Emerging Technologies in Low Vision — MCQs
A 50-year-old patient has difficulty reading close objects. Likely diagnosis?
A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
Visual cycle refers to
A child presents with night blindness, delayed dark adaptation. Which investigation is to be done further to confirm the diagnosis?
According to the WHO, what is the minimum distance at which a person is considered blind if they cannot count fingers in daylight?
In a patient with a metallic foreign body in the eye, which investigation should NOT be done?
A patient with visual acuity of less than 6/60 but more than 3/60 in the better eye is considered to have:
Visual acuity of 6/60 is classified as?
Which of the following best defines blindness?
A person is not able to count fingers from a distance of 6 meters. He shall be categorized into which type of blindness?
Emerging Technologies in Low Vision Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
- A. LASIK
- B. Spherical Specs
- C. Contact lenses (Toric) (Correct Answer)
- D. FEMTO Lasik
Explanation: ***Contact lenses (Toric)*** - **Toric contact lenses** are specifically designed to correct **astigmatism**, along with myopia or hyperopia, by having different refractive powers in different meridians. - They offer a non-surgical alternative to glasses, addressing the patient's desire not to wear spectacles, and are generally safe and effective for teenagers. *LASIK* - **LASIK (Laser-Assisted In Situ Keratomileusis)** is a surgical procedure to correct refractive errors, but it is not typically recommended for individuals under **18-21 years of age** due to continued eye growth and refractive changes. - The patient's age of 15 makes her an unsuitable candidate for LASIK at this time. *Spherical Specs* - **Spherical spectacles** are designed to correct myopia or hyperopia but cannot adequately correct **astigmatism**, which is a significant component of this patient's refractive error. - The patient also explicitly states she does not want to wear glasses, making this option undesirable. *FEMTO Lasik* - **FEMTO LASIK** is an advanced form of LASIK that uses a femtosecond laser to create the corneal flap, offering higher precision and safety. - However, similar to traditional LASIK, it is a **refractive surgical procedure** and typically not performed on patients younger than **18 years old** due to ongoing eye development.
Question 3: Visual cycle refers to
- A. Day vision and colour vision
- B. Photodecomposition and regeneration of visual pigments (Correct Answer)
- C. Alternate distance and near fixation
- D. Cycle of night vision and colour vision
Explanation: **Photodecomposition and regeneration of visual pigments** * The visual cycle describes the continuous process of **photodecomposition** (bleaching) of rhodopsin in response to light and its subsequent **regeneration** to a light-sensitive state. * This cycle is essential for maintaining the eye's ability to detect light and adapt to varying light intensities. *Day vision and colour vision* * Day vision (photopic vision) and color vision are functions of the **cones** in the retina. * While dependent on photopigment activity, these terms refer to specific *types* of vision, not the underlying biochemical cycle. *Alternate distance and near fixation* * This describes the process of **accommodation**, which is the eye’s ability to change focus from distant to near objects. * Accommodation is controlled by the ciliary muscle and lens, and is distinct from the molecular processes of the visual cycle. *Cycle of night vision and colour vision* * Night vision (scotopic vision) is primarily mediated by **rods**, and color vision by cones. * While both involve visual pigments, the "visual cycle" specifically refers to the *biochemical pathway* of pigment breakdown and regeneration, not a cycle that alternates between these two types of vision.
Question 4: A child presents with night blindness, delayed dark adaptation. Which investigation is to be done further to confirm the diagnosis?
- A. ERG (Correct Answer)
- B. Retinoscopy
- C. Dark adaptometry
- D. EOG
Explanation: ***ERG*** - **Electroretinography (ERG)** measures the electrical responses of various retinal cells, including **rods** and **cones**, to light stimuli. - In conditions like **retinitis pigmentosa** which cause night blindness and delayed dark adaptation, ERG will show characteristic abnormal or extinguished responses, confirming retinal dysfunction. *Retinoscopy* - **Retinoscopy** is an objective method to assess the refractive error of the eye by observing the light reflex from the retina. - It does not directly evaluate the functional integrity of photoreceptors or diagnose conditions causing **night blindness**. *Dark adaptometry* - **Dark adaptometry** measures the time it takes for the eye to adapt to dim light after exposure to bright light, quantifying the function of **rod photoreceptors**. - While it can *detect* delayed dark adaptation, it is a functional test that assesses the symptom, not the underlying cause provided by ERG. *EOG* - **Electrooculography (EOG)** measures the potential difference between the cornea and the retina, primarily assessing the function of the **retinal pigment epithelium (RPE)**. - While useful for conditions like **Best's disease**, it is less direct for evaluating generalized rod dysfunction causing night blindness compared to ERG.
Question 5: According to the WHO, what is the minimum distance at which a person is considered blind if they cannot count fingers in daylight?
- A. 1 metre
- B. 2 metres
- C. 3 metres (Correct Answer)
- D. 4 metres
Explanation: ***3 metres*** - The **WHO definition of blindness** includes the inability to count fingers at 3 meters (or 10 feet) in daylight. - This serves as a practical measure for severe **visual impairment** when standard acuity charts are unavailable. *1 metre* - While a significant visual impairment, the inability to count fingers at 1 meter is typically categorized as **severe visual impairment**, not outright blindness, by the WHO. - Severe visual impairment has a slightly less stringent threshold than the definition of blindness. *2 metres* - The inability to count fingers at 2 meters also falls under the category of **severe visual impairment**, according to WHO criteria. - It indicates significant vision loss but is not the specific distance used to define blindness when counting fingers. *4 metres* - A person unable to count fingers at 4 meters would certainly meet the criteria for **blindness**, as this is a greater distance than the 3-meter threshold. - However, the 3-meter mark is the **minimum specified distance** for this particular criterion of blindness by the WHO.
Question 6: In a patient with a metallic foreign body in the eye, which investigation should NOT be done?
- A. X-ray
- B. MRI (Correct Answer)
- C. CT
- D. USG
Explanation: ***MRI*** - **Magnetic Resonance Imaging (MRI)** is contraindicated in patients with suspected **metallic foreign bodies** in the eye. - The powerful magnetic fields of an MRI can cause the metallic object to move, potentially leading to further **tissue damage** or even loss of vision. *X-ray* - **X-rays** are often the initial investigation of choice for detecting **radio-opaque foreign bodies** within the eye. - They can effectively localize larger metallic objects and are readily available in most emergency settings. *CT* - **Computed Tomography (CT)** scans provide detailed cross-sectional images and are excellent for precisely localizing **intraocular foreign bodies**, especially smaller ones. - CT can differentiate between metallic and non-metallic objects and assess for associated injuries like orbital fractures. *USG* - **Ultrasound (USG)** of the eye can be useful for detecting **intraocular foreign bodies**, especially if they are non-metallic or located in the posterior segment. - It can also assess for associated complications such as **retinal detachment** or vitreous hemorrhage.
Question 7: A patient with visual acuity of less than 6/60 but more than 3/60 in the better eye is considered to have:
- A. Economical blindness (Correct Answer)
- B. Social blindness
- C. Legal blindness
- D. Absolute blindness
Explanation: ### Explanation **1. Why Economical Blindness is Correct:** In ophthalmology, **Economical Blindness** is defined as visual acuity of **less than 6/60 but better than or equal to 3/60** in the better eye with best possible correction. This threshold is significant because, at this level of vision, an individual is generally unable to perform any work for which eyesight is essential, leading to a loss of earning capacity. **2. Analysis of Incorrect Options:** * **Social Blindness:** This refers to visual acuity of **less than 3/60** in the better eye. At this stage, the individual cannot socially interact or move about independently in a strange environment. * **Legal Blindness:** This is a term used for administrative purposes (like disability benefits). According to the WHO and the National Programme for Control of Blindness (NPCB) India, it is defined as visual acuity **less than 3/60** or a visual field loss of **less than 10 degrees** in the better eye. * **Absolute Blindness:** This is the total absence of sight. Clinically, it is defined as **No Perception of Light (No PL)** in both eyes. **3. NEET-PG High-Yield Pearls:** * **WHO Definition of Blindness:** Visual acuity < 3/60 or visual field < 10° in the better eye. * **NPCB India Definition (Revised):** To align with WHO, India now defines blindness as visual acuity **< 3/60** (previously it was < 6/60). * **Low Vision:** Visual acuity between **< 6/18 and 3/60** in the better eye. * **One-Eyed Person:** If the vision in one eye is 6/6 and the other is No PL, the person is **not** considered blind by WHO/NPCB standards as the better eye is used for classification.
Question 8: Visual acuity of 6/60 is classified as?
- A. Low vision (Correct Answer)
- B. Normal vision
- C. Blindness
- D. Visual morbidity
Explanation: ### Explanation The classification of visual impairment is based on the **WHO (World Health Organization)** criteria, which are high-yield for NEET-PG. **1. Why Option A is Correct:** According to the WHO classification (ICD-10), **Low Vision** is defined as visual acuity of **less than 6/18 but equal to or better than 3/60** in the better eye with best possible correction. Since 6/60 falls within this range, it is categorized as low vision. Additionally, a visual field of less than 20 degrees around central fixation also qualifies as low vision, even if acuity is better. **2. Why the other options are incorrect:** * **Option B (Normal vision):** Normal visual acuity is defined as **6/6 or better**. Vision between 6/6 and 6/18 is considered "Mild or No Visual Impairment." * **Option C (Blindness):** Under WHO criteria, **Blindness** is defined as visual acuity **worse than 3/60** (less than 3/60 to no light perception) or a visual field of less than 10 degrees in the better eye. * **Option D (Visual morbidity):** This is a general term referring to any visual loss that interferes with daily activities; it is not a formal WHO classification category for specific acuity levels. **Clinical Pearls for NEET-PG:** * **NPCB (National Programme for Control of Blindness - India) Criteria:** Note that India previously used <6/60 as the cutoff for blindness to prioritize surgical backlogs, but it has now aligned with WHO criteria (**<3/60**) to match global standards. * **Categories of Impairment:** * Category 1 (Moderate): <6/18 to 6/60 * Category 2 (Severe): <6/60 to 3/60 * Category 3, 4, 5: Blindness (starting from <3/60) * **Visual Field:** Remember that a field of **<10°** is the threshold for blindness, regardless of Snellen acuity.
Question 9: Which of the following best defines blindness?
- A. Visual acuity less than 3/60 in the better eye after best possible correction (Correct Answer)
- B. Visual field less than 10 degrees from fixation in the better eye
- C. Inability to perceive light in both eyes
- D. Visual acuity less than 6/60 in the better eye
Explanation: ***Visual acuity less than 3/60 in the better eye after best possible correction*** - This defines **blindness** according to the **WHO/ICD-11 classification** (Category 3 and 4). - VA < 3/60 to 1/60 is **Category 3 blindness**, and VA < 1/60 to light perception is **Category 4 blindness**. - This is the internationally accepted standard definition of blindness. *Visual acuity less than 6/60 in the better eye* - In **India**, the National Programme for Control of Blindness and Visual Impairment (NPCB&VI) defines blindness as VA < 6/60 in the better eye with best correction. - However, the **WHO international standard** uses the more stringent criterion of < 3/60. - For global standardization and comparison, the **WHO definition (< 3/60)** is considered the primary reference. *Visual field less than 10 degrees from fixation in the better eye* - This is an **alternative criterion** for defining blindness according to WHO guidelines. - A person with VF < 10° (or < 20° in some definitions) is considered legally blind even if VA is better than 3/60. - Both VA and VF criteria are valid, but the question asks for the "best" single definition, where the **VA criterion** is most commonly cited. *Inability to perceive light in both eyes* - This represents **No Light Perception (NLP)** or **total blindness** (WHO Category 5). - This is the most severe form of blindness but is too restrictive as a general definition, as it excludes individuals with light perception or minimal vision who are still legally and functionally blind.
Question 10: A person is not able to count fingers from a distance of 6 meters. He shall be categorized into which type of blindness?
- A. Moderate visual impairment
- B. Severe visual impairment (Correct Answer)
- C. Near-total blindness
- D. Profound visual impairment
Explanation: ***Severe visual impairment*** - Severe visual impairment is defined as visual acuity **less than 6/60 to 3/60** (presenting visual acuity). - The key clinical threshold is the **inability to count fingers at 6 meters**, which corresponds to VA < 6/60. - This category represents a significant functional vision loss where the person can typically still count fingers at 3 meters but not at 6 meters. - According to **WHO ICD-10 classification**, this falls under **Category H1** (severe visual impairment). *Moderate visual impairment* - Moderate visual impairment is characterized by visual acuity of **less than 6/18 to 6/60**. - A person with moderate visual impairment would **still be able to count fingers at 6 meters**. - This does not match the clinical presentation described in the question. *Profound visual impairment* - Profound visual impairment (also called **Blindness Category 1**) is defined as visual acuity **less than 3/60 to 1/60**. - The key threshold here is the **inability to count fingers at 3 meters** (but can count at 1 meter). - This is more severe than what is described in the question, as the question only specifies inability at 6 meters. *Near-total blindness* - Near-total blindness (**Blindness Category 2**) refers to visual acuity **less than 1/60 to light perception only**. - This represents the ability to perceive hand movements close to the face or only light perception. - This is far more severe than the presentation described in the question.
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