Pediatric Ophthalmology and Strabismus Practice Questions

Q: Strabismic amblyopia is more common in patients with:

Constant strabismus. **Constant Strabismus** - In **constant strabismus**, one eye is always deviated, leading to **continuous suppression** of the image from the deviated eye by the brain. - This consistent suppression prevents proper visual development in the deviated eye, resulting in **amblyopia**. *Alternating strabismus* - In **alternating strabismus**, the deviation switches between the two eyes, allowing each eye to take turns fixing. - This alternation helps maintain relatively good visual acuity in both eyes, making **amblyopia less common** or severe. *Latent strabismus* - **Latent strabismus** (phoria) is a deviation that is only present when binocular fusion is disrupted (e.g., when one eye is covered). - Since fusion is typically maintained in daily vision, there is **no constant suppression** of one eye, and amblyopia is rare. *Intermittent strabismus* - **Intermittent strabismus** involves periods of deviation alternating with periods of straight eye alignment, often varying with fatigue or visual tasks. - While it can lead to amblyopia, it is **less common and severe** than with constant strabismus because there are periods when the visual input from both eyes is utilized.

Q: The most common type of strabismus seen in myopes is?

Intermittent Exotropia. ***Intermittent Exotropia*** - Myopes often employ less **accommodative effort** for near tasks, leading to reduced **accommodative convergence** and an increased tendency for the eyes to drift outwards. - This outward deviation, or **exotropia**, is frequently intermittent, especially during fatigue or inattention. *Intermittent Esotropia* - **Esotropia** is an inward turn of the eye and is typically associated with **hyperopia** due to excessive accommodative effort leading to increased accommodative convergence. - While it can be intermittent, it is not the most common form of strabismus in myopic individuals. *Esotropia hypotropia complex* - This complex involves both an inward deviation (**esotropia**) and a downward deviation (**hypotropia**). - It is not typically seen in healthy myopes and would suggest other underlying **neurological** or **structural abnormalities**. *Exotropia Hypotropia complex* - While **exotropia** can be common in myopes, the additional presence of **hypotropia** (downward deviation) suggests a more complex strabismic picture. - This combination is not the most frequent strabismus seen in uncomplicated myopia and may indicate **cranial nerve palsies** or **orbital anomalies**.

Q: Binocular single vision is tested by?

Synoptophore. ***Synoptophore*** - The **synoptophore** is an ophthalmic instrument used to diagnose and treat various binocular vision anomalies, including **strabismus** and suppression. - It allows for the precise measurement and assessment of the eyes' ability to **fuse images** from both eyes into a single perception, which is the essence of **binocular single vision**. *Amsler grid* - The **Amsler grid** is primarily used to detect central visual field defects, such as those caused by **macular degeneration** or other retinal pathologies. - It does not directly assess the brain's ability to fuse images from both eyes into a single vision. *Cardboard test* - The "cardboard test" is not a standard ophthalmic test for binocular single vision. - It may refer to various informal or rudimentary tests, but it lacks the precision and standardization required for accurate assessment of binocular functions. *Maddox rod* - The **Maddox rod** is used to detect and measure **heterophoria** (latent strabismus) or **heterotropia** (manifest strabismus). - It dissociates the images seen by each eye, preventing fusion and revealing the deviation of the eyes, rather than directly testing the ability to achieve binocular single vision.

Q: Forced duction test is to find out?

Mechanical restriction of eye movement. ***Mechanical restriction of eye movement*** - The forced duction test is specifically designed to **detect mechanical restriction** that prevents free passive movement of the globe. - Performed under **topical anesthesia**, the examiner grasps the eye at the limbus with forceps and attempts to passively rotate it in the direction of limited motility. - A **positive test** (resistance to passive movement) indicates mechanical restriction from causes like **thyroid-associated orbitopathy, orbital floor fracture, entrapment, or fibrosis**. - This is the **primary clinical indication** for performing the test - to differentiate restrictive from paretic causes of strabismus. *Ocular muscle palsy* - In muscle palsy (paretic strabismus), the forced duction test is **negative** - the eye moves freely with passive movement. - The test helps **differentiate paretic from restrictive causes** of limited motility, but the test itself detects restriction, not palsy. - Free passive movement confirms that the limitation is due to muscle weakness rather than mechanical factors. *Ocular muscle spasm* - Active muscle spasm would not be detected by this test because it is performed **under topical or general anesthesia**, which eliminates active muscle contraction. - The test assesses **passive mechanical restriction**, not active muscle activity or spasm. - Spasm would be a neurogenic rather than mechanical cause and would show free passive movement on testing. *Angle of deviation* - The forced duction test does not measure the **degree or angle of deviation** in strabismus. - Tests like the **prism cover test** or **Hirschberg test** are used to quantify deviation. - The forced duction test provides qualitative information about the cause of limitation, not quantitative measurement of misalignment.

Q: In which condition is a positive forced duction test observed?

Mechanical restriction of ocular movement. ***Mechanical restriction of ocular movement*** - A **positive forced duction test** indicates a physical impediment to eye movement, meaning the eye cannot be passively moved beyond a certain point. - This test is crucial for differentiating between **muscle restriction** (e.g., thyroid eye disease, orbital floor fracture with muscle entrapment, post-surgical adhesions) and muscle weakness or paralysis. - When the examiner attempts to passively rotate the globe, there is **resistance** indicating mechanical tethering or restriction of the extraocular muscles. *Non-concomitant strabismus* - This refers to a squint where the magnitude of deviation varies with the direction of gaze. - While it can be caused by muscle restriction, non-concomitant strabismus itself is a **type of ocular misalignment**, not the specific finding of a forced duction test. - The forced duction test helps determine the **cause** of non-concomitant strabismus (mechanical vs. paralytic). *No condition* - This option is incorrect because a positive forced duction test specifically indicates mechanical obstruction or restriction in eye movement. - A positive result always points to an underlying pathological condition affecting ocular motility, not a normal finding. *Extraocular muscle paralysis* - In cases of **muscle paralysis**, the eye cannot move actively in the direction of the paralyzed muscle's action. - However, the **forced duction test would be negative** as the globe can be passively moved in all directions because there is no mechanical restriction. - This differentiates paralytic strabismus (negative test) from restrictive strabismus (positive test).

Q: Which muscle is primarily affected in Duane syndrome?

Lateral rectus muscle. ***Lateral rectus muscle*** - In Duane syndrome, the **lateral rectus muscle** is the primarily affected muscle due to **congenital absence or hypoplasia of the abducens nucleus (CN VI)**. - The lateral rectus receives **aberrant innervation from branches of the oculomotor nerve (CN III)** instead of normal abducens innervation. - This leads to **co-contraction** of both medial and lateral rectus muscles during attempted adduction, causing the characteristic **globe retraction and narrowing of palpebral fissure**. - The hallmark clinical finding is **limited or absent abduction** of the affected eye due to the primary lateral rectus dysfunction. *Medial rectus muscle* - The medial rectus has normal innervation from CN III in Duane syndrome. - While it participates in the co-contraction phenomenon, it is **not the primarily affected muscle**. - The pathology originates in the lateral rectus, not the medial rectus. *Superior rectus muscle* - The superior rectus muscle is responsible for **elevation, adduction, and intorsion** of the eye. - Its dysfunction is not characteristic of Duane syndrome, which primarily affects **horizontal eye movements**. *Superior oblique muscle* - The superior oblique muscle primarily causes **depression, abduction, and intorsion** of the eye. - Duane syndrome's core pathology involves the lateral rectus and horizontal gaze limitations, not superior oblique function.

Q: Yoke muscle for the right superior rectus is:

Left Inferior Oblique. ***Left Inferior Oblique*** - Yoke muscles are pairs of synergistic muscles, one in each eye, that act together to produce conjugate eye movements in the same direction of gaze. - The **right superior rectus** and **left inferior oblique** are yoke muscles that work together during **upward and rightward gaze** (dextro-elevation) [1]. - Right SR elevates the **adducted** right eye, while left IO elevates the **abducted** left eye, producing coordinated upward-right movement [1]. - This follows **Hering's Law of Equal Innervation**, where yoke muscles receive equal and simultaneous innervation. *Left Superior rectus* - The left superior rectus is the **contralateral homologous muscle**, not a yoke muscle for the right superior rectus. - Both superior recti work together for **upward gaze in primary position**, but they are versional muscles, not yoke pairs. - Yoke muscles produce conjugate movements in oblique directions, not straight up. *Left Inferior rectus* - The left inferior rectus depresses the left eye and is an antagonist to elevation. - It would pair with the **right superior oblique** for downward-left gaze (levo-depression), not with the right superior rectus. *Left Lateral Rectus* - The left lateral rectus is responsible for **abduction** of the left eye (leftward gaze). - Its yoke muscle is the **right medial rectus** for leftward horizontal gaze (levoversion), not for upward-right gaze.

Q: Normal level of visual acuity is attained at which age

6 years. ***6 years*** - **Normal adult visual acuity (20/20 or 6/6)** is typically achieved around the age of **6 years** as the visual system fully matures. - This age allows for the complete development of **foveal vision** and **binocular functions**. *6 months* - At 6 months of age, an infant's visual acuity is still developing and is typically around **20/200 to 20/400**. - While significant visual development occurs by this age, including **face recognition and tracking objects**, it is not yet at adult levels. *1 year* - By one year, visual acuity improves to approximately **20/50 to 20/100**. - Infants at this age are able to **distinguish fine details** and have improved **depth perception**, but full maturity is still some years away. *3 years* - At 3 years of age, visual acuity is generally around **20/30 to 20/40**. - Children at this stage are able to perform **visual tasks** like drawing and recognizing letters, but subtle refinements are still ongoing.

Q: Iris coloboma is most common in which location?

Inferonasal. ***Inferonasal*** - **Iris coloboma** most commonly occurs in the **inferonasal quadrant** (at approximately the **6 o'clock position**) - This location corresponds to the site of the **embryonic fetal fissure** (choroidal fissure), which normally closes during the **5th to 7th week of gestation** - When the fetal fissure fails to close completely, it results in a **keyhole-shaped defect** in the iris, and potentially involves other ocular structures (ciliary body, choroid, retina, optic nerve) along the same inferonasal axis - This is a well-established anatomical pattern seen in **congenital colobomas** *Inferotemporal* - The inferotemporal quadrant is **not the typical location** for iris coloboma - Embryologically, the fetal fissure does not extend into the temporal region, making colobomas in this location extremely rare - Colobomas outside the inferonasal location are usually **atypical colobomas** caused by different mechanisms *Superotemporal* - The superotemporal quadrant is **not associated** with the fetal fissure closure pathway - Colobomas in this location would be considered atypical and not related to embryonic fissure closure defects - This is not a common presentation for congenital iris coloboma *Superonasal* - The superonasal quadrant is also **not part of the fetal fissure pathway** - While superior colobomas can occasionally occur as atypical variants, they do not represent the classic congenital coloboma pattern - The embryological basis for typical coloboma formation does not involve the superior regions of the eye

Q: What is the treatment of choice for amblyopia?

Occlusion therapy. ***Occlusion therapy*** - **Occlusion therapy** involves patching the stronger eye to force the weaker, amblyopic eye to work harder, thereby strengthening its neural connections. - This treatment is most effective when initiated during the **critical period of visual development** in childhood. *Corrective spectacles* - While essential for addressing **refractive errors** that may contribute to amblyopia, spectacles alone are often insufficient to resolve the amblyopia. - Spectacles primarily optimize the image quality on the retina, but don't directly address the **cortical suppression** of the amblyopic eye. *Surgical intervention* - **Surgical intervention** is typically reserved for correcting structural issues like **strabismus** (misalignment of the eyes) that contribute to amblyopia. - Surgery for strabismus aims to align the eyes, which can then be followed by occlusion therapy or other treatments to address the functional amblyopia. *Convergent exercises for vision therapy* - **Vision therapy exercises**, including convergent exercises, may be used as an adjunct to occlusion therapy or in cases of **convergence insufficiency**. - However, they are not the primary or solitary treatment of choice for amblyopia, which requires direct stimulation of the amblyopic eye.

Question 1

Strabismic amblyopia is more common in patients with:

Accepted Answer

Constant strabismus

Answer

Alternating strabismus

Answer

Latent strabismus

Answer

Intermittent strabismus

Question 2

The most common type of strabismus seen in myopes is?

Accepted Answer

Intermittent Exotropia

Answer

Intermittent Esotropia

Answer

Esotropia Hypotropia complex

Answer

Exotropia Hypotropia complex

Question 3

Binocular single vision is tested by?

Accepted Answer

Synoptophore

Answer

Amsler grid

Answer

Cardboard test

Answer

Maddox rod

Question 4

Forced duction test is to find out?

Accepted Answer

Mechanical restriction of eye movement

Answer

Ocular muscle palsy

Answer

Ocular muscle spasm

Answer

Angle of deviation

Question 5

In which condition is a positive forced duction test observed?

Accepted Answer

Mechanical restriction of ocular movement

Answer

Non-concomitant strabismus

Answer

No condition

Answer

Extraocular muscle paralysis

Question 6

Which muscle is primarily affected in Duane syndrome?

Accepted Answer

Lateral rectus muscle

Answer

Superior rectus muscle

Answer

Medial rectus muscle

Answer

Superior oblique muscle

Question 7

Yoke muscle for the right superior rectus is:

Accepted Answer

Left Inferior Oblique

Answer

Left Lateral Rectus

Answer

Left Superior rectus

Answer

Left Inferior rectus

Question 8

Normal level of visual acuity is attained at which age

Accepted Answer

6 years

Answer

6 months

Answer

1 year

Answer

3 years

Question 9

Iris coloboma is most common in which location?

Accepted Answer

Inferonasal

Answer

Superotemporal

Answer

Inferotemporal

Answer

Superonasal

Question 10

What is the treatment of choice for amblyopia?

Accepted Answer

Occlusion therapy

Answer

Corrective spectacles

Answer

Surgical intervention

Answer

Convergent exercises for vision therapy

Pediatric Ophthalmology and Strabismus — MCQs

Pediatric Ophthalmology and Strabismus — MCQs

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