Diseases of the Retina — MCQs

Diseases of the Retina Indian Medical PG Practice Questions and MCQs

Question 221: Which of the following conditions is characterized by a "brush fire" appearance of the fundus?

A. Toxoplasmosis
B. CMV retinitis (Correct Answer)
C. Chloroquine toxicity
D. Bacterial endocarditis

Explanation: **Explanation:** **CMV Retinitis (Correct Answer):** Cytomegalovirus (CMV) retinitis is the most common opportunistic ocular infection in patients with AIDS (typically when CD4 counts are <50 cells/µL). The "brush fire" appearance refers to the characteristic fundus finding of **fulminant necrosis** spreading peripherally, featuring a leading edge of white opacified retina (necrosis) associated with prominent intraretinal hemorrhages. This is also famously described as the **"Pizza-pie"** or **"Tomato-catsup"** appearance. **Analysis of Incorrect Options:** * **Toxoplasmosis:** Characterized by a "Headlight in the fog" appearance, which represents an active focus of yellow-white chorioretinitis seen through a hazy, vitreous inflammatory reaction (vitritis). * **Chloroquine Toxicity:** Classically presents with a **"Bull’s eye maculopathy"** due to a ring of retinal pigment epithelium (RPE) atrophy surrounding a central spared foveal area. * **Bacterial Endocarditis:** Associated with **Roth spots**, which are retinal hemorrhages with a central white/pale spot (representing fibrin-platelet plugs). **NEET-PG High-Yield Pearls:** * **Drug of Choice:** Ganciclovir (Intravenous or Intravitreal) is the first-line treatment for CMV retinitis. Foscarnet and Cidofovir are alternatives. * **Frosted Branch Angiitis:** Another presentation of CMV retinitis characterized by severe perivascular sheathing. * **Immune Recovery Uveitis (IRU):** A paradoxical inflammatory response seen in CMV patients after starting HAART as their CD4 count improves. * **Differentiating Feature:** Unlike Toxoplasmosis, CMV retinitis typically presents with **minimal vitritis** ("cold" inflammation) because the patient is severely immunocompromised.

Question 222: Visual loss in diabetic retinopathy is due to all except?

A. Cataract formation
B. Background diabetic retinopathy (Correct Answer)
C. Ischaemic maculopathy
D. Vitreous hemorrhage

Explanation: **Explanation:** The primary goal of this question is to distinguish between the stages of diabetic retinopathy (DR) that cause significant visual impairment versus those that are typically asymptomatic. **Why "Background Diabetic Retinopathy" is the correct answer:** Background Diabetic Retinopathy (BDR) is the earliest clinical stage of DR. It is characterized by microaneurysms, dot-and-blot hemorrhages, and hard exudates. In this stage, the lesions are confined to the retina and do not involve the fovea. Therefore, BDR is generally **asymptomatic** and does not cause vision loss unless it progresses to Diabetic Macular Edema (DME). **Analysis of Incorrect Options (Causes of Vision Loss):** * **Cataract formation:** Diabetes accelerates metabolic changes in the lens (e.g., sorbitol accumulation), leading to "Snowflake cataracts" or early-onset senile cataracts, both of which cause painless, progressive vision loss. * **Ischaemic maculopathy:** This occurs due to the closure of retinal capillaries at the fovea (foveal avascular zone enlargement). It is a major cause of irreversible central vision loss in diabetics and carries a poor prognosis. * **Vitreous hemorrhage:** A hallmark of Proliferative Diabetic Retinopathy (PDR). New vessels (neovascularization) are fragile and bleed into the vitreous cavity, causing sudden, painless floaters or total vision loss. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of legal blindness** in DR: Diabetic Macular Edema (DME). * **Most common cause of sudden vision loss** in DR: Vitreous hemorrhage. * **Earliest clinical sign** of DR: Microaneurysms. * **Earliest functional change** in DR: Loss of blue-yellow color vision and altered Contrast Sensitivity. * **Investigation of choice** for Macular Edema: Optical Coherence Tomography (OCT). * **Investigation of choice** for Macular Ischemia: Fundus Fluorescein Angiography (FFA).

Question 223: Which of the following is the commonest infectious cause for posterior uveitis?

A. Toxocara
B. Toxoplasma gondii (Correct Answer)
C. Taenia solium
D. Plasmodium falciparum

Explanation: **Explanation:** **Toxoplasma gondii** is the most common cause of infectious posterior uveitis worldwide. It typically presents as a **focal necrotizing retinochoroiditis**. The infection can be congenital or acquired. In most cases, it occurs due to the reactivation of a latent cyst in a previous scar, leading to the classic **"Headlight in the fog"** appearance (an active creamy-white lesion adjacent to an old pigmented chorioretinal scar, seen through a hazy vitreous). **Analysis of Incorrect Options:** * **Toxocara (Option A):** While *Toxocara canis* causes ocular larva migrans, it typically presents as a unilateral solitary posterior pole granuloma or endophthalmitis in children, rather than being the most common cause of posterior uveitis. * **Taenia solium (Option B):** This causes **Cysticercosis**. In the eye, the cyst is most commonly found in the subretinal space or vitreous, but it is a parasitic infestation rather than a primary cause of diffuse infectious uveitis. * **Plasmodium falciparum (Option D):** Malaria primarily affects the systemic vasculature. Ocular involvement (Malarial retinopathy) involves hemorrhages and vessel whitening but is not a standard cause of posterior uveitis. **High-Yield Clinical Pearls for NEET-PG:** * **Primary site of infection:** In Toxoplasmosis, the primary site is the **retina** (Retinitis), and the choroid is involved secondarily. * **Treatment of choice:** Triple therapy (Sulfadiazine + Pyrimethamine + Folinic acid) or Clindamycin. * **Steroids:** Always used in conjunction with anti-parasitic drugs, never alone, to prevent rapid multiplication of the organism. * **Differential Diagnosis:** CMV Retinitis (commonest in HIV/AIDS patients, characterized by "Pizza-pie" or "Cheese and Ketchup" fundus).

Question 224: In a detached retina, what is the usual site of detachment?

A. Within the outer plexiform layer
B. Within the inner plexiform layer
C. Between the inner nuclear layer and the outer nuclear layer
D. Between the pigment epithelial layer and the layer of outer segments of rods and cones (Correct Answer)

Explanation: ### Explanation **Core Concept:** Retinal detachment (RD) is a misnomer; it is not a separation of the entire retina from the choroid, but rather a separation of the **neurosensory retina** from the **Retinal Pigment Epithelium (RPE)**. Embryologically, the retina develops from the two layers of the optic cup. The outer layer forms the RPE, while the inner layer forms the neurosensory retina (which includes the photoreceptors). The space between these two layers, known as the **subretinal space**, is a "potential space." In a healthy eye, these layers are held together by the RPE pump and physiological forces. In RD, fluid accumulates in this potential space, separating the layer of rods and cones from the underlying RPE. **Analysis of Options:** * **Option D (Correct):** This describes the anatomical junction between the neurosensory retina and the RPE. This is the weakest point of attachment and the site where clinical detachment occurs. * **Options A, B, and C (Incorrect):** These describe separations *within* the layers of the neurosensory retina. Splitting within the retinal layers is termed **retinoschisis**, not retinal detachment. Specifically, degenerative retinoschisis usually occurs at the outer plexiform layer. **NEET-PG High-Yield Pearls:** * **Most common type of RD:** Rhegmatogenous (due to a retinal break/hole). * **Most common site of a retinal break:** Superotemporal quadrant. * **Clinical Triad:** Photopsia (flashes), floaters (Muscae volitantes), and a "curtain-like" visual field loss. * **Shafer’s Sign:** "Tobacco dust" (pigment cells) in the anterior vitreous; highly suggestive of a retinal tear. * **Macula-on vs. Macula-off:** This is the most important prognostic factor for visual recovery after surgery.

Question 225: A cherry red spot is seen in which of the following conditions?

A. Central retinal vein occlusion
B. Eales' disease
C. Retinitis pigmentosa
D. Central retinal artery occlusion (Correct Answer)

Explanation: ### Explanation **1. Why Central Retinal Artery Occlusion (CRAO) is Correct:** The "Cherry Red Spot" is a classic ophthalmoscopic finding in CRAO. When the central retinal artery is obstructed, the inner layers of the retina become ischemic and edematous, appearing **milky white and opaque**. However, the fovea is the thinnest part of the retina and lacks these inner layers; instead, it receives its blood supply from the underlying **choriocapillaris** (via the ciliary arteries). Consequently, the reddish color of the vascular choroid shines through the thin fovea, creating a sharp contrast against the surrounding pale, edematous retina. **2. Why the Other Options are Incorrect:** * **Central Retinal Vein Occlusion (CRVO):** Characterized by a **"Blood and Thunder"** appearance with extensive superficial hemorrhages, tortuous veins, and disc edema. There is no localized foveal sparing causing a red spot. * **Eales' Disease:** An idiopathic peripheral perivasculitis. It typically presents with peripheral neovascularization and recurrent **vitreous hemorrhages**, not a cherry red spot. * **Retinitis Pigmentosa:** A degenerative condition characterized by the triad of **bony spicule pigmentation**, arteriolar attenuation, and waxy pallor of the optic disc. **3. NEET-PG High-Yield Pearls:** * **Differential Diagnosis of Cherry Red Spot:** Remember the mnemonic **"OCHRE"**: **O**-CRAO, **C**-Congenital (Storage diseases like Tay-Sachs, Niemann-Pick, Gaucher’s), **H**-Hallervorden-Spatz syndrome, **R**-Retinal trauma (Berlin’s edema/Commotio Retinae), **E**-Emetine toxicity. * **CRAO Presentation:** Sudden, painless, profound loss of vision with an **Afferent Pupillary Defect (APD)**. * **Cilioretinal Artery:** In 15-20% of the population, this artery (a branch of the ciliary system) spares a portion of the macula, preserving central vision despite CRAO.

Question 226: Retinal neovascularization is seen in which of the following conditions?

A. Diabetic retinopathy
B. Eale's disease
C. Retinitis pigmentosa (Correct Answer)
D. Retinopathy of prematurity

Explanation: **Explanation:** The presence of **Retinal Neovascularization (NV)** is a hallmark of ischemic retinal diseases where hypoxia triggers the release of Vascular Endothelial Growth Factor (VEGF). **Why Retinitis Pigmentosa is the Correct Answer (in the context of this specific question):** While Diabetic Retinopathy, Eale’s disease, and ROP are classic causes of neovascularization, this question likely focuses on identifying the condition where NV is **NOT** a primary or defining feature. In **Retinitis Pigmentosa (RP)**, the primary pathology is the progressive degeneration of photoreceptors and the retinal pigment epithelium (RPE). While rare complications like Coats-like exudative response can occur, **neovascularization is not a standard clinical feature of RP**. *Note: In many standard exams, this question is framed as "Retinal neovascularization is seen in all EXCEPT," where RP would be the outlier. If the question asks where it is seen, and RP is marked correct, it may be a "recall error" in the question stem or refers to the rare vasoproliferative tumors associated with RP.* **Analysis of Other Options:** * **Diabetic Retinopathy:** Proliferative Diabetic Retinopathy (PDR) is defined by the presence of NVD (at the disc) or NVE (elsewhere). * **Eale’s Disease:** An idiopathic peripheral perivasculitis (common in young males) that leads to peripheral non-perfusion and subsequent neovascularization and vitreous hemorrhage. * **Retinopathy of Prematurity (ROP):** Characterized by abnormal vascular growth at the junction of vascularized and non-vascularized retina due to oxygen-induced metabolic changes. **NEET-PG High-Yield Pearls:** * **Common causes of NV:** "DR VOS" – Diabetes, ROP, Vein occlusions (CRVO/BRVO), Ocular Ischemic Syndrome, Sickle cell retinopathy. * **RP Triad:** Bony spicules, Arteriolar attenuation, and Waxy pallor of the disc. * **Eale's Disease:** Often associated with Mantoux positivity (TB hypersensitivity).

Question 227: Peripheral retinal degeneration is most commonly associated with which refractive error?

A. Myopia (Correct Answer)
B. Presbyopia
C. Hypermetropia
D. Astigmatism

Explanation: **Explanation:** **Why Myopia is Correct:** Peripheral retinal degenerations, particularly **Lattice Degeneration**, are most strongly associated with **Myopia (Nearsightedness)**, especially high myopia. The underlying mechanism is the increased **axial length** of the eyeball. As the globe elongates, the retina and choroid are stretched and thinned, particularly at the periphery (the ora serrata and equator). This mechanical stretching leads to vitreoretinal thinning, ischemia, and subsequent degenerative changes. Lattice degeneration is found in approximately 8–10% of the general population but is significantly more prevalent in myopes, serving as a major precursor to rhegmatogenous retinal detachment. **Why Other Options are Incorrect:** * **Presbyopia:** This is an age-related loss of lens elasticity affecting accommodation, not the anatomical length of the globe or retinal integrity. * **Hypermetropia:** In hypermetropia, the eyeball is shorter than normal. The retina is not under stretching tension; instead, these patients are more predisposed to conditions like angle-closure glaucoma due to a crowded anterior segment. * **Astigmatism:** This relates to irregularities in the curvature of the cornea or lens. It does not involve the elongation of the posterior segment or thinning of the peripheral retina. **High-Yield Clinical Pearls for NEET-PG:** * **Lattice Degeneration:** The most common peripheral degeneration predisposing to retinal holes and detachment. * **Snail Track Degeneration:** Another high-myopia associated degeneration characterized by glistening white specks. * **Pathologic Myopia:** Defined as myopia > -6.00D or axial length > 26.5 mm; associated with **Foster-Fuchs spots** (pigmented macula), **Lacquer cracks** (breaks in Bruch’s membrane), and posterior staphyloma. * **Prophylaxis:** Asymptomatic lattice degeneration in high myopes often requires monitoring, but laser photocoagulation is indicated if there are symptomatic tears or a history of detachment in the fellow eye.

Question 228: Subretinal demarcation lines indicate:

A. Fresh rhegmatogenous retinal detachment
B. Old rhegmatogenous retinal detachment (Correct Answer)
C. Retinopathy of prematurity
D. Retinitis pigmentosa

Explanation: **Explanation:** **Subretinal demarcation lines** (also known as "high-water marks") are a hallmark clinical sign of a **chronic or old rhegmatogenous retinal detachment (RRD)**. When a retinal detachment remains stationary for several weeks (usually 3 months or more), a reactive proliferation of the Retinal Pigment Epithelium (RPE) occurs at the junction of the detached and attached retina. This leads to the formation of a pigmented or white line on the subretinal surface. These lines indicate that the detachment has been present long enough for the eye to attempt to "wall off" the fluid. **Analysis of Options:** * **A. Fresh RRD:** In acute cases, the retina appears mobile, translucent, and convex with loss of underlying choroidal detail. There has not been sufficient time for RPE proliferation or demarcation line formation. * **C. Retinopathy of Prematurity (ROP):** This is characterized by peripheral vascular non-perfusion and a "demarcation line" or "ridge" at the **junction of vascular and avascular retina**, but it is an intraretinal/surface fibrovascular change, not a subretinal RPE response. * **D. Retinitis Pigmentosa:** This presents with "bone-spicule" pigmentation, arteriolar attenuation, and waxy disc pallor. It does not typically feature linear subretinal demarcation lines. **High-Yield Clinical Pearls for NEET-PG:** * **Timeframe:** It takes approximately **3 to 6 months** for a demarcation line to form. * **Significance:** Their presence suggests a relatively stable, long-standing detachment and carries a slightly better prognosis for surgical reattachment, though visual recovery depends on macular involvement. * **Other signs of Old RRD:** Secondary intraretinal cysts, retinal thinning (atrophy), and subretinal fibrosis. * **Convexity:** Remember that RRD is typically **convex** toward the vitreous, whereas tractional RD is often concave.

Question 229: The pigmented neurosensory epithelium of the retina is a continuation of which structure?

A. Pigmentary retinal epithelium
B. Bruch's membrane of the choroid
C. Ora serrata
D. Non-pigmented epithelium of the choroid (Correct Answer)

Explanation: **Explanation:** The development of the uveal tract and the retina is a high-yield topic in ocular embryology. The correct answer is **D (Non-pigmented epithelium of the ciliary body)**. *Note: There appears to be a minor typographical error in the option provided ("choroid" instead of "ciliary body"), but in the context of anatomical continuity, the neurosensory retina transitions into the ciliary body layers.* **1. Why the Correct Answer is Right:** The retina and the ciliary body epithelium both derive from the **optic cup**. The optic cup has two layers: * The **Outer Layer** becomes the **Retinal Pigment Epithelium (RPE)**. This layer continues anteriorly to become the **Pigmented Epithelium** of the ciliary body and the iris. * The **Inner Layer** becomes the **Neurosensory Retina**. This layer continues anteriorly past the ora serrata to become the **Non-pigmented Epithelium** of the ciliary body and the **Posterior Pigmented Epithelium** of the iris. **2. Why Incorrect Options are Wrong:** * **A. Pigmentary retinal epithelium:** This is the outer layer of the retina itself, not a structure it "continues" from in an anterior-posterior anatomical transition. * **B. Bruch's membrane:** This is a thin, acellular layer separating the RPE from the choriocapillaris; it is not epithelial tissue. * **C. Ora serrata:** This is the anatomical junction/boundary where the multi-layered neurosensory retina ends and the bilayered ciliary epithelium begins; it is a landmark, not the structure of origin. **Clinical Pearls for NEET-PG:** * **Blood-Aqueous Barrier:** Formed by the tight junctions of the **non-pigmented ciliary epithelium**. * **Retinal Detachment:** Occurs at the potential space between the RPE (outer layer) and the neurosensory retina (inner layer). * **Aqueous Secretion:** The non-pigmented epithelium of the ciliary body is actively involved in the production of aqueous humor.

Question 230: What is the confirmatory investigation in retinitis pigmentosa?

A. Optical coherence tomography
B. Pachymetry
C. Visual acuity testing
D. Electroretinogram (Correct Answer)

Explanation: **Explanation:** **Retinitis Pigmentosa (RP)** is a hereditary, progressive dystrophy primarily affecting the rod photoreceptors, followed by the cones. **Why Electroretinogram (ERG) is the Correct Answer:** The ERG is the **gold standard and confirmatory investigation** for RP. It measures the electrical response of the retina to light stimulation. In RP, the ERG typically shows a **marked reduction in amplitude (subnormal)** or is **non-recordable (extinguished)** even in the early stages of the disease, often before visible fundus changes (RP sine pigmento) or visual field loss occur. Specifically, the scotopic ERG (rod-driven) is affected first and more severely than the photopic ERG (cone-driven). **Why Other Options are Incorrect:** * **A. Optical Coherence Tomography (OCT):** While OCT is useful to detect complications like Cystoid Macular Edema (CME) or to see thinning of the outer nuclear layer, it is not used for the primary diagnosis of RP. * **B. Pachymetry:** This measures corneal thickness (used in glaucoma or refractive surgery) and has no role in retinal dystrophy diagnosis. * **C. Visual Acuity Testing:** This measures central vision, which often remains preserved until the late stages of RP. It is a functional assessment, not a confirmatory diagnostic tool. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Arteriolar attenuation (narrowing), Bony spicule pigmentation (perivascular), and Waxy pallor of the optic disc. * **Earliest Symptom:** Nyctalopia (Night blindness). * **Visual Field:** Characterized by a **Ring scotoma**, which progresses to "Tunnel vision." * **Inheritance:** Most common is Autosomal Recessive; most severe is X-linked Recessive. * **Associated Syndromes:** Usher Syndrome (deafness) and Refsum Disease (phytanic acid accumulation).

Practice by Chapter

Retinal Anatomy and Physiology

Practice Questions

Age-Related Macular Degeneration

Practice Questions

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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