Diseases of the Retina — MCQs

Diseases of the Retina Indian Medical PG Practice Questions and MCQs

Question 631: Which of the following features is characteristic of familial retinoblastoma?

A. Autosomal recessive inheritance
B. Mutation in the RB gene
C. Bilateral occurrence (Correct Answer)
D. Higher incidence than sporadic retinoblastoma

Explanation: ***Bilateral occurrence*** - Familial retinoblastoma is characterized by **bilateral involvement** of the eyes in approximately 60-70% of cases, as the inherited germline mutation in the **RB1 gene** predisposes both retinas. - The presence of the germline mutation means that every cell in the body carries the predisposition, increasing the likelihood of multiple primary tumor events, often in both eyes. - **Bilaterality** is the key **clinical characteristic** that distinguishes familial from sporadic retinoblastoma (which is typically unilateral). *Autosomal recessive inheritance* - Retinoblastoma, including familial forms, typically follows an **autosomal dominant inheritance pattern** with incomplete penetrance (~90%), not autosomal recessive. - A single mutated copy of the **RB1 gene** inherited from a parent is sufficient to predispose individuals to the disease. *Mutation in the RB gene* - While **germline mutation in the RB1 gene** is indeed present in familial retinoblastoma (and somatic mutations occur in sporadic forms), the question asks for a *characteristic feature* that distinguishes familial from sporadic forms. - Both familial and sporadic retinoblastoma involve RB1 gene dysfunction, but the **clinical presentation** (bilateral vs. unilateral), **age of onset** (earlier in familial), and **heritability** are the distinguishing features, not simply the presence of an RB1 mutation. - The hallmark clinical characteristic is **bilaterality**, not just the genetic mutation. *Higher incidence than sporadic retinoblastoma* - Familial retinoblastoma accounts for only a **smaller proportion** (about 25-40%) of all retinoblastoma cases. - **Sporadic retinoblastoma** (non-heritable, de novo somatic mutation) is actually more common, comprising 60-75% of all cases.

Question 632: Which of the following conditions is associated with granulomatous uveitis?

A. Fuchs' heterochromic iridocyclitis
B. Behcet's disease
C. Vogt-Koyanagi-Harada's disease (Correct Answer)
D. Psoriatic arthritis

Explanation: ***Vogt-Koyanagi-Harada's disease*** - This systemic autoimmune condition characteristically presents with **bilateral, chronic granulomatous panuveitis**. - Other typical findings include **neurologic symptoms** (meningism, tinnitus) and **dermatologic manifestations** (vitiligo, poliosis, alopecia). *Fuchs' heterochromic iridocyclitis* - This condition is typically associated with **non-granulomatous anterior uveitis**. - Key features include **heterochromia** (different colored irises), diffuse stellate keratic precipitates, and often a cataract. *Behcet's disease* - Behcet's disease causes a **non-granulomatous panuveitis**, which is often recurrent and severe. - It is characterized by **recurrent oral and genital ulcers**, erythema nodosum, and pathergy. *Psoriatic arthritis* - Uveitis associated with psoriatic arthritis is usually **acute, unilateral, and non-granulomatous anterior uveitis**. - It is often seen in conjunction with **psoriatic skin lesions** and arthritis, commonly affecting the peripheral joints.

Question 633: Which of the following conditions does not lead to neovascularization of the iris?

A. CRVO
B. Diabetic retinopathy
C. Fuch's heterochromic cyclitis
D. Congenital cataract (Correct Answer)

Explanation: ***Congenital cataract*** - **Congenital cataract** is a clouding of the lens present at birth and typically does not lead to **retinal ischemia** or subsequent **neovascularization** of the iris. - The primary issue is obstruction of light transmission rather than a vascular derangement prompting new vessel formation. - This is the correct answer as it does NOT cause iris neovascularization. *CRVO* - **Central Retinal Vein Occlusion (CRVO)** leads to significant **retinal ischemia**, which triggers the release of **pro-angiogenic factors** like VEGF. - These factors cause **neovascularization of the iris** (rubeosis iridis) and angle, leading to **neovascular glaucoma**. *Diabetic retinopathy* - **Proliferative diabetic retinopathy** is a leading cause of **iris neovascularization** due to widespread retinal **ischemia** and subsequent release of **VEGF**. - The new vessels grow on the iris surface and into the angle, causing **neovascular glaucoma**. *Fuchs heterochromic iridocyclitis* - **Fuchs heterochromic iridocyclitis** is a chronic, low-grade **anterior uveitis** characterized by iris heterochromia and fine keratic precipitates. - The fine vessels visible on the iris are **normal iris vessels made prominent** due to **iris stromal atrophy**, NOT true pathological neovascularization (rubeosis iridis). - Unlike CRVO and diabetic retinopathy, Fuchs does **NOT** cause true iris neovascularization driven by retinal ischemia and VEGF.

Question 634: Mizuo's phenomenon is seen in:

A. Oguchi's disease (Correct Answer)
B. Fundus albipunctatus
C. Fundus flavimaculatus
D. Choroideremia

Explanation: ***Oguchi's disease*** - **Mizuo's phenomenon** is a characteristic feature of **Oguchi's disease**, an **autosomal recessive** form of congenital stationary night blindness. - It involves the unusual finding of a **golden-yellowish or grayish discoloration of the fundus** in the light-adapted state, which disappears after prolonged dark adaptation. *Fundus albipunctatus* - This condition is characterized by **numerous small, discrete white or yellow-white flecks** scattered diffusely across the fundus. - While it is also a form of congenital stationary night blindness, it does not exhibit the **Mizuo's phenomenon**. *Fundus flavimaculatus* - This term is often used interchangeably with **Stargardt's disease**, which is a **macular dystrophy** characterized by progressive vision loss and yellow flecks around the macula. - This condition does not involve **Mizuo's phenomenon** or night blindness of the static type. *Choroideremia* - This is an **X-linked recessive** progressive chorioretinal degeneration primarily affecting males, leading to severe vision loss and night blindness due to loss of the **choroid**, **retinal pigment epithelium**, and **photoreceptors**. - It is a degenerative condition and does not present with the reversible fundus discoloration seen in **Mizuo's phenomenon**.

Question 635: A cherry red spot is found in which of the following conditions?

A. GM1 gangliosidosis
B. Tay-Sach's disease (Correct Answer)
C. Retinopathy of prematurity
D. Gaucher's disease

Explanation: ***Tay-Sach's disease*** - The **cherry-red spot** in Tay-Sachs disease is due to the accumulation of **GM2 gangliosides** in the retinal ganglion cells, making the fovea appear red due to the normal choroidal vasculature. - This is a classic finding in **infantile Tay-Sachs disease**, a lysosomal storage disorder caused by a deficiency of the **hexosaminidase A enzyme**. *Gangliosidosis* - While GM1 gangliosidosis can rarely present with a cherry-red spot, it is more commonly associated with **coarse facial features**, hepatosplenomegaly, and skeletal abnormalities. - The **enzyme deficiency** in GM1 gangliosidosis is **beta-galactosidase**, differing from Tay-Sachs disease. *Retinopathy of prematurity* - This condition involves **abnormal blood vessel growth in the retina** of premature infants, often leading to retinal detachment and vision loss. - It does not typically present with a **cherry-red spot**; rather, it is characterized by areas of vascularized and avascular retina. *Gaucher's disease* - Gaucher's disease is characterized by the accumulation of **glucocerebroside** in macrophages, leading to hepatosplenomegaly, bone pain, and neurological symptoms in some types. - A **cherry-red spot** is not a typical ocular finding in Gaucher's disease; **strabismus** and **oculomotor apraxia** are more common.

Question 636: What is the best diagnostic test for Best's disease?

A. Dark adaptation
B. ERG
C. EOG (Correct Answer)
D. Gonioscopy

Explanation: ***EOG*** - The **electro-oculogram (EOG)** measures the potential difference between the cornea and Bruch's membrane, which is severely abnormal in **Best's disease**. - A characteristic feature is a **reduced Arden ratio (Light Peak/Dark Trough)**, typically below 1.5, even in asymptomatic carriers. *Dark adaptation* - This test assesses the eye's ability to adapt to low light conditions, primarily indicative of **rod photoreceptor function**. - While visual disturbances can occur in Best's disease, dark adaptation is not the primary diagnostic test and might be normal or mildly affected. *ERG* - The **electroretinogram (ERG)** measures the electrical responses of the **photoreceptors and inner retinal cells** to light stimuli. - In Best's disease, the ERG is typically **normal**, as the primary pathology affects the RPE and not directly the photoreceptors (initially). *Gonioscopy* - **Gonioscopy** is an examination technique used to visualize the **anterior chamber angle** of the eye, mainly for diagnosing and managing **glaucoma**. - It is unrelated to Best's disease, which is a **macular dystrophy** affecting the retina and RPE.

Question 637: Fluorescein dye for ophthalmological diagnosis is injected into:

A. Antecubital vein (Correct Answer)
B. Popliteal vein
C. Femoral vein
D. Subclavian vein

Explanation: ***Antecubital vein*** - Fluorescein angiography requires rapid delivery of the dye into the **systemic circulation** for quick visualization of retinal and choroidal vasculature. - The **antecubital vein** is a readily accessible, large superficial vein that allows for quick and efficient intravenous dye injection. *Popliteal vein* - The popliteal vein is located behind the **knee** and is not a standard or practical site for routine intravenous injections, especially when rapid delivery to the eye is needed. - Its location makes it less accessible and potentially more uncomfortable for the patient compared to an arm vein. *Femoral vein* - The femoral vein is a large, deep vein in the **groin**, typically reserved for central venous access or specific procedures due to the increased risk of complications like infection or hematoma. - It is not routinely used for peripheral intravenous injections such as fluorescein, where a more superficial and accessible vein is preferred. *Subclavian vein* - The subclavian vein is a **central vein** located under the clavicle, accessed via a more invasive procedure, usually for central venous catheters or hemodialysis access. - It carries higher risks compared to peripheral venipuncture and is not chosen for simple diagnostic dye injections like fluorescein.

Question 638: Which of the following conditions is NOT associated with retinitis pigmentosa?

A. Kearns-Sayre Syndrome
B. Usher Syndrome
C. Marfan's Syndrome (Correct Answer)
D. Bassen-Kornzweig Syndrome

Explanation: ***Marfan's Syndrome*** - Marfan's Syndrome is primarily a **connective tissue disorder** affecting the **cardiovascular system**, **skeletal system**, and **eyes** (e.g., lens dislocation). - It is **not directly associated** with the progressive **photoreceptor degeneration** characteristic of retinitis pigmentosa. *Usher Syndrome* - Usher Syndrome is a **recessive genetic disorder** characterized by **hearing loss** and progressive **vision loss** due to retinitis pigmentosa. - It involves both **auditory** and **visual impairments**, directly linking it to retinitis pigmentosa. *Kearns-Sayre Syndrome* - Kearns-Sayre Syndrome is a **mitochondrial disorder** that includes **external ophthalmoplegia**, **cardiac conduction defects**, and often **pigmentary retinopathy** resembling retinitis pigmentosa. - The retinal degeneration in Kearns-Sayre syndrome is a **hallmark ocular manifestation**. *Bassen-Kornzweig Syndrome* - Also known as **abetalipoproteinemia**, this is a rare **autosomal recessive disorder** characterized by the inability to absorb **dietary fats and fat-soluble vitamins** (especially vitamin A). - Severe **vitamin A deficiency** can lead to atypical retinitis pigmentosa-like retinal degeneration and **night blindness**.

Practice by Chapter

Retinal Anatomy and Physiology

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Age-Related Macular Degeneration

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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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