Diseases of the Retina Practice Questions

Q: What condition presents with a 'cattle truck' appearance on fundus examination?

Incomplete Central Retinal Artery Occlusion (CRAO). ### Explanation The correct answer is **Incomplete Central Retinal Artery Occlusion (CRAO)**. **1. Why it is correct:** The "cattle truck" appearance (also known as **segmentation** or **box-carring**) of the retinal blood column is a classic sign of severely slowed blood flow. In CRAO, the arterial supply is obstructed, leading to the fragmentation of the blood column into segments of red cells separated by clear plasma. This phenomenon is most visible in the veins and arteries during an *incomplete* or *evolving* occlusion, where the flow is sluggish but not entirely absent. **2. Why the other options are incorrect:** * **Central Retinal Vein Occlusion (CRVO):** This presents with a "Blood and Thunder" fundus, characterized by massive retinal hemorrhages, dilated tortuous veins, and disc edema. * **Incomplete CRVO:** While flow is slowed, the primary clinical feature is venous engorgement and scattered hemorrhages, not the distinct segmentation of the blood column seen in arterial compromise. * **Hypertensive Retinopathy:** This is characterized by arteriolar narrowing, AV nipping, flame-shaped hemorrhages, and Cotton Wool spots (Grade III) or papilledema (Grade IV), but not segmentation of the blood flow. **3. NEET-PG High-Yield Clinical Pearls:** * **CRAO Classic Triad:** Sudden painless loss of vision, Cherry Red Spot (at the fovea), and Cattle-trucking/Box-carring. * **Cherry Red Spot:** Occurs because the thin fovea allows the underlying vascular choroid to show through, while the surrounding macula is pale due to retinal edema. * **Amaurosis Fugax:** A common precursor to CRAO, often described as a "curtain falling" over the eye. * **Management:** CRAO is an ophthalmic emergency. Immediate measures include digital ocular massage and paracentesis to lower Intraocular Pressure (IOP) in an attempt to dislodge the embolus.

Q: All of the following are causes of exudative retinal detachment, EXCEPT:

Retinopathy of prematurity. **Explanation:** The core concept in this question is distinguishing between the three types of retinal detachment (RD): **Rhegmatogenous** (due to a break/hole), **Tractional** (due to pulling by membranes), and **Exudative** (due to fluid accumulation under the retina without a break). **Why Retinopathy of Prematurity (ROP) is the correct answer:** ROP is a vasoproliferative disorder where abnormal fibrovascular membranes grow into the vitreous. These membranes contract, pulling the neurosensory retina away from the retinal pigment epithelium (RPE). Therefore, ROP causes a **Tractional Retinal Detachment**, not an exudative one. **Analysis of Incorrect Options (Causes of Exudative RD):** Exudative RD occurs when fluid leaks from the choroidal vessels or RPE due to inflammation, tumors, or vascular anomalies. * **Sympathetic Ophthalmitis:** A bilateral granulomatous panuveitis following trauma. The intense choroidal inflammation leads to fluid leakage (exudation) under the retina. * **Posterior Scleritis:** Inflammation of the posterior sclera causes thickening and secondary subretinal fluid accumulation. * **Orbital Cellulitis:** Severe orbital inflammation can spread to the posterior segment of the eye, leading to reactive choroidal effusion and exudative RD. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of RD:** Rhegmatogenous (associated with Myopia and Lattice degeneration). * **Shifting Fluid Sign:** Pathognomonic for Exudative RD (fluid moves with gravity). * **Tobacco Dust (Shafer’s Sign):** Pigment cells in the vitreous, highly suggestive of a retinal tear (Rhegmatogenous RD). * **Concave vs. Convex:** Tractional RD typically has a **concave** configuration and is non-mobile, whereas Rhegmatogenous/Exudative RDs are usually **convex**.

Q: Retinoblastoma spreads to the CNS through which route?

Direct extension. **Explanation:** Retinoblastoma is the most common intraocular malignancy of childhood. Understanding its routes of metastasis is crucial for NEET-PG. **Why "Direct Extension" is correct:** The most common route for Retinoblastoma to involve the Central Nervous System (CNS) is via **direct extension through the optic nerve**. The tumor cells invade the lamina cribrosa, travel along the optic nerve, and reach the subarachnoid space at the level of the optic chiasm. From there, they spread into the cerebrospinal fluid (CSF) and the brain. Direct extension can also occur through the sclera into the orbit. **Analysis of Incorrect Options:** * **Lymphatic spread:** The eye lacks a traditional lymphatic drainage system. Lymphatic spread only occurs if the tumor involves the conjunctiva or eyelids, draining to preauricular or submandibular nodes. It is not the route to the CNS. * **Arterial embolization:** While Retinoblastoma spreads hematogenously (most commonly to bone marrow, liver, and lungs), this occurs via **venous** channels, not arterial embolization. * **Vitreous seeding:** This refers to the internal shedding of tumor cells into the vitreous cavity. While this is a hallmark of endophytic growth and complicates local treatment, it is an intraocular event and not a mechanism for CNS metastasis. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of distant metastasis:** Bone marrow. * **Flexner-Wintersteiner Rosettes:** Pathognomonic histological feature (indicates photoreceptor differentiation). * **Homer-Wright Rosettes:** Seen in Retinoblastoma but also in Neuroblastoma and Medulloblastoma (less specific). * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pineal gland tumor (Pineoblastoma). * **Calcification:** A key radiological sign on CT scans, helping differentiate it from Coats' disease.

Q: Asteroid hyalosis is composed of which of the following?

Calcium. **Explanation:** **Asteroid Hyalosis** is a common, benign vitreous condition characterized by the accumulation of tiny, spherical, white or creamy-white opacities suspended within the vitreous gel. **Why Calcium is Correct:** The "asteroid bodies" are biochemically composed of **calcium-lipid complexes** (specifically calcium hydroxyapatite and phospholipids) associated with a collagenous matrix. These bodies are suspended in a structurally normal vitreous and move with the vitreous during eye movements, returning to their original position once the eye is still (unlike synchysis scintillans). **Why Other Options are Incorrect:** * **Iron (A):** Iron deposition in the eye is known as **Siderosis Bulbi**, typically resulting from a retained intraocular foreign body. It leads to retinal toxicity and heterochromia iridis. * **Copper (B):** Copper deposition is known as **Chalcosis**. It classically presents as a "Sunflower Cataract" or a Kayser-Fleischer ring (in Wilson’s disease), not vitreous opacities. * **Silica (D):** Silica is not a standard metabolic or degenerative deposit found in the vitreous. **High-Yield Clinical Pearls for NEET-PG:** * **Appearance:** Often described as "Stars in the night sky" on ophthalmoscopy. * **Vision:** Surprisingly, it rarely affects visual acuity significantly, though it can make the fundus examination difficult for the surgeon. * **Association:** It is usually unilateral (80% of cases) and is frequently associated with **Diabetes Mellitus**, hypertension, and hypercholesterolemia. * **Differential Diagnosis:** Must be distinguished from **Synchysis Scintillans**, which consists of **cholesterol crystals**, is usually bilateral, occurs in liquefied vitreous (synchysis), and the crystals settle at the bottom of the globe.

Q: Which of the following conditions is characterized by a "cattle truck" appearance on fundoscopy?

Central retinal artery occlusion (CRAO). **Explanation:** **Central Retinal Artery Occlusion (CRAO)** is a true ophthalmic emergency. The "cattle truck" appearance (also known as **segmentation** or **box-carring**) refers to the fragmentation of the blood column within the retinal arterioles. This occurs because the total cessation of arterial blood flow causes erythrocytes to clump together, separated by clear plasma, resembling a line of moving cattle cars. **Why the other options are incorrect:** * **Central Serous Retinopathy (CSR):** Characterized by a localized sensory retinal detachment at the macula, typically presenting with a "smokestack" or "ink-blot" appearance on Fundus Fluorescein Angiography (FFA), not the vessels. * **Coat’s Disease:** An idiopathic condition featuring telangiectatic and aneurysmal retinal vessels with massive subretinal exudation ("lightbulb" appearance on imaging), usually seen in young males. * **Retinopathy of Prematurity (ROP):** Characterized by peripheral retinal neovascularization, a "demarcation line," or a "ridge" in preterm infants, often leading to tractional retinal detachment. **Clinical Pearls for NEET-PG:** * **Classic Triad of CRAO:** Sudden painless loss of vision, **Cherry Red Spot** (due to the choroidal vasculature showing through the thin fovea amidst surrounding retinal edema), and **Cattle-trucking**. * **Afferent Pupillary Defect (Marcus Gunn Pupil):** Usually present in the affected eye. * **Management:** Immediate ocular massage, anterior chamber paracentesis, and inhalation of Carbogen (95% $O_2$, 5% $CO_2$) to induce vasodilation and dislodge the embolus. * **Time Window:** Irreversible retinal damage occurs within 90–100 minutes of complete occlusion.

Q: Which of the following types of macular dystrophy is associated with the typical egg yolk lesion located in the central macula?

Best disease. **Explanation:** **Best Disease (Vitelliform Macular Dystrophy)** is the correct answer. It is an autosomal dominant condition caused by a mutation in the **BEST1 gene** on chromosome 11, which encodes the protein **bestrophin-1**. This protein acts as a chloride channel in the Retinal Pigment Epithelium (RPE). Dysfunction leads to an abnormal accumulation of **lipofuscin** between the RPE and Bruch’s membrane, resulting in the classic **"egg-yolk" (vitelliform) lesion** at the macula. A hallmark diagnostic feature is a **normal Electroretinogram (ERG)** but an **abnormal Electro-oculogram (EOG)** with an Arden index < 1.5. **Why other options are incorrect:** * **Stargardt Disease:** The most common macular dystrophy, characterized by a **"beaten bronze"** appearance and peripheral yellow-white **pisciform (fish-shaped) flecks**. It shows a "dark choroid" sign on Fundus Fluorescein Angiography (FFA). * **Cone-Rod Dystrophies:** These typically present with a **"bull’s eye maculopathy"** (similar to chloroquine toxicity) and result in early loss of color vision and central visual acuity. * **X-Linked Juvenile Retinoschisis:** Characterized by a **spoke-wheel pattern** of cystoid spaces in the macula and splitting of the retinal layers (usually the nerve fiber layer). **High-Yield Clinical Pearls for NEET-PG:** * **Stages of Best Disease:** Pre-vitelliform → Vitelliform (Egg-yolk) → Pseudohypopyon (partial absorption) → Vitelliruptive (Scrambled egg) → Atrophic/Cicatricial. * **EOG vs. ERG:** Best disease is the classic example where EOG is subnormal despite a normal ERG. * **Inheritance:** Best disease is Autosomal Dominant; Stargardt is usually Autosomal Recessive.

Q: Which of the following is true about inverse Retinitis pigmentosa?

X linked recessive inheritance. **Explanation:** **Inverse Retinitis Pigmentosa (RP)**, also known as Central Retinitis Pigmentosa, is a rare variant of the RP spectrum where the pigmentary changes and photoreceptor degeneration begin centrally rather than in the periphery. 1. **Why Option A is Correct:** While Retinitis Pigmentosa as a whole most commonly follows an Autosomal Recessive pattern, **Inverse RP** is specifically associated with an **X-linked recessive inheritance** pattern (linked to the *RPGR* gene). This makes it more common and typically more severe in males. 2. **Why the other options are incorrect:** * **Options B & C:** In Inverse RP, the characteristic "bony spicule" pigmentary changes are notably **absent**. Instead, patients present with macular atrophy, "bull’s eye" maculopathy, or fine granular pigmentary changes in the foveal/parafoveal region. Bony spicules are the hallmark of *classic* (peripheral) RP. * **Option D:** Progressive choroidal degeneration is the hallmark of **Choroideremia** or **Gyrate Atrophy**, not Inverse RP. Inverse RP primarily affects the cone-rod system starting at the macula. **Clinical Pearls for NEET-PG:** * **Symptom Triad:** Unlike classic RP (which starts with night blindness), Inverse RP presents with **early loss of central vision**, **color vision defects**, and **photophobia**. * **Visual Fields:** Shows a **central scotoma** with preserved peripheral fields (the "inverse" of the ring scotoma seen in classic RP). * **ERG Findings:** Shows a marked decrease in **photopic** (cone) responses early in the disease, while scotopic (rod) responses may remain normal until later stages. * **Differential Diagnosis:** Must be distinguished from Stargardt’s disease and Cone-Rod Dystrophy.

Question 1

What condition presents with a 'cattle truck' appearance on fundus examination?

Accepted Answer

Incomplete Central Retinal Artery Occlusion (CRAO)

Answer

Central Retinal Vein Occlusion (CRVO)

Answer

Incomplete Central Retinal Vein Occlusion (CRVO)

Answer

Hypertensive Retinopathy

Question 2

All of the following are causes of exudative retinal detachment, EXCEPT:

Accepted Answer

Retinopathy of prematurity

Answer

Sympathetic ophthalmitis

Answer

Posterior scleritis

Answer

Orbital cellulitis

Question 3

Which of the following is useful in the management of choroiditis?

Accepted Answer

Steroids

Answer

Antibiotics

Answer

Miotics

Answer

Padding

Question 4

Retinoblastoma spreads to the CNS through which route?

Accepted Answer

Direct extension

Answer

Lymphatic spread

Answer

Arterial embolization

Answer

Vitreous seeding

Question 5

Asteroid hyalosis is composed of which of the following?

Accepted Answer

Calcium

Answer

Iron

Answer

Copper

Answer

Silica

Question 6

Which of the following conditions is characterized by a "cattle truck" appearance on fundoscopy?

Accepted Answer

Central retinal artery occlusion (CRAO)

Answer

Central serous retinopathy

Answer

Coat's disease

Answer

Retinopathy of prematurity (ROP)

Question 7

Which of the following is true regarding intraocular retinoblastoma?

Accepted Answer

Intraocular Retinoblastoma Classification (ICRB) is presently being followed to decide the treatment modality.

Answer

60% are familial and the rest about 40% occur sporadically.

Answer

Leukocoria or yellowish-white pupillary reflex is the second commonest presenting feature.

Answer

All of the above

Question 8

Which of the following types of macular dystrophy is associated with the typical egg yolk lesion located in the central macula?

Accepted Answer

Best disease

Answer

Stargardt Disease

Answer

Cone Rod Dystrophies

Answer

X-Linked Juvenile Retinoschisis

Question 9

Which of the following is true about inverse Retinitis pigmentosa?

Accepted Answer

X linked recessive inheritance

Answer

Bony spicules in the fovea

Answer

Bony spicules in the parafovea

Answer

Progressive choroidal degeneration

Question 10

Which of the following statements is not true regarding rhegmatogenous retinal detachment?

Accepted Answer

It is caused by vitreous traction or fibrous bands within the vitreous.

Answer

Patients may present with symptoms such as floaters and flashes of light.

Answer

Surgical intervention is the primary modality of treatment.

Answer

The detachment can involve the entire retina, extending from the ora serrata to the optic disc.

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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