Pediatric Ophthalmology and Strabismus Practice Questions

Q: Which of the following statements about Retinoblastoma is true?

Rosettes suggest good prognosis.. **Explanation:** **Retinoblastoma (RB)** is the most common primary intraocular malignancy of childhood. The correct statement is that **Rosettes suggest a good prognosis**. 1. **Why Option C is Correct:** Histologically, RB presents with two types of rosettes: **Flexner-Wintersteiner rosettes** (highly specific, representing photoreceptor differentiation) and **Homer-Wright rosettes** (less specific). The presence of these rosettes indicates a higher degree of cellular differentiation. In oncology, well-differentiated tumors generally carry a better prognosis compared to undifferentiated (anaplastic) tumors. 2. **Why Other Options are Incorrect:** * **Option A:** Only **40%** of cases are heritable (germline mutation). The remaining 60% are sporadic/non-heritable. * **Option B:** RB is caused by a mutation or deletion in the **RB1 gene** located on chromosome **13q14**, not 11q14. It follows Knudson’s "Two-Hit" hypothesis. * **Option D:** With modern management (chemotherapy, plaque brachytherapy, and enucleation), the survival rate in developed countries like the UK is over **95%**. High mortality is only seen in resource-limited settings due to delayed presentation. **High-Yield Clinical Pearls for NEET-PG:** * **Most common presenting sign:** Leukocoria (White pupillary reflex) > Strabismus. * **Calcification:** Pathognomonic feature seen on USG/CT scan (differentiates it from Coats' disease). * **Trilateral Retinoblastoma:** Bilateral RB associated with a pinealoblastoma. * **Risk of secondary malignancies:** Patients with the heritable form are at high risk for **Osteosarcoma** later in life. * **Flexner-Wintersteiner rosettes** surround a central lumen, whereas **Homer-Wright rosettes** surround a central fibrillar meshwork.

Q: Retrolental fibroplasia is due to which of the following?

Hyperoxygenemia. **Explanation:** **Retrolental Fibroplasia (RLF)**, now more commonly known as **Retinopathy of Prematurity (ROP)**, is a vasoproliferative disorder affecting preterm infants. **Why Hyperoxygenemia is Correct:** The primary trigger for ROP is the administration of high concentrations of supplemental oxygen (**Hyperoxygenemia**) to premature neonates. The pathophysiology occurs in two stages: 1. **Vaso-obliteration:** High oxygen levels cause the premature retinal vessels to constrict and cease growing (obliterate). 2. **Vasoproliferation:** When the infant is moved to room air, the previously obliterated areas become ischemic. This triggers the release of **VEGF (Vascular Endothelial Growth Factor)**, leading to neovascularization, vitreous hemorrhage, and tractional retinal detachment (the "retrolental" membrane). **Why Other Options are Incorrect:** * **Hypoxia:** While hypoxia occurs in the *second* phase of the disease (triggering VEGF), it is not the primary cause of the initial fibroplasia; rather, it is the relative drop from a hyperoxic state. * **CO2 / Hypocapnia:** While fluctuations in carbon dioxide levels (especially hypocapnia) can affect cerebral blood flow and are associated with periventricular leukomalacia, they are not the direct causative agents for the fibrovascular proliferation seen in RLF. **Clinical Pearls for NEET-PG:** * **Risk Factors:** Low birth weight (<1500g), low gestational age (<32 weeks), and prolonged oxygen therapy. * **Screening Rule:** In India, infants <34 weeks or <1750g (or those with stormy neonatal courses) must be screened. * **Timing:** The first screening should be done at **4 weeks** post-natal age or **31 weeks** post-menstrual age (whichever is later). * **Treatment:** Laser photocoagulation (Gold Standard) or Anti-VEGF injections (e.g., Ranibizumab). * **Zone I** involvement carries the worst prognosis.

Q: The reciprocal inhibition of the antagonist muscle upon lateral gaze is explained by which law?

Sherrington's law. **Explanation:** The correct answer is **Sherrington’s Law of Reciprocal Innervation**. **1. Why Sherrington’s Law is Correct:** Sherrington’s law states that when an agonist muscle receives an increased nerve impulse to contract, there is a simultaneous and proportional decrease in the nerve impulse to its **antagonist muscle** in the **same eye**. * **Mechanism:** During lateral gaze (e.g., looking to the right), the right Lateral Rectus (agonist) contracts while the right Medial Rectus (antagonist) relaxes. This ensures smooth, coordinated movement without resistance from the opposing muscle. **2. Analysis of Incorrect Options:** * **Hering’s Law:** This law governs **yoke muscles** (muscles in opposite eyes that move the eyes in the same direction). It states that equal and simultaneous innervation is sent to the yoke muscles (e.g., right Lateral Rectus and left Medial Rectus) during version movements. * **Laplace’s Law:** A principle of physics/cardiology relating the pressure within a hollow viscus (like the heart or alveoli) to the wall tension and radius. It is not related to ocular motility. * **Hick’s Law:** A psychological principle describing the time it takes for a person to make a decision as a result of the possible choices. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sherrington’s Law** applies to **Monocular** movements (one eye). * **Hering’s Law** applies to **Binocular** movements (both eyes). * **Clinical Application:** Sherrington’s law is the basis for **Duane’s Retraction Syndrome**, where co-contraction of the medial and lateral recti occurs due to aberrant innervation, leading to globe retraction—a failure of reciprocal inhibition. * **Hering’s Law** explains "Secondary Deviation" in paralytic squint, where the deviation is greater when the paralyzed eye fixes because of increased innervation sent to both eyes.

Q: The Reese-Ellsworth classification is used for which condition?

Retinoblastoma. The **Reese-Ellsworth classification** was historically the primary system used to predict the prognosis for **eye salvage** (vision preservation) in patients with **Retinoblastoma** treated with external beam radiotherapy (EBRT). ### Why Retinoblastoma is Correct Retinoblastoma is the most common intraocular malignancy of childhood. The Reese-Ellsworth system (developed in the 1960s) categorizes tumors into five groups (Group I to V) based on: * **Tumor size** (measured in disc diameters). * **Location** (at or behind the equator). * **Number of tumors.** * **Presence of vitreous seeding.** *Group I represents a very favorable prognosis, while Group V represents a very unfavorable prognosis for saving the eye.* ### Why Other Options are Incorrect * **Rhabdomyosarcoma:** This is the most common primary orbital malignancy in children. It is staged using the **IRS (Intergroup Rhabdomyosarcoma Study)** grouping system, not Reese-Ellsworth. * **Optic Nerve Sheath Tumor (Meningioma/Glioma):** These are classified based on anatomical location and histopathological grading (WHO classification). * **Meningioma:** Specifically, Sphenoid wing or orbital meningiomas are classified based on their surgical extent and histological grade. ### High-Yield Clinical Pearls for NEET-PG * **Current Trend:** The Reese-Ellsworth classification has largely been replaced by the **International Classification of Retinoblastoma (ICRB)**, which better predicts success with modern **chemotherapy** (chemoreduction) rather than radiotherapy. * **Most Common Sign:** Leukocoria (white pupillary reflex). * **Genetics:** Mutation in the **RB1 gene** on chromosome **13q14**. * **Pathology:** Look for **Flexner-Wintersteiner rosettes** (highly specific) and Homer-Wright rosettes. * **Calcification:** Retinoblastoma is the most common cause of intraocular calcification in a child under 3 years old.

Q: Which of the following muscles produce intorsion of the eyeball?

Superior rectus and superior oblique. To master extraocular muscle actions for NEET-PG, it is essential to categorize their movements into primary, secondary, and tertiary actions. ### **Explanation of the Correct Answer** The correct answer is **A (Superior rectus and superior oblique)**. The mnemonic **"SIN"** (Superior muscles are INtorsionists) is the gold standard for remembering this. Both the Superior Rectus (SR) and the Superior Oblique (SO) are responsible for rotating the 12 o'clock position of the cornea medially toward the nose (intorsion). * **Superior Oblique:** Intorsion is its **primary** action. * **Superior Rectus:** Intorsion is its **secondary** action (elevation is primary). ### **Analysis of Incorrect Options** * **B & C (Inferior muscles):** Using the mnemonic **"RAD"** (Recti are ADductors), we know that inferior muscles are **Extorsionists**. The Inferior Rectus (IR) and Inferior Oblique (IO) rotate the eye outward. * **D (Superior rectus and inferior oblique):** While the SR intorts, the IO is a powerful extortor. These two muscles act as antagonists regarding torsional movement. ### **NEET-PG High-Yield Clinical Pearls** 1. **The "SIN-RAD" Rule:** * **S**uperior muscles are **IN**torsionists. * **R**ecti muscles are **AD**ductors (except lateral rectus). * *Corollary:* Inferior muscles are Extorsionists; Obliques are Abductors. 2. **Primary Actions to Remember:** * **Superior Oblique:** Intorsion (Depression occurs only when the eye is adducted). * **Inferior Oblique:** Extorsion (Elevation occurs only when the eye is adducted). 3. **Clinical Correlation:** In **4th Nerve Palsy (Superior Oblique Palsy)**, the patient loses intorsion power. To compensate and prevent diplopia, they present with a characteristic **head tilt** toward the opposite shoulder to ocularly extort the unaffected eye.

Q: Ophthalmic examination to screen for retinopathy of prematurity is mandatory for newborns with birth weight less than?

1500 grams. ### Explanation **1. Why 1500 grams is correct:** Retinopathy of Prematurity (ROP) is a vasoproliferative disorder affecting the incomplete vascularization of the retina in preterm infants. According to the **National Neonatology Forum (NNF) of India** and international guidelines (like AAP), screening is mandatory for infants with a **birth weight ≤ 1500 grams** or a **gestational age ≤ 30 weeks**. These infants are at the highest risk because their retinal vessels have not reached the periphery (ora serrata), making them vulnerable to hypoxia-induced overproduction of VEGF (Vascular Endothelial Growth Factor) and subsequent abnormal neovascularization. **2. Why the other options are incorrect:** * **A (1000 grams):** While "Extremely Low Birth Weight" (ELBW) infants (<1000g) are at the highest risk for aggressive ROP, using this as the cutoff would miss a significant number of "Very Low Birth Weight" (VLBW) infants who also develop treatable disease. * **C & D (2000g & 2500g):** These weights are generally too high for routine screening. However, in developing countries like India, screening is extended to infants between **1500–2000g** only if they have an unstable clinical course (e.g., prolonged oxygen therapy, sepsis, or blood transfusions). 2500g is considered a normal birth weight. **3. Clinical Pearls for NEET-PG:** * **Timing of First Screen:** Usually at **4 weeks (30 days)** of life. For very preterm infants (<28 weeks), it is done at 2–3 weeks of life. * **"When to Screen" Rule:** "30-30 Rule" (≤30 weeks gestation or ≤1500g birth weight). * **Plus Disease:** Characterized by dilatation and tortuosity of posterior pole retinal vessels; it is a key indicator for treatment. * **Treatment of Choice:** Laser photocoagulation (diode laser) of the avascular retina. Intravitreal Anti-VEGF (Ranibizumab/Bevacizumab) is an emerging alternative.

Question 1

Which of the following statements about Retinoblastoma is true?

Accepted Answer

Rosettes suggest good prognosis.

Answer

It is inherited in 50% of cases.

Answer

It is caused by deletion of 11q14.

Answer

It causes death in 60% of sufferers in the UK.

Question 2

Retrolental fibroplasia is due to which of the following?

Accepted Answer

Hyperoxygenemia

Answer

Hypocapnia

Answer

CO2

Answer

Hypoxia

Question 3

In paralytic squint, what is the relationship between the primary deviation and the secondary deviation?

Accepted Answer

The primary deviation is less than the secondary deviation.

Answer

The primary deviation is more than the secondary deviation.

Answer

The primary deviation is equal to the secondary deviation.

Answer

The relationship between primary and secondary deviation is variable.

Question 4

What is the ideal treatment for bilateral retinoblastoma?

Accepted Answer

Radiation

Answer

Enucleation

Answer

Chemotherapy

Answer

Cyclophotocoagulation

Question 5

The reciprocal inhibition of the antagonist muscle upon lateral gaze is explained by which law?

Accepted Answer

Sherrington's law

Answer

Hering's law

Answer

Laplace's law

Answer

Hick's law

Question 6

A 2-week-old infant presents with excessive tearing in the left eye, overflow of tears in the lower eyelid, and frequent appearance of mucoid material for the last week. The baby was delivered at home to a multigravida mother who had regular antenatal visits. There were no maternal or fetal complications perinatally. What is the most appropriate next step in management?

Accepted Answer

Nasolacrimal sac massaging

Answer

Probing of nasolacrimal duct

Answer

Application of erythromycin drops

Answer

Instillation of steroid drops

Question 7

The Reese-Ellsworth classification is used for which condition?

Accepted Answer

Retinoblastoma

Answer

Rhabdomyosarcoma

Answer

Optic nerve sheath tumor

Answer

Meningioma

Question 8

Which of the following muscles produce intorsion of the eyeball?

Accepted Answer

Superior rectus and superior oblique

Answer

Inferior rectus and inferior oblique

Answer

Inferior rectus and superior oblique

Answer

Superior rectus and inferior oblique

Question 9

A 5-year-old boy presents with leukocoria in the right eyeball, diagnosed as retinoblastoma involving the entire eyeball. The other eye has 2-3 small lesions in the periphery. What is the ideal management for this patient?

Accepted Answer

Enucleation of the right eye and focal therapy of the other eye

Answer

Enucleation of both eyes

Answer

Enucleation of the right eye and conservative management of the other eye

Answer

6 cycles of chemotherapy

Question 10

Ophthalmic examination to screen for retinopathy of prematurity is mandatory for newborns with birth weight less than?

Accepted Answer

1500 grams

Answer

1000 grams

Answer

2000 grams

Answer

2500 grams

Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus — MCQs

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