Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus Indian Medical PG Practice Questions and MCQs

Question 31: Under what circumstance should a pediatrician refer a baby to an ophthalmologist for examination?

A. Baby born at 28 weeks gestation (Correct Answer)
B. Baby has respiratory distress
C. Birth weight of the baby is 2.3 kg
D. Jaundice

Explanation: ### Explanation The correct answer is **A. Baby born at 28 weeks gestation**. This question pertains to the screening guidelines for **Retinopathy of Prematurity (ROP)**, a vasoproliferative disorder of the retina that can lead to permanent blindness if untreated. The primary risk factors for ROP are prematurity and low birth weight. **Why Option A is correct:** According to the National Neonatology Forum (NNF) and RBSK guidelines in India, mandatory ROP screening is required for: 1. Infants born at **≤32 weeks** of gestation. 2. Infants with a birth weight of **≤1500 grams (1.5 kg)**. 3. Infants with a birth weight between 1501–2000g with an unstable clinical course (e.g., prolonged oxygen therapy). Since 28 weeks is well below the 32-week threshold, immediate referral for screening (usually at 4 weeks of life) is mandatory. **Why the other options are incorrect:** * **Option B (Respiratory Distress):** While oxygen therapy for respiratory distress is a risk factor, it is not an independent criterion for referral unless accompanied by prematurity or very low birth weight. * **Option C (Birth weight 2.3 kg):** This weight is above the 1.5 kg (or even the 2 kg "unstable") threshold for routine screening. * **Option D (Jaundice):** Neonatal jaundice is common and does not typically require an ophthalmological referral unless it is associated with specific syndromes or kernicterus. **High-Yield Clinical Pearls for NEET-PG:** * **Timing of First Screening:** "4 weeks or 30 days." For very preterm babies (<28 weeks), it may be done at 2–3 weeks. * **Zone I Disease:** Most severe; involves the area around the optic nerve and macula. * **Plus Disease:** Characterized by dilatation and tortuosity of retinal vessels; indicates active, severe ROP. * **Treatment of Choice:** Laser photocoagulation (Gold Standard) or Anti-VEGF (Ranibizumab/Bevacizumab) injections.

Question 32: Distant metastasis in Retinoblastoma is commonly seen in which of the following sites?

A. Long bones
B. Lungs
C. Brain (Correct Answer)
D. Liver

Explanation: **Explanation:** Retinoblastoma (RB) is the most common intraocular malignancy of childhood. Understanding its spread is crucial for NEET-PG. **Why Brain is the Correct Answer:** Retinoblastoma spreads via three main routes: local extension, hematogenous spread, and lymphatic spread. The most common route of extraocular extension is **direct invasion along the optic nerve**. Once the tumor crosses the lamina cribrosa and reaches the subarachnoid space, it spreads via the **Cerebrospinal Fluid (CSF)** directly to the **Brain** and leptomeninges. This intracranial extension is the most frequent site of systemic involvement and a leading cause of mortality in these patients. **Analysis of Incorrect Options:** * **Long Bones (A):** While hematogenous spread can occur to the bone marrow and long bones (humerus, femur, skull), it is statistically less common than direct intracranial extension via the optic nerve. * **Lungs (B):** Unlike many adult sarcomas or carcinomas, the lungs are a relatively rare site for distant metastasis in Retinoblastoma. * **Liver (D):** Hematogenous spread to visceral organs like the liver can occur in advanced stages, but it is not the primary or most common site of distant involvement. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site of distant metastasis:** Brain (via optic nerve/CSF). * **Most common site of hematogenous metastasis:** Bone marrow. * **Most common presenting sign:** Leukocoria (White pupillary reflex). * **Pathognomonic Histology:** Flexner-Wintersteiner rosettes (true rosettes with a central lumen). * **Genetics:** Mutation in the *RB1* gene on Chromosome **13q14**. * **Trilateral Retinoblastoma:** Bilateral RB associated with a pinealoblastoma (ectopic intracranial RB).

Question 33: What is the investigation of choice for retinoblastoma?

A. X-ray
B. Ultrasound (USG)
C. Contrast-Enhanced Computed Tomography (CECT)
D. Magnetic Resonance Imaging (MRI) (Correct Answer)

Explanation: **Explanation:** **1. Why MRI is the Correct Answer:** Magnetic Resonance Imaging (MRI) is the **investigation of choice** for Retinoblastoma (RB) because of its superior soft-tissue contrast. Its primary role is to evaluate **extraocular extension** and **optic nerve involvement** (up to the optic chiasm), which are critical for staging and prognosis. Crucially, MRI is essential for detecting **Trilateral Retinoblastoma** (associated pinealoblastoma), which CT might miss. Unlike CT, MRI does not use ionizing radiation—a vital consideration for children with the *RB1* gene mutation who are highly predisposed to secondary radiation-induced malignancies. **2. Analysis of Incorrect Options:** * **X-ray:** Historically used to find intraocular calcification, but it lacks sensitivity and provides no information on tumor extent. It is now obsolete. * **Ultrasound (USG):** B-scan is often the *initial* screening tool. It is highly sensitive for detecting **calcification** (appearing as "high-echo" spikes with posterior shadowing), but it cannot accurately assess the optic nerve or intracranial spread. * **CECT:** While excellent at detecting pathognomonic calcification, it is **avoided** due to the risk of radiation-induced secondary sarcomas in these genetically vulnerable patients. **3. Clinical Pearls for NEET-PG:** * **Most common presentation:** Leukocoria (White pupillary reflex). * **Pathognomonic finding:** Calcification (present in >90% of cases). * **Histopathology:** Look for **Flexner-Wintersteiner rosettes** (specific) and Homer-Wright rosettes (non-specific). * **Management:** The goal is life first, then the eye, then vision. Small tumors are treated with focal therapy (cryo/laser); large tumors often require chemotherapy or enucleation.

Question 34: What is the most common cause of intraocular calcification in a child?

A. Toxocara
B. Retinoblastoma (Correct Answer)
C. Angiomatosis retinae
D. Malignant melanoma of choroid

Explanation: **Explanation:** **Retinoblastoma** is the most common primary intraocular malignancy of childhood and the most common cause of intraocular calcification in children. The underlying medical concept is **dystrophic calcification**, which occurs due to rapid tumor growth outstripping its blood supply, leading to areas of necrosis. Calcium deposits within these necrotic zones are a hallmark of the disease, occurring in approximately **90% of cases**. On imaging (B-scan Ultrasound or CT scan), this appears as high-reflectivity spots or "chalky white" masses. **Analysis of Incorrect Options:** * **Toxocara (Ocular Larva Migrans):** While it can cause a white pupillary reflex (leukocoria) due to an inflammatory granuloma, calcification is rare. It is typically characterized by tractional retinal detachment. * **Angiomatosis Retinae (von Hippel-Lindau disease):** These are vascular hamartomas (hemangioblastomas). While they can cause exudation and hemorrhage, they do not typically undergo calcification. * **Malignant Melanoma of Choroid:** This is the most common primary intraocular tumor in **adults**, not children. Furthermore, calcification is an extremely rare finding in choroidal melanomas. **Clinical Pearls for NEET-PG:** * **Leukocoria (White pupillary reflex):** Retinoblastoma is the most common life-threatening cause. * **Imaging Gold Standard:** **CT scan** is highly sensitive for detecting calcium, but **MRI** is preferred to evaluate optic nerve involvement and pineal gland tumors (Trilateral Retinoblastoma) to avoid radiation. * **Pathology:** Look for **Flexner-Wintersteiner rosettes** (highly specific) and Homer-Wright rosettes. * **Rule of Thumb:** Any intraocular mass with calcification in a child under age 3 is Retinoblastoma until proven otherwise.

Question 35: In the Hirschberg corneal reflex test, if the corneal light reflex falls midway between the pupil and the limbus, what is the approximate angle of the squint?

A. 15°
B. 30° (Correct Answer)
C. 45°
D. 60°

Explanation: **Explanation:** The **Hirschberg test** (Corneal Light Reflex test) is a rapid, objective method used to estimate the magnitude of strabismus (squint). It relies on the position of the light reflex on the cornea relative to the pupillary center. **Why 30° is correct:** The estimation follows a standardized clinical rule where every **1 mm** of displacement from the pupillary center corresponds to approximately **7° (or 15 prism diopters)** of deviation. * **At the pupillary margin:** The displacement is ~2 mm, representing **15°**. * **Midway between the pupil and limbus:** The displacement is ~4 mm, representing **30°**. * **At the limbus:** The displacement is ~6 mm, representing **45°**. **Analysis of Incorrect Options:** * **A. 15°:** This occurs when the reflex is at the **pupillary margin** (approx. 2 mm from the center). * **C. 45°:** This occurs when the reflex is at the **limbus** (the junction of the cornea and sclera, approx. 6 mm from the center). * **D. 60°:** This represents a very large deviation where the reflex falls beyond the limbus onto the **sclera**. **High-Yield Clinical Pearls for NEET-PG:** 1. **Prism Conversion:** Remember the ratio **1° = 2 Prism Diopters (Δ)**. Therefore, a 30° squint equals 60Δ. 2. **Pseudo-strabismus:** A positive Hirschberg test distinguishes true strabismus from pseudo-strabismus (e.g., caused by epicanthal folds). 3. **Krimsky Test:** This is a refinement of the Hirschberg test where prisms are placed in front of the fixating eye until the light reflex is centered in the deviating eye, allowing for a more accurate measurement. 4. **Direction:** If the reflex is temporal, it indicates **Esotropia**; if nasal, it indicates **Exotropia**.

Question 36: All of the following findings can be seen in Axenfeld's anomaly, except:

A. Posterior embryotoxon
B. Iris synechiae to Schwalbe's line
C. Ectopia of the lens (Correct Answer)
D. Glaucoma

Explanation: **Explanation:** Axenfeld-Rieger Syndrome (ARS) is a spectrum of autosomal dominant disorders involving the maldevelopment of the anterior segment (neural crest cell dysgenesis). The correct answer is **Ectopia of the lens**, as it is not a feature of this spectrum; it is instead characteristically associated with conditions like Marfan syndrome, Homocystinuria, or Weill-Marchesani syndrome. **Analysis of Options:** * **Posterior Embryotoxon (Option A):** This is the hallmark of the Axenfeld-Rieger spectrum. It represents an anteriorly displaced and prominent Schwalbe’s line (the junction of Descemet’s membrane and trabecular meshwork). * **Iris Synechiae (Option B):** In Axenfeld’s anomaly, peripheral iris strands (synechiae) extend across the angle to attach to the prominent Schwalbe’s line. * **Glaucoma (Option D):** Approximately 50% of patients with Axenfeld-Rieger spectrum develop glaucoma due to associated angle dysgenesis or secondary obstruction of aqueous outflow by iris strands. **Clinical Pearls for NEET-PG:** * **Axenfeld Anomaly:** Posterior embryotoxon + Iris strands. * **Axenfeld Syndrome:** Axenfeld anomaly + Glaucoma. * **Rieger Anomaly:** Axenfeld anomaly + Iris thinning, corectopia (displaced pupil), and polycoria (multiple pupils). * **Rieger Syndrome:** Rieger anomaly + Systemic findings (dental hypoplasia/microdontia, redundant periumbilical skin, and maxillary hypoplasia). * **Genetics:** Most cases are associated with mutations in **PITX2** and **FOXC1** genes.

Question 37: The axial length of the eyeball at birth is what percentage of an adult eye?

A. 100%
B. 90%
C. 70% (Correct Answer)
D. 40%

Explanation: **Explanation:** The growth of the eyeball is a critical concept in pediatric ophthalmology. At birth, the human eye is relatively large compared to the rest of the body but is still underdeveloped in its dimensions. **1. Why 70% is correct:** The average axial length of a newborn's eye is approximately **17–17.5 mm**. In contrast, the average axial length of an adult eye is approximately **24 mm**. Mathematically, $17 / 24 \approx 70.8\%$. Therefore, the eyeball at birth is roughly **70%** of its adult size. Most of this growth occurs rapidly within the first two years of life (reaching ~22–23 mm) and slows down until puberty. **2. Analysis of incorrect options:** * **A (100%):** If the eye were 100% of its adult size at birth, there would be no "emmetropization" process, and the infant would likely suffer from severe refractive errors as the head grew. * **B (90%):** This overestimates the size at birth. The eye reaches 90% of its adult volume by age 3, but not at birth. * **D (40%):** This is far too small. If the eye were only 40% (approx. 9.6 mm), the resulting hypermetropia would be physiologically impossible to compensate for. **3. High-Yield Clinical Pearls for NEET-PG:** * **Refractive Status:** Most newborns are physiologically **hypermetropic** (approx. +2.0 to +3.0 D) because the short axial length is not fully compensated by the higher curvature of the lens and cornea. * **Corneal Diameter:** At birth, it is ~10 mm; it reaches the adult size of ~11.7 mm by age 2. (Clinical note: A diameter >12 mm in a newborn suggests infantile glaucoma/buphthalmos). * **Lens:** The lens is more spherical at birth and has a higher refractive power to compensate for the short axial length. * **Volume:** The volume of a newborn eye is roughly 50% of an adult eye.

Question 38: A preterm baby of 26 weeks of gestation is born. At what age should screening for Retinopathy of Prematurity (ROP) be done?

A. 2 weeks postnatal life
B. 3 weeks postnatal life (Correct Answer)
C. 4 weeks postnatal life
D. 5 weeks postnatal life

Explanation: ### Explanation The screening for **Retinopathy of Prematurity (ROP)** is based on the timing of retinal vascularization, which is often delayed or abnormal in preterm infants. According to the **National Neonatology Forum (NNF)** and the **Revised Screening Guidelines for ROP in India**, the timing of the first screening depends on the gestational age at birth. **1. Why Option B is Correct:** For infants born at **<28 weeks of gestation** (like the 26-week baby in this question), the first screening should be performed at **3 weeks of postnatal life**. In extremely premature infants, the risk of aggressive ROP is higher, necessitating earlier intervention compared to more mature preterm babies. **2. Why Other Options are Incorrect:** * **Option A (2 weeks):** This is generally too early, as the pathological changes of ROP (neovascularization) typically take at least 3–4 weeks to manifest after the initial insult of premature birth and oxygen exposure. * **Option C (4 weeks):** This is the standard screening time for infants born **>28 weeks of gestation**. For a 26-week baby, waiting until 4 weeks might result in missing the window for treating aggressive posterior ROP (AP-ROP). * **Option D (5 weeks):** This is too late for any high-risk preterm infant and increases the risk of the disease progressing to retinal detachment (Stage 4 or 5) before the first exam. **High-Yield Clinical Pearls for NEET-PG:** * **Screening Criteria (India):** Birth weight **<2000g** OR Gestational Age **<34 weeks**. * **"When" to screen:** * <28 weeks: At 3 weeks. * >28 weeks: At 4 weeks. * **The "Rule of 4":** Screening is often simplified as 4 weeks after birth for most, but remember the "3-week rule" for extremely premature babies (<28 weeks). * **Key Finding:** The first sign of ROP is a **demarcation line** (Stage 1) between the vascularized and non-vascularized retina. * **Plus Disease:** Characterized by dilatation and tortuosity of posterior pole retinal vessels; it is a sign of active, severe disease.

Question 39: The amount of deviation in squint varies with the direction of gaze. What is this type of squint called?

A. Comitant squint
B. Incomitant squint (Correct Answer)
C. Intermittent squint
D. Alternate squint

Explanation: **Explanation:** The core concept tested here is the classification of strabismus based on the consistency of the angle of deviation. **1. Why Incomitant Squint is Correct:** An **incomitant (paralytic or restrictive) squint** is defined by a deviation that **changes in magnitude** depending on the direction of gaze or the eye used for fixation. This occurs because the limitation is caused by a specific muscle weakness (paralysis) or mechanical tethering (restriction). The deviation is maximal when the eyes attempt to move in the direction of the affected muscle's action. **2. Analysis of Incorrect Options:** * **A. Comitant squint:** In this type, the angle of deviation remains **constant** (within 5 prism diopters) regardless of the direction of gaze. It is usually due to an imbalance in the extraocular muscle tone rather than paralysis. * **C. Intermittent squint:** This refers to the **frequency** of the squint (sometimes present, sometimes controlled by fusion), not the variation with gaze direction. * **D. Alternate squint:** This describes a **fixation pattern** where the patient can use either eye to fixate while the other eye deviates. **3. Clinical Pearls for NEET-PG:** * **Primary vs. Secondary Deviation:** In incomitant squints, the **secondary deviation** (deviation of the normal eye when the paralyzed eye fixates) is always **greater** than the **primary deviation** (deviation of the paralyzed eye when the normal eye fixates), according to **Hering’s Law** of equal innervation. * **Diplopia:** Incomitant squints are typically associated with diplopia and compensatory head tilts (torticollis) to maintain binocular vision. * **Key Causes:** Cranial nerve palsies (III, IV, VI), Myasthenia Gravis, and restrictive conditions like Graves' Orbitopathy or Blow-out fractures.

Question 40: In congenital dacryocystitis, which structure is typically blocked?

A. Upper lacrimal puncta
B. Lower lacrimal puncta
C. Lacrimal canaliculi
D. Nasolacrimal duct (Correct Answer)

Explanation: ### Explanation **1. Why the Correct Answer is Right:** Congenital dacryocystitis (and the more common Congenital Nasolacrimal Duct Obstruction - CNLDO) is primarily caused by the **failure of canalization** of the nasolacrimal duct (NLD). The most frequent site of blockage is at the distal end of the NLD, where it opens into the inferior meatus of the nose. This specific point of obstruction is guarded by a mucosal fold known as the **Valve of Hasner**. When this membrane fails to perforate at birth, it leads to stasis of tears in the lacrimal sac, resulting in epiphora (watering) and secondary infection (dacryocystitis). **2. Why Incorrect Options are Wrong:** * **Options A & B (Upper/Lower Lacrimal Puncta):** These are the entry points of the lacrimal system. While "punctal agenesis" can occur, it is a rare congenital anomaly and not the standard cause of congenital dacryocystitis. * **Option C (Lacrimal Canaliculi):** Obstruction here (canaliculitis or atresia) would prevent tears from reaching the lacrimal sac. However, the hallmark of congenital dacryocystitis is a blockage *distal* to the sac, allowing the sac to distend with mucoid material. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common site of obstruction:** Valve of Hasner (distal NLD). * **Clinical Presentation:** Epiphora and "matting" of eyelashes; pressure over the lacrimal sac produces a **mucoid regurgitation** (Regurgitation Test Positive). * **Management Protocol:** 1. **Conservative (up to 1 year):** Crigler’s massage (Lacrimal sac massage) + Topical antibiotics. 90% of cases resolve spontaneously. 2. **Age 1 year:** Probing with Bowman’s probe. 3. **Age 1.5 - 2 years:** Repeat probing or Intubation with silicone tubes. 4. **Age >3-4 years:** Dacryocystorhinostomy (DCR).

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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