Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus Indian Medical PG Practice Questions and MCQs

Question 181: Which of the following tests are appropriate for visual testing in a child?

A. Visual evoked potential and Teller's acuity card test
B. Visual evoked potential
C. Visual evoked potential and Keratometry
D. Visual evoked potential and Teller's acuity card test (Correct Answer)

Explanation: **Explanation:** Assessment of visual acuity in children requires specialized techniques because infants and toddlers are non-verbal and cannot cooperate with standard Snellen charts. **Why Option D is Correct:** Visual assessment in children is categorized into objective and subjective (behavioral) methods: * **Visual Evoked Potential (VEP):** This is an **objective** electrophysiological test. It measures the electrical response of the visual cortex to retinal stimulation. It is highly useful in infants or children with developmental delays as it does not require active participation. * **Teller’s Acuity Cards:** This is a **subjective/behavioral** test based on the principle of **Preferential Looking**. Infants naturally prefer to look at patterned stimuli (stripes) rather than a plain background. By observing the child's head or eye movements toward cards with varying spatial frequencies (grating acuity), the clinician can estimate visual acuity. **Analysis of Incorrect Options:** * **Option B:** While VEP is correct, it is incomplete. Clinical practice utilizes both electrophysiological and behavioral tests (like Teller’s) to get a comprehensive picture of a child's vision. * **Option C:** **Keratometry** measures the curvature of the anterior corneal surface. While used to calculate IOL power or assess astigmatism, it is not a test for visual acuity. **NEET-PG High-Yield Pearls:** * **Preferential Looking Tests:** Include Teller’s Acuity Cards, Cardiff Acuity Cards (uses pictures), and Keeler Cards. * **Optokinetic Nystagmus (OKN):** Another objective method where an infant follows moving stripes on a rotating drum. * **Fix and Follow:** The simplest clinical assessment; a child should be able to "fix and follow" a bright object by **3 months** of age. * **Sheridan Gardiner Test:** Uses "HOTV" letters; ideal for preschool children (3–5 years) who can match letters but not yet read the alphabet.

Question 182: A child presents with a unilateral white reflex and raised intraocular pressure (IOP). What are the required investigations?

A. Ultrasonography (USG)
B. Observation under anesthesia
C. Tonometry
D. All of the above (Correct Answer)

Explanation: ### Explanation The clinical presentation of a **unilateral white reflex (leukocoria)** associated with **raised intraocular pressure (IOP)** in a child is a classic red flag for **Retinoblastoma**. In pediatric patients, leukocoria necessitates an urgent and thorough workup to differentiate life-threatening malignancies from other conditions like Coats' disease or persistent fetal vasculature. **Why "All of the Above" is Correct:** Managing a child with suspected intraocular pathology requires a multi-modal approach, often under **Examination Under Anesthesia (EUA)** because children are typically non-compliant with slit-lamp or formal fundus exams. * **Ultrasonography (USG B-Scan):** This is the most crucial initial imaging tool. It helps identify an intraocular mass and is highly sensitive for detecting **calcification** (the "pathognomonic" sign of Retinoblastoma). * **Observation Under Anesthesia (EUA):** This allows for a detailed 360-degree evaluation of the retina using indirect ophthalmoscopy and scleral depression to determine the size and extent of the tumor. * **Tonometry:** Since the patient has raised IOP (secondary glaucoma), measuring the pressure (using a Schiotz or Perkins tonometer) is essential to assess the severity of the disease and the risk of optic nerve damage or extraocular extension. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of Leukocoria:** Congenital Cataract. * **Most common intraocular malignancy in children:** Retinoblastoma. * **Secondary Glaucoma in Retinoblastoma:** Usually occurs due to neovascularization of the iris (NVI) or forward displacement of the lens-iris diaphragm by a large endophytic mass. * **Imaging Gold Standard:** While USG is the first-line, **MRI** is the investigation of choice to check for optic nerve involvement or intracranial (trilateral) extension. **CT is generally avoided** due to radiation risk in children with the RB1 mutation.

Question 183: For preventing Retinopathy of Prematurity, what concentration of oxygen should be maintained?

A. 20-30%
B. 30-40%
C. 50-60% (Correct Answer)
D. 60-70%

Explanation: **Explanation:** Retinopathy of Prematurity (ROP) is a vasoproliferative disorder affecting the incomplete vascularization of the retina in preterm infants. The primary pathophysiology involves two phases: initial hyperoxia causing vaso-obliteration, followed by relative hypoxia triggering compensatory but pathological neovascularization. **Why 50-60% is the correct answer:** In clinical practice, the goal is to balance the prevention of ROP with the prevention of respiratory distress syndrome and cerebral hypoxia. For a premature infant requiring supplemental oxygen, maintaining an inspired oxygen concentration (FiO2) of **50-60%** is considered the threshold to prevent the severe hyperoxic insult that triggers ROP, while ensuring systemic stability. This range is historically cited in standard ophthalmology textbooks (like Khurana) as the target for preventing ROP. **Analysis of Incorrect Options:** * **A (20-30%) & B (30-40%):** These concentrations are often insufficient for premature infants with underdeveloped lungs (surfactant deficiency), leading to systemic hypoxia and increased mortality. * **D (60-70%):** Concentrations above 60% significantly increase the risk of oxygen toxicity, leading to both ROP and Bronchopulmonary Dysplasia (BPD). **High-Yield Clinical Pearls for NEET-PG:** * **Target SpO2:** Modern neonatal guidelines (SUPPORT trial) recommend maintaining oxygen saturation between **85-93%** or **91-95%**; however, for exam purposes, the FiO2 concentration remains a classic question. * **Screening Criteria:** Infants with birth weight **<1500g** or gestational age **<32 weeks** must be screened. * **First Screening:** Should be done at **4 weeks** post-natal age or **31 weeks** post-menstrual age (whichever is later). * **Zone I** involvement is the most severe. * **Plus Disease:** Characterized by dilatation and tortuosity of retinal vessels at the posterior pole; it is a key indicator for treatment.

Question 184: Secondary deviation of the eye is based on which law?

A. Hering's law
B. Sherrington's law (Correct Answer)
C. Brown's law
D. Duane's law

Explanation: The correct answer is **Sherrington’s Law of Reciprocal Innervation**. ### **Explanation of the Correct Answer** **Sherrington’s Law** states that when an agonist muscle contracts, its direct antagonist muscle receives an equal and opposite amount of inhibitory signal to relax. This allows for smooth, coordinated ocular movement. * **Secondary Deviation** refers to the deviation of the normal eye when the paralyzed eye is used for fixation. It occurs because the paretic muscle requires excessive nervous impulse to move the eye; according to **Hering’s Law**, this increased impulse is sent to the yoke muscle of the sound eye. * However, the **mechanism within a single eye** that allows the antagonist to relax while the paretic agonist struggles to contract is governed by **Sherrington’s Law**. In the context of paralytic strabismus, secondary deviation is always greater than primary deviation because of the interplay between these two laws. ### **Explanation of Incorrect Options** * **A. Hering’s Law:** This law states that equal and simultaneous innervation is sent to **yoke muscles** (muscles in both eyes that move the eyes in the same direction, e.g., Right LR and Left MR). While Hering's law explains why the sound eye overshoots, the fundamental physiological principle of muscle innervation balance is Sherrington's. * **C. Brown’s Law:** This is not a standard law of ocular motility. It is often confused with **Brown’s Syndrome**, a structural anomaly of the Superior Oblique tendon causing restricted elevation in adduction. * **D. Duane’s Law:** There is no "Duane’s Law." **Duane’s Retraction Syndrome** is a clinical condition involving co-contraction of the medial and lateral recti due to anomalous innervation. ### **High-Yield Clinical Pearls for NEET-PG** * **Primary Deviation:** Deviation of the paralyzed eye when the sound eye fixates. * **Secondary Deviation:** Deviation of the sound eye when the paralyzed eye fixates (**Secondary > Primary**). * **Sherrington’s Law** applies to **monocular** movement (Agonist/Antagonist). * **Hering’s Law** applies to **binocular** movement (Yoke muscles). * **Past-pointing (False Orientation):** A clinical feature of paralytic squint where the patient points beyond the object due to excessive innervation (Hering's Law).

Question 185: Diplopia is a characteristic feature of which type of squint?

A. Concomitant squint
B. Non-paralytic squint
C. Paralytic squint (Correct Answer)
D. Latent squint

Explanation: **Explanation:** **1. Why Paralytic Squint is the Correct Answer:** Diplopia (double vision) is the hallmark of **Paralytic (Incomitant) Squint**. It occurs because of a sudden loss of motor coordination between the two eyes due to nerve or muscle palsy. When the eyes are not aligned, the image of an object falls on the fovea of the unaffected eye but on a non-foveal (peripheral) retinal point in the paralyzed eye. This leads to **visual confusion** and the perception of two different images. In paralytic squint, the brain has not had time to develop compensatory mechanisms like suppression, making diplopia a primary symptom. **2. Why the Other Options are Incorrect:** * **Concomitant Squint (Option A) & Non-paralytic Squint (Option B):** These terms are often used interchangeably. In these cases, the angle of deviation remains constant in all directions of gaze. These usually develop in early childhood. Because the pediatric brain is plastic, it quickly employs compensatory mechanisms such as **suppression** (ignoring the image from the deviated eye) or **amblyopia**, thereby preventing diplopia. * **Latent Squint (Option D):** Also known as **Heterophoria**, this is a condition where the deviation is kept hidden by the power of sensory fusion. Diplopia does not occur because the eyes remain straight under normal binocular viewing conditions; the squint only becomes manifest when fusion is disrupted (e.g., covering one eye). **3. High-Yield Clinical Pearls for NEET-PG:** * **Secondary Deviation > Primary Deviation:** In paralytic squint, the deviation is greater when the paralyzed eye is used for fixation. * **False Orientation (Past-pointing):** A characteristic feature of paralytic squint where the patient points beyond the object in the direction of the paralyzed muscle’s action. * **Compensatory Head Posture:** Patients often tilt or turn their heads to minimize diplopia and maintain binocular single vision. * **Hering’s Law of Equal Innervation** explains why secondary deviation is greater than primary deviation.

Question 186: Which childhood malignancy commonly produces proptosis?

A. Neuroblastoma
B. Retinoblastoma
C. Nephroblastoma
D. All of the above (Correct Answer)

Explanation: **Explanation:** Proptosis (protrusion of the eyeball) in children is a critical clinical sign that often indicates an underlying malignancy, either through direct orbital involvement or metastatic spread. * **Neuroblastoma:** This is the **most common metastatic orbital tumor** in children. It typically originates from the adrenal glands or sympathetic chain. Metastasis to the orbital bones (specifically the zygomatic bone) leads to rapid-onset proptosis, often accompanied by characteristic periorbital ecchymosis known as **"Raccoon eyes."** * **Retinoblastoma:** While primarily an intraocular tumor, advanced cases can exhibit **extraocular extension**. Once the tumor breaches the sclera or invades the optic nerve, it enters the orbital space, leading to significant proptosis and a fungating mass. * **Nephroblastoma (Wilms Tumor):** Although less common than neuroblastoma, Wilms tumor is a known primary site that can metastasize to the orbit, resulting in secondary proptosis. **Clinical Pearls for NEET-PG:** * **Most common primary orbital malignancy in children:** Rhabdomyosarcoma (presents with sudden, painless proptosis). * **Most common intraocular tumor in children:** Retinoblastoma (presents with Leukocoria). * **Most common cause of bilateral proptosis in children:** Thyroid Eye Disease (though rare) or Neuroblastoma (metastatic). * **Differential Diagnosis Tip:** If a child presents with rapid proptosis and bruising, always prioritize Neuroblastoma in your differentials. If it presents with a "cherry-red" appearance and rapid growth, think Rhabdomyosarcoma.

Question 187: Pseudorosettes are a characteristic histological finding in which of the following conditions?

A. Retinoblastoma (Correct Answer)
B. Ophthalmic nodosa
C. Phacolytic glaucoma
D. Trachoma

Explanation: **Explanation:** **Retinoblastoma** is the most common intraocular malignancy of childhood. Histologically, it is characterized by the presence of rosettes, which represent attempts at retinal differentiation. The correct answer is **Retinoblastoma** because it classically exhibits two types of rosettes: 1. **Homer-Wright Rosettes (Pseudorosettes):** These consist of tumor cells arranged around a central tangle of neural fibrils (no central lumen). They are "pseudo" because they lack a true basement membrane or lumen. They are also seen in neuroblastoma and medulloblastoma. 2. **Flexner-Wintersteiner Rosettes (True Rosettes):** These are highly specific for retinoblastoma, featuring cells arranged around a central empty lumen. **Analysis of Incorrect Options:** * **B. Ophthalmic nodosa:** A granulomatous inflammatory reaction caused by caterpillar hairs (urshiol) entering the eye. Histology shows granulomas, not rosettes. * **C. Phacolytic glaucoma:** An inflammatory glaucoma caused by the leakage of lens proteins through an intact capsule in a hypermature cataract. Histology shows macrophages laden with lens material (eosinophilic) in the anterior chamber. * **D. Trachoma:** A chronic keratoconjunctivitis caused by *Chlamydia trachomatis*. Histology reveals **Leber cells** (large macrophages containing phagocytosed debris) and lymphoid follicles. **High-Yield Clinical Pearls for NEET-PG:** * **Most specific finding:** Flexner-Wintersteiner rosettes. * **Most common sign:** Leukocoria (white pupillary reflex). * **Calcification:** Dystrophic calcification is a hallmark (visible on CT scan). * **Genetic association:** Mutation of the **RB1 gene** on Chromosome **13q14**. * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pinealoblastoma.

Question 188: What is the inheritance pattern of familial retinoblastomas?

A. Autosomal dominant (Correct Answer)
B. Autosomal recessive
C. X-linked dominant
D. X-linked recessive

Explanation: **Explanation:** **1. Why Autosomal Dominant is Correct:** Retinoblastoma is caused by a mutation in the **RB1 gene** located on chromosome **13q14**. While the cellular mechanism of the RB1 gene is recessive (both alleles must be inactivated for a tumor to form, as per **Knudson’s Two-Hit Hypothesis**), the **inheritance pattern** of familial retinoblastoma is **Autosomal Dominant**. This is because an individual inheriting one mutated allele has such a high probability (nearly 90% penetrance) of acquiring a second somatic mutation in any retinal cell that the disease manifests in every generation. **2. Why Other Options are Incorrect:** * **Autosomal Recessive:** Though the gene is a tumor suppressor (recessive at the molecular level), the pedigree shows dominant transmission because the "second hit" is almost inevitable. * **X-linked Dominant/Recessive:** The RB1 gene is located on an autosome (Chromosome 13), not on the sex chromosomes (X or Y). Therefore, it affects males and females equally and can be passed from father to son. **3. Clinical Pearls for NEET-PG:** * **Knudson’s Two-Hit Hypothesis:** In familial cases, the 1st hit is germline (inherited) and the 2nd is somatic. In sporadic cases, both hits are somatic. * **Clinical Presentation:** The most common sign is **Leukocoria** (white pupillary reflex), followed by strabismus. * **Bilateralism:** Familial cases are typically **bilateral and multifocal**, whereas sporadic cases are usually unilateral. * **Associated Tumors:** Patients with familial RB1 mutations are at a higher risk for secondary non-ocular tumors, most commonly **Osteosarcoma**. * **Trilateral Retinoblastoma:** Bilateral RB associated with a pineal gland tumor (Pineoblastoma).

Question 189: Hereditary retinoblastomas develop the following chromosomal deletion?

A. 13q14 (Correct Answer)
B. 13p14
C. 14p13
D. 14p13

Explanation: **Explanation:** **Retinoblastoma (RB)** is the most common primary intraocular malignancy of childhood. The genetic basis of this tumor lies in the mutation or deletion of the **RB1 gene**, which is a classic tumor suppressor gene. **1. Why 13q14 is Correct:** The RB1 gene is located on the **long arm (q)** of **chromosome 13** at the **band 14** (specifically 13q14.2). According to Knudson’s "Two-Hit Hypothesis," hereditary retinoblastoma occurs when a child inherits one defective copy of the RB1 gene (the first "hit" is germline) and subsequently acquires a mutation in the second allele (the second "hit" is somatic). In approximately 5–10% of cases, this genetic defect is visible as a cytogenetic deletion of the 13q14 region. **2. Why the other options are incorrect:** * **13p14:** The letter 'p' refers to the short arm (*petit*) of the chromosome. The RB1 gene is located on the long arm (q), not the short arm. * **14p13 / 14q13:** These options refer to Chromosome 14. While chromosomal abnormalities on 14 can be associated with other conditions, they have no primary association with the RB1 gene or Retinoblastoma. **Clinical Pearls for NEET-PG:** * **Inheritance:** Hereditary RB is typically **Autosomal Dominant** with high penetrance (90%). * **Presentation:** The most common sign is **Leukocoria** (white pupillary reflex), followed by strabismus. * **Histopathology:** Look for **Flexner-Wintersteiner rosettes** (pathognomonic, surrounding a central lumen) and Homer Wright rosettes. * **Trilateral Retinoblastoma:** This refers to bilateral RB associated with a pinealoblastoma (pineal gland tumor). * **Secondary Malignancies:** Patients with the germline 13q14 deletion are at a significantly higher risk of developing **Osteosarcoma** later in life.

Question 190: Which of the following statements about retinoblastoma is FALSE?

A. Retinoblastomas are hereditary in 40% of cases and non-hereditary in 60%.
B. Retinoblastomas are bilateral in 30% of cases and unilateral in 70%.
C. Retinoblastomas are familial in 6% of cases and non-familial in 94%.
D. All of the above statements are true. (Correct Answer)

Explanation: Retinoblastoma is the most common primary intraocular malignancy of childhood. Understanding its genetic distribution is crucial for NEET-PG, as it follows Knudson’s "Two-Hit" Hypothesis. **Explanation of the Correct Answer:** All the provided statements are statistically accurate representations of the disease's epidemiology: * **Hereditary vs. Non-hereditary (40% vs. 60%):** Hereditary cases (40%) involve a germline mutation in the *RB1* gene (13q14). These patients are predisposed to bilateral tumors and secondary malignancies (like osteosarcoma). Non-hereditary cases (60%) occur due to somatic mutations and are always unilateral. * **Bilateral vs. Unilateral (30% vs. 70%):** While all bilateral cases are hereditary, not all hereditary cases present bilaterally (some remain unilateral due to incomplete penetrance). Thus, the clinical presentation is roughly 30% bilateral and 70% unilateral. * **Familial vs. Non-familial (6% vs. 94%):** This is a common point of confusion. While 40% are *hereditary* (germline mutation), only about 6% of patients have a positive *family history*. The remaining 34% of hereditary cases result from new (de novo) germline mutations. **Why other options are "wrong":** Since options A, B, and C are all factual clinical statistics regarding the inheritance and presentation of retinoblastoma, Option D is the only logical choice. **High-Yield Clinical Pearls for NEET-PG:** * **Most common sign:** Leukocoria (white pupillary reflex), followed by strabismus. * **Pathology:** Flexner-Wintersteiner rosettes (highly specific) and Homer-Wright rosettes. * **Calcification:** Dystrophic calcification is a hallmark; seen on CT scan as "intraocular calcification." * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pinealoblastoma. * **Treatment:** Chemoreduction (Vincristine, Etoposide, Carboplatin) is the current standard to shrink tumors before local therapy.

Practice by Chapter

Amblyopia

Practice Questions

Esotropia

Practice Questions

Exotropia

Practice Questions

Vertical Deviations

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Special Forms of Strabismus

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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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