Diseases of the Retina Practice Questions

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: A premature baby weighing 1000 gms or less is most likely to suffer from which of the following conditions?

Retinopathy of prematurity (ROP). **Explanation:** The correct answer is **Retinopathy of Prematurity (ROP)**. **Why ROP is the correct answer:** ROP is a vasoproliferative disorder affecting the incomplete vascularization of the retina in premature infants. The retinal blood vessels begin to develop at the 16th week of gestation and reach the nasal periphery by 36 weeks and the temporal periphery by 40 weeks. In a baby weighing ≤1000g (Extremely Low Birth Weight), the retina is significantly immature. Exposure to high oxygen concentrations post-delivery causes vasoconstriction and vaso-obliteration, followed by a compensatory release of **VEGF (Vascular Endothelial Growth Factor)**, leading to neovascularization, hemorrhages, and potentially tractional retinal detachment. **Analysis of Incorrect Options:** * **A. Cataract:** While congenital cataracts can occur due to infections (TORCH) or genetics, they are not specifically linked to low birth weight or prematurity. * **B. Glaucoma:** Congenital glaucoma is typically due to maldevelopment of the trabecular meshwork (dysgenesis) rather than prematurity. * **D. Retinal Detachment:** While ROP can *lead* to retinal detachment (Stage 4 and 5), the primary underlying condition the baby suffers from is ROP itself. **Clinical Pearls for NEET-PG:** * **Screening Criteria (India):** All infants with birth weight **<2000g** or gestational age **<34 weeks** must be screened. * **Timing:** The first screening should be done at **4 weeks** (30 days) of life, or **3 weeks** if the baby is <28 weeks/ <1200g. * **Plus Disease:** Characterized by dilatation and tortuosity of posterior pole retinal vessels; it indicates active, severe ROP. * **Treatment:** Laser photocoagulation (Gold Standard) or Anti-VEGF injections (e.g., Ranibizumab).

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).

Q: A young adult presented with diminished vision. On examination, he has anterior uveitis, vitritis, focal necrotizing granuloma, and macular spot. What is the probable diagnosis?

Ocular toxoplasmosis. **Explanation:** The clinical presentation of **Ocular Toxoplasmosis**, caused by the parasite *Toxoplasma gondii*, typically features a "headlight in the fog" appearance. This is due to active **focal necrotizing retinochoroiditis** (the granuloma) associated with significant overlying **vitritis**. The presence of anterior uveitis and macular involvement (macular spot) are common complications. In young adults, this is often a reactivation of congenital infection. **Why the other options are incorrect:** * **Proteus Syndrome:** This is a rare genetic condition characterized by overgrowth of bones, skin, and other tissues (e.g., macrodactyly). It does not typically present with posterior segment inflammatory granulomas. * **White Dot Syndromes:** This is a group of idiopathic inflammatory conditions (like APMPPE or Birdshot chorioretinopathy). While they involve the choroid/retina, they present with multiple, small, discrete white lesions rather than a single focal necrotizing granuloma with intense vitritis. * **Multifocal Choroiditis (MFC):** As the name suggests, this involves multiple inflammatory foci. While it can cause vitritis, it lacks the classic focal necrotizing "granuloma" appearance characteristic of Toxoplasmosis. **Clinical Pearls for NEET-PG:** * **Classic Sign:** "Headlight in the fog" (active yellowish-white retinal lesion seen through dense vitreous haze). * **Most common cause** of posterior uveitis worldwide. * **Treatment:** The "Triple Therapy" includes Pyrimethamine, Sulfadiazine, and Folinic acid (to prevent bone marrow suppression). Systemic steroids are added only *after* starting anti-parasitic drugs. * **Kyrieleis Arteritis:** A specific type of retinal periarteritis sometimes seen in ocular toxoplasmosis.

Q: Which among the following is the commonest parasitic cause of uveitis?

Toxocara. **Explanation:** **Toxocariasis (Option A)** is the most common parasitic cause of uveitis worldwide. It is caused by the larvae of *Toxocara canis* (dog roundworm) or *Toxocara cati* (cat roundworm). In humans, the larvae cannot mature and instead migrate through tissues, a condition known as **Visceral Larva Migrans**. When they reach the eye, it is termed **Ocular Larva Migrans**. It typically presents as a unilateral posterior uveitis, often manifesting as a localized retinal granuloma (posterior pole or periphery) or chronic endophthalmitis, primarily in children. **Why other options are incorrect:** * **Amoebiasis (Option B):** While *Acanthamoeba* is a significant cause of severe keratitis (especially in contact lens users), it rarely causes primary uveitis. * **Taenia solium (Option C):** This causes **Cysticercosis**. While the larvae (*Cysticercus cellulosae*) can lodge in the subretinal space or vitreous, it is less frequent than Toxocara and usually presents as a space-occupying cyst rather than classic uveitis. * **Onchocercosis (Option D):** Caused by *Onchocerca volvulus* ("River Blindness"), it is a major cause of blindness in endemic regions (Africa/South America) but is geographically restricted and less common globally than Toxocara. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Posterior Uveitis overall:** Toxoplasmosis (Protozoal, not Helminthic/Parasitic). * **Toxocara Presentation:** Characteristically presents as a **white pupillary reflex (Leukocoria)**, making it a crucial differential diagnosis for Retinoblastoma. * **Diagnosis:** Primarily clinical and serological (ELISA); aqueous or vitreous fluids may show eosinophilia. * **Treatment:** Periocular or systemic steroids to control inflammation; anthelmintics (Albendazole) are used if active larvae are suspected.

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

"Trucking" of the vessel is a characteristic sign.. ### 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.

Q: What is haemorrhage at the macular spot in high myopia called?

Foster-Fuchs flecks. **Explanation:** **Foster-Fuchs Flecks (Correct Answer):** In pathological (high) myopia, the eyeball undergoes progressive axial elongation. This stretching leads to thinning of the choroid and cracks in the Bruch’s membrane (known as Lacquer cracks). These cracks predispose the eye to **Choroidal Neovascularization (CNV)**. A Foster-Fuchs fleck is a circular, pigmented, or subretinal hemorrhagic lesion at the macula that occurs following a subretinal hemorrhage associated with these neovascular membranes. It eventually heals into a pigmented scar, leading to a permanent loss of central vision. **Analysis of Incorrect Options:** * **Lacquer’s lines:** These are fine, irregular, yellow-white streaks representing mechanical breaks in the **Bruch’s membrane**. While they are a precursor to Foster-Fuchs flecks, they represent the *crack* itself, not the resulting hemorrhage or pigmented spot. * **Dalen-Fuchs nodules:** These are small, yellow-white inflammatory nodules seen in **Sympathetic Ophthalmitis** and Vogt-Koyanagi-Harada (VKH) syndrome. They are located between the RPE and Bruch’s membrane. * **Berlin’s oedema:** Also known as *Commotio Retinae*, this is a milky-white cloudiness of the retina caused by **blunt trauma**, typically involving the macula. **High-Yield Clinical Pearls for NEET-PG:** * **Pathological Myopia Definition:** Myopia > -6.00D or axial length > 26.5 mm. * **Staphyloma:** Posterior staphyloma (bulging of weakened sclera) is the hallmark of pathological myopia. * **Retinal Detachment:** High myopes are at a significantly increased risk for rhegmatogenous retinal detachment due to peripheral degenerations like **Lattice degeneration**.

Question 1

Subretinal demarcation lines indicate:

Accepted Answer

Old rhegmatogenous retinal detachment

Answer

Fresh rhegmatogenous retinal detachment

Answer

Retinopathy of prematurity

Answer

Retinitis pigmentosa

Question 2

A 5-year-old boy presents with leukocoria in the right eye, diagnosed as diffuse retinoblastoma involving the entire globe. Examination of the left eye reveals a small 2-3 mm tumor in the periphery. What is the ideal management of this patient?

Accepted Answer

Enucleation of the right eye and local therapy for the left eye

Answer

Enucleation of both eyes

Answer

Enucleation of the right eye and observation for the left eye

Answer

Six cycles of chemotherapy

Question 3

A premature baby weighing 1000 gms or less is most likely to suffer from which of the following conditions?

Accepted Answer

Retinopathy of prematurity (ROP)

Answer

Cataract

Answer

Glaucoma

Answer

Retinal detachment

Question 4

Regarding intraocular retinoblastoma, which of the following statements is FALSE?

Accepted Answer

Patients with sporadic retinoblastoma do not pass their genetic mutation to their offspring

Answer

94% of cases are sporadic

Answer

Calcification in the tumor can be detected on ultrasound scan

Answer

The Reese-Ellsworth classification is useful in predicting visual prognosis following radiotherapy

Question 5

What is the confirmatory investigation in retinitis pigmentosa?

Accepted Answer

Electroretinogram

Answer

Optical coherence tomography

Answer

Pachymetry

Answer

Visual acuity testing

Question 6

A young adult presented with diminished vision. On examination, he has anterior uveitis, vitritis, focal necrotizing granuloma, and macular spot. What is the probable diagnosis?

Accepted Answer

Ocular toxoplasmosis

Answer

Proteus syndrome

Answer

White dot syndrome

Answer

Multifocal choroiditis

Question 7

Which among the following is the commonest parasitic cause of uveitis?

Accepted Answer

Toxocara

Answer

Amoebiasis

Answer

Taenia solium

Answer

Onchocercosis

Question 8

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

Accepted Answer

"Trucking" of the vessel is a characteristic sign.

Answer

Embolism is the main cause.

Answer

It causes painful loss of vision.

Answer

It involves the ophthalmic artery.

Question 9

A healed patch of chorioretinitis gives rise to:

Accepted Answer

Negative scotoma

Answer

Positive scotoma

Answer

Both

Answer

None

Question 10

What is haemorrhage at the macular spot in high myopia called?

Accepted Answer

Foster-Fuchs flecks

Answer

Lacquer's lines

Answer

Dalen-Fuchs nodules

Answer

Berlin's oedema

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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