NEET-PG 2020 — Ophthalmology

Q: Esotropia is common in

Hypermetropia. ***Hypermetropia*** - **Esotropia**, or inward turning of the eye, is common in **hypermetropia** (farsightedness) due to the accommodative effort required to focus. - In hypermetropia, **excessive accommodation** is needed to see clearly at all distances, especially for **near vision**. - This constant **accommodative effort** stimulates convergence through the **accommodation-convergence reflex**, predisposing to **accommodative esotropia**, particularly in children. *Myopia* - **Myopia** (nearsightedness) is typically associated with **exotropia** (outward turning of the eye). - This is because myopic individuals exert less accommodative effort for near vision, reducing the stimulus for convergence and potentially leading to divergence of the eyes. *Emmetropia* - **Emmetropia** describes an eye with **no refractive error**, where light focuses perfectly on the retina without accommodation for distance. - Individuals with emmetropia generally have **orthophoria** (proper alignment of the eyes) and are less prone to strabismus like esotropia unless an underlying muscle imbalance is present. *Astigmatism* - **Astigmatism** is an optical defect in which the eye does not focus light evenly onto the retina, causing blurred vision at any distance. - While it can be associated with other refractive errors, **astigmatism itself is not directly or commonly associated with esotropia**. [Practice more Ophthalmology PYQs on OnCourse]

Q: A 65-year-old male with a history of hypertension and diabetes presents to the OPD with complaints of diplopia and squint. On examination, the secondary deviation is more than the primary deviation. Which of the following is the most likely diagnosis?

paralytic squint. ***Paralytic squint*** The key finding of **secondary deviation being greater than primary deviation** is a classic sign of **paralytic strabismus**. This occurs because the paretic eye (due to neurological deficit) has to work harder to fixate, leading to an exaggerated innervation to the yoked muscle in the healthy eye, causing a larger deviation (Hering's law of equal innervation). The patient's age and history of **hypertension and diabetes** increase the risk of **cranial nerve palsies** (e.g., oculomotor, trochlear, abducens), which are common causes of paralytic squint due to microvascular ischemia. *Concomitant strabismus* In **concomitant strabismus**, the degree of deviation remains constant in all directions of gaze, meaning **primary and secondary deviations are equal**. This contradicts the clinical finding in the patient. Concomitant strabismus often presents in childhood and is typically non-paralytic, with no underlying neurological deficit affecting muscle action. *Restrictive strabismus* **Restrictive strabismus** is characterized by physical limitation of eye movement due to mechanical restriction of an extraocular muscle, often seen in conditions like **thyroid eye disease** or **orbital trauma**. While restrictive strabismus can cause diplopia and reduced eye movement, it typically involves a **limited range of motion** and usually does not present with secondary deviation being greater than primary deviation in the same manner as a paralytic squint. *Pseudo strabismus* **Pseudo strabismus** is an apparent misalignment of the eyes where the eyes are actually straight. This can be due to features like a **wide epicanthal fold** or a **small interpupillary distance**. In pseudo strabismus, there is **no true deviation** on cover-uncover testing, and therefore, the concepts of primary and secondary deviation do not apply, nor would there be actual diplopia. [Practice more Ophthalmology PYQs on OnCourse]

Q: What is the most common cause of sympathetic ophthalmia?

Penetrating injury to the eye. **Penetrating injury to the eye** - **Sympathetic ophthalmia** is a rare, bilateral granulomatous inflammation that occurs after a **penetrating ocular injury** to one eye. - The injury to the affected eye (the **exciting eye**) exposes intraocular antigens to the immune system, leading to an autoimmune response that affects both eyes. *Blunt ocular trauma* - While blunt trauma can cause significant ocular damage, it typically does not expose the intraocular antigens necessary to trigger **sympathetic ophthalmia**. - **Blunt trauma** often leads to conditions like hyphema, orbital fractures, or commotio retinae, but not generalized autoimmune inflammation of both eyes. *Chemical injury to the eye* - **Chemical injuries** primarily cause damage to the ocular surface and anterior segment structures through direct tissue necrosis. - This type of injury rarely leads to the exposure of deep intraocular antigens required to initiate an autoimmune response like that seen in sympathetic ophthalmia. *Retinal detachment* - **Retinal detachment** is the separation of the neurosensory retina from the underlying retinal pigment epithelium. - Although it is a serious ocular condition, it is not a typical prerequisite for **sympathetic ophthalmia** as it generally does not involve a penetrating wound that exposes uveal tissue. [Practice more Ophthalmology PYQs on OnCourse]

Q: In the context of retinal conditions, what is the primary cause of shifting fluid beneath the retina?

Exudative Retinal detachment. ***Exudative Retinal detachment*** - This condition is characterized by the accumulation of **serous fluid** beneath the retina without a retinal break, causing the retina to detach. The fluid can shift with changes in head position due to gravity, leading to a **"shifting fluid" phenomenon**. - It results from conditions that compromise the **retinal pigment epithelium (RPE)** or choroidal vasculature, such as **choroidal tumors**, **inflammatory diseases**, or **severe hypertension**, leading to leakage of fluid. *Tractional Retinal Detachment* - This type of detachment occurs when **fibrovascular membranes** on the retinal surface contract and pull the neurosensory retina away from the RPE. - The detachment is usually **immobile** or minimally mobile because it is held in place by fibrous adhesions, and therefore, does not typically exhibit shifting fluid. *Rhegmatogenous retinal detachment* - This is the most common type of retinal detachment and occurs due to a **full-thickness break or tear** in the retina, allowing vitreous fluid to pass into the subretinal space. - While fluid is present, the key feature is a retinal break, and the detached retina is typically more fixed by the flow through the break rather than gravitationally shifting. *Retinodialysis* - Retinodialysis is a specific type of **rhegmatogenous retinal detachment** characterized by a **disinsertion of the retina from its ora serrata attachment**, often due to trauma. - Similar to other rhegmatogenous detachments, fluid accumulates in the subretinal space, but the primary cause is the tear/disinsertion, and it doesn't primarily manifest as a shifting fluid characteristic, which is more indicative of exudative causes. [Practice more Ophthalmology PYQs on OnCourse]

Q: What is the diagnosis for a patient with unilateral proptosis with bilateral 6th nerve palsy with chemosis and euthyroid status?

Cavernous sinus thrombosis. ***Cavernous sinus thrombosis*** - The combination of **unilateral proptosis**, **bilateral 6th nerve palsy**, and **chemosis** strongly suggests cavernous sinus thrombosis. - The cavernous sinus contains cranial nerves III, IV, V1, V2, and VI; thrombosis can lead to dysfunction of these nerves, particularly the **abducens nerve (VI)**, and venous congestion causing proptosis and chemosis. *Retinoblastoma* - Typically presents in **children** with **leukocoria**, strabismus, and sometimes proptosis. - It is a primary intraocular tumor and does not usually cause acute bilateral cranial nerve palsies and chemosis. *Thyroid ophthalmopathy* - Characterized by proptosis, lid retraction, and ophthalmoplegia, often with chemosis and conjunctival injection, but usually in the context of thyroid dysfunction (hyperthyroidism). - While it can cause proptosis, the presence of **bilateral 6th nerve palsy** and a **euthyroid** status makes cavernous sinus thrombosis more likely, as thyroid ophthalmopathy typically presents with restrictive ophthalmoplegia rather than isolated cranial nerve palsies. *Orbital pseudotumour* - Presents with painful proptosis, chemosis, and ophthalmoplegia, which can be unilateral or bilateral. - Differentiating features include a good response to **steroids** and usually **no associated cranial nerve palsies** in the pattern described. [Practice more Ophthalmology PYQs on OnCourse]

6 Previous Year Questions with Answers & Explanations

Questions

Esotropia is common in

A 65-year-old male with a history of hypertension and diabetes presents to the OPD with complaints of diplopia and squint. On examination, the secondary deviation is more than the primary deviation. Which of the following is the most likely diagnosis?

What is the most common cause of sympathetic ophthalmia?

In the context of retinal conditions, what is the primary cause of shifting fluid beneath the retina?

What is the diagnosis for a patient with unilateral proptosis with bilateral 6th nerve palsy with chemosis and euthyroid status?

The shifting fluid sign is characteristic of which condition?

NEET-PG 2020 - Ophthalmology NEET-PG Practice Questions and MCQs

Question 1: Esotropia is common in

A. Myopia
B. Hypermetropia (Correct Answer)
C. Emmetropia
D. Astigmatism

Explanation: ***Hypermetropia*** - **Esotropia**, or inward turning of the eye, is common in **hypermetropia** (farsightedness) due to the accommodative effort required to focus. - In hypermetropia, **excessive accommodation** is needed to see clearly at all distances, especially for **near vision**. - This constant **accommodative effort** stimulates convergence through the **accommodation-convergence reflex**, predisposing to **accommodative esotropia**, particularly in children. *Myopia* - **Myopia** (nearsightedness) is typically associated with **exotropia** (outward turning of the eye). - This is because myopic individuals exert less accommodative effort for near vision, reducing the stimulus for convergence and potentially leading to divergence of the eyes. *Emmetropia* - **Emmetropia** describes an eye with **no refractive error**, where light focuses perfectly on the retina without accommodation for distance. - Individuals with emmetropia generally have **orthophoria** (proper alignment of the eyes) and are less prone to strabismus like esotropia unless an underlying muscle imbalance is present. *Astigmatism* - **Astigmatism** is an optical defect in which the eye does not focus light evenly onto the retina, causing blurred vision at any distance. - While it can be associated with other refractive errors, **astigmatism itself is not directly or commonly associated with esotropia**.

Question 2: A 65-year-old male with a history of hypertension and diabetes presents to the OPD with complaints of diplopia and squint. On examination, the secondary deviation is more than the primary deviation. Which of the following is the most likely diagnosis?

A. paralytic squint (Correct Answer)
B. concomitant strabismus
C. restrictive strabismus
D. pseudo strabismus

Explanation: ***Paralytic squint*** The key finding of **secondary deviation being greater than primary deviation** is a classic sign of **paralytic strabismus**. This occurs because the paretic eye (due to neurological deficit) has to work harder to fixate, leading to an exaggerated innervation to the yoked muscle in the healthy eye, causing a larger deviation (Hering's law of equal innervation). The patient's age and history of **hypertension and diabetes** increase the risk of **cranial nerve palsies** (e.g., oculomotor, trochlear, abducens), which are common causes of paralytic squint due to microvascular ischemia. *Concomitant strabismus* In **concomitant strabismus**, the degree of deviation remains constant in all directions of gaze, meaning **primary and secondary deviations are equal**. This contradicts the clinical finding in the patient. Concomitant strabismus often presents in childhood and is typically non-paralytic, with no underlying neurological deficit affecting muscle action. *Restrictive strabismus* **Restrictive strabismus** is characterized by physical limitation of eye movement due to mechanical restriction of an extraocular muscle, often seen in conditions like **thyroid eye disease** or **orbital trauma**. While restrictive strabismus can cause diplopia and reduced eye movement, it typically involves a **limited range of motion** and usually does not present with secondary deviation being greater than primary deviation in the same manner as a paralytic squint. *Pseudo strabismus* **Pseudo strabismus** is an apparent misalignment of the eyes where the eyes are actually straight. This can be due to features like a **wide epicanthal fold** or a **small interpupillary distance**. In pseudo strabismus, there is **no true deviation** on cover-uncover testing, and therefore, the concepts of primary and secondary deviation do not apply, nor would there be actual diplopia.

Question 3: What is the most common cause of sympathetic ophthalmia?

A. Blunt ocular trauma
B. Chemical injury to the eye
C. Penetrating injury to the eye (Correct Answer)
D. Retinal detachment

Explanation: **Penetrating injury to the eye** - **Sympathetic ophthalmia** is a rare, bilateral granulomatous inflammation that occurs after a **penetrating ocular injury** to one eye. - The injury to the affected eye (the **exciting eye**) exposes intraocular antigens to the immune system, leading to an autoimmune response that affects both eyes. *Blunt ocular trauma* - While blunt trauma can cause significant ocular damage, it typically does not expose the intraocular antigens necessary to trigger **sympathetic ophthalmia**. - **Blunt trauma** often leads to conditions like hyphema, orbital fractures, or commotio retinae, but not generalized autoimmune inflammation of both eyes. *Chemical injury to the eye* - **Chemical injuries** primarily cause damage to the ocular surface and anterior segment structures through direct tissue necrosis. - This type of injury rarely leads to the exposure of deep intraocular antigens required to initiate an autoimmune response like that seen in sympathetic ophthalmia. *Retinal detachment* - **Retinal detachment** is the separation of the neurosensory retina from the underlying retinal pigment epithelium. - Although it is a serious ocular condition, it is not a typical prerequisite for **sympathetic ophthalmia** as it generally does not involve a penetrating wound that exposes uveal tissue.

Question 4: In the context of retinal conditions, what is the primary cause of shifting fluid beneath the retina?

A. Exudative Retinal detachment (Correct Answer)
B. Tractional Retinal Detachment
C. Rhegmatogenous retinal detachment
D. Retinodialysis

Explanation: ***Exudative Retinal detachment*** - This condition is characterized by the accumulation of **serous fluid** beneath the retina without a retinal break, causing the retina to detach. The fluid can shift with changes in head position due to gravity, leading to a **"shifting fluid" phenomenon**. - It results from conditions that compromise the **retinal pigment epithelium (RPE)** or choroidal vasculature, such as **choroidal tumors**, **inflammatory diseases**, or **severe hypertension**, leading to leakage of fluid. *Tractional Retinal Detachment* - This type of detachment occurs when **fibrovascular membranes** on the retinal surface contract and pull the neurosensory retina away from the RPE. - The detachment is usually **immobile** or minimally mobile because it is held in place by fibrous adhesions, and therefore, does not typically exhibit shifting fluid. *Rhegmatogenous retinal detachment* - This is the most common type of retinal detachment and occurs due to a **full-thickness break or tear** in the retina, allowing vitreous fluid to pass into the subretinal space. - While fluid is present, the key feature is a retinal break, and the detached retina is typically more fixed by the flow through the break rather than gravitationally shifting. *Retinodialysis* - Retinodialysis is a specific type of **rhegmatogenous retinal detachment** characterized by a **disinsertion of the retina from its ora serrata attachment**, often due to trauma. - Similar to other rhegmatogenous detachments, fluid accumulates in the subretinal space, but the primary cause is the tear/disinsertion, and it doesn't primarily manifest as a shifting fluid characteristic, which is more indicative of exudative causes.

Question 5: What is the diagnosis for a patient with unilateral proptosis with bilateral 6th nerve palsy with chemosis and euthyroid status?

A. Retinoblastoma
B. Thyroid ophthalmopathy
C. Cavernous sinus thrombosis (Correct Answer)
D. Orbital pseudotumour

Explanation: ***Cavernous sinus thrombosis*** - The combination of **unilateral proptosis**, **bilateral 6th nerve palsy**, and **chemosis** strongly suggests cavernous sinus thrombosis. - The cavernous sinus contains cranial nerves III, IV, V1, V2, and VI; thrombosis can lead to dysfunction of these nerves, particularly the **abducens nerve (VI)**, and venous congestion causing proptosis and chemosis. *Retinoblastoma* - Typically presents in **children** with **leukocoria**, strabismus, and sometimes proptosis. - It is a primary intraocular tumor and does not usually cause acute bilateral cranial nerve palsies and chemosis. *Thyroid ophthalmopathy* - Characterized by proptosis, lid retraction, and ophthalmoplegia, often with chemosis and conjunctival injection, but usually in the context of thyroid dysfunction (hyperthyroidism). - While it can cause proptosis, the presence of **bilateral 6th nerve palsy** and a **euthyroid** status makes cavernous sinus thrombosis more likely, as thyroid ophthalmopathy typically presents with restrictive ophthalmoplegia rather than isolated cranial nerve palsies. *Orbital pseudotumour* - Presents with painful proptosis, chemosis, and ophthalmoplegia, which can be unilateral or bilateral. - Differentiating features include a good response to **steroids** and usually **no associated cranial nerve palsies** in the pattern described.

Question 6: The shifting fluid sign is characteristic of which condition?

A. Exudative retinal detachment (Correct Answer)
B. Retinal hole
C. Tractional retinal detachment
D. Rhegmatogenous retinal detachment

Explanation: ***Exudative retinal detachment (fluid accumulation in subretinal space)*** - The **shifting fluid sign** is pathognomonic for **exudative retinal detachment**, as the subretinal fluid can move with changes in head position due to gravity. - This type of detachment is caused by conditions that lead to abnormal accumulation of fluid under the retina, such as **choroidal tumors**, inflammatory processes, or **severe hypertension**. *Retinal hole (localized retinal break)* - A **retinal hole** is a full-thickness defect in the retina, but it does not inherently cause a shifting fluid sign unless it progresses to a rhegmatogenous detachment. - While it can be a precursor to retinal detachment, the fluid itself is not subject to gravitational shifting in the same way as in exudative detachment. *Tractional retinal detachment (retinal pulling forces)* - **Tractional retinal detachments** occur when **fibrovascular membranes** on the retinal surface contract, pulling the retina away from the underlying choroid. - The detachment is usually localized and fixed by the tractional forces, meaning the fluid (if present) does not shift freely with changes in head position. *Rhegmatogenous retinal detachment (retinal break with vitreous fluid entry)* - This type of detachment involves a **retinal break** through which **liquefied vitreous** gains access to the subretinal space. - Although there is subretinal fluid, the fluid is generally trapped and the detachment is less mobile than in an exudative case; thus, a pronounced shifting fluid sign is not typical.