Contact Lens — MCQs

Contact Lens Indian Medical PG Practice Questions and MCQs

Question 71: Which prominent ocular manifestation is associated with Marfan syndrome?

A. Microcornea
B. Megalocornea
C. Ectopia lentis (Correct Answer)
D. Microspherophakia

Explanation: **Explanation:** **Ectopia lentis** (subluxation of the lens) is the hallmark ocular manifestation of Marfan syndrome, occurring in approximately 50–80% of patients. The underlying pathology is a mutation in the **FBN1 gene** on chromosome 15, which leads to a defect in **fibrillin-1**. Since ciliary zonules are composed primarily of fibrillin, they become weak and prone to stretching or snapping. Classically, in Marfan syndrome, the lens displaces **superotemporally** (upward and outward), and the zonules typically remain intact but stretched. **Analysis of Incorrect Options:** * **Microcornea (A):** This refers to a corneal diameter <10 mm. While it can occur in various congenital syndromes (like Nanophthalmos), it is not a primary feature of Marfan syndrome. * **Megalocornea (B):** This is a non-progressive enlargement of the cornea (>13 mm). While Marfan patients may have slightly larger corneas or increased axial length (leading to myopia), megalocornea is more specifically associated with X-linked Megalocornea or Congenital Glaucoma (Buphthalmos). * **Microspherophakia (D):** This describes a small, spherical lens. While it causes ectopia lentis, it is the classic feature of **Weill-Marchesani syndrome**, not Marfan syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Direction of Displacement:** Marfan = Upward (Superior); Homocystinuria = Downward (Inferior). * **Zonular Integrity:** In Marfan, zonules are stretched/intact; in Homocystinuria, zonules are absent/broken due to cysteine deficiency. * **Other Marfan Ocular Features:** High axial myopia, increased risk of Rhegmatogenous Retinal Detachment (RRD), and flat cornea (cornea plana). * **Systemic Association:** Always check for aortic root dilation or mitral valve prolapse in these patients.

Question 72: What is the name of the structure connecting the posterior surface of the lens to the capsule?

A. Hyaloideocapsular ligament of Weiger (Correct Answer)
B. Vitreous Base
C. Cloquet's canal
D. Collagen fibers

Explanation: ### Explanation The correct answer is **A. Hyaloideocapsular ligament of Weiger**. **1. Why the correct answer is right:** The **Hyaloideocapsular ligament of Weiger** (also known as the ligamentum hyaloideocapsulare) is a circular adhesion between the anterior face of the vitreous (the anterior hyaloid membrane) and the posterior capsule of the crystalline lens. It forms a ring-like attachment approximately 8–9 mm in diameter. Within this ring lies a potential space called the **Space of Berger** (retrolental space), where the vitreous is not directly attached to the lens. **2. Why the incorrect options are wrong:** * **B. Vitreous Base:** This is the strongest area of vitreous attachment, located at the ora serrata. It straddles the ora serrata, extending 2 mm anteriorly and 3 mm posteriorly. * **C. Cloquet’s canal:** This is an S-shaped transparent channel running through the vitreous from the optic nerve head to the posterior lens. It represents the remnant of the primary vitreous and the hyaloid artery system. * **D. Collagen fibers:** While collagen (primarily Type II) is the structural framework of the vitreous, it refers to the biochemical composition rather than the specific anatomical ligament connecting the lens to the vitreous. **3. Clinical Pearls for NEET-PG:** * **Age-related change:** The ligament of Weiger is very strong in children and young adults but weakens with age. This is why **Intracapsular Cataract Extraction (ICCE)** is contraindicated in young patients (risk of vitreous loss) but was possible in the elderly. * **Space of Berger:** High-yield anatomical landmark located central to the ligament of Weiger. * **Egger’s Line:** The actual line of attachment of the ligament to the lens capsule. * **Vitreous Attachments (Strongest to Weakest):** Vitreous Base > Optic Disc > Fovea > Ligament of Weiger.

Question 73: What is the most common type of cataract found in newborns?

A. Zonular cataract
B. Morganian cataract
C. Anterior polar cataract
D. Posterior polar cataract (Correct Answer)

Explanation: **Explanation** The correct answer is **Posterior polar cataract**. **1. Why Posterior Polar Cataract is Correct:** In the context of congenital cataracts, the **posterior polar cataract** is frequently cited in clinical literature and examinations as the most common morphological type found in newborns. It is characterized by a well-defined, circular opacity located on the posterior capsule. Pathophysiologically, it often results from the persistence of the **tunica vasculosa lentis** (remnants of the hyaloid artery system). These cataracts are significant because they are often associated with a weakened or absent posterior capsule, increasing the risk of posterior capsule rupture during future surgical intervention. **2. Why the Other Options are Incorrect:** * **Zonular (Lamellar) Cataract:** While this is the most common type of congenital cataract that causes **visual impairment** and often presents later in childhood, it is not the most common type strictly found at birth (newborn period). It involves specific layers (zones) of the lens. * **Morganian Cataract:** This is a form of hypermature **senile cataract** where the cortex liquefies, allowing the nucleus to sink inferiorly. It is an acquired condition of the elderly, not newborns. * **Anterior Polar Cataract:** These are common and usually small, bilateral, and non-progressive. However, statistically, they occur less frequently than posterior polar variants in the neonatal population. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of congenital cataract:** Idiopathic (followed by genetic/autosomal dominant). * **Most common infectious cause:** Rubella (presents as "pearllike" nuclear opacification). * **Surgical Timing:** To prevent amblyopia, surgery is ideally performed within **4–6 weeks** of birth for dense bilateral cataracts. * **Association:** Posterior polar cataracts are a classic "red flag" for surgeons due to the high risk of **posterior capsular dehiscence**.

Question 74: What is the treatment of choice for congenital cataract?

A. Pharmacotherapy
B. Combined cataract surgery and goniotomy
C. Cataract surgery with IOL implant (Correct Answer)
D. Pars plana lensectomy with no IOL implant

Explanation: **Explanation:** The primary goal in managing congenital cataract is the prevention of **amblyopia** (lazy eye) by ensuring a clear visual axis during the critical period of visual development. **Why Option C is Correct:** The current standard of care is **Cataract surgery with Intraocular Lens (IOL) implantation**. Modern surgical techniques (Phacoaspiration + Posterior Capsulotomy + Anterior Vitrectomy) combined with IOL implantation provide the best permanent optical correction. While IOL power calculation is challenging in infants due to the rapidly growing eye, it is preferred over aphakic glasses or contact lenses for better compliance and binocularity. **Why Other Options are Incorrect:** * **Option A:** Pharmacotherapy has no role in treating a lens opacity; surgery is the only definitive treatment. * **Option B:** Goniotomy is a treatment for congenital glaucoma, not cataract. While the two can coexist (e.g., in Lowe syndrome), it is not the standard treatment for isolated cataract. * **Option D:** Pars plana lensectomy was historically common, but leaving a child **aphakic** (no IOL) leads to severe refractive errors and high risk of amblyopia due to non-compliance with heavy glasses or contact lenses. **High-Yield NEET-PG Pearls:** * **Timing:** Surgery should ideally be performed within **4–6 weeks** of birth for unilateral cataracts and **8–10 weeks** for bilateral cases to prevent stimulus-deprivation amblyopia. * **IOL Age:** Most surgeons prefer IOL implantation for children **>6 months to 1 year** of age. For infants <6 months, some still prefer aphakic contact lenses due to the high risk of postoperative inflammation and "myopic shift." * **Surgical Note:** In children, a **Primary Posterior Capsulotomy (PPC)** and **Anterior Vitrectomy** are mandatory because the posterior capsule opacifies rapidly (100% rate) if left intact.

Question 75: Ring of Sommering is seen in which of the following conditions?

A. Galactosemia
B. Dislocation of lens
C. Acute congestive glaucoma
D. After cataract (Correct Answer)

Explanation: **Explanation:** **Soemmering’s Ring** is a specific type of **After-cataract** (Posterior Capsular Opacification). It occurs following extracapsular cataract extraction (ECCE) or ocular trauma. When the central part of the lens is removed or lost, but the peripheral subcapsular lens epithelial cells (LECs) remain, these cells proliferate and undergo fiber metamorphosis within the "capsular bag" (the space between the anterior and posterior capsule). This creates a doughnut-shaped ring of cortical matter hidden behind the iris, while the central pupillary area remains clear. **Analysis of Options:** * **A. Galactosemia:** Characterized by **"Oil droplet cataracts"** due to the accumulation of dulcitol. * **B. Dislocation of lens:** Associated with conditions like Marfan syndrome or homocystinuria; it involves zonular weakness, not specific ring-shaped opacification. * **C. Acute congestive glaucoma:** Associated with **"Glaukomflecken"** (small, grey-white subcapsular opacities) due to high intraocular pressure causing focal lens necrosis. **High-Yield Facts for NEET-PG:** * **Elschnig’s Pearls:** Another form of after-cataract where subcapsular LECs proliferate and migrate onto the posterior capsule, appearing like "clusters of grapes" or pearls. * **Treatment:** The gold standard for symptomatic after-cataract is **Nd:YAG Laser Capsulotomy**. * **Prevention:** Square-edge Intraocular Lenses (IOLs) are more effective at preventing LEC migration compared to round-edge lenses.

Question 76: When are spectacles advised after cataract surgery?

A. 8 weeks (Correct Answer)
B. 10 weeks
C. 12 weeks
D. 14 weeks

Explanation: **Explanation:** The primary goal of cataract surgery is to achieve a stable refractive state. Following the procedure, the eye undergoes a period of wound healing and structural remodeling, which leads to fluctuations in corneal curvature and astigmatism. **Why 8 weeks is correct:** Post-operative refractive stability is generally achieved by **6 to 8 weeks**. During this period, the surgical incision (especially in conventional ECCE or SICS) heals sufficiently, and the "surgical induced astigmatism" (SIA) stabilizes. Prescribing spectacles before this period often results in an inaccurate prescription as the refraction is still shifting. While modern Phacoemulsification with micro-incisions allows for earlier stabilization (often by 3-4 weeks), **8 weeks** remains the standard textbook and clinical benchmark for final glass prescription to ensure the most accurate and permanent correction. **Why other options are incorrect:** * **10, 12, and 14 weeks:** While prescribing glasses at these intervals is safe, it is unnecessarily delayed. By 8 weeks, the wound is physiologically stable enough for a definitive prescription. Delaying beyond this point unnecessarily prolongs the patient's visual rehabilitation. **High-Yield Clinical Pearls for NEET-PG:** * **Refractive Stabilization:** In Phacoemulsification (valvular, sutureless), stabilization is faster (3-4 weeks) compared to SICS or ECCE (6-8 weeks). * **Aphakia:** If no IOL is implanted, the patient typically requires a high plus power lens (approx. +10D) and a +3D addition for near work. * **Pseudophakia:** Most patients receive a monofocal IOL calculated for distance; thus, they require near-vision glasses (+2.5D to +3D) starting at 6-8 weeks. * **Immediate Post-op:** Patients are usually given temporary dark glasses to protect against photophobia and trauma, but not for refractive correction.

Question 77: Uniocular polyopia is seen in which stage of cataract?

A. Incipient (Correct Answer)
B. Intumescent
C. Mature
D. Hypermature

Explanation: **Explanation:** **1. Why Incipient Cataract is the Correct Answer:** In the **incipient stage** of cortical cataract, there is the formation of "water clefts" or vacuoles between the lens fibers. This leads to an **irregular change in the refractive index** across different sectors of the lens. When light passes through these varying refractive zones, it is focused on multiple points on the retina instead of a single point. This optical phenomenon results in **uniocular polyopia** (seeing multiple images with one eye). **2. Why the Other Options are Incorrect:** * **Intumescent Cataract:** At this stage, the lens becomes swollen due to the rapid imbibition of water. While it causes a significant myopic shift (index myopia), the primary clinical concern is the shallowing of the anterior chamber, which can lead to secondary angle-closure glaucoma. * **Mature Cataract:** The entire lens becomes completely opaque. Since light cannot pass through the lens to form a clear image on the retina, polyopia is impossible; the patient only perceives light (PL) and accurate projection of rays (PR). * **Hypermature Cataract:** The lens cortex liquefies (Morgagnian) or the lens shrivels (Sclerotic). Similar to the mature stage, the density of the opacity precludes the formation of multiple images. **3. Clinical Pearls for NEET-PG:** * **Uniocular Diplopia/Polyopia:** Always think of **Incipient Cataract**, **Keratoconus** (irregular astigmatism), or **Subluxated Lens** (Ectopia lentis). * **Second Sight Phenomenon:** Seen in early nuclear sclerosis where the increased refractive index causes "index myopia," allowing elderly patients to read without glasses again. * **Cuneiform vs. Cupuliform:** Cuneiform (cortical) cataracts start at the periphery (wedge-shaped opacities), while Cupuliform (posterior subcapsular) cataracts are most visually disturbing in bright light due to miosis.

Question 78: What is the most common cause of cataract?

A. Age-related changes (Correct Answer)
B. Hereditary factors
C. Diabetes mellitus
D. Trauma

Explanation: **Explanation:** **Cataract** is defined as any opacification of the crystalline lens or its capsule that leads to a visual impairment. **Why Option A is correct:** The most common cause of cataract worldwide is **age-related (senile) changes**. As the eye ages, the lens undergoes physiological changes including increased hydration, compaction of lens fibers, and oxidative modification of lens proteins (crystallins). This leads to the formation of **Senile Cataract**, which typically presents after the age of 50. It is the leading cause of preventable blindness globally. **Why other options are incorrect:** * **B. Hereditary factors:** While genetic mutations can cause congenital or developmental cataracts (e.g., zonular cataract), these represent a much smaller percentage of the total global burden compared to age-related cases. * **C. Diabetes mellitus:** Diabetes is a significant risk factor that leads to "Snowflake cataracts" or early-onset senile cataracts due to sorbitol accumulation via the polyol pathway. However, it is a metabolic *complication*, not the most common primary cause. * **D. Trauma:** Traumatic cataracts (often presenting as "Rosette-shaped") occur due to blunt or penetrating injury. While common in younger populations, they are sporadic and not as prevalent as degenerative changes. **High-Yield NEET-PG Pearls:** * **Most common type of senile cataract:** Nuclear sclerosis. * **Most common cause of blindness in India:** Cataract. * **Cuneiform cataract:** Characterized by wedge-shaped opacities in the cortex (peripheral to central). * **Cupuliform cataract:** Also known as Posterior Subcapsular Cataract (PSC); it significantly affects near vision and is associated with steroid use.

Question 79: Intraocular lenses are made up of which of the following materials?

A. Polymethyl methacrylate (PMMA)
B. Hydrophilic acrylic
C. Silicone
D. All of the above (Correct Answer)

Explanation: **Explanation:** Intraocular lenses (IOLs) are prosthetic devices implanted in the eye to replace the natural crystalline lens, typically following cataract surgery. Over the decades, biomaterial science has evolved to offer various options based on surgical technique and patient needs. * **Polymethyl methacrylate (PMMA):** This was the first material used for IOLs (Sir Harold Ridley, 1949). It is a **rigid, non-foldable** plastic. While highly biocompatible and stable, it requires a larger incision (approx. 5-6 mm) for insertion, which often necessitates sutures. * **Hydrophilic Acrylic:** These are **foldable** lenses with high water content. They are easy to handle and have excellent optical clarity. However, they are associated with a slightly higher rate of Posterior Capsular Opacification (PCO) compared to hydrophobic acrylics. * **Silicone:** These were the first foldable lenses available. They allow for small-incision surgery but are generally avoided in patients who may require vitreoretinal surgery involving silicone oil, as the oil can adhere to the lens. **Conclusion:** Since PMMA, Hydrophilic Acrylic, and Silicone are all established materials used in the manufacturing of IOLs, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** Currently, **Hydrophobic Acrylic** is the most commonly used material because it has the lowest rate of PCO due to its "square-edge" design and bio-adhesive properties. * **Historical Fact:** PMMA is the material used in the "Ridley Lens." * **Foldable vs. Rigid:** Foldable lenses (Acrylic, Silicone) are preferred for Phacoemulsification (small incision), while rigid lenses (PMMA) are used in ECCE (Large incision). * **Square Edge Design:** This is the most important structural feature of modern IOLs to prevent PCO.

Question 80: Which of the following ocular structures continues to grow throughout a person's lifetime?

A. Cornea
B. Iris
C. Lens (Correct Answer)
D. Retina

Explanation: **Explanation:** The correct answer is **C. Lens**. **Why the Lens grows throughout life:** The crystalline lens is a unique structure derived from the surface ectoderm. It is enclosed within a non-elastic basement membrane called the lens capsule. Throughout life, the subcapsular epithelium continues to divide and produce new lens fibers. Since the lens cannot shed its old cells (due to the capsule), these new fibers are continuously added to the periphery, compressing the older fibers toward the center (nucleus). This process leads to an increase in the size, weight, and density of the lens as a person ages. **Why the other options are incorrect:** * **Cornea:** The cornea reaches its adult size (approximately 11.5–12 mm in horizontal diameter) by the age of 2 years. It does not grow significantly thereafter. * **Iris:** The iris reaches its definitive structure and size in early childhood. While it may undergo atrophy or pigmentary changes with age, it does not grow. * **Retina:** The retina is neural tissue. Like the brain, its development and cell count are finalized in the early postnatal period; it does not continue to grow or regenerate new neurons throughout life. **Clinical Pearls for NEET-PG:** * **Presbyopia:** The continuous growth and increasing density of the lens contribute to the loss of elasticity, leading to a decrease in accommodative power with age. * **Nuclear Sclerosis:** The lifelong compression of central fibers results in the hardening of the lens nucleus, a hallmark of senile cataract formation. * **Dimensions:** The newborn lens is nearly spherical; as it grows, it becomes more ellipsoid. The adult lens is approximately 9-10 mm in diameter and 4-5 mm in thickness.

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