Below is a detailed explanation of the first 20 multiple-choice questions (MCQs), Each explanation includes the correct answer, reasoning, and relevant background information to clarify the concepts.
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Q31. What is the primary effect of a concave lens on light that passes through it in terms of refraction through spherical surfaces?
Options:
- 1. It causes light rays to diverge away from the optical axis.
- 2. It focuses light rays to the retina.
- 3. It bends light rays parallel to the optical axis.
- 4. It causes light rays to converge at a single point.
Correct Answer: 1. It causes light rays to diverge away from the optical axis.
Explanation:
A concave lens is a diverging lens, meaning it spreads out light rays that pass through it. When parallel light rays (e.g., from a distant object) enter a concave lens, they are refracted in such a way that they appear to diverge from a virtual focal point on the same side as the incident light. This divergence occurs because the lens is thinner at the center than at the edges, causing the light rays to bend outward, away from the optical axis.
- Option 2: is incorrect because focusing light rays to the retina is a function of the eye’s natural lens or a convex lens, not a concave lens.
- Option 3: is misleading; while a concave lens bends light rays, it does not make them parallel to the optical axis—it causes divergence.
- Option 4: describes a convex (converging) lens, which focuses light rays to a single point (real focus), not a concave lens.
Relevance for Optometry: Concave lenses are used to correct myopia (nearsightedness), where the eye focuses light in front of the retina. The diverging effect of the concave lens helps shift the focus back to the retina.
Q32. Which of the following are the correct base pairs in DNA?
Options:
- 1. Adenine-Cytosine and Guanine-Thymine
- 2. Adenine-Thymine and Guanine-Cytosine
- 3. Adenine-Guanine and Thymine-Cytosine
- 4. Adenine-Uracil and Guanine-Cytosine
Correct Answer: 2. Adenine-Thymine and Guanine-Cytosine
Explanation:
In DNA (deoxyribonucleic acid), the nitrogenous bases form specific complementary pairs through hydrogen bonding:
- Adenine (A) pairs with Thymine (T) via two hydrogen bonds.
- Guanine (G) pairs with Cytosine (C) via three hydrogen bonds.
This base-pairing rule is fundamental to DNA’s double-helix structure and its replication process.
- Option 1: is incorrect because Adenine does not pair with Cytosine, and Guanine does not pair with Thymine.
- Option 3: is incorrect because Adenine and Guanine are both purines and do not pair with each other, nor do Thymine and Cytosine (both pyrimidines).
- Option 4: is incorrect because Uracil is found in RNA, not DNA. In RNA, Adenine pairs with Uracil, but in DNA, Adenine pairs with Thymine.
Relevance for Optometry: Understanding DNA base pairing is relevant in genetic eye disorders (e.g., retinitis pigmentosa), where mutations in DNA sequences can lead to vision impairment.
Q33. Which of the following is a common symptom of tuberculosis (TB)?
Options:
- 1. Night sweats and chills
- 2. Persistent cough and fatigue
- 3. Shortness of breath
- 4. Swollen joints
Correct Answer: 2. Persistent cough and fatigue
Explanation:
Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs (pulmonary TB). A hallmark symptom is a persistent cough lasting more than three weeks, often accompanied by fatigue, weight loss, and sometimes hemoptysis (coughing up blood). Fatigue is a systemic symptom due to the body’s immune response to the infection.
- Option 1: Night sweats and chills are associated with TB, especially in advanced or disseminated cases, but they are less specific and not as universally present as a persistent cough.
- Option 3: Shortness of breath may occur in severe TB with extensive lung damage, but it is not a primary or common early symptom.
- Option 4: Swollen joints are more characteristic of conditions like rheumatoid arthritis or septic arthritis, not TB (though TB can rarely cause joint involvement in extrapulmonary forms).
Relevance for Optometry: TB can affect the eye (ocular TB), causing uveitis or choroiditis. Recognizing systemic symptoms like persistent cough aids in suspecting TB-related ocular manifestations.
Q34. What does the Hirschberg test primarily assess?
Options:
- 1. Refractive error
- 2. Intraocular pressure
- 3. Visual acuity
- 4. Ocular alignment
Correct Answer: 4. Ocular alignment
Explanation:
The Hirschberg test is a simple, non-invasive clinical test used to assess ocular alignment, specifically to detect strabismus (misalignment of the eyes, e.g., esotropia or exotropia). It involves shining a light into the patient’s eyes and observing the reflection (corneal light reflex) on the cornea. If the reflections are symmetric and centered, the eyes are aligned. Asymmetry indicates a deviation of one or both eyes.
- Option 1: Refractive error (e.g., myopia, hyperopia) is assessed using refraction techniques like retinoscopy or subjective refraction, not the Hirschberg test.
- Option 2: Intraocular pressure is measured with tonometry, not the Hirschberg test.
- Option 3: Visual acuity is tested using charts like the Snellen chart, not the Hirschberg test.
Relevance for Optometry: The Hirschberg test is a quick screening tool in pediatric and adult eye exams to identify strabismus, which can lead to amblyopia (lazy eye) if untreated.
Q35. Which of the following statements about the refractive index of spectacle lens material is correct?
Options:
- 1. A lower refractive index means the lens will be thinner for the same prescription.
- 2. High-index lenses are always heavier than standard plastic lenses.
- 3. A higher refractive index bends light more efficiently, allowing the lens to be thinner.
- 4. The refractive index has no effect on the thickness of the lens.
Correct Answer: 3. A higher refractive index bends light more efficiently, allowing the lens to be thinner.
Explanation:
The refractive index (n) of a lens material determines how much it bends light. A higher refractive index means the material bends light more efficiently, requiring less curvature and thickness to achieve the same refractive power (measured in diopters). High-index lenses are thus thinner and lighter for high prescriptions (e.g., strong myopia or hyperopia), improving comfort and aesthetics.
- Option 1: Incorrect. A lower refractive index requires a thicker lens to achieve the same power, as it bends light less efficiently.
- Option 2: Incorrect. High-index lenses are generally lighter than standard plastic lenses (e.g., CR-39, n ≈ 1.5) because they are thinner, despite sometimes being denser materials.
- Option 4: Incorrect. The refractive index directly affects lens thickness; higher-index materials reduce thickness.
Relevance for Optometry: Optometrists recommend high-index lenses for patients with high prescriptions to reduce lens thickness, improving cosmetic appearance and comfort.
Q36. Which of the following statements is true about convergence insufficiency?
Options:
- 1. It is not related to binocular vision.
- 2. A symptom is the inability to turn the eyes outward.
- 3. It involves reduced ability of the eyes to turn inward while focusing on a near object.
- 4. It is caused by excessive accommodation.
Correct Answer: 3. It involves reduced ability of the eyes to turn inward while focusing on a near object.
Explanation:
Convergence insufficiency (CI) is a binocular vision disorder where the eyes have difficulty turning inward (converging) to focus on a near object, such as during reading. This leads to symptoms like eye strain, double vision (diplopia), headaches, and difficulty concentrating on near tasks. CI is often diagnosed using tests like near point of convergence (NPC).
- Option 1: Incorrect. CI is directly related to binocular vision, as it affects the coordinated movement of both eyes.
- Option 2: Incorrect. The issue in CI is difficulty turning eyes inward (convergence), not outward (divergence).
- Option 4: Incorrect. CI is not caused by excessive accommodation (focusing effort of the lens); however, accommodation and convergence are linked, and CI may strain the accommodative system.
Relevance for Optometry: CI is a common condition treated with vision therapy, prism lenses, or exercises to improve convergence ability, especially in children and young adults.
Q37. A converging lens is also known as:
Options:
- 1. Convex lens
- 2. Plano-concave lens
- 3. Plano-convex lens
- 4. Concave lens
Correct Answer: 1. Convex lens
Explanation:
A converging lens focuses parallel light rays to a single point (real focus) after refraction. This is achieved by a convex lens, which is thicker at the center than at the edges, causing light rays to bend inward (converge). Both plano-convex (one flat side, one convex side) and biconvex (both sides convex) lenses are types of convex lenses, but the general term for a converging lens is “convex lens.”
- Option 2: Incorrect. A plano-concave lens is a diverging lens, as one side is concave, causing light to spread out.
- Option 3: Incorrect. While a plano-convex lens is a type of convex lens, the question asks for the general term, which is “convex lens.”
- Option 4: Incorrect. A concave lens is a diverging lens, not a converging one.
Relevance for Optometry: Convex lenses are used to correct hyperopia (farsightedness) and presbyopia, where the eye cannot focus light properly on the retina.
Q38. Which infection is caused by the varicella zoster virus?
Options:
- 1. Conjunctivitis
- 2. Herpes zoster ophthalmicus
- 3. Keratitis
- 4. Endophthalmitis
Correct Answer: 2. Herpes zoster ophthalmicus
Explanation:
The varicella zoster virus (VZV) causes chickenpox during primary infection and can remain dormant in nerve ganglia. Reactivation later in life leads to herpes zoster (shingles). When the ophthalmic division of the trigeminal nerve (CN V1) is involved, it causes herpes zoster ophthalmicus (HZO), characterized by a painful rash on the forehead, eyelid, or face, and potential ocular complications like conjunctivitis, keratitis, or uveitis.
- Option 1: Conjunctivitis can be caused by various pathogens (e.g., bacteria, other viruses), but not specifically VZV.
- Option 3: Keratitis (corneal inflammation) can be a complication of HZO, but it is not the primary infection caused by VZV.
- Option 4: Endophthalmitis is a severe intraocular infection, typically bacterial or fungal, not caused by VZV.
Relevance for Optometry: HZO is a serious condition requiring urgent antiviral treatment to prevent vision-threatening complications like corneal scarring or glaucoma.
Q39. Which of the following structures plays a primary role in the outflow of aqueous humor and is most commonly implicated in the pathophysiology of primary open-angle glaucoma?
Options:
- 1. Schlemm's canal
- 2. Zonules of Zinn
- 3. Iris root
- 4. Vitreous body
Correct Answer: 1. Schlemm's canal
Explanation:
Aqueous humor, produced by the ciliary body, flows from the posterior chamber through the pupil to the anterior chamber and drains primarily via the trabecular meshwork into Schlemm’s canal. In primary open-angle glaucoma (POAG), the most common form of glaucoma, resistance to aqueous outflow in the trabecular meshwork or Schlemm’s canal increases, elevating intraocular pressure (IOP) and damaging the optic nerve.
- Option 2: Zonules of Zinn are fibers that suspend the lens, not involved in aqueous outflow.
- Option 3: The iris root is part of the anterior chamber angle but not the primary outflow structure.
- Option 4: The vitreous body is a gel-like structure in the posterior segment, unrelated to aqueous humor dynamics.
Relevance for Optometry: Understanding aqueous outflow is critical for diagnosing and managing glaucoma, as treatments (e.g., medications, laser trabeculoplasty) target the trabecular meshwork or Schlemm’s canal to lower IOP.
Q40. Which of the following best describes an integrated approach to tackling avoidable blindness, and how is it different from traditional models in terms of sustainability and accessibility?
Options:
- 1. Focuses on expensive laser-based technology and urban tertiary care centers.
- 2. Performs cataract surgeries for elderly patients only in city hospitals.
- 3. Relies entirely on government funding and rural volunteers.
- 4. Combines community-based screening, cross-subsidized care, and high-volume surgical efficiency.
Correct Answer: 4. Combines community-based screening, cross-subsidized care, and high-volume surgical efficiency.
Explanation:
An integrated approach to tackling avoidable blindness (e.g., from cataracts, refractive errors, or glaucoma) emphasizes accessibility and sustainability. It involves:
Community-based screening: to identify cases in underserved areas.
Cross-subsidized care: where revenue from paying patients subsidizes free or low-cost care for the poor.
High-volume surgical efficiency: like that seen in models such as Aravind Eye Care System, to reduce costs and increase output.
This approach differs from traditional models, which often rely on centralized, expensive facilities with limited reach to rural populations, making them less sustainable and accessible.
- Option 1: Incorrect. Expensive laser technology and urban centers limit accessibility and are not sustainable for widespread blindness prevention.
- Option 2: Incorrect. Restricting surgeries to elderly patients in city hospitals excludes other causes of blindness and rural populations.
- Option 3: Incorrect. Sole reliance on government funding and volunteers is unsustainable due to inconsistent resources and scalability issues.
Relevance for Optometry: Integrated approaches are vital for public health optometry, ensuring equitable access to eye care in resource-limited settings.
Q41. During the inflammation process, which of the following is the primary response of ocular tissue?
Options:
- 1. Inhibition of immune cell activity
- 2. Decreased blood flow to the affected area
- 3. Vasodilation and increased vascular permeability
- 4. Complete healing without scarring
Correct Answer: 3. Vasodilation and increased vascular permeability
Explanation:
Inflammation in ocular tissues (e.g., conjunctivitis, uveitis) follows the general inflammatory response. The primary response includes:
Vasodilation: Blood vessels widen, increasing blood flow to the affected area, causing redness (e.g., conjunctival injection).
Increased vascular permeability: Blood vessel walls become leaky, allowing immune cells and plasma proteins to enter the tissue, leading to swelling (edema) and aiding in pathogen clearance.
- Option 1: Incorrect. Inflammation involves activation, not inhibition, of immune cells (e.g., neutrophils, macrophages).
- Option 2: Incorrect. Blood flow increases due to vasodilation, not decreases.
- Option 4: Incorrect. Healing without scarring is a potential outcome, not the primary response during active inflammation.
Relevance for Optometry: Recognizing signs of inflammation (redness, swelling) is crucial for diagnosing ocular conditions like uveitis or keratitis and guiding treatment (e.g., corticosteroids).
Q42. What is the main feature of bifocal lenses?
Options:
- 1. They have two different focal lengths
- 2. They are used only for reading
- 3. They are used for color correction
- 4. They are designed for single-vision use
Correct Answer: 1. They have two different focal lengths
Explanation:
Bifocal lenses have two distinct optical zones with different focal lengths (powers):
- The upper portion corrects for distance vision (e.g., for myopia or hyperopia).
- The lower portion, often a visible segment, corrects for near vision (e.g., for presbyopia).
This allows wearers to switch between distance and near tasks without changing glasses.
- Option 2: Incorrect. Bifocals are used for both distance and near vision, not only reading.
- Option 3: Incorrect. Bifocals correct refractive errors, not color vision deficiencies.
- Option 4: Incorrect. Single-vision lenses have one focal length, unlike bifocals.
Relevance for Optometry: Bifocals are commonly prescribed for presbyopia, an age-related condition where the eye loses near-focusing ability.
Q43. Which of the following cranial nerves is responsible for the movement of the lateral rectus muscle in the eye?
Options:
- 1. Oculomotor nerve (CN III)
- 2. Trochlear nerve (CN IV)
- 3. Abducens nerve (CN VI)
- 4. Trigeminal nerve (CN V)
Correct Answer: 3. Abducens nerve (CN VI)
Explanation:
The lateral rectus muscle abducts the eye (moves it outward). It is innervated by the abducens nerve (cranial nerve VI). The extraocular muscles are controlled by three cranial nerves:
- Oculomotor nerve (CN III): Innervates superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris.
- Trochlear nerve (CN IV): Innervates superior oblique.
- Abducens nerve (CN VI): Innervates lateral rectus.
- Option 1: Incorrect. CN III controls most eye muscles but not the lateral rectus.
- Option 2: Incorrect. CN IV controls the superior oblique, not the lateral rectus.
- Option 4: Incorrect. CN V (trigeminal) is sensory for the face and cornea, not motor for eye muscles.
Relevance for Optometry: Damage to CN VI can cause esotropia (inward eye deviation) and diplopia, which optometrists may detect during motility testing.
Q44. What is the primary use of a fundus camera?
Options:
1. Measuring the cornea
2. Measuring intraocular pressure
3. Taking photographs of the retina
4. Checking lens clarity
Correct Answer: 3. Taking photographs of the retina
Explanation:
A fundus camera is a specialized imaging device used to capture detailed photographs of the retina, optic disc, macula, and blood vessels at the back of the eye (fundus). These images are critical for diagnosing and monitoring conditions like diabetic retinopathy, glaucoma, and macular degeneration.
- Option 1: Incorrect. Corneal measurements are done with keratometry or topography.
- Option 2: Incorrect. Intraocular pressure is measured with tonometry.
- Option 4: Incorrect. Lens clarity (e.g., for cataracts) is assessed with a slit lamp or ophthalmoscopy, not primarily a fundus camera.
Relevance for Optometry: Fundus photography is a routine tool for retinal screening and documentation in optometric practice.
Q45. Which of the following is considered a subjective method of refraction?
Options:
- 1. Retinoscopy
- 2. Autorefraction
- 3. Trial frame testing
- 4. Keratometry
Correct Answer: 3. Trial frame testing
Explanation:
Subjective refraction relies on the patient’s feedback to determine the optimal lens prescription. In trial frame testing, the optometrist places lenses of varying powers in a trial frame and asks the patient to compare clarity (e.g., “Which is better, lens 1 or lens 2?”) to refine the prescription.
- Option 1: Retinoscopy is an objective method, as it uses the reflection of light from the retina to estimate refractive error without patient input.
- Option 2: Autorefraction is an objective method, using automated instruments to measure refractive error.
- Option 4: Keratometry measures corneal curvature, not refractive error, and is objective.
Relevance for Optometry: Subjective refraction, like trial frame testing, is essential for finalizing prescriptions, especially for complex cases or when objective methods are less accurate.
Q46. What is the unit of measurement for the power of a lens?
Options:
- 1. Hertz
- 2. Meter
- 3. Diopter
- 4. Newton
Correct Answer: 3. Diopter
Explanation:
The power of a lens, which indicates its ability to converge or diverge light, is measured in diopters (D). The power (P) is defined as the reciprocal of the focal length (f, in meters):
\[ P = \frac{1}{f} \]
For example, a lens with a focal length of 0.5 meters has a power of \( \frac{1}{0.5} = 2 \, \text{D} \). Convex lenses have positive power, and concave lenses have negative power.
- Option 1: Hertz measures frequency (e.g., of light waves).
- Option 2: Meter measures length, not lens power.
- Option 4: Newton measures force, not optical power.
Relevance for Optometry: Diopters are used to prescribe corrective lenses for conditions like myopia (-D) or hyperopia (+D).
Q47. A patient reports difficulty seeing distant objects clearly but has no issues with reading. What is the likely refractive error?
Options:
- 1. Hyperopia
- 2. Presbyopia
- 3. Myopia
- 4. Astigmatism
Correct Answer: 3. Myopia
Explanation:
Myopia (nearsightedness) is a refractive error where the eye focuses light in front of the retina, causing distant objects to appear blurry while near objects are clear. This occurs due to an elongated eyeball or excessive corneal/lens curvature.
- Option 1: Hyperopia (farsightedness) causes difficulty with near vision, not distance vision.
- Option 2: Presbyopia is an age-related loss of near focusing ability, affecting reading, not distance vision.
- Option 4: Astigmatism causes blurred vision at all distances due to irregular corneal or lens curvature, but the question specifies only distance vision issues.
Relevance for Optometry: Myopia is corrected with concave (minus) lenses, and optometrists must accurately diagnose it to prescribe appropriate glasses or contact lenses.
Q48. Which layer of the eye contains blood vessels and provides oxygen and nutrients to the retina?
Options:
- 1. Cornea
- 2. Sclera
- 3. Iris
- 4. Choroid
Correct Answer: 4. Choroid
Explanation:
The choroid is a vascular layer of the eye located between the retina and the sclera. It contains a dense network of blood vessels that supply oxygen and nutrients to the outer retina (e.g., photoreceptors) and other ocular structures. The choroid also absorbs stray light to prevent reflections within the eye.
- Option 1: The cornea is avascular (lacking blood vessels) and transparent, relying on aqueous humor and tears for nutrients.
- Option 2: The sclera is the fibrous outer layer, providing structural support, not blood supply.
- Option 3: The iris controls pupil size and has some blood vessels but is not the primary supplier to the retina.
Relevance for Optometry: Choroidal abnormalities (e.g., in choroiditis or neovascularization) can affect retinal health, detectable during fundus examination.
Q49. What is the function of the macula in the eye?
Options:
1. Provides peripheral vision
2. Controls eye movement
3. Facilitates night vision
4. Enables sharp central vision
Correct Answer: 4. Enables sharp central vision
Explanation:
The macula is a small, central area of the retina rich in cone photoreceptors, responsible for high-acuity vision, color perception, and fine detail (e.g., reading, recognizing faces). The fovea, at the macula’s center, has the highest cone density, providing the sharpest vision.
- Option 1: Peripheral vision is mediated by the peripheral retina, rich in rod photoreceptors.
- Option 2: Eye movement is controlled by extraocular muscles, not the macula.
- Option 3: Night vision is facilitated by rods, which are sparse in the macula but abundant in the peripheral retina.
Relevance for Optometry: Macular disorders (e.g., macular degeneration) severely impair central vision, and optometrists use tests like Amsler grid to assess macular function.
Q50. Which vitamin deficiency is most commonly associated with night blindness?
Options:
- 1. Vitamin A
- 2. Vitamin B12
- 3. Vitamin C
- 4. Vitamin D
Correct Answer: 1. Vitamin A
Explanation:
Vitamin A is essential for producing rhodopsin, a pigment in rod photoreceptors that enables vision in low-light conditions. A deficiency in vitamin A impairs rod function, leading to night blindness (nyctalopia), where individuals struggle to see in dim light or at night. Severe deficiency can also cause xerophthalmia or keratomalacia, affecting the cornea.
- Option 2: Vitamin B12 deficiency causes neurological issues (e.g., optic neuropathy), not night blindness.
- Option 3: Vitamin C deficiency causes scurvy, affecting connective tissues, not vision directly.
- Option 4: Vitamin D deficiency is linked to bone health, not night blindness.
Relevance for Optometry: Night blindness due to vitamin A deficiency is a key diagnostic clue in regions with malnutrition, and optometrists may recommend supplementation or referral.
Q51. Which part of the eye is responsible for focusing light onto the retina?
Options:
- 1. Cornea
- 2. Iris
- 3. Lens
- 4. Pupil
Correct Answer: 3. Lens
Explanation:
The lens, located behind the iris, is a transparent, biconvex structure that fine-tunes the focus of light onto the retina by changing its shape (accommodation). The cornea also contributes significantly to focusing light (about 70% of the eye’s refractive power), but the lens adjusts focus for near and far objects.
- Option 1: The cornea refracts light but does not adjust focus dynamically like the lens.
- Option 2: The iris controls the pupil size to regulate light entry, not focusing.
- Option 4: The pupil is an aperture that controls light intensity, not a focusing structure.
Relevance for Optometry: The lens’s role in accommodation is critical for diagnosing refractive errors like presbyopia (age-related loss of lens flexibility) and prescribing corrective lenses.
Q52. What is the normal range of intraocular pressure (IOP) in mmHg?
Options:
- 1. 5-10
- 2. 10-21
- 3. 22-30
- 4. 30-40
Correct Answer: 2. 10-21
Explanation:
Intraocular pressure (IOP) is the pressure exerted by the aqueous humor within the eye, typically measured in millimeters of mercury (mmHg). The normal range for most individuals is 10-21 mmHg, with slight variations. Elevated IOP (>21 mmHg) is a hallmark of glaucoma, though not all cases of glaucoma have high IOP (e.g., normal-tension glaucoma).
- Option 1: 5-10 mmHg is too low and may indicate hypotony, which can cause retinal or choroidal issues.
- Option 3: 22-30 mmHg is elevated and suggestive of ocular hypertension or glaucoma.
- Option 4: 30-40 mmHg is significantly elevated and associated with advanced glaucoma or acute angle-closure glaucoma.
Relevance for Optometry: Optometrists measure IOP using tonometry to screen for glaucoma, a leading cause of irreversible blindness.
Q53. What condition is characterized by increased intraocular pressure causing optic nerve damage?
Options:
- 1. Cataract
- 2. Glaucoma
- 3. Macular degeneration
- 4. Retinal detachment
Correct Answer: 2. Glaucoma
Explanation:
Glaucoma is a group of eye diseases characterized by increased intraocular pressure (IOP) that damages the optic nerve, leading to progressive vision loss, particularly peripheral vision. Primary open-angle glaucoma (POAG) is the most common form, involving impaired aqueous humor outflow.
- Option 1: Cataract involves lens clouding, not IOP or optic nerve damage.
- Option 3: Macular degeneration affects central vision due to retinal damage, not IOP.
- Option 4: Retinal detachment involves the retina separating from underlying tissue, unrelated to IOP.
Relevance for Optometry: Early detection of glaucoma through IOP measurement, optic disc evaluation, and visual field testing is critical for preventing vision loss.
Q54. Which of the following is the most common cause of refractive error in the human eye?
Options:
- 1. Myopia
- 2. Cataract
- 3. Glaucoma
- 4. Presbyopia
Correct Answer: 1. Myopia
Explanation:
Myopia (nearsightedness) is the most common refractive error globally, particularly in younger populations and urban areas with high near-work demands (e.g., reading, screen time). It occurs when the eyeball is too long or the cornea/lens is too curved, causing light to focus in front of the retina.
- Option 2: Cataract causes vision blur due to lens opacity, not a refractive error in the optical sense.
- Option 3: Glaucoma affects IOP and optic nerve health, not refractive error.
- Option 4: Presbyopia is common in older adults due to loss of lens elasticity, but myopia is more prevalent across all age groups.
Relevance for Optometry: Myopia management, including corrective lenses, contact lenses, or orthokeratology, is a core part of optometric practice, especially with rising myopia prevalence.
Q55. What is the primary function of rods in the retina?
Options:
- 1. Color vision
- 2. Peripheral and night vision
- 3. Sharp central vision
- 4. Depth perception
Correct Answer:2. Peripheral and night vision
Explanation:
Rods are photoreceptor cells in the retina, concentrated in the peripheral regions, and are highly sensitive to low light levels. They enable night vision (scotopic vision) and contribute to peripheral vision but do not detect color or fine detail.
- Option 1: Color vision is mediated by cone photoreceptors, not rods.
- Option 3: Sharp central vision is provided by cones, particularly in the macula.
- Option 4: Depth perception involves binocular vision and brain processing, not a specific retinal cell function.
Relevance for Optometry: Rod dysfunction (e.g., in retinitis pigmentosa or vitamin A deficiency) causes night blindness, which optometrists diagnose through history and fundus examination.
Q56. Which test measures the curvature of the cornea?
Options:
- 1. Retinoscopy
- 2. Keratometry
- 3. Tonometry
- 4. Visual acuity test
Correct Answer: 2. Keratometry
Explanation:
Keratometry measures the curvature of the cornea’s anterior surface, typically in diopters or millimeters of radius, to assess its refractive power. It is used in contact lens fitting, refractive surgery planning, and diagnosing conditions like keratoconus (irregular corneal curvature).
- Option 1: Retinoscopy estimates refractive error by observing light reflections from the retina.
- Option 3: Tonometry measures intraocular pressure, not corneal curvature.
- Option 4: Visual acuity tests (e.g., Snellen chart) assess clarity of vision, not corneal shape.
Relevance for Optometry: Keratometry is essential for fitting contact lenses and diagnosing corneal disorders, ensuring optimal vision correction.
Q57. What does the Snellen chart test?
Options:
- 1. Color vision
- 2. Visual acuity
- 3. Depth perception
- 4. Eye pressure
Correct Answer: 2. Visual acuity
Explanation:
The Snellen chart is a standardized tool used to measure visual acuity, the clarity or sharpness of vision, typically at a distance of 20 feet (6 meters). It consists of letters of decreasing size, with results expressed as a fraction (e.g., 20/20 indicates normal vision).
- Option 1: Color vision is tested with tools like Ishihara plates.
- Option 3: Depth perception is assessed with stereopsis tests (e.g., Randot test).
- Option 4: Eye pressure is measured with tonometry.
Relevance for Optometry: Visual acuity testing with the Snellen chart is a fundamental part of eye exams to diagnose refractive errors and monitor vision changes.
Q58. Which nerve is responsible for the sensation of the cornea?
Options:
- 1. Optic nerve (CN II)
- 2. Oculomotor nerve (CN III)
- 3. Trigeminal nerve (CN V)
- 4. Facial nerve (CN VII)
Correct Answer:3. Trigeminal nerve (CN V)
Explanation:
The cornea is innervated by the ophthalmic branch (V1) of the trigeminal nerve (cranial nerve V), which provides sensory innervation for touch, pain, and temperature sensations. This makes the cornea highly sensitive, aiding in protective reflexes like blinking.
- Option 1: The optic nerve (CN II) transmits visual information from the retina, not corneal sensation.
- Option 2: The oculomotor nerve (CN III) controls eye muscles and pupil constriction, not sensation.
- Option 4: The facial nerve (CN VII) controls facial muscles and tearing, not corneal sensation.
Relevance for Optometry: Corneal sensation testing (e.g., with a cotton wisp) assesses trigeminal nerve function, important in diagnosing conditions like neurotrophic keratitis.
Q59. Which condition causes clouding of the eye's natural lens?
Options:
- 1. Glaucoma
- 2. Cataract
- 3. Macular degeneration
- 4. Diabetic retinopathy
Correct Answer: 2. Cataract
Explanation:
A cataract is the clouding of the eye’s natural lens, leading to blurred vision, glare, and reduced color perception. It is often age-related but can also result from trauma, medications, or systemic diseases.
- Option 1: Glaucoma involves optic nerve damage due to increased IOP, not lens clouding.
- Option 3: Macular degeneration affects the retina’s macula, impairing central vision.
- Option 4: Diabetic retinopathy involves retinal blood vessel damage, not lens opacity.
Relevance for Optometry: Cataracts are diagnosed via slit-lamp examination, and optometrists refer patients for surgical intervention (lens replacement) when vision is significantly impaired.
Q60. What type of lens is used to correct hyperopia (farsightedness)?
Options:
- 1. Convex lens
- 2. Concave lens
- 3. Cylindrical lens
- 4. Plano lens
Correct Answer: 1. Convex lens
Explanation:
Hyperopia (farsightedness) occurs when light focuses behind the retina due to a short eyeball or insufficient refractive power. Convex lenses (positive power, converging) add focusing power to shift the focal point forward onto the retina.
- Option 2: Concave lenses (negative power, diverging) correct myopia, not hyperopia.
- Option 3: Cylindrical lenses correct astigmatism, not spherical errors like hyperopia.
- Option 4: Plano lenses have no refractive power and do not correct hyperopia.
Relevance for Optometry: Convex lenses are prescribed for hyperopia to improve near and sometimes distance vision, depending on the degree of error.
Q61. Which layer of the retina contains photoreceptor cells?
Options:
- 1. Ganglion cell layer
- 2. Inner nuclear layer
- 3. Outer nuclear layer
- 4. Nerve fiber layer
Correct Answer: 3. Outer nuclear layer
Explanation:
The retina has multiple layers, and the outer nuclear layer (ONL) contains the cell bodies of photoreceptors (rods and cones), which detect light and initiate visual signal transduction. The photoreceptor outer segments, where light absorption occurs, extend toward the retinal pigment epithelium.
- Option 1: The ganglion cell layer contains ganglion cells, which transmit visual signals to the brain via the optic nerve.
- Option 2: The inner nuclear layer contains bipolar, amacrine, and horizontal cells, which process signals between photoreceptors and ganglion cells.
- Option 4: The nerve fiber layer contains axons of ganglion cells, forming the optic nerve.
Relevance for Optometry: Damage to the outer nuclear layer (e.g., in retinal dystrophies) impairs photoreceptor function, leading to vision loss detectable on fundus examination or OCT.
Q62. What is the primary cause of diabetic retinopathy?
Options:
- 1. High intraocular pressure
- 2. Damage to retinal blood vessels due to high blood sugar
- 3. Aging of the lens
- 4. Trauma to the eye
Correct Answer: 2. Damage to retinal blood vessels due to high blood sugar
Explanation:
Diabetic retinopathy is caused by chronic high blood sugar levels damaging retinal blood vessels, leading to leakage, hemorrhages, or abnormal vessel growth (neovascularization). It is a complication of diabetes and can progress from non-proliferative to proliferative stages, risking vision loss.
- Option 1: High IOP causes glaucoma, not diabetic retinopathy.
- Option 3: Lens aging causes cataracts, not retinal vessel damage.
- Option 4: Trauma can cause retinal damage but is not the primary cause of diabetic retinopathy.
Relevance for Optometry: Optometrists screen for diabetic retinopathy using fundus photography and refer patients for treatment (e.g., anti-VEGF injections, laser) to prevent blindness.
Q63. Which eye condition is characterized by the detachment of the retina from its underlying tissue?
Options:
- 1. Cataract
- 2. Retinal detachment
- 3. Glaucoma
- 4. Macular degeneration
Correct Answer: 2. Retinal detachment
Explanation:
Retinal detachment occurs when the retina separates from its underlying supportive tissue (retinal pigment epithelium), disrupting photoreceptor nourishment and causing vision loss in the affected area. Symptoms include floaters, flashes, and a curtain-like shadow.
- Option 1: Cataract involves lens clouding, not retinal separation.
- Option 3: Glaucoma affects the optic nerve, not retinal attachment.
- Option 4: Macular degeneration damages the macula, not the entire retina’s attachment.
Relevance for Optometry: Retinal detachment is an emergency requiring urgent referral for surgical repair (e.g., scleral buckling or vitrectomy) to restore vision.
Q64. What is the function of the iris?
Options:
- 1. Controls the amount of light entering the eye
- 2. Focuses light on the retina
- 3. Produces tears
- 4. Detects color
Correct Answer: 1. Controls the amount of light entering the eye
Explanation:
The iris is a pigmented, muscular structure surrounding the pupil. It adjusts pupil size via contraction (miosis) or dilation (mydriasis) to regulate the amount of light entering the eye, protecting the retina and optimizing vision in varying light conditions.
- Option 2: Focusing is done by the cornea and lens, not the iris.
- Option 3: Tears are produced by the lacrimal gland, not the iris.
- Option 4: Color detection is a function of retinal cone cells, not the iris.
Relevance for Optometry: Iris abnormalities (e.g., anisocoria, iritis) can affect pupil function and are assessed during slit-lamp exams.
Q65. Which of the following is a surgical treatment for retinal detachment?
Options:
- 1. LASIK
- 2. Scleral buckling
- 3. Cataract surgery
- 4. Photocoagulation
Correct Answer: 2. Scleral buckling
Explanation:
Scleral buckling is a surgical procedure used to treat retinal detachment by placing a silicone band around the sclera to indent the eye wall, closing the retinal break and reattaching the retina. Other treatments include vitrectomy or pneumatic retinopexy.
- Option 1: LASIK corrects refractive errors by reshaping the cornea, not treating retinal detachment.
- Option 3: Cataract surgery replaces the clouded lens, unrelated to retinal detachment.
- Option 4: Photocoagulation uses laser to seal retinal tears but is not a primary surgical repair for detachment.
Relevance for Optometry: Optometrists identify retinal detachment signs (e.g., floaters, flashes) and refer patients urgently for surgical intervention.
Q66. What does the term "acuity" refer to in vision?
Options:
- 1. Color perception
- 2. Sharpness or clarity of vision
- 3. Peripheral vision
- 4. Depth perception
Correct Answer: 2. Sharpness or clarity of vision
Explanation:
Visual acuity refers to the clarity or sharpness of vision, typically measured using a Snellen chart at a standard distance (e.g., 20 feet). It quantifies the ability to discern fine details, expressed as a fraction (e.g., 20/20 for normal vision).
- Option 1: Color perception is tested separately (e.g., Ishihara plates).
- Option 3: Peripheral vision is assessed with visual field testing.
- Option 4: Depth perception is evaluated with stereopsis tests.
Relevance for Optometry: Visual acuity is a key metric in eye exams to diagnose refractive errors, cataracts, or other vision-impairing conditions.
Q67. Which vitamin deficiency can cause keratomalacia and night blindness?
Options:
- 1. Vitamin A
- 2. Vitamin C
- 3. Vitamin D
- 4. Vitamin E
Correct Answer: 1. Vitamin A
Explanation:
Vitamin A deficiency impairs rhodopsin production in rods, causing night blindness (nyctalopia). Severe deficiency leads to keratomalacia, a softening and ulceration of the cornea due to impaired epithelial maintenance, potentially causing blindness.
- Option 2: Vitamin C deficiency causes scurvy, affecting connective tissues, not the cornea or night vision.
- Option 3: Vitamin D deficiency affects bone health, not vision.
- Option 4: Vitamin E deficiency is linked to neurological issues, not keratomalacia or night blindness.
Relevance for Optometry: Vitamin A deficiency is a major cause of preventable blindness in developing countries, and optometrists may recommend supplementation.
Q68. Which instrument is used to measure intraocular pressure?
Options:
- 1. Retinoscope
- 2. Tonometer
- 3. Ophthalmoscope
- 4. Slit lamp
Correct Answer: 2. Tonometer
Explanation:
A tonometer measures intraocular pressure (IOP), typically in mmHg, to screen for glaucoma. Common methods include Goldmann applanation tonometry (using a slit lamp) and non-contact (air-puff) tonometry.
- Option 1: A retinoscope is used for objective refraction, not IOP measurement.
- Option 3: An ophthalmoscope visualizes the retina and optic disc, not IOP.
- Option 4: A slit lamp is used for anterior segment examination but requires a tonometer attachment to measure IOP.
Relevance for Optometry: Tonometry is a routine procedure in glaucoma screening, critical for early detection and management.
Q69. What is the function of the conjunctiva?
Options:
- 1. Protects the cornea and lubricates the eye
- 2. Focuses light onto the retina
- 3. Controls pupil size
- 4. Contains photoreceptor cells
Correct Answer: 1. Protects the cornea and lubricates the eye
Explanation:
The conjunctiva is a thin, transparent membrane covering the sclera and inner eyelids. It protects the cornea by providing a barrier against pathogens and debris and lubricates the eye via mucin secretion, aiding smooth eye movement.
- Option 2: Focusing is done by the cornea and lens, not the conjunctiva.
- Option 3: Pupil size is controlled by the iris.
- Option 4: Photoreceptors are in the retina, not the conjunctiva.
Relevance for Optometry: Conjunctival inflammation (conjunctivitis) is a common condition diagnosed by optometrists, often presenting with redness and discharge.
Q70. What is presbyopia?
Options:
- 1. Nearsightedness
- 2. Farsightedness
- 3. Age-related loss of accommodation
- 4. Eye infection
Correct Answer: 3. Age-related loss of accommodation
Explanation:
Presbyopia is an age-related condition (typically starting around age 40) where the lens loses elasticity, reducing the eye’s ability to accommodate (focus on near objects). This leads to difficulty with tasks like reading, requiring corrective lenses (e.g., reading glasses, bifocals).
- Option 1: Nearsightedness is myopia, a refractive error, not age-related.
- Option 2: Farsightedness is hyperopia, unrelated to lens elasticity loss.
- Option 4: Eye infections (e.g., conjunctivitis) are unrelated to accommodation.
Relevance for Optometry: Presbyopia is a common condition managed with reading glasses, bifocals, or progressive lenses, a key focus in optometric care for aging patients.
Q71. Which type of lens is used to correct myopia (nearsightedness)?
Options:
- 1. Convex lens
- 2. Concave lens
- 3. Cylindrical lens
- 4. Plano lens
Correct Answer: 2. Concave lens
Explanation:
Myopia (nearsightedness) occurs when the eyeball is too long or the cornea/lens has excessive curvature, causing light to focus in front of the retina, making distant objects blurry. Concave lenses (negative power, diverging) spread light rays outward, shifting the focal point back to the retina to correct distance vision.
- Option 1: Convex lenses (positive power, converging) correct hyperopia, not myopia.
- Option 3: Cylindrical lenses correct astigmatism, not spherical errors like myopia.
- Option 4: Plano lenses have no refractive power and do not correct myopia.
Relevance for Optometry: Concave lenses are prescribed in glasses or contact lenses for myopic patients, and optometrists may also recommend myopia control strategies (e.g., orthokeratology) for children.
Q72. What is the primary role of the vitreous humor?
Options:
- 1. Provides nutrients to the lens
- 2. Maintains the shape of the eye and supports the retina
- 3. Controls pupil size
- 4. Focuses light on the retina
Correct Answer: 2. Maintains the shape of the eye and supports the retina
Explanation:
The vitreous humor is a clear, gel-like substance filling the posterior segment of the eye (between the lens and retina). Its primary roles are to maintain the eye’s spherical shape, provide structural support to the retina, and allow light to pass through to the retina with minimal distortion.
- Option 1: The lens is nourished by the aqueous humor, not the vitreous.
- Option 3: Pupil size is controlled by the iris, not the vitreous.
- Option 4: Focusing is done by the cornea and lens, not the vitreous.
Relevance for Optometry: Vitreous abnormalities (e.g., floaters, posterior vitreous detachment) can affect vision and are assessed during fundus examination, often indicating retinal issues.
Q73. Which condition is an inflammation of the uveal tract?
Options:
- 1. Conjunctivitis
- 2. Uveitis
- 3. Keratitis
- 4. Blepharitis
Correct Answer: 2. Uveitis
Explanation:
Uveitis is inflammation of the uveal tract, which includes the iris, ciliary body, and choroid. It can cause symptoms like eye pain, redness, photophobia, and blurred vision, and may be associated with systemic diseases (e.g., autoimmune disorders).
Option 1: Conjunctivitis is inflammation of the conjunctiva, not the uveal tract.
Option 3: Keratitis is inflammation of the cornea.
Option 4: Blepharitis is inflammation of the eyelid margins.
Relevance for Optometry: Uveitis requires urgent diagnosis and treatment (e.g., corticosteroids) to prevent complications like glaucoma or cataracts, and optometrists often co-manage with ophthalmologists.
Q74. What part of the eye is affected in glaucoma?
Options:
1. Retina
2. Optic nerve
3. Cornea
4. Lens
Correct Answer: 2. Optic nerve
Explanation:
Glaucoma is characterized by progressive damage to the optic nerve, often due to elevated intraocular pressure (IOP), leading to loss of peripheral vision and, if untreated, blindness. The optic disc may show cupping (enlarged cup-to-disc ratio) due to nerve fiber loss.
Option 1: The retina is affected in conditions like diabetic retinopathy or retinal detachment, not primarily in glaucoma.
Option 3: The cornea is unaffected in most glaucoma cases, though high IOP can cause corneal edema in acute cases.
Option 4: The lens is involved in cataracts, not glaucoma.
Relevance for Optometry: Optometrists screen for glaucoma using tonometry (IOP), ophthalmoscopy (optic disc), and visual field testing, referring patients for treatment to preserve vision.
Q75. Which condition causes clouding of the lens leading to vision loss?
Options:
1. Cataract
2. Glaucoma
3. Retinal detachment
4. Macular degeneration
Correct Answer: 1. Cataract
Explanation:
A cataract is the clouding of the eye’s natural lens, leading to blurred vision, glare, and reduced color perception. It is often age-related but can result from trauma, medications, or systemic conditions like diabetes.
Option 2: Glaucoma damages the optic nerve, not the lens.
Option 3: Retinal detachment involves retinal separation, not lens clouding.
Option 4: Macular degeneration affects the retina’s macula, impairing central vision.
Relevance for Optometry: Cataracts are diagnosed via slit-lamp examination, and optometrists refer patients for surgical lens replacement when vision is significantly impaired.
Q76. What is astigmatism?
Options:
1. Difficulty seeing distant objects
2. Irregular curvature of the cornea causing blurred vision
3. Age-related farsightedness
4. Inflammation of the eyelids
Correct Answer: 2. Irregular curvature of the cornea causing blurred vision
Explanation:
Astigmatism is a refractive error caused by an irregular curvature of the cornea or lens, leading to unequal focusing of light in different meridians. This results in blurred or distorted vision at all distances.
Option 1: Difficulty seeing distant objects describes myopia, not astigmatism.
Option 3: Age-related farsightedness is presbyopia, not astigmatism.
Option 4: Inflammation of the eyelids is blepharitis, unrelated to astigmatism.
Relevance for Optometry: Astigmatism is corrected with cylindrical lenses or toric contact lenses, and optometrists use keratometry or topography to assess corneal shape.
Q77. What is the role of the macula in the retina?
Options:
1. Peripheral vision
2. Central sharp vision
3. Night vision
4. Color blindness
Correct Answer: 2. Central sharp vision
Explanation:
The macula, located at the center of the retina, is rich in cone photoreceptors and is responsible for high-acuity central vision, color perception, and fine detail (e.g., reading, recognizing faces). The fovea, within the macula, provides the sharpest vision.
Option 1: Peripheral vision is mediated by the peripheral retina, rich in rods.
Option 3: Night vision is facilitated by rods, not the macula.
Option 4: Color blindness is due to cone dysfunction, not a macular role.
Relevance for Optometry: Macular health is assessed using tools like the Amsler grid or OCT to detect conditions like macular degeneration.
Q78. Which of the following conditions is a leading cause of blindness worldwide?
Options:
1. Cataract
2. Glaucoma
3. Diabetic retinopathy
4. All of the above
Correct Answer: 4. All of the above
Explanation:
Cataract, glaucoma, and diabetic retinopathy are among the leading causes of blindness globally, per the World Health Organization. Cataracts cause reversible blindness via lens clouding, treatable with surgery. Glaucoma causes irreversible optic nerve damage. Diabetic retinopathy involves retinal vessel damage, leading to vision loss if untreated.
Option 1: Cataract is the leading cause of reversible blindness.
Option 2: Glaucoma is a major cause of irreversible blindness.
Option 3: Diabetic retinopathy is a growing cause due to increasing diabetes prevalence.
Relevance for Optometry: Optometrists play a critical role in screening, managing, and referring patients with these conditions to prevent blindness.
Q79. Which of the following is an objective method of refraction?
Options:
1. Subjective refraction
2. Retinoscopy
3. Trial frame testing
4. Visual acuity test
Correct Answer: 2. Retinoscopy
Explanation:
Retinoscopy is an objective refraction method where the examiner observes the movement of a light reflex from the patient’s retina to estimate refractive error, without relying on patient feedback. It is useful for children or non-communicative patients.
Option 1: Subjective refraction relies on patient responses (e.g., “Which lens is clearer?”).
Option 3: Trial frame testing is subjective, using patient feedback to refine prescriptions.
Option 4: Visual acuity testing assesses vision clarity, not refraction directly.
Relevance for Optometry: Retinoscopy provides a starting point for refraction, which is then refined with subjective methods for accurate prescriptions.
Q80. Which part of the eye controls the size of the pupil?
Options:
1. Iris
2. Lens
3. Retina
4. Cornea
Correct Answer: 1. Iris
Explanation:
The iris is a muscular, pigmented structure surrounding the pupil. It contains sphincter and dilator muscles that adjust pupil size (miosis or mydriasis) to control the amount of light entering the eye, optimizing vision in different lighting conditions.
Option 2: The lens focuses light, not controls pupil size.
Option 3: The retina detects light, not regulates pupil size.
Option 4: The cornea (misspelled as “Corned” in the document) refracts light, not controls pupil size.
Relevance for Optometry: Iris function is assessed in pupil response tests to evaluate neurological and ocular health.
Q81. Which is the transparent front part of the eye that covers the iris and pupil?
Options:
1. Cornea
2. Sclera
3. Retina
4. Lens
Correct Answer: 1. Cornea
Explanation:
The cornea is the transparent, dome-shaped anterior surface of the eye that covers the iris and pupil. It provides about 70% of the eye’s refractive power and acts as a protective barrier.
Option 2: The sclera is the opaque, white outer layer, not transparent.
Option 3: The retina is the light-sensitive layer at the back of the eye.
Option 4: The lens is behind the iris, not the front covering.
Relevance for Optometry: Corneal health is critical for clear vision, and optometrists assess it for conditions like keratitis or keratoconus using slit-lamp examination.
Q82. What type of vision is primarily mediated by cones in the retina?
Options:
1. Night vision
2. Peripheral vision
3. Color and sharp central vision
4. Depth perception
Correct Answer: 3. Color and sharp central vision
Explanation:
Cones are photoreceptors concentrated in the macula, particularly the fovea, and are responsible for color vision (photopic vision) and sharp central vision for detailed tasks like reading or recognizing faces.
Option 1: Night vision is mediated by rods, not cones.
Option 2: Peripheral vision is primarily rod-mediated.
Option 4: Depth perception involves binocular vision and brain processing, not solely cones.
Relevance for Optometry: Cone dysfunction (e.g., in color blindness or macular degeneration) affects color perception and central vision, detectable through specific tests.
Q83. Which eye condition is commonly treated with laser surgery?
Options:
1. Cataract
2. Glaucoma
3. Retinal detachment
4. Myopia
Correct Answer: 2. Glaucoma
Explanation:
Laser surgery is commonly used to treat glaucoma, such as in selective laser trabeculoplasty (SLT) for open-angle glaucoma to improve aqueous outflow, or laser peripheral iridotomy (LPI) for angle-closure glaucoma to create a drainage pathway.
Option 1: Cataract is treated with surgical lens replacement, not laser (though lasers assist in some procedures).
Option 3: Retinal detachment is treated with scleral buckling or vitrectomy, though laser photocoagulation may seal retinal tears.
Option 4: Myopia is corrected with refractive surgeries like LASIK, which reshape the cornea, not treat a disease.
Relevance for Optometry: Optometrists refer glaucoma patients for laser treatment to manage IOP and prevent optic nerve damage.
Q84. What is the main function of the aqueous humor?
Options:
1. Nourish the cornea and lens
2. Control eye movement
3. Focus light on the retina
4. Protect the optic nerve
Correct Answer: 1. Nourish the cornea and lens
Explanation:
The aqueous humor is a clear fluid in the anterior and posterior chambers of the eye. It provides nutrients and oxygen to the avascular cornea and lens, maintains intraocular pressure (IOP), and supports the eye’s shape.
Option 2: Eye movement is controlled by extraocular muscles.
Option 3: Focusing is done by the cornea and lens.
Option 4: The optic nerve is not directly protected by aqueous humor.
Relevance for Optometry: Aqueous humor dynamics are critical in glaucoma, where impaired outflow elevates IOP, assessed by tonometry.
Q85. What is the common symptom of conjunctivitis?
Options:
1. Eye pain
2. Redness and itching
3. Blurred vision
4. Loss of peripheral vision
Correct Answer: 2. Redness and itching
Explanation:
Conjunctivitis (pink eye) is inflammation of the conjunctiva, commonly causing redness (due to vasodilation) and itching. Other symptoms may include discharge or tearing, depending on the cause (bacterial, viral, or allergic).
Option 1: Eye pain is more typical of keratitis or uveitis, not conjunctivitis.
Option 3: Blurred vision is not a primary symptom unless the cornea is involved.
Option 4: Loss of peripheral vision is associated with glaucoma or retinal issues, not conjunctivitis.
Relevance for Optometry: Optometrists diagnose conjunctivitis via slit-lamp examination and prescribe treatments like antibiotic drops or antihistamines based on the cause.
Q86. Which part of the eye contains photoreceptors?
Options:
1. Cornea
2. Lens
3. Retina
4. Iris
Correct Answer: 3. Retina
Explanation:
The retina is the light-sensitive layer at the back of the eye containing photoreceptors (rods and cones). Rods enable night and peripheral vision, while cones provide color and sharp central vision.
Option 1: The cornea refracts light, not detects it.
Option 2: The lens focuses light, not detects it.
Option 4: The iris regulates light entry, not detects it.
Relevance for Optometry: Retinal health is assessed with fundus photography or OCT to diagnose conditions like diabetic retinopathy or macular degeneration.
Q87. What is the measurement unit for the curvature of lenses?
Options:
1. Diopter
2. Millimetre
3. Newton
4. Hertz
Correct Answer: 1. Diopter
Explanation:
The diopter (D) measures the power of a lens, which is related to its curvature and focal length (P = 1/f, where f is the focal length in meters). A lens’s curvature determines how much it bends light, and diopters quantify this refractive power.
Option 2: Millimetres measure physical dimensions, not lens power.
Option 3: Newtons measure force, not optical properties.
Option 4: Hertz measures frequency, not lens curvature.
Relevance for Optometry: Diopters are used to prescribe lenses for refractive errors, guiding optometrists in selecting appropriate corrections.
Q88. What is the function of the sclera?
Options:
1. Controls light entry
2. Provides structural support and protection
3. Contains photoreceptors
4. Focuses light on the retina
Correct Answer: 2. Provides structural support and protection
Explanation:
The sclera is the tough, white outer layer of the eye, providing structural support and protection to the eye’s internal structures. It maintains the eye’s shape and serves as an attachment for extraocular muscles.
Option 1: Light entry is controlled by the iris and pupil.
Option 3: Photoreceptors are in the retina, not the sclera.
Option 4: Focusing is done by the cornea and lens.
Relevance for Optometry: Scleral abnormalities (e.g., thinning in scleritis) are assessed during external eye exams and may indicate systemic disease.
Q89. Which disease is associated with increased intraocular pressure damaging the optic nerve?
Options:
1. Cataract
2. Glaucoma
3. Diabetic retinopathy
4. Macular degeneration
Correct Answer: 2. Glaucoma
Explanation:
Glaucoma involves elevated intraocular pressure (IOP) damaging the optic nerve, leading to progressive vision loss, particularly in the peripheral visual field. It includes types like primary open-angle and angle-closure glaucoma.
Option 1: Cataract affects the lens, not the optic nerve.
Option 3: Diabetic retinopathy damages retinal blood vessels, not the optic nerve directly.
Option 4: Macular degeneration affects the macula, not IOP or the optic nerve.
Relevance for Optometry: Glaucoma screening is a critical optometric task, using tools like tonometry and visual field testing to detect early optic nerve damage.
Q90. What is the primary purpose of a visual field test?
Options:
1. To assess central vision clarity
2. To measure intraocular pressure
3. To evaluate peripheral vision
4. To check color vision
Correct Answer: 3. To evaluate peripheral vision
Explanation:
A visual field test (e.g., automated perimetry) assesses the full extent of a patient’s peripheral and central visual fields, detecting defects like those in glaucoma (peripheral loss) or neurological conditions (e.g., hemianopia).
Option 1: Central vision clarity is tested with visual acuity tests (e.g., Snellen chart).
Option 2: Intraocular pressure is measured with tonometry.
Option 4: Color vision is tested with Ishihara plates or similar tools.
Relevance for Optometry: Visual field testing is essential for diagnosing and monitoring glaucoma, optic nerve disorders, and neurological conditions affecting vision.