Orbital Diseases — MCQs

Orbital Diseases Indian Medical PG Practice Questions and MCQs

Question 141: What is the most common cause of intermittent proptosis in adults?

A. Orbital varix (Correct Answer)
B. Thyroid ophthalmopathy
C. Neuroblastoma
D. Retinoblastoma

Explanation: ***Orbital varix*** - An **orbital varix** is essentially a varicose vein within the orbit, which can cause intermittent proptosis. - Proptosis in an orbital varix is often exacerbated by activities that increase venous pressure, such as **Valsalva maneuvers**, crying, or bending over. *Thyroid ophthalmopathy* - This condition is characterized by **persistent proptosis**, lid retraction, and ophthalmoplegia, rather than intermittent symptoms. - While it can cause proptosis, it typically presents as **constant and progressive** rather than intermittent proptosis that varies with head position or straining. *Neuroblastoma* - This is a **malignant tumor** that primarily affects infants and young children, not typically adults. - Orbital metastasis from neuroblastoma would cause **progressive, constant proptosis** rather than intermittent proptosis. *Retinoblastoma* - **Retinoblastoma** is a malignant tumor of the retina that primarily affects young children, typically under the age of 5. - While it can cause proptosis in advanced stages, it presents as **constant and progressive proptosis** due to tumor growth, not intermittent proptosis.

Question 142: The muscle first affected in thyroid ophthalmopathy is:

A. Medial rectus
B. Lateral rectus
C. Inferior rectus (Correct Answer)
D. Superior rectus

Explanation: ***Inferior rectus*** - The **inferior rectus** is the extrinsic eye muscle most commonly and earliest affected in **thyroid ophthalmopathy**, making it difficult to look upwards. - This involvement leads to **fibrosis** and **restriction**, causing **diplopia** and **proptosis**. *Medial rectus* - While the medial rectus can be affected in thyroid ophthalmopathy, it is typically involved later or less severely than the **inferior rectus**. - Involvement may lead to **difficulty with adduction** (moving the eye medially). *Lateral rectus* - The **lateral rectus** is generally one of the **least affected muscles** in thyroid ophthalmopathy. - Its involvement would primarily impact **abduction** (moving the eye laterally). *Superior rectus* - The **superior rectus** can be affected in thyroid ophthalmopathy, but it is less frequently the initial muscle involved compared to the **inferior rectus**. - Dysfunction would primarily cause **difficulty looking downwards**.

Question 143: Which condition is associated with pseudoproptosis?

A. Elongation of the eyeball (High myopia) (Correct Answer)
B. Hyperthyroidism (Thyrotoxicosis)
C. True exophthalmos (Orbital proptosis)
D. Orbital mass (Deep orbital tumour)

Explanation: ***Elongation of the eyeball (High myopia)*** - **Pseudoproptosis** refers to the appearance of prominent eyes without actual forward displacement of the globe, often seen in conditions like **high myopia** due to the elongated eyeball. - In high myopia, the **axial length of the eye** is significantly increased, which can make the eye appear to protrude more anteriorly. *Hyperthyroidism (Thyrotoxicosis)* - While hyperthyroidism can cause **exophthalmos** (true proptosis), it is due to orbital inflammation and fat expansion, not pseudoproptosis. - **Thyroid eye disease** involves immune-mediated changes in the orbital tissues, leading to actual forward displacement of the eye. *True exophthalmos (Orbital proptosis)* - **True exophthalmos** denotes actual anterior displacement of the eyeball from the orbit, which is distinct from pseudoproptosis where the eye only appears prominent. - It results from increased orbital content pushing the globe forward, rather than the eye's shape or size. *Orbital mass (Deep orbital tumour)* - An **orbital mass** can cause **true proptosis** by occupying space within the orbit and physically pushing the globe forward. - This is a structural cause of actual globe displacement, unlike the appearance of prominence in pseudoproptosis.

Question 144: Which of the following is the MOST characteristic feature of thyroid ophthalmopathy?

A. External ophthalmoplegia
B. Proptosis (Correct Answer)
C. Large extraocular muscle
D. Lid lag

Explanation: ***Proptosis*** - **Proptosis** (exophthalmos), or anterior bulging of the eyes, is the **hallmark and most characteristic clinical sign** of **thyroid ophthalmopathy** (Graves' ophthalmopathy). - Results from inflammation, edema, and expansion of retro-orbital tissues, particularly extraocular muscles and orbital fat. - **Bilateral proptosis** is the defining feature that distinguishes thyroid eye disease from other orbital conditions. - Present in approximately **60-70% of patients** with Graves' disease and is often the presenting complaint. *External ophthalmoplegia* - **Restrictive myopathy** affecting extraocular muscles is common in thyroid ophthalmopathy, leading to diplopia and limited eye movements. - However, this represents a **secondary manifestation** due to muscle enlargement and fibrosis rather than the primary characteristic feature. - Most commonly affects inferior and medial recti muscles. *Large extraocular muscle* - **Enlargement of extraocular muscles** is indeed characteristic on imaging (CT/MRI) in thyroid ophthalmopathy. - Typically shows **muscle belly enlargement with tendon sparing** (unlike myositis where tendons are involved). - While this is a defining imaging finding, **proptosis remains the primary clinical characteristic** that is most recognizable and diagnostically significant. *Lid lag* - **Lid lag** (von Graefe's sign) is a common clinical sign where the upper eyelid lags behind the eyeball during downward gaze. - Results from sympathetic overactivity and increased Müller's muscle tone in hyperthyroidism. - While frequently present, it is **less specific** than proptosis and can occur in other hyperthyroid states without significant ophthalmopathy.

Question 145: Which of the following statements about optic nerve glioma is false?

A. Can cause bilateral proptosis
B. Most common primary orbital tumour among children (Correct Answer)
C. Is associated with neurofibromatosis type 1
D. Typically presents with unilateral axial proptosis

Explanation: ***Most common primary orbital tumour among children*** - This statement is **FALSE** - optic nerve glioma is the most common **optic nerve tumor** in children, but NOT the most common **primary orbital tumor**. - **Capillary hemangioma** is the most common primary orbital tumor in the pediatric age group. - This is an important distinction: optic nerve gliomas account for 1-6% of all orbital tumors in children. *Can cause bilateral proptosis* - This is TRUE - optic nerve gliomas can cause bilateral proptosis, particularly in patients with **neurofibromatosis type 1 (NF1)**. - Bilateral involvement occurs in **10-15% of cases**, especially when there is chiasmal involvement extending to both optic nerves. - While unilateral presentation is more common, bilateral disease is well-recognized. *Is associated with neurofibromatosis type 1* - This is TRUE - **15-20% of patients with NF1** develop optic pathway gliomas during childhood. - Conversely, **25-50% of children with optic nerve gliomas** have underlying NF1. - This strong association makes NF1 screening essential in children diagnosed with optic nerve gliomas. *Typically presents with unilateral axial proptosis* - This is TRUE - the classic presentation is **slowly progressive unilateral axial proptosis**. - The tumor grows within the optic nerve sheath, pushing the eye forward in an axial direction. - Associated findings include visual loss, optic disc swelling, and optociliary shunt vessels.

Question 146: Most common ocular movement affected in thyroid ophthalmopathy:

A. Elevation (Correct Answer)
B. Adduction
C. Abduction
D. Depression

Explanation: ***Elevation*** - **Restrictive myopathy** of the **inferior rectus muscle** is the most common cause of impaired eye elevation in thyroid ophthalmopathy. - This typically leads to **diplopia** on upward gaze, known as **Graves' ophthalmopathy**. - The inferior rectus is the **most frequently affected** muscle, followed by medial rectus, superior rectus, and lateral rectus (mnemonic: "I'M SLow"). *Adduction* - Impaired adduction (inward movement) is less common and usually associated with **medial rectus restriction**. - While it can occur (second most common muscle involvement), it is not the most frequent manifestation of thyroid ophthalmopathy. *Abduction* - Impaired abduction (outward movement) suggests **lateral rectus involvement**, which is the least common in thyroid ophthalmopathy. - **Sixth nerve palsy** would also cause impaired abduction but is not typically directly caused by thyroid ophthalmopathy. *Depression* - Impaired depression (downward movement) is uncommon in thyroid ophthalmopathy. - Depression is primarily controlled by the **inferior rectus** (which is commonly affected but causes elevation problems, not depression problems) and inferior oblique. - Superior rectus involvement would cause impaired elevation, not depression.

Practice by Chapter

Orbital Anatomy

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Orbital Imaging Techniques

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Orbital Inflammations

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Orbital Infections

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Orbital Tumors: Primary

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Orbital Tumors: Secondary

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Vascular Lesions of Orbit

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Thyroid Orbitopathy

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Orbital Trauma

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Congenital Orbital Anomalies

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Orbital Surgery Techniques

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Enucleation and Exenteration

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