Amblyopia — MCQs
Strabismic amblyopia is more common in patients with:
What does a visual acuity test primarily assess?
A 50-year-old patient has difficulty reading close objects. Likely diagnosis?
The most common type of strabismus seen in myopes is?
The most common cause of myopia is –
Treatment of presbyopia is by use of which type of lens?
A patient presents with convergent squint in one eye. Vision in the squinting eye is 6/60, and vision in the non-squinting eye is also 6/60. What is the most appropriate next step in management?
Retinoblastoma is bilateral in what percentage of cases?
Which of the following is NOT true about retinoblastoma?
Esotrotropia is most commonly associated with which refractive error?
Amblyopia Indian Medical PG Practice Questions and MCQs
Question 1: Strabismic amblyopia is more common in patients with:
- A. Constant strabismus (Correct Answer)
- B. Alternating strabismus
- C. Latent strabismus
- D. Intermittent strabismus
Explanation: **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.
Question 2: What does a visual acuity test primarily assess?
- A. Ability to perceive light
- B. Ability to differentiate colors
- C. Ability to recognize shapes and details (Correct Answer)
- D. Ability to detect contrast
Explanation: ***Ability to recognize shapes and details*** - A visual acuity test, typically using a **Snellen chart**, measures the sharpness of vision, specifically the ability to discern letters or symbols at a given distance. - It assesses the eye's capacity to resolve fine **spatial detail**, which is crucial for tasks like reading and recognizing faces. - This is the fundamental definition of visual acuity and what these tests are specifically designed to measure. *Ability to perceive light* - This refers to **light perception (LP)**, the most basic form of vision, indicating whether a person can detect the presence or absence of light. - While essential for vision, it is a much simpler function than what visual acuity tests measure and is assessed separately. *Ability to differentiate colors* - This is assessed by **color vision tests**, such as the Ishihara plates, which evaluate the function of cone photoreceptors. - It specifically checks for **color blindness** (e.g., red-green or blue-yellow deficiencies) and is distinct from the sharpness of vision. *Ability to detect contrast* - This is measured by **contrast sensitivity tests**, which evaluate the ability to distinguish objects from their background at various contrast levels. - While related to overall visual quality, it is a different aspect of vision than the ability to recognize fine details at high contrast.
Question 3: A 50-year-old patient has difficulty reading close objects. Likely diagnosis?
- A. Hypermetropia
- B. Astigmatism
- C. Myopia
- D. Presbyopia (Correct Answer)
Explanation: ***Presbyopia*** - This condition is characterized by the **loss of elasticity** in the lens of the eye, which occurs naturally with age, making it difficult to focus on **near objects**. - Its typical presentation, as seen in this 50-year-old patient, is **difficulty reading close objects** or performing other tasks requiring near vision. *Hypermetropia* - Often causes **farsightedness**, meaning distant objects are seen clearly, but near objects appear blurry due to the eye attempting to constantly accommodate. - While it can make near vision difficult, it is not primarily an age-related loss of accommodation and can affect individuals of various ages. *Astigmatism* - Results from an **irregular curvature of the cornea or lens**, causing blurred or distorted vision at all distances, rather than specifically difficulty with close objects. - This condition makes it difficult for the eye to focus light uniformly on the retina, leading to multiple focal points or streaks. *Myopia* - This is commonly known as **nearsightedness**, where distant objects appear blurry while near objects are seen clearly. - It occurs when the eyeball is too long or the cornea is too steeply curved, causing light to focus in front of the retina.
Question 4: The most common type of strabismus seen in myopes is?
- A. Intermittent Exotropia (Correct Answer)
- B. Intermittent Esotropia
- C. Esotropia Hypotropia complex
- D. Exotropia Hypotropia complex
Explanation: ***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**.
Question 5: The most common cause of myopia is –
- A. Altered curvature of the lens
- B. Increased anteroposterior (A–P) diameter of the eye (Correct Answer)
- C. Increased intraocular pressure
- D. Changes in the vitreous humor structure
Explanation: ***Increased anteroposterior (A–P) diameter of the eye*** - This leads to the light rays focusing **in front of the retina**, which is the hallmark of **myopia** (nearsightedness) - The longer axial length means the eye's refractive power is too strong for its length - **Axial myopia** is the most common type, accounting for approximately **90% of all myopia cases** - Each 1 mm increase in axial length causes approximately **3 diopters of myopia** *Altered curvature of the lens* - While changes in lens curvature can contribute to refractive errors, they are a **less common primary cause** of myopia compared to increased axial length - These changes typically result in **refractive myopia** (curvature myopia), which accounts for only a small percentage of cases - More commonly associated with lenticular changes in conditions like early cataracts or keratoconus *Increased intraocular pressure* - **Increased intraocular pressure** is the primary characteristic of **glaucoma** and does **not directly cause myopia** - Elevated pressure can damage the optic nerve leading to vision loss, but it doesn't typically alter the eye's focal length - However, chronic angle-closure glaucoma can sometimes lead to secondary changes, but this is not a primary cause *Changes in the vitreous humor structure* - Changes in the **vitreous humor**, such as liquefaction or detachment, can cause symptoms like **floaters** or flashes of light - However, these changes do **not directly lead to myopia** or alter the eye's refractive power significantly to cause nearsightedness - Vitreous changes are typically age-related or associated with high myopia as a consequence, not a cause
Question 6: Treatment of presbyopia is by use of which type of lens?
- A. Convex (Correct Answer)
- B. Concave
- C. Biconcave
- D. Concavoconvex
Explanation: **Convex** - **Presbyopia** is an age-related condition where the **lens stiffens**, impairing its ability to accommodate and focus on near objects. - **Convex lenses** add converging power to the eye, helping to bring near objects into focus on the retina. *Concave* - **Concave lenses** diverge light rays and are used to correct **myopia (nearsightedness)**, where the eye focuses images in front of the retina. - They spread light out before it enters the eye, pushing the focal point back onto the retina. *Biconcave* - **Biconcave lenses** are a type of concave lens with two concave surfaces, used for correcting severe **myopia (nearsightedness)**. - These lenses further diverge light rays and are not suitable for presbyopia, which requires converging power. *Concavoconvex* - A **concavoconvex lens** has one concave and one convex surface; its overall power depends on the relative curvatures of the two surfaces. - While some forms might be used in specialized optical systems, they are not the primary or standard correction for presbyopia, which typically requires a simple converging (convex) power.
Question 7: A patient presents with convergent squint in one eye. Vision in the squinting eye is 6/60, and vision in the non-squinting eye is also 6/60. What is the most appropriate next step in management?
- A. Glasses
- B. Refraction and treat underlying cause of poor vision (Correct Answer)
- C. Squint surgery
- D. Botulinum toxin
Explanation: ***Refraction and treat underlying cause of poor vision*** - When **both eyes have equally poor vision (6/60)** with a convergent squint, this suggests a **bilateral pathology** affecting visual acuity, not simply a refractive accommodative esotropia. - The **first step** is comprehensive **cycloplegic refraction** to determine if refractive error contributes to the poor vision. - **Equally important** is identifying the **underlying cause** of bilateral vision loss (6/60 in both eyes), which could be: - **Bilateral amblyopia** (though unusual to have equal severity) - **Uncorrected high refractive error** (hypermetropia causing accommodative esotropia) - **Cataracts** (congenital or developmental) - **Retinal pathology** or **optic nerve disorders** - Only after identifying and treating the underlying cause can definitive management of the squint be planned. *Glasses* - While **glasses** may be part of the treatment if refractive error is found, **prescribing glasses alone** without first performing refraction and investigating why both eyes have 6/60 vision is incomplete management. - This option is too narrow and doesn't address the need to identify the underlying pathology causing bilateral poor vision. *Squint surgery* - **Squint surgery** addresses ocular misalignment but does **not improve vision**. - Surgery should only be considered **after** refractive correction, treatment of amblyopia (if present), and management of any underlying pathology. - Operating without addressing the cause of poor vision would be premature. *Botulinum toxin* - **Botulinum toxin** is used for certain types of strabismus as a temporary or alternative to surgery. - Like surgery, it addresses alignment but **not visual acuity**. - The priority is to improve vision and identify the underlying cause before considering alignment procedures.
Question 8: Retinoblastoma is bilateral in what percentage of cases?
- A. 100% of cases
- B. 1% of cases
- C. 50% of cases
- D. 30% of cases (Correct Answer)
Explanation: **Explanation:** Retinoblastoma (RB) is the most common primary intraocular malignancy of childhood. Its occurrence is governed by **Knudson’s "Two-Hit" Hypothesis**, which explains the distribution of unilateral and bilateral cases. **Why 30% is correct:** Approximately **25–30% of cases** are bilateral. These cases are almost always **hereditary (germline mutations)**, meaning the first "hit" (mutation in the *RB1* gene on chromosome 13q14) is present in every cell of the body. A second somatic hit in the retinal cells leads to tumor formation, often affecting both eyes and presenting at an earlier age (average 12 months). **Analysis of Incorrect Options:** * **A (100%):** Incorrect. While the germline mutation predisposes both eyes, not all RB cases are hereditary. * **B (1%):** Incorrect. This is far too low; bilateral involvement is a hallmark of the genetic form of the disease. * **C (50%):** Incorrect. While some older texts might suggest higher ranges, the standard epidemiological consensus for bilateral cases remains 25–30%. The remaining 70–75% are unilateral (mostly sporadic). **High-Yield Clinical Pearls for NEET-PG:** * **Most common presentation:** Leukocoria (white pupillary reflex), followed by strabismus. * **Genetics:** *RB1* gene on **Chromosome 13q14**. * **Pathology:** Look for **Flexner-Wintersteiner rosettes** (highly specific) and Homer-Wright rosettes. * **Trilateral Retinoblastoma:** Bilateral RB associated with a pinealoblastoma (pineal gland tumor). * **Calcification:** RB is the most common cause of intraocular calcification in an infant (visible on CT/Ultrasound). * **Treatment:** Chemoreduction is now preferred over enucleation to save the eye and vision where possible.
Question 9: Which of the following is NOT true about retinoblastoma?
- A. Bilateral in 20-30% of cases
- B. Affects the age group of 1-5 years
- C. More common in males (Correct Answer)
- D. Leukocoria is the earliest symptom
Explanation: **Explanation:** Retinoblastoma is the most common primary intraocular malignancy of childhood. Understanding its epidemiological and clinical profile is crucial for NEET-PG. **Why Option C is the correct answer (The False Statement):** Retinoblastoma shows **no gender predilection**. It affects males and females equally. There is also no significant racial predilection. Therefore, stating it is more common in males is incorrect. **Analysis of other options:** * **Option A (Bilateral in 20-30%):** This is true. Approximately 25-30% of cases are bilateral (usually germinal mutations). Unilateral cases account for about 70-75%. * **Option B (Age group 1-5 years):** This is true. Most cases present before age 5. The average age of diagnosis is 18 months for bilateral cases and 24-30 months for unilateral cases. It is rarely seen after age 6. * **Option D (Leukocoria is the earliest symptom):** This is true. **Leukocoria** (white pupillary reflex or "cat’s eye reflex") is the most common presenting sign (60%), followed by **strabismus** (20%). **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Associated with the **RB1 gene** on chromosome **13q14**. It follows Knudson’s "Two-hit hypothesis." * **Pathology:** Look for **Flexner-Wintersteiner rosettes** (highly specific) and Homer-Wright rosettes. * **Calcification:** Intraocular calcification in a child under 3 years is pathognomonic for retinoblastoma on CT/Ultrasound. * **Trilateral Retinoblastoma:** Bilateral retinoblastoma associated with a pinealoblastoma. * **Most common spread:** Direct spread via the optic nerve to the brain.
Question 10: Esotrotropia is most commonly associated with which refractive error?
- A. Hyperopia (Correct Answer)
- B. Myopia
- C. Presbyopia
- D. Astigmatism
Explanation: ### Explanation **Correct Answer: A. Hyperopia** **Mechanism:** The association between esotropia (inward deviation of the eye) and hyperopia is rooted in the **AC/A ratio (Accommodative Convergence to Accommodation)**. A hyperopic individual must constantly accommodate to see clearly, even for distance. Because accommodation and convergence are neurologically linked in the near reflex triad, excessive accommodative effort triggers excessive **accommodative convergence**. If the patient’s fusional divergence mechanisms cannot compensate for this inward pull, an **Accommodative Esotropia** develops. This is the most common cause of childhood strabismus. **Analysis of Incorrect Options:** * **B. Myopia:** Myopia is more commonly associated with **Exotropia** (outward deviation). Since myopes do not need to accommodate for near tasks, they lack the stimulus for accommodative convergence, leading to a tendency for the eyes to drift outward. * **C. Presbyopia:** This is an age-related loss of lens elasticity affecting near vision in adults. While it involves accommodation failure, it is not a primary cause of pediatric esotropia. * **D. Astigmatism:** While uncorrected astigmatism can cause blurred vision and contribute to amblyopia, it does not have a direct physiological link to the convergence reflex like hyperopia does. **High-Yield Clinical Pearls for NEET-PG:** * **Management:** The first line of treatment for accommodative esotropia is the **full cycloplegic refraction** and prescription of corrective plus (+) lenses. This relaxes accommodation and often straightens the eyes without surgery. * **Donders' Theory:** This is the classical theory explaining the link between hyperopia and esotropia. * **Infantile Esotropia:** Unlike accommodative esotropia, this occurs within the first 6 months of life and is usually *not* related to refractive errors; it requires surgical correction. * **Pseudoesotropia:** Often seen in infants with a wide nasal bridge or **epicanthal folds**; it is an illusion of crossing, but the corneal light reflex (Hirschberg test) is central.
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