Diseases of the Retina Practice Questions

Q: The outer blood-retinal barrier is formed by which structure?

Retinal pigment epithelium. ### Explanation The **Blood-Retinal Barrier (BRB)** is a physiological barrier that regulates the movement of fluids and nutrients into the retina, maintaining a dry environment essential for clear vision. It consists of two distinct components: 1. **Outer Blood-Retinal Barrier (Correct Option C):** This is formed by the **Retinal Pigment Epithelium (RPE)**. The RPE cells are joined by **tight junctions (Zonula occludens)**, which prevent the leakage of large molecules and fluid from the underlying fenestrated choriocapillaris into the subretinal space. 2. **Inner Blood-Retinal Barrier:** This is formed by the **non-fenestrated endothelial cells** of the retinal capillaries. These cells also utilize tight junctions to prevent leakage from the retinal circulation. #### Analysis of Incorrect Options: * **Option A (Internal Limiting Membrane):** This is the innermost layer of the retina, formed by the basement membrane of Müller cells. It separates the retina from the vitreous but does not function as a blood barrier. * **Option B (Endothelium):** While endothelial cells form the *Inner* BRB, they do not form the *Outer* BRB. * **Option D (Ganglion cells):** These are the second-order neurons of the visual pathway; they have no structural role in forming physiological barriers. #### High-Yield Clinical Pearls for NEET-PG: * **Breakdown of Outer BRB:** Leads to conditions like **Central Serous Chorioretinopathy (CSCR)** and **Exudative Age-related Macular Degeneration (AMD)**. * **Breakdown of Inner BRB:** Leads to **Macular Edema** (e.g., Diabetic Retinopathy, RVO). * **Fluorescein Angiography (FFA):** The "background glow" or choroidal flush seen in FFA is due to the fenestrated nature of the choriocapillaris, while the RPE acts as a filter (the "RPE screen effect").

Q: About retinitis pigmentosa, all are true EXCEPT?

Central scotoma. **Explanation:** Retinitis Pigmentosa (RP) is a hereditary, progressive dystrophy primarily affecting the **rod photoreceptors** (rod-cone dystrophy). Because rods are concentrated in the mid-periphery of the retina, the disease typically begins there and spares the central cone-rich macula until the very late stages. **Why "Central Scotoma" is the correct answer (the exception):** In RP, the initial visual field defect is an isolated scotoma in the mid-periphery. These scotomas eventually coalesce to form a **Ring Scotoma**. As the disease progresses, the field constricts further, leading to "tubular vision." **Central scotoma** is characteristic of macular diseases (like ARMD or Stargardt disease) or optic nerve pathologies, not typical RP, where central vision is usually preserved until the end-stage. **Analysis of other options:** * **Ring Scotoma (Option A):** This is the classic visual field defect in RP, resulting from the circumferential degeneration of rods in the mid-peripheral retina. * **Waxy Pallor of Disc (Option C):** Part of the "Classic Triad" of RP. It is caused by glial proliferation over the optic nerve head (gliosis), rather than true optic atrophy. * **Bone Spicule Pigmentation (Option D):** Part of the "Classic Triad." It occurs due to the migration of pigment from the Retinal Pigment Epithelium (RPE) into the sensory retina, typically following a perivascular distribution in the mid-periphery. **NEET-PG High-Yield Pearls:** 1. **Classic Triad:** (1) Bone spicule pigmentation, (2) Waxy pallor of the disc, (3) Arteriolar attenuation (narrowing). 2. **Earliest Symptom:** Nyctalopia (Night blindness). 3. **Earliest Sign:** Exhaustion of the a-wave on Electroretinogram (ERG). Note: ERG is subnormal or extinguished. 4. **Inheritance:** Most common is Autosomal Recessive; most severe is X-linked Recessive. 5. **Associated Systemic Syndrome:** Usher Syndrome (RP + Sensorineural deafness) is the most common.

Q: In cystoid macular edema, fluid collects in the macular region at the level of which layer?

Outer plexiform layer. ### Explanation **Cystoid Macular Edema (CME)** is characterized by the accumulation of fluid in the macula, leading to the formation of cyst-like spaces. **1. Why the Outer Plexiform Layer (OPL) is correct:** In the macular region, the fibers of the outer plexiform layer are oriented obliquely; these are known as **Henle’s layer**. Because of this loose, radial arrangement, the OPL has a high capacity to accumulate extracellular fluid. In CME, fluid primarily collects in these spaces, creating the characteristic **"petaloid" pattern** seen on Fluorescein Angiography (FA). **2. Analysis of Incorrect Options:** * **Outer Nuclear Layer (A):** While some fluid may involve the inner nuclear layer in chronic cases, the primary and initial site of collection is the plexiform layer. * **Inner Plexiform Layer (C):** This layer is more compact and is not the primary site for fluid accumulation in CME. * **Between RPE and Neurosensory Retina (D):** This describes a **Subretinal Detachment** (e.g., Central Serous Chorioretinopathy), not intraretinal edema. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pathophysiology:** Breakdown of the blood-retinal barrier (usually the inner barrier/retinal capillaries). * **Gold Standard Diagnosis:** **Optical Coherence Tomography (OCT)**, which shows "honeycomb" cystic spaces. * **Fluorescein Angiography (FA):** Shows a classic **Flower-petal appearance** due to the radial arrangement of Henle’s layer. * **Irvine-Gass Syndrome:** CME occurring specifically after cataract surgery (typically 4–6 weeks post-op). * **Common Causes:** Diabetes (DME), Uveitis, Retinal Vein Occlusion (RVO), and Prostaglandin analogues (Latanoprost).

Question 1

A 52-year-old woman with a 15-year history of poorly controlled type 2 diabetes mellitus presents with gradual blurring of central vision in both eyes over the past 6 months. Her HbA1c is 10.2%. Fundus examination reveals dot-blot haemorrhages and hard exudates in the macular region bilaterally. Her best-corrected visual acuity is 6/24 in the right eye. The OCT is shown (Image 2). According to current evidence-based guidelines, which of the following represents the most appropriate first-line treatment for the condition demonstrated on imaging in this eye?

Accepted Answer

A. Intravitreal anti-VEGF injection (e.g., ranibizumab or bevacizumab)

Answer

B. Focal/grid macular laser photocoagulation to all areas of retinal thickening

Answer

C. Intravitreal triamcinolone acetonide as monotherapy

Answer

D. Pars plana vitrectomy with internal limiting membrane peeling

Question 2

A 62-year-old man with a family history of glaucoma attends a routine eye clinic. He reports no visual symptoms. Intraocular pressure is 26 mmHg in the right eye. Gonioscopy reveals an open angle. The appearance of the right-eye optic disc is shown in Image 2 (standard fundus orientation: superior disc pole at top, inferior disc pole at bottom, nasal side to the right). Automated perimetry reveals an arcuate scotoma in the superior field. Which of the following best describes the structural finding visible in the image that accounts for this visual field loss?

Accepted Answer

A. Inferior neuroretinal rim loss with violation of the ISNT rule, consistent with preferential damage to the inferior disc pole

Answer

B. Superior neuroretinal rim loss with an enlarged blind spot, consistent with preferential damage to the superior disc pole

Answer

C. Diffuse concentric enlargement of the cup with preserved neuroretinal rim tissue at all poles

Answer

D. Nasal displacement of vessels with superior rim thinning, consistent with a compressive optic neuropathy

Question 3

The outer blood-retinal barrier is formed by which structure?

Accepted Answer

Retinal pigment epithelium

Answer

Internal limiting membrane

Answer

Endothelium

Answer

Ganglion cells

Question 4

About retinitis pigmentosa, all are true EXCEPT?

Accepted Answer

Central scotoma

Answer

Ring scotoma

Answer

Waxy pallor of disc

Answer

Bone spicule pigmentation in retina

Question 5

In cystoid macular edema, fluid collects in the macular region at the level of which layer?

Accepted Answer

Outer plexiform layer

Answer

Outer nuclear layer

Answer

Inner plexiform layer

Answer

Between pigment epithelium and neurosensory retina

Diseases of the Retina — MCQs

Diseases of the Retina — MCQs

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