Diseases of the Retina Practice Questions

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

CMV retinitis. **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.

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

Background diabetic retinopathy. **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).

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

Toxoplasma gondii. **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).

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

Central retinal artery occlusion. ### 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.

Q: Subretinal demarcation lines indicate:

Old rhegmatogenous retinal detachment. **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.

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

Non-pigmented epithelium of the choroid. **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.

Q: What is the confirmatory investigation in retinitis pigmentosa?

Electroretinogram. **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).

Question 1

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

Accepted Answer

CMV retinitis

Answer

Toxoplasmosis

Answer

Chloroquine toxicity

Answer

Bacterial endocarditis

Question 2

Visual loss in diabetic retinopathy is due to all except?

Accepted Answer

Background diabetic retinopathy

Answer

Cataract formation

Answer

Ischaemic maculopathy

Answer

Vitreous hemorrhage

Question 3

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

Accepted Answer

Toxoplasma gondii

Answer

Toxocara

Answer

Taenia solium

Answer

Plasmodium falciparum

Question 4

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

Accepted Answer

Between the pigment epithelial layer and the layer of outer segments of rods and cones

Answer

Within the outer plexiform layer

Answer

Within the inner plexiform layer

Answer

Between the inner nuclear layer and the outer nuclear layer

Question 5

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

Accepted Answer

Central retinal artery occlusion

Answer

Central retinal vein occlusion

Answer

Eales' disease

Answer

Retinitis pigmentosa

Question 6

Retinal neovascularization is seen in which of the following conditions?

Accepted Answer

Retinitis pigmentosa

Answer

Diabetic retinopathy

Answer

Eale's disease

Answer

Retinopathy of prematurity

Question 7

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

Accepted Answer

Myopia

Answer

Presbyopia

Answer

Hypermetropia

Answer

Astigmatism

Question 8

Subretinal demarcation lines indicate:

Accepted Answer

Old rhegmatogenous retinal detachment

Answer

Fresh rhegmatogenous retinal detachment

Answer

Retinopathy of prematurity

Answer

Retinitis pigmentosa

Question 9

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

Accepted Answer

Non-pigmented epithelium of the choroid

Answer

Pigmentary retinal epithelium

Answer

Bruch's membrane of the choroid

Answer

Ora serrata

Question 10

What is the confirmatory investigation in retinitis pigmentosa?

Accepted Answer

Electroretinogram

Answer

Optical coherence tomography

Answer

Pachymetry

Answer

Visual acuity testing

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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