Pediatric Ophthalmology and Strabismus Practice Questions

Q: Uncrossed diplopia is seen in which of the following conditions?

Esotropia. ### Explanation The type of diplopia (double vision) experienced in strabismus is determined by the relationship between the deviated eye's position and the projection of the image on the retina. **1. Why Esotropia is Correct:** In **Esotropia** (convergent squint), the eye is deviated medially (inward). Because of this inward deviation, light from an object falls on the **nasal retina**. In the visual cortex, images falling on the nasal retina are projected to the **temporal visual field**. Therefore, the image seen by the right eye appears on the right side, and the image seen by the left eye appears on the left side. This is known as **Uncrossed (Homonymous) Diplopia**. **2. Why the other options are incorrect:** * **Exotropia (A):** In divergent squint, the eye turns outward, and light falls on the **temporal retina**. Images on the temporal retina are projected to the **nasal visual field**. Thus, the image from the right eye appears on the left side, resulting in **Crossed (Heteronymous) Diplopia**. * **Exophoria (B) and Esophoria (D):** These are "latent" squints. In phorias, the eyes are normally kept in alignment by sensory fusion. Diplopia only occurs when the deviation becomes manifest (tropia). While the *potential* for crossed or uncrossed diplopia exists if they break down, the question refers to the clinical manifestation seen in manifest deviations. **Clinical Pearls for NEET-PG:** * **Rule of Thumb:** * **E**sotropia = **U**ncrossed (Mnemonic: **E** is close to **U** in the alphabet, or "Esotropia stays on its own side"). * **E**xotropia = **C**rossed (Mnemonic: **X** looks like a **Cross**). * **Maddox Rod Test:** Used to differentiate these. In Esotropia, the red line is seen on the same side as the red filter. * **False Macula:** In long-standing childhood strabismus, diplopia may disappear due to **suppression** or **abnormal retinal correspondence (ARC)**.

Q: Typical coloboma of the iris occurs:

Inferonasally. **Explanation:** The correct answer is **Inferonasally (Option A)**. **1. Why Inferonasally is correct:** A typical coloboma is a congenital defect resulting from the **incomplete closure of the embryonic (optic) fissure** during the 5th to 7th week of intrauterine life. In normal development, this fissure closes from the center, extending anteriorly and posteriorly. The final point of closure is located in the **inferonasal quadrant**. Failure of this fusion leads to a gap in the ocular tissues, most commonly affecting the iris, ciliary body, choroid, or optic nerve. **2. Why other options are incorrect:** * **Options B, C, and D:** These locations do not correspond to the anatomical site of the embryonic fissure. Any coloboma occurring in these quadrants is termed an **atypical coloboma**. Atypical colobomas are not caused by fissure closure defects but may result from intrauterine inflammation, trauma, or persistent pupillary membranes. **3. Clinical Pearls for NEET-PG:** * **Appearance:** A typical iris coloboma gives the pupil a characteristic **"keyhole" appearance**. * **Associations:** It is a key component of the **CHARGE syndrome** (Coloboma, Heart defects, Atresia choanae, Retardation of growth, Genitourinary anomalies, and Ear anomalies). * **Extent:** It can be "complete" (extending from the pupil to the root) or "incomplete" (not involving the full thickness or length). * **Vision:** Iris colobomas alone usually cause photophobia; however, if the coloboma involves the optic nerve or macula, significant visual acuity loss occurs.

Q: Secondary detorsion of the eye is an example of which of the following laws?

Herring's law. **Explanation:** **Hering’s Law of Equal Innervation** states that during any conjugate eye movement, equal and simultaneous innervation is sent to the **yoke muscles** (muscles in both eyes that move the eyes in the same direction). **Secondary detorsion** occurs during head tilting. When the head tilts to one side (e.g., the right), the vestibular system triggers a compensatory reflex: the right eye incyclotorts and the left eye excyclotorts to maintain a level image. Because this involves the coordinated action of yoke muscle pairs (e.g., Right Superior Oblique and Left Inferior Oblique) receiving simultaneous nervous impulses, it is a classic application of Hering’s Law. **Analysis of Incorrect Options:** * **Listing’s Law:** Describes the axes of rotation. It states that when the eye moves from the primary position to any other position, the axis of rotation lies in a single plane called Listing’s plane. * **Sherrington’s Law (Reciprocal Innervation):** Applies to a **single eye**. It states that when an agonist muscle contracts, its antagonist muscle simultaneously relaxes (e.g., when the Right Lateral Rectus contracts, the Right Medial Rectus relaxes). * **Donder’s Law:** States that for any given position of gaze, the orientation of the eye (torsion) is always the same, regardless of the path the eye took to get there. **High-Yield Clinical Pearls for NEET-PG:** * **Hering’s Law Clinical Application:** It explains **"inhibitional palsy"** of the contralateral antagonist and why the **secondary deviation** is greater than the primary deviation in paralytic squint. * **Sherrington’s Law Clinical Application:** Failure of this law is seen in **Duane’s Retraction Syndrome**, where co-contraction of the medial and lateral recti occurs. * **Yoke Muscles:** Remember the "R-S-O" and "L-I-O" pairing for head tilting—essential for solving Bielschowsky head tilt test questions.

Q: The Worth 4 dot test is performed to assess:

Binocular vision function. ### Explanation The **Worth 4 Dot Test (W4DT)** is a clinical test used to assess **Binocular Single Vision (BSV)**, specifically to detect suppression, diplopia, and the presence of fusion. **Why the correct answer is right:** The test utilizes the principle of **dissociation** through color filters. The patient wears red-green goggles (Red over the right eye, Green over the left) and views four lights: one red, two green, and one white. * **Normal BSV:** The patient sees four dots (the white dot is fused by both eyes). * **Suppression:** If the patient sees only two red dots, the left eye is suppressed; if they see three green dots, the right eye is suppressed. * **Diplopia:** If the patient sees five dots, it indicates a lack of fusion (strabismus). **Why the incorrect options are wrong:** * **A. Color vision deficiency:** This is assessed using **Ishihara charts**, Hardy-Rand-Rittler (HRR) plates, or the Farnsworth-Munsell 100 hue test. * **B. Visual acuity:** This measures the clarity of vision, typically using the **Snellen chart** (distance) or Jaeger chart (near). * **D. Ocular alignment:** While W4DT can indicate a misalignment (diplopia), the primary tools for measuring alignment are the **Cover-Uncover test**, Hirschberg corneal reflex test, and Prism Cover Test. **High-Yield Clinical Pearls for NEET-PG:** * **Anomalous Retinal Correspondence (ARC):** A patient with a manifest squint who sees 4 dots on W4DT has ARC (harmonious). * **Testing Distance:** It is performed at both 6 meters (assesses central fusion) and 33 cm (assesses peripheral fusion). * **Suppression Scotoma:** W4DT is highly sensitive for detecting a central suppression scotoma, commonly seen in **Monofixation Syndrome**.

Q: What are the grades of binocular vision?

Grade 2: Fusion. **Explanation:** Binocular Single Vision (BSV) is the ability of both eyes to work together to perceive a single, three-dimensional image. According to **Worth’s Classification**, binocular vision is divided into three distinct grades of increasing complexity: 1. **Grade 1: Simultaneous Perception:** This is the most basic level. It is the ability of the brain to perceive two different images (one from each eye) at the same time. This is tested using a Synoptophore with dissimilar slides (e.g., a bird and a cage). 2. **Grade 2: Fusion (Correct Answer):** This is the intermediate level. The brain not only perceives both images but also blends them into a single composite picture. It involves a motor component (aligning the eyes) and a sensory component. This is tested using similar slides with minor "control" differences (e.g., two rabbits, one with a tail and one with a flower). 3. **Grade 3: Stereopsis:** This is the highest grade of binocular vision. It is the ability to perceive depth (3D vision) through the fusion of slightly disparate images from both eyes. **Analysis of Incorrect Options:** * **Grade 1: Fusion/Stereopsis (Options A & C):** Incorrect, as Grade 1 is strictly Simultaneous Perception. * **Grade 2: Stereopsis (Option D):** Incorrect, as Stereopsis represents the most advanced level, which is Grade 3. **High-Yield Clinical Pearls for NEET-PG:** * **Worth’s Four Dot Test (WFDT):** A common clinical test used to assess BSV and detect suppression or diplopia. * **Titmus Fly Test:** The gold standard for assessing **Stereopsis** (Grade 3). * **Prism Cover Test:** Used to measure the motor component of fusion (fusion vergence). * **Suppression:** If the brain cannot fuse images (Grade 2), it may ignore the input from one eye to avoid double vision, leading to amblyopia.

Q: What is the primary action of the inferior oblique muscle?

Extorsion. To master the actions of the extraocular muscles for NEET-PG, it is essential to distinguish between primary, secondary, and tertiary actions based on the muscle's anatomical insertion and the visual axis. ### **Explanation** The **Inferior Oblique (IO)** originates from the orbital floor (medial side) and inserts into the posterior-temporal quadrant of the globe, passing under the inferior rectus. Because it inserts behind the equator at an angle of **51°** to the visual axis, its **primary action is Extorsion**. When the eye is adducted (turned inward), the muscle's pull aligns more closely with the visual axis, making **elevation** its secondary action. In abduction, its tertiary action is **abduction**. ### **Analysis of Options** * **C. Extorsion (Correct):** This is the primary action. Remember the mnemonic **"Obliques are Extors"** (Inferior Oblique extorts; Superior Oblique intorts). * **A. Adduction:** This is incorrect. The inferior oblique acts as a weak **abductor** (tertiary action). * **B. Depression:** This is the primary action of the **Inferior Rectus**. The Inferior Oblique acts as an **elevator**. * **D. Intorsion:** This is the primary action of the **Superior Oblique** (mnemonic: **SIN** – **S**uperior muscles are **In**torsionists). ### **High-Yield Clinical Pearls for NEET-PG** 1. **Mnemonic "SIN":** **S**uperior **I**ntort (Superior Oblique and Superior Rectus both intort the eye). By default, Inferior muscles extort. 2. **RAD Rule:** **R**ecti are **AD**ductors (except Lateral Rectus). Therefore, Obliques are Abductors. 3. **Testing Position:** To isolate the elevating action of the Inferior Oblique clinically, the patient is asked to look **up and in** (elevation in adduction). 4. **Nerve Supply:** All muscles are supplied by CN III except the Superior Oblique (CN IV) and Lateral Rectus (CN VI) — **LR6(SO4)3**.

Question 1

Uncrossed diplopia is seen in which of the following conditions?

Accepted Answer

Esotropia

Answer

Exotropia

Answer

Exophoria

Answer

Esophoria

Question 2

Typical coloboma of the iris occurs:

Accepted Answer

Inferonasally

Answer

Superonasally

Answer

Inferotemporally

Answer

Superotemporally

Question 3

What type of intraocular lens (IOL) is preferred in children?

Accepted Answer

Foldable acrylic lens

Answer

Foldable silicone lens

Answer

Three-piece PMMA lens

Answer

Single-piece PMMA lens

Question 4

A 3-year-old child with convergent squint requires refraction. Which of the following is the most appropriate pharmacological agent for cycloplegia?

Accepted Answer

Atropine ointment

Answer

Tropicamide eye drops

Answer

Atropine eye drops

Answer

Cyclopentolate eye drops

Question 5

Secondary detorsion of the eye is an example of which of the following laws?

Accepted Answer

Herring's law

Answer

Listing's law

Answer

Sherrington's law

Answer

Donder's law

Question 6

The Worth 4 dot test is performed to assess:

Accepted Answer

Binocular vision function

Answer

Color vision deficiency

Answer

Visual acuity

Answer

Ocular alignment

Question 7

What are the grades of binocular vision?

Accepted Answer

Grade 2: Fusion

Answer

Grade 1: Fusion

Answer

Grade 1: Stereopsis

Answer

Grade 2: Stereopsis

Question 8

A feature of paralytic squint is?

Accepted Answer

Associated with decreased vision

Answer

Detected by cover uncover test

Answer

Always divergent

Answer

Clinically called tropia

Question 9

What is the primary action of the inferior oblique muscle?

Accepted Answer

Extorsion

Answer

Adduction

Answer

Depression

Answer

Intorsion

Question 10

What is the most common cause of amblyopia?

Accepted Answer

Squint

Answer

Tobacco

Answer

Methyl Alcohol

Answer

Hypermetropia

Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus — MCQs

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