Pediatric Ophthalmology and Strabismus Practice Questions

Q: Which two muscles are primarily responsible for the elevation of the eye?

Superior Rectus (SR) and Inferior Oblique (IO). **Explanation:** The vertical movements of the eye (elevation and depression) are governed by the coordinated action of the recti and oblique muscles. **1. Why Option A is Correct:** The **Superior Rectus (SR)** and the **Inferior Oblique (IO)** are the two primary elevators of the eye. * **Superior Rectus:** Its primary action is elevation. This action is most efficient when the eye is in a position of **abduction** (23°), as the visual axis aligns with the muscle's pull. * **Inferior Oblique:** Its primary action is excyclotorsion, but its secondary action is elevation. This elevation is most efficient when the eye is in a position of **adduction** (51°). Together, they ensure smooth upward movement across the entire horizontal field of gaze. **2. Why Other Options are Incorrect:** * **Option B & C:** The **Superior Oblique (SO)** and **Inferior Rectus (IR)** are primarily **depressors** of the eye. The SO is the main depressor in adduction, while the IR is the main depressor in abduction. * **Option D:** While the SR elevates, the SO acts as a depressor, making this combination functionally antagonistic in the vertical plane. **Clinical Pearls for NEET-PG:** * **RAD Rule:** **R**ecti are **AD**ductors (except Lateral Rectus). * **SIN Rule:** **S**uperior muscles are **IN**torters (Superior Rectus and Superior Oblique). * **Testing Position:** To isolate the **Superior Rectus**, ask the patient to look **up and out** (abduction). To isolate the **Inferior Oblique**, ask the patient to look **up and in** (adduction). * **Nerve Supply:** All extraocular muscles are supplied by the 3rd Cranial Nerve except the Superior Oblique (CN IV) and Lateral Rectus (CN VI) — Formula: **LR6(SO4)3**.

Q: All of the following are true regarding paralytic squint, except:

Amblyopia. **Explanation:** The correct answer is **Amblyopia** because it is a characteristic feature of **non-paralytic (concomitant) squint**, not paralytic squint. **1. Why Amblyopia is the exception:** Amblyopia (lazy eye) typically develops in children during the "plastic period" of visual development (usually under age 7-8). In **paralytic squint**, the onset is usually sudden and occurs in adults or older children. Because the visual system is already mature, the brain cannot suppress the blurred image from the deviated eye, leading to persistent diplopia rather than amblyopia. **2. Analysis of other options:** * **Diplopia (C):** This is the hallmark of paralytic squint. Since the eyes are not aligned and the brain cannot suppress the second image, the patient experiences double vision, which is maximal in the direction of the paralyzed muscle's action. * **Head Tilt/Abnormal Head Posture (A):** Patients adopt a compensatory head posture (tilting, turning, or chin elevation/depression) to minimize diplopia by moving the eyes into a position where the paralyzed muscle is least required. * **Lateral Deviation (B):** Paralytic squint results in an objective deviation of the ocular axis (e.g., an abducens nerve palsy causes medial deviation, while a third nerve palsy causes lateral deviation/exotropia). **Clinical Pearls for NEET-PG:** * **Primary vs. Secondary Deviation:** In paralytic squint, the **secondary deviation** (measured with the paralyzed eye fixing) is always **greater** than the primary deviation (measured with the normal eye fixing) due to Hering’s Law of equal innervation. * **False Orientation (Past-pointing):** A classic sign of paralytic squint where the patient points beyond the object in the direction of the paralyzed muscle. * **Non-paralytic Squint:** Characterized by constant angle of deviation in all gazes, absence of diplopia, and high risk of amblyopia.

Q: A patient presents with diplopia when looking up and out. Which extraocular muscle is defective?

Right Superior rectus. To solve this question, one must understand the **primary, secondary, and tertiary actions** of the extraocular muscles (EOMs). ### **Why Right Superior Rectus is Correct** The **Superior Rectus (SR)** is the primary elevator of the eye. However, its efficiency as an elevator depends on the position of the globe. Because the SR muscle makes an angle of **23°** with the optical axis, its elevating action is maximal when the eye is **abducted (turned out)**. * **Clinical Logic:** Diplopia occurs when a muscle cannot move the eye into its field of maximal action. Since the patient experiences diplopia when looking **up (elevation)** and **out (abduction)**, the defective muscle is the Superior Rectus. ### **Analysis of Incorrect Options** * **B & C (Superior Oblique):** The Superior Oblique (SO) is primarily a **depressor** in the adducted position. SO palsy typically causes diplopia when looking **down and in** (e.g., reading or walking down stairs). * **D (Right Inferior Rectus):** The Inferior Rectus is a **depressor**. Its action is maximal when the eye is **abducted**. Therefore, a defect here would cause diplopia when looking **down and out**. ### **High-Yield Clinical Pearls for NEET-PG** * **The "Rule of O's":** **O**bliques act **O**pposite to their name (Superior Oblique moves the eye down) and are tested in **A**dduction (**O**bliques = **A**dduction). * **Rectus Muscles:** All Recti (except Medial/Lateral) are tested in **Abduction**. * **Superior Rectus Palsy:** Often associated with ptosis because the SR and Levator Palpebrae Superioris (LPS) share a common embryological origin and nerve supply (CN III). * **Parks Three-Step Test:** Used specifically to identify the palsied muscle in vertical diplopia (most commonly the Superior Oblique).

Q: Which of the following is the commonest malignancy causing bilateral proptosis in the pediatric population?

Acute Myeloid Leukemia (AML). **Explanation:** The correct answer is **Acute Myeloid Leukemia (AML)**. In the pediatric population, leukemia is a leading cause of orbital metastasis. Specifically, **AML (FAB M2 subtype)** is the most common malignancy to cause **bilateral proptosis** due to orbital infiltration. This clinical presentation is known as **Granulocytic Sarcoma (Chloroma)**—a solid tumor composed of leukemic myeloblasts. It often presents with a rapid onset of proptosis, ecchymosis of the eyelids, and may even precede systemic bone marrow involvement. **Analysis of Incorrect Options:** * **Acute Lymphoblastic Leukemia (ALL):** While ALL is the most common childhood leukemia overall, it is significantly less likely than AML to cause orbital infiltration and proptosis. * **Retinoblastoma:** This is the most common primary intraocular malignancy in children. While it can cause proptosis if it spreads extraocularly, it typically presents as **leukocoria** (white pupillary reflex) and is usually unilateral. Bilateral proptosis from retinoblastoma is rare and signifies advanced, neglected disease. * **Rhabdomyosarcoma:** This is the most common **primary orbital malignancy** in children. It typically presents as a very rapid, **unilateral** proptosis. **High-Yield Clinical Pearls for NEET-PG:** * **Commonest cause of unilateral proptosis (Pediatric):** Orbital Cellulitis (Inflammatory). * **Commonest primary orbital malignancy (Pediatric):** Rhabdomyosarcoma. * **Commonest secondary orbital malignancy (Pediatric):** Neuroblastoma (often presents with "raccoon eyes" or periorbital ecchymosis). * **Commonest cause of bilateral proptosis (Pediatric):** AML (Chloroma). * **Commonest cause of bilateral proptosis (Adults):** Thyroid Eye Disease.

Q: Pseudoexotropia is associated with:

Positive angle kappa. **Explanation:** Pseudoexotropia refers to a clinical appearance of an outward deviation of the eyes (exotropia) when no actual ocular misalignment is present. **Why Positive Angle Kappa is correct:** The **Angle Kappa** is the angle between the visual axis (line from the fovea to the object of regard) and the pupillary axis (line through the center of the pupil). * In a **Positive Angle Kappa**, the fovea is situated slightly temporal to the posterior pole, causing the eye to shift slightly outward to align the visual axis. * This results in the light reflex being displaced nasally, mimicking the appearance of exotropia. While a small positive angle is physiological, an abnormally large one causes pseudoexotropia. **Analysis of Incorrect Options:** * **A. Prominent epicanthal fold:** This is the most common cause of **pseudotropia**, specifically **pseudoesotropia**. The skin folds cover the nasal sclera, making the eyes appear turned inward, especially on lateral gaze. * **C. Negative angle kappa:** This occurs when the fovea is nasal to the pupillary axis. It causes the light reflex to be displaced temporally, creating the appearance of an inward deviation or **pseudoesotropia**. It is commonly seen in high myopia or retinopathy of prematurity (due to macular dragging). **High-Yield Clinical Pearls for NEET-PG:** 1. **Cover-Uncover Test:** The definitive way to differentiate pseudotropia from true strabismus is the absence of any corrective movement during the cover test. 2. **Hirschberg Test:** In pseudoexotropia, the corneal light reflex is displaced nasally, but remains stationary when one eye is covered. 3. **Associations:** Large positive angle kappa is often associated with **hypertelorism** (increased distance between the orbits).

Q: Vision is tested in the newborn by?

Visual Evoked Potentials. **Explanation:** The assessment of vision in newborns is challenging because they cannot provide subjective feedback. Therefore, objective electrophysiological or behavioral methods must be used. **Why Visual Evoked Potentials (VEP) is the Correct Answer:** VEP measures the electrical activity of the visual cortex in response to light stimuli (flash or pattern). It is the most sensitive objective method to assess the **entire visual pathway**, from the retina to the occipital cortex. In newborns, "Flash VEP" is typically used to confirm that the visual signals are reaching the brain, making it the gold standard for assessing functional integrity of the visual system in non-verbal infants. **Analysis of Incorrect Options:** * **A. Electrooculogram (EOG):** This measures the resting potential between the cornea and the retina (the standing potential). It primarily assesses the health of the **Retinal Pigment Epithelium (RPE)** and is not a test of visual acuity or cortical vision. * **B. Electroretinogram (ERG):** This measures the electrical response of the **retinal layers** (photoreceptors and inner retinal cells) to light. While it confirms the retina is functioning, it cannot determine if the brain is "seeing" the signal. * **D. Brainstem Response Assessment (BERA/BAER):** This is a gold-standard screening test for **hearing**, not vision. It measures the electrical activity of the auditory pathway up to the brainstem. **NEET-PG High-Yield Pearls:** * **Preferential Looking (Teller Acuity Cards):** The most common **behavioral** method to assess vision in infants. * **Optokinetic Nystagmus (OKN):** Another objective method; the presence of nystagmus in response to a moving drum indicates intact subcortical visual pathways. * **Fix and Follow:** Usually develops by 6–8 weeks of age. * **Visual Acuity at Birth:** Approximately 6/60 to 6/120; it reaches adult levels (6/6) by 3–5 years of age.

Q: Dissociated vertical deviation is seen in which of the following conditions?

Vertical deviation on looking down. **Explanation:** **Dissociated Vertical Deviation (DVD)** is a unique ocular motility disorder characterized by the upward drifting and outward rotation of an eye when it is covered (occluded) or when the patient is fatigued/inattentive. **Why Option C is Correct:** The hallmark of DVD is that the deviating eye moves **upward** when dissociated (covered). However, according to **Bielschowsky’s Phenomenon**, if increasing neutral density filters are placed over the fixating eye, the dissociated (elevated) eye will gradually move **downward** (below the midline). This paradoxical downward movement upon stimulation/fixation changes is a classic clinical feature, making "vertical deviation on looking down" the characteristic finding in specific clinical tests for DVD. **Why Other Options are Incorrect:** * **Option A:** While the eye drifts "up" during dissociation, "vertical deviation on looking up" usually refers to overaction of the inferior oblique muscle, which is a separate entity (though often co-exists with DVD). * **Options B & D:** DVD is primarily a vertical and torsional deviation. While it often has an associated outward (exotropic) component, it is not defined as a horizontal deviation on looking in or out. **High-Yield Clinical Pearls for NEET-PG:** * **Association:** DVD is most commonly associated with **Infantile Esotropia** (seen in 50-90% of cases). * **Bilateral but Asymmetric:** It is usually bilateral but often asymmetrical. * **Hering’s Law Violation:** DVD is unique because it **defies Hering’s Law** of equal innervation (the eye drifts up without a corresponding downward movement of the other eye). * **Management:** Surgical intervention (e.g., Superior Rectus recession) is indicated only if the deviation is cosmetically significant.

Q: A 22-year-old emmetropic male has exotropia in his right eye. What surgical intervention is indicated to correct this to an orthophoric state?

Lateral rectus recession without glasses. **Explanation:** The patient presents with **Exotropia** (outward deviation of the eye). To correct this surgically, the goal is to either weaken the "pull" of the lateral muscle or strengthen the "pull" of the medial muscle. 1. **Why Option D is correct:** A **Lateral Rectus (LR) recession** is a weakening procedure where the muscle is detached and reattached further back on the globe. This reduces its outward pull, allowing the eye to return to an orthophoric (straight) position. Since the patient is **emmetropic** (normal refractive state), no corrective glasses (convex or concave) are required post-surgery. 2. **Why the other options are incorrect:** * **Option A:** Medial rectus recession would weaken the inward pull, worsening the exotropia. Convex lenses are used for accommodative esotropia, not exotropia. * **Option B:** While LR recession is correct, **convex lenses** (plus lenses) relax accommodation and can actually worsen an exotropia by decreasing accommodative convergence. * **Option C:** **Resection** is a strengthening procedure. Resecting the Lateral Rectus would pull the eye further outward, severely aggravating the exotropia. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** To correct a deviation, **Recess** (weaken) the muscle in the direction of the deviation or **Resect** (strengthen) the muscle opposite to the deviation. * **Exotropia Surgery:** Standard approach is Bilateral LR Recession or Unilateral LR Recession + Medial Rectus Resection (R&R). * **Refraction & Squint:** Hypermetropia is associated with Esotropia (due to over-accommodation); Myopia is often associated with Exotropia. * **Prism Base:** Exotropia is measured/corrected with a **Base-In (BI)** prism.

Q: Which of the following is FALSE regarding incomitant squint?

The primary deviation is equal to the secondary deviation.. In incomitant squint (paralytic or restrictive), the angle of deviation varies with the direction of gaze and the eye used for fixation. **Explanation of the Correct Answer:** **Option D is FALSE** because in incomitant squint, the **secondary deviation is always greater than the primary deviation**. This is based on **Desmarres’ Law** (derived from Hering’s Law of equal innervation). When the paretic eye fixates (secondary deviation), the brain sends excessive nervous impulse to the weak muscle to move it; according to Hering’s Law, an equal amount of increased innervation is sent to the yoke muscle of the sound eye, causing it to overact and produce a larger deviation. In contrast, primary and secondary deviations are equal only in **comitant (non-paralytic) squint**. **Analysis of Incorrect Options:** * **Option A:** True. Incomitant squints (due to trauma, vascular issues like diabetes, or tumors) are the most common type of squint seen in adults, whereas comitant squints are more common in children. * **Option B:** True. Paralysis or paresis of one or more extraocular muscles (e.g., 6th nerve palsy) is the hallmark of paralytic incomitant squint. * **Option C:** True. Limitation of ocular movement in the field of action of the paralyzed muscle is a characteristic clinical finding. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Deviation:** Deviation of the affected eye when the normal eye fixates. * **Secondary Deviation:** Deviation of the normal eye when the affected eye fixates. * **Diplopia:** Incomitant squints typically present with binocular diplopia, which is maximal in the field of action of the paralyzed muscle. * **Compensatory Head Posture:** Patients often adopt a head tilt or face turn to minimize diplopia and maintain binocular single vision.

Question 1

Which two muscles are primarily responsible for the elevation of the eye?

Accepted Answer

Superior Rectus (SR) and Inferior Oblique (IO)

Answer

Inferior Oblique (IO) and Superior Oblique (SO)

Answer

Inferior Rectus (IR) and Superior Oblique (SO)

Answer

Superior Oblique (SO) and Superior Rectus (SR)

Question 2

All of the following are true regarding paralytic squint, except:

Accepted Answer

Amblyopia

Answer

Head tilt

Answer

Lateral deviation

Answer

Diplopia

Question 3

A patient presents with diplopia when looking up and out. Which extraocular muscle is defective?

Accepted Answer

Right Superior rectus

Answer

Right Superior oblique

Answer

Left Superior oblique

Answer

Right Inferior rectus

Question 4

Which of the following is the commonest malignancy causing bilateral proptosis in the pediatric population?

Accepted Answer

Acute Myeloid Leukemia (AML)

Answer

Acute Lymphoblastic Leukemia (ALL)

Answer

Retinoblastoma

Answer

Rhabdomyosarcoma

Question 5

Inferior oblique muscle is most weakened by which surgical procedure?

Accepted Answer

Anteriorization

Answer

Disinsertion

Answer

Recession

Answer

Myotomy

Question 6

Pseudoexotropia is associated with:

Accepted Answer

Positive angle kappa

Answer

Prominent epicanthal fold

Answer

Negative angle kappa

Answer

None of the above

Question 7

Vision is tested in the newborn by?

Accepted Answer

Visual Evoked Potentials

Answer

Electrooculogram

Answer

Electroretinogram

Answer

Brainstem Response Assessment

Question 8

Dissociated vertical deviation is seen in which of the following conditions?

Accepted Answer

Vertical deviation on looking down

Answer

Vertical deviation on looking up

Answer

Horizontal deviation on looking in

Answer

Horizontal deviation on looking out

Question 9

A 22-year-old emmetropic male has exotropia in his right eye. What surgical intervention is indicated to correct this to an orthophoric state?

Accepted Answer

Lateral rectus recession without glasses

Answer

Medial rectus recession with convex lens prescription

Answer

Lateral rectus recession with convex lens prescription

Answer

Lateral rectus resection without glasses

Question 10

Which of the following is FALSE regarding incomitant squint?

Accepted Answer

The primary deviation is equal to the secondary deviation.

Answer

It is the most common type of squint in adults.

Answer

Paralysis of an extraocular muscle is often present.

Answer

Restricted ocular movements are typically observed.

Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus — MCQs

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