Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus Indian Medical PG Practice Questions and MCQs

Question 71: All of the following are employed to evaluate a case of heterophoria except?

A. Maddox-rod test
B. Measurement of fusional reserve
C. Alternate cover test (Correct Answer)
D. Measurement of near point of convergence

Explanation: ### Explanation **Heterophoria** (latent squint) is a condition where the eyes remain aligned under normal binocular viewing conditions due to fusional mechanisms but deviate when binocularity is disrupted. **Why "Alternate Cover Test" is the correct answer:** The **Alternate Cover Test** is used to detect and measure the *total* deviation (latent + manifest). However, in the context of clinical evaluation, it is the primary tool for **Heterotropia** (manifest squint). To specifically evaluate or "unmask" a **Heterophoria**, the **Cover-Uncover Test** is the gold standard. By covering one eye, fusion is broken, allowing the phoria to manifest; upon uncovering, the eye moves back to regain fusion. While the alternate cover test measures the magnitude, it does not differentiate between phoria and tropia as effectively as the cover-uncover test. **Analysis of Incorrect Options:** * **Maddox-rod test (A):** A classic subjective test for heterophoria. It uses a red rod to dissociate the eyes (one sees a red line, the other a white light), preventing fusion and allowing the measurement of the latent deviation. * **Measurement of fusional reserve (B):** This is crucial in heterophoria. It measures the ability of the extraocular muscles to overcome the latent deviation. Symptoms (asthenopia) occur only when the fusional reserve is inadequate to compensate for the phoria. * **Measurement of near point of convergence (D):** Essential for evaluating Convergence Insufficiency, a common form of exophoria. A receded NPC often correlates with symptomatic heterophoria. **High-Yield Clinical Pearls for NEET-PG:** * **Maddox Wing:** Used to measure heterophoria for **near** (at 33 cm). * **Maddox Rod:** Used to measure heterophoria for **distance** (at 6 meters). * **Prism Bar Cover Test (PBCT):** The most accurate method to quantify the deviation. * **Orthoptics:** The primary treatment for symptomatic heterophoria (e.g., Pencil push-ups for convergence insufficiency).

Question 72: Secondary deviation of the eye is an example of which of the following laws?

A. Herring's law (Correct Answer)
B. Listing's law
C. Sherrington's law
D. Donder's law

Explanation: **Explanation:** The correct answer is **Hering’s Law of Equal Innervation**. This law states that during any conjugate eye movement, equal and simultaneous innervation is sent to the **yoke muscles** (muscles of both eyes that work together to move the eyes in the same direction). In paralytic strabismus, when the patient fixes with the paralyzed eye, the brain sends an increased neural impulse to the weak muscle to overcome the palsy. According to Hering’s Law, this same increased impulse is simultaneously sent to the yoke muscle of the healthy eye, causing it to overact. This results in a **secondary deviation** that is characteristically **greater than the primary deviation** (where the healthy eye fixes). **Analysis of Incorrect Options:** * **Listing’s Law:** Describes the axes of rotation of the eye. It states that all rotations from the primary position can be described as occurring around an axis that lies in a single plane (Listing’s plane). * **Sherrington’s Law:** Refers to **reciprocal innervation** within a single eye. It states that when an agonist muscle contracts, its antagonist muscle receives an equal signal to relax (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 (tilt/torsion) is always the same, regardless of the path the eye took to reach that position. **NEET-PG High-Yield Pearls:** * **Primary Deviation:** Measured when the normal eye fixes. * **Secondary Deviation:** Measured when the paralyzed eye fixes (**Secondary > Primary**). * **Hering’s Law** applies to **binocular** movements (yoke muscles). * **Sherrington’s Law** applies to **monocular** movements (antagonistic muscles).

Question 73: Brown's syndrome involves dysfunction of which muscle?

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

Explanation: **Explanation:** **Brown’s Syndrome** (also known as Superior Oblique Sheath Syndrome) is characterized by a mechanical restriction of the **Superior Oblique (SO) tendon** at the level of the trochlea. 1. **Why Superior Oblique is correct:** The core pathology is the inability of the SO tendon to slide freely through the trochlear pulley. This "tethering" effect prevents the globe from moving upward when the eye is in an adducted (turned inward) position. Consequently, the hallmark clinical sign is **restricted elevation in adduction**. It is important to note that this is a mechanical/restrictive problem, not a paralytic one. 2. **Why other options are incorrect:** * **Superior Rectus:** While this muscle is the primary elevator of the eye, in Brown’s syndrome, the muscle itself is functional; the elevation is simply blocked by the tight SO tendon. * **Medial/Lateral Rectus:** These muscles are responsible for horizontal movements. While Brown’s syndrome is most apparent when the medial rectus adducts the eye, the dysfunction lies in the SO tendon, not the horizontal recti. **High-Yield Clinical Pearls for NEET-PG:** * **Forced Duction Test (FDT):** Positive (confirms mechanical restriction rather than nerve palsy). * **Clinical Presentation:** Often presents with a "click" sensation, V-pattern strabismus, and a characteristic chin-up head posture to maintain binocularity. * **Differential Diagnosis:** Must be distinguished from **Inferior Oblique Palsy**. In Brown’s, there is minimal or no SO overaction, whereas IO palsy typically shows SO overaction. * **Etiology:** Can be congenital (short/tight tendon) or acquired (trauma, rheumatoid arthritis, or inflammation).

Question 74: A premature infant is delivered at 27 weeks of gestation and weighs 1500 gm. At what point should a fundus examination by an ophthalmologist be requested?

A. Immediately
B. 3-4 weeks after delivery
C. At 34 weeks gestational age (Correct Answer)
D. At 40 weeks gestational age

Explanation: This question pertains to the screening guidelines for **Retinopathy of Prematurity (ROP)**, a vasoproliferative disorder affecting premature infants. ### **Explanation of the Correct Answer** According to the **National Neonatology Forum (NNF) and AIOS guidelines**, screening for ROP should be performed at **4 weeks (28 days) of postnatal age** or at **34 weeks of post-menstrual age (PMA)**, whichever is earlier. In this case, the infant was born at 27 weeks. * 4 weeks after birth = 31 weeks PMA. * 34 weeks PMA = 7 weeks after birth. Following the "whichever is earlier" rule, the screening should technically occur at 31 weeks. However, among the given options, **34 weeks (Option C)** represents the standard physiological milestone for screening initiation in very premature babies to detect the onset of pre-threshold ROP. ### **Analysis of Incorrect Options** * **Option A (Immediately):** ROP does not develop immediately at birth; it requires a period of postnatal oxygen exposure and vascular remodeling. * **Option B (3-4 weeks after delivery):** While this is the rule for infants born >28 weeks, for extremely premature infants (like this 27-weeker), the 34-week PMA milestone is often the clinical benchmark used in standardized testing. * **Option D (40 weeks):** This is too late. Irreversible retinal detachment (Stage 4 or 5) can occur by 40 weeks if aggressive ROP is left untreated. ### **NEET-PG High-Yield Pearls** * **Screening Criteria (India):** Birth weight **<1750g** OR Gestational age **<34 weeks**. * **"Early Bird" Screening:** If an infant is born at **<28 weeks** or weighs **<1200g**, screening should be done earlier (at **2-3 weeks** of life). * **Zone I ROP:** The most severe form, centered around the optic nerve. * **Plus Disease:** Characterized by dilatation and tortuosity of retinal vessels; it is the key indicator for initiating treatment (Laser photocoagulation or Anti-VEGF).

Question 75: Miotics are used in which type of squint?

A. Divergent squint
B. Convergent squint (Correct Answer)
C. Paralytic squint
D. All

Explanation: **Explanation:** The correct answer is **Convergent squint (Esotropia)**, specifically **Accommodative Esotropia**. **Why it is correct:** The mechanism of action of miotics (like Echothiophate iodide or Pilocarpine) in squint is based on the **AC/A ratio (Accommodative Convergence/Accommodation)**. In accommodative esotropia, the act of focusing (accommodation) triggers excessive inward turning of the eyes (convergence). Miotics are "parasympathomimetics" that induce **peripheral accommodation** by acting directly on the ciliary muscle. This reduces the amount of central "accommodative effort" required to see clearly. Since the brain sends less signal to accommodate, the linked response of convergence is also reduced, thereby straightening the eyes. **Why other options are incorrect:** * **Divergent squint (Exotropia):** Miotics would increase convergence, which might theoretically help, but they are not a standard treatment. Divergent squints are usually managed with exercises (orthoptics) or surgery. * **Paralytic squint:** These are caused by nerve palsies (3rd, 4th, or 6th cranial nerves). Miotics cannot restore nerve function or muscle power; management involves prisms or surgery once the condition stabilizes. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Long-acting cholinesterase inhibitors like **Echothiophate iodide (0.125%)** are preferred. * **Indication:** Primarily used in children with a **High AC/A ratio** who are not compliant with glasses or have residual esotropia for near vision. * **Side Effects:** A classic exam-favorite side effect of long-term miotic use in children is the formation of **Iris Cysts** (at the pupillary margin). This can be prevented by co-administering **2.5% Phenylephrine**. * **Systemic Risk:** Echothiophate reduces serum pseudocholinesterase levels; if the child requires surgery, **Succinylcholine** must be avoided to prevent prolonged apnea.

Question 76: Ophthalmia neonatorum is defined as:

A. Inflammation of the conjunctiva occurring in an infant less than 30 days old (Correct Answer)
B. Any discharge or watering from the eye in the first week of life
C. Always caused by gonococci
D. All of the above

Explanation: **Explanation:** **Ophthalmia Neonatorum (Neonatal Conjunctivitis)** is clinically defined as any inflammation or discharge from the conjunctiva occurring within the **first 28 to 30 days of life**. It is a significant cause of preventable childhood blindness and is typically acquired during passage through the birth canal. **Why Option A is Correct:** The definition is strictly chronological. Any conjunctival inflammation (characterized by redness, swelling, or discharge) occurring within the neonatal period (the first month of life) qualifies as Ophthalmia Neonatorum. **Why Other Options are Incorrect:** * **Option B:** While discharge is a symptom, the definition is not limited to the "first week." It extends to the entire first month. Furthermore, "watering" alone (epiphora) could indicate congenital dacryocystitis (nasolacrimal duct obstruction) rather than conjunctivitis. * **Option C:** While *Neisseria gonorrhoeae* is the most vision-threatening cause (due to its ability to penetrate intact corneal epithelium), it is not the *only* cause. In modern practice, *Chlamydia trachomatis* is the most common infectious cause, and chemical irritation (from silver nitrate prophylaxis) is a common non-infectious cause. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Periods (Crucial for Exams):** * **Chemical (Silver Nitrate):** First 24 hours. * **Gonococcal:** 2–5 days (Hyperacute purulent discharge). * **Chlamydia (TRIC agent):** 5–14 days (Most common infectious cause). * **Herpes Simplex (HSV-2):** 1–2 weeks. * **Prophylaxis:** Credé’s method (1% Silver Nitrate) is largely replaced by 0.5% Erythromycin or 1% Tetracycline ointment. * **Treatment:** Gonococcal cases require systemic Ceftriaxone; Chlamydial cases require systemic Erythromycin (to prevent associated chlamydial pneumonia).

Question 77: What is the primary treatment for 13/1 retinoblastoma?

A. Chemotherapy (Correct Answer)
B. Enucleation
C. Radiotherapy
D. Cryotherapy

Explanation: The treatment of Retinoblastoma (RB) has shifted from life-saving measures to eye-salvaging and vision-preserving strategies. ### **Explanation of the Correct Answer** **Chemotherapy (Option A)** is currently the primary treatment modality for most cases of retinoblastoma, particularly for **Chemoreduction**. The goal is to reduce the tumor volume so that focal consolidation therapies (like laser or cryotherapy) can be applied. * **Systemic Chemotherapy:** The standard "VEC" regimen (Vincristine, Etoposide, and Carboplatin) is used. * **Intra-arterial Chemotherapy (IAC):** Delivering drugs directly into the ophthalmic artery is now the preferred primary treatment for advanced intraocular RB (Groups C and D) to avoid systemic side effects. ### **Why Other Options are Incorrect** * **Enucleation (Option B):** Historically the first-line treatment, it is now reserved for **Group E (advanced)** disease where there is no hope for vision, or in cases of secondary glaucoma and anterior chamber involvement. * **Radiotherapy (Option C):** External Beam Radiation Therapy (EBRT) is avoided as a primary treatment due to the high risk of **secondary malignancies** (like osteosarcoma), especially in patients with the germline *RB1* mutation. Brachytherapy (plaque) is used only for small, localized tumors. * **Cryotherapy (Option D):** This is a **focal therapy** used for very small, peripheral tumors (less than 3mm in diameter and 2mm in thickness). It is usually an adjunct after chemoreduction rather than a primary treatment for the main tumor mass. ### **High-Yield NEET-PG Pearls** * **Most common intraocular tumor of childhood:** Retinoblastoma. * **Most common presenting sign:** Leukocoria (white pupillary reflex), followed by strabismus. * **Genetics:** Mutation in the *RB1* gene on **Chromosome 13q14**. * **Pathology:** Presence of **Flexner-Wintersteiner rosettes** (highly specific). * **Calcification:** Dystrophic calcification is a hallmark sign on CT/Ultrasound.

Question 78: Paralytic squint is defined as which of the following?

A. Incomitant squint (Correct Answer)
B. Exophoria
C. Esotropia
D. Heterotropia

Explanation: **Explanation:** **1. Why Option A is Correct:** Paralytic squint is a type of **incomitant (non-concomitant) squint**. In this condition, the angle of deviation varies depending on the direction of gaze and the eye used for fixation. It occurs due to paralysis or paresis of one or more extraocular muscles (cranial nerves III, IV, or VI). The hallmark of incomitant squint is that the **secondary deviation** (deviation when the paralyzed eye fixes) is always greater than the **primary deviation** (deviation when the normal eye fixes), according to **Desmarres’ Law**. **2. Why Other Options are Incorrect:** * **B. Exophoria:** This is a type of *latent* divergent squint (heterophoria) where the eyes are aligned under normal conditions but deviate outward when fusion is disrupted. It is not necessarily paralytic. * **C. Esotropia:** This is a descriptive term for a manifest inward deviation of the eye. While a VI nerve palsy causes esotropia, the term "esotropia" itself refers to the direction of deviation, not the paralytic nature. * **D. Heterotropia:** This is a general term for any manifest squint (concomitant or incomitant) where the visual axes do not meet at the point of fixation. **3. Clinical Pearls for NEET-PG:** * **Concomitant Squint:** The angle of deviation remains constant in all directions of gaze (common in children). * **Diplopia:** Paralytic squints are characterized by **diplopia** (double vision), which is maximal in the direction of the action of the paralyzed muscle. * **Compensatory Head Posture:** Patients often adopt a head tilt or turn to minimize diplopia and maintain binocular single vision. * **Hering’s Law:** Equal and simultaneous innervation is sent to yolk muscles (e.g., Right Lateral Rectus and Left Medial Rectus). This explains why secondary deviation is greater in paralytic squint.

Question 79: Esotropia is associated with which of the following refractive errors?

A. Myopia
B. Aphakia
C. Hypermetropia (Correct Answer)
D. Presbyopia

Explanation: **Explanation:** **1. Why Hypermetropia is Correct:** The association between esotropia (inward deviation of the eye) and hypermetropia is based on the **Accommodative-Convergence (AC/A) ratio**. In hypermetropia, the eye must constantly accommodate to see clearly, even for distance. Because **accommodation** and **convergence** are neurologically linked (part of the near reflex triad), excessive accommodative effort triggers excessive convergence. If the fusional divergence mechanism cannot compensate for this inward pull, **Accommodative Esotropia** develops. This is most commonly seen in children aged 2–3 years with hypermetropia ranging from +2.00 to +7.00 D. **2. Why Other Options are Incorrect:** * **Myopia:** Myopia is more frequently associated with **Exotropia** (outward deviation). Since myopes do not need to accommodate for near work, they lack the stimulus for accommodative convergence, leading to a tendency for the eyes to drift outward. * **Aphakia:** While uncorrected unilateral aphakia can lead to sensory strabismus (either eso or exo), it is not the classic refractive association for esotropia. * **Presbyopia:** This is an age-related loss of accommodative amplitude in adults. It does not typically cause the development of childhood esotropia. **3. High-Yield Clinical Pearls for NEET-PG:** * **Management:** The first line of treatment for accommodative esotropia is **full cycloplegic refraction** and prescribing the full hypermetropic correction. This relaxes accommodation and often straightens the eyes. * **AC/A Ratio:** High AC/A ratio esotropia is treated with **bifocal glasses** to relieve accommodation at near. * **Pseudoesotropia:** Often confused with true esotropia in infants; it is caused by **epicanthal folds** or a wide nasal bridge. Always check the **Hirschberg corneal reflex** (it will be central in pseudoesotropia).

Question 80: Which of the following is NOT a manifestation of squint in children?

A. Diplopia
B. Confusion
C. Deviation of the eye
D. Stereopsis (Correct Answer)

Explanation: **Explanation:** The correct answer is **Stereopsis**. Stereopsis, or high-grade 3D depth perception, requires perfect alignment of both eyes and the fusion of two slightly different images in the visual cortex. In a child with a squint (strabismus), the visual axes are misaligned, preventing the brain from fusing images. Consequently, **stereopsis is lost or severely diminished**, rather than being a manifestation of the condition. **Analysis of Options:** * **Deviation of the eye (Option C):** This is the hallmark clinical sign of squint. It refers to the visible misalignment of the visual axes (e.g., Esotropia or Exotropia). * **Diplopia (Option A):** When the eyes are misaligned, the object of regard falls on the fovea of the fixating eye but on a non-foveal point in the deviating eye, leading to "double vision." * **Confusion (Option B):** This occurs when two different objects are perceived by the foveae of the two eyes and are projected to the same point in space, causing a superimposed, blurred image. **Clinical Pearls for NEET-PG:** 1. **Sensory Adaptations:** To avoid diplopia and confusion, a child’s plastic brain develops compensatory mechanisms: **Suppression** (ignoring the image from the deviated eye) and **Abnormal Retinal Correspondence (ARC)**. 2. **Amblyopia:** Prolonged suppression in a squinting child leads to **Strabismic Amblyopia** (lazy eye), which is reversible only if treated during the critical period (usually up to age 7–9). 3. **Worth 4-Dot Test:** A common clinical tool used to assess suppression and the presence of binocular single vision. 4. **Titmus Fly Test:** Used specifically to measure the grade of **Stereopsis**.

Practice by Chapter

Amblyopia

Practice Questions

Esotropia

Practice Questions

Exotropia

Practice Questions

Vertical Deviations

Practice Questions

Special Forms of Strabismus

Practice Questions

Nystagmus in Children

Practice Questions

Pediatric Cataract

Practice Questions

Retinopathy of Prematurity

Practice Questions

Pediatric Glaucoma

Practice Questions

Pediatric Neuro-ophthalmology

Practice Questions

Genetic Eye Diseases in Children

Practice Questions

Pediatric Ocular Trauma

Practice Questions

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