterol crystals (Correct Answer)
C. Shower of gold rain
D. Secondary to trauma or inflammation of the eye

Explanation: **Explanation:** **Synchysis Scintillans** (also known as Cholesterolosis Bulbi) is a degenerative condition characterized by the accumulation of cholesterol crystals in the vitreous. **Why Option B is the Correct Answer (The "Except"):** The crystals in synchysis scintillans are **flat, angular, and needle-like or rhombic-shaped** plates of cholesterol, not spherical. Spherical bodies (calcium-lipid complexes) are the hallmark of **Asteroid Hyalosis**, which is the primary differential diagnosis. **Analysis of Other Options:** * **A. Fluid vitreous:** Synchysis scintillans always occurs in a **liquefied vitreous** (synchysis). This allows the crystals to settle at the bottom of the vitreous cavity due to gravity when the eye is at rest. * **C. Shower of gold rain:** This is the classic clinical description. When the patient moves their eye, the settled crystals are stirred up and shimmer like a "shower of gold," then rapidly sink back to the bottom. * **D. Secondary to trauma/inflammation:** Unlike Asteroid Hyalosis (which occurs in healthy eyes), synchysis scintillans is typically a **sequela of chronic ocular disease**, such as trauma, vitreous hemorrhage, or chronic uveitis. **High-Yield Clinical Pearls for NEET-PG:** | Feature | Synchysis Scintillans | Asteroid Hyalosis | | :--- | :--- | :--- | | **Composition** | Cholesterol crystals | Calcium-lipid complexes | | **Vitreous State** | Liquefied (Synchysis) | Solid/Normal | | **Movement** | Settle inferiorly (Gravity-dependent) | Move with vitreous, return to original position | | **Shape** | Flat, rhombic plates | **Spherical** (Snowball appearance) | | **Association** | Post-traumatic/Inflammatory | Ageing, Diabetes (weakly) |

Question 236: Which of the following should not be given in the prophylaxis of Dry Age-Related Macular Degeneration (ARMD)?

A. Vitamin A (Correct Answer)
B. Vitamin C
C. Vitamin E
D. Lutein

Explanation: The management of Age-Related Macular Degeneration (ARMD) is a high-yield topic for NEET-PG, specifically regarding the **AREDS (Age-Related Eye Disease Study)** protocols. ### **Explanation** The correct answer is **Vitamin A**. While Vitamin A is essential for general retinal health, it is specifically excluded from the modern prophylaxis of ARMD. This is based on the findings of the **AREDS-2 trial**. In the original AREDS-1 study, **Beta-carotene** (a precursor of Vitamin A) was used. However, it was discovered that Beta-carotene supplementation significantly increases the risk of **lung cancer in smokers and former smokers**. Consequently, in the AREDS-2 formulation, Beta-carotene was replaced by Lutein and Zeaxanthin, which are safer and equally effective. ### **Analysis of Options** * **Vitamin C & Vitamin E (Options B & C):** These are potent antioxidants included in both AREDS-1 and AREDS-2 formulations. They help neutralize free radicals that cause oxidative stress in the retinal pigment epithelium (RPE). * **Lutein (Option D):** Along with Zeaxanthin, Lutein is a carotenoid that forms the macular pigment. It was added to the AREDS-2 formula as a safer alternative to Beta-carotene to provide photoprotection and antioxidant effects without the risk of lung malignancy. ### **High-Yield Clinical Pearls for NEET-PG** * **AREDS-2 Formulation:** Includes Vitamin C (500mg), Vitamin E (400 IU), Zinc (80mg), Copper (2mg), Lutein (10mg), and Zeaxanthin (2mg). * **Zinc:** Added to the formula because it is found in high concentrations in the retina/choroid; Copper is added to prevent **Zinc-induced copper deficiency anemia**. * **Indication:** Prophylaxis is indicated for patients with **Intermediate ARMD** or **Advanced ARMD in one eye** to prevent progression. It is *not* indicated for early-stage ARMD. * **Amsler Grid:** Used for home monitoring to detect the transition from Dry to Wet ARMD (metamorphopsia).

Question 237: What is the most common site of obstruction in the central retinal artery?

A. In front of the lamina cribrosa
B. At the lamina cribrosa (Correct Answer)
C. Behind the lamina cribrosa
D. The point where the artery enters the optic nerve

Explanation: **Explanation:** The **Central Retinal Artery (CRA)** is a branch of the ophthalmic artery. It enters the optic nerve approximately 10–15 mm behind the globe and travels centrally within the nerve. **Why Option B is correct:** The **lamina cribrosa** is a sieve-like meshwork of collagen and elastic fibers in the sclera through which the optic nerve fibers and the CRA pass. This is the **narrowest point** of the artery’s lumen. Due to this anatomical constriction, it is the most common site for an embolus (usually derived from the carotid arteries or heart) to become lodged, leading to **Central Retinal Artery Occlusion (CRAO)**. **Analysis of Incorrect Options:** * **Option A (In front of the lamina cribrosa):** Once the artery passes the lamina, it enters the eye and divides into superior and inferior branches. While branch retinal artery occlusions (BRAO) occur here, the primary trunk obstruction typically occurs at the point of maximum constriction (the lamina). * **Option C (Behind the lamina cribrosa):** While the artery is within the optic nerve, the lumen is relatively wider compared to the exit point at the lamina. * **Option D (Point of entry into the optic nerve):** This is a common site for inflammatory or compressive pathologies, but not the most common site for embolic obstruction. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Presentation:** Sudden, painless, profound loss of vision. * **Fundus Findings:** "Cherry-red spot" at the fovea (due to the choroidal vasculature showing through the thin fovea) and "cattle-trucking" (segmentation) of blood in the retinal veins. * **Cilioretinal Artery:** Present in ~15-20% of the population; if present, it may spare central vision in CRAO as it is derived from the posterior ciliary circulation. * **Management:** Ocular emergency! Digital massage, paracentesis, and acetazolamide are used to lower IOP and dislodge the embolus.

Question 238: Which part of the optic disc shows the broadest neuroretinal rim?

A. Superior pole
B. Inferior pole (Correct Answer)
C. Nasal pole
D. Temporal lobe

Explanation: **Explanation:** The thickness of the neuroretinal rim in a healthy optic disc follows a specific anatomical pattern known as the **ISNT Rule**. This rule dictates that the rim width is not uniform but follows a decreasing order of thickness: **I**nferior > **S**uperior > **N**asal > **T**emporal. 1. **Inferior Pole (Correct):** Anatomically, the inferior neuroretinal rim is the broadest part of the disc. This is due to the high density of retinal nerve fibers entering the disc from the inferior arcuate bundle. 2. **Superior Pole:** This is the second thickest part of the rim. While broad, it is typically narrower than the inferior pole. 3. **Nasal Pole:** This represents the third thickest area. 4. **Temporal Pole:** This is the thinnest part of the neuroretinal rim. It contains the papillomacular bundle, which consists of fine fibers, resulting in a narrower rim appearance compared to the poles. **Clinical Pearls for NEET-PG:** * **ISNT Rule:** Essential for diagnosing Glaucoma. In early primary open-angle glaucoma (POAG), the ISNT rule is often "broken." * **Glaucomatous Changes:** The inferior and superior poles are the first areas to undergo thinning (notching). Therefore, a rim that is thinner superiorly or inferiorly than temporally is highly suggestive of glaucomatous optic neuropathy. * **Vertical Cup-Disc Ratio:** Because the superior and inferior rims are naturally the thickest, their thinning leads to vertical enlargement of the cup, a hallmark sign of glaucoma.

Question 239: Calcification is seen in all of the following conditions except?

A. Persistent hyperplastic primary vitreous (Correct Answer)
B. Retinoblastoma
C. Choroidal osteoma
D. Optic nerve head drusen

Explanation: **Explanation:** The presence of intraocular calcification is a critical diagnostic marker in pediatric and adult ophthalmology. This question tests the ability to differentiate between common calcified intraocular lesions and those that typically lack calcification. **1. Why Persistent Hyperplastic Primary Vitreous (PHPV) is the correct answer:** PHPV (now commonly termed Persistent Fetal Vasculature or PFV) is a congenital anomaly where the primary vitreous fails to regress. While it presents with **leukocoria** (white pupillary reflex) and a small eye (microphthalmos), it is **characteristically non-calcified** on imaging (CT/Ultrasound). This is the key radiological feature used to differentiate it from Retinoblastoma. **2. Analysis of Incorrect Options:** * **Retinoblastoma:** This is the most common intraocular tumor of childhood. Calcification is a hallmark feature, seen in over **90% of cases** (dystrophic calcification). On CT scan, it appears as a high-density mass. * **Choroidal Osteoma:** This is a benign ossifying tumor of the choroid. It consists of mature bone; therefore, it shows **intense calcification** on CT and high reflectivity with acoustic shadowing on B-scan ultrasonography. * **Optic Nerve Head Drusen:** These are hyaline-like deposits located within the optic nerve head. They often undergo **calcification** over time and are easily detected as "autofluorescent" or highly echogenic spots on ultrasound. **Clinical Pearls for NEET-PG:** * **Differential Diagnosis of Leukocoria:** Always remember the mnemonic **"R-C-P"** (Retinoblastoma, Coats disease, PHPV). Among these, Retinoblastoma is calcified, while PHPV is not. * **Imaging Gold Standard:** While Ultrasound (B-scan) is excellent for detecting calcification, **CT scan** is the most sensitive modality for confirming intraocular calcium. * **Phthisis Bulbi:** End-stage shrunken eyes (Phthisis bulbi) also frequently show dystrophic calcification of the lens or choroid.

Question 240: Chorioretinitis is commonly caused by all of the following except?

A. Cryptococcosis
B. Onchocerciasis (Correct Answer)
C. Cytomegalovirus infection
D. Toxoplasmosis

Explanation: **Explanation:** The correct answer is **Onchocerciasis (B)**. In ophthalmology, **Chorioretinitis** refers to inflammation of the choroid and retina, typically caused by hematogenous spread of infections. While **Onchocerciasis** (River Blindness) is a major cause of blindness, it primarily causes **Sclerosing Keratitis** (anterior segment) and **Chorioretinal Degeneration/Atrophy** (posterior segment) rather than active chorioretinitis. The ocular damage in Onchocerciasis is due to a chronic inflammatory response to microfilariae, leading to "punched-out" lesions and optic atrophy, but it is not classified as a classic cause of infectious chorioretinitis. **Analysis of Incorrect Options:** * **Toxoplasmosis (D):** This is the **most common cause** of posterior uveitis/chorioretinitis worldwide. It typically presents as a "headlight in the fog" appearance (active white lesion next to an old pigmented scar). * **Cytomegalovirus (C):** CMV retinitis is the most common opportunistic ocular infection in AIDS patients (CD4 <50). It presents with a characteristic "pizza-pie" or "cheese and ketchup" fundus appearance. * **Cryptococcosis (A):** Fungal infections like Cryptococcus often cause multifocal chorioretinitis, especially in immunocompromised individuals, spreading via the CSF or bloodstream. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Chorioretinitis:** Toxoplasmosis. * **Candida Albicans:** Causes "string of pearls" vitreous opacities. * **Onchocerciasis:** Caused by *Onchocerca volvulus* (Vector: Blackfly/Simulium). It is the second leading infectious cause of blindness worldwide. * **Syphilis:** Known as the "Great Mimicker," it can cause any form of uveitis, including salt-and-pepper fundus.

Practice by Chapter

Retinal Anatomy and Physiology

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Age-Related Macular Degeneration

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Diabetic Retinopathy

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Retinal Vascular Diseases

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Retinal Detachment

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Hereditary Retinal Dystrophies

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Inflammatory Retinal Diseases

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Retinal Tumors

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Retinopathy of Prematurity

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Retinal Imaging Techniques

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Intravitreal Pharmacotherapy

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Vitreoretinal Surgery

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