Diseases of the Lens — MCQs
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A 60-year-old man, who underwent phacoemulsification surgery one year back, presents with a one-month history of gradual blurring of vision in the operated eye. The condition is not associated with pain, redness, or watering. He reports clear vision immediately following the surgery. What is the most common cause of this delayed visual impairment?
Ectopia lentis is caused by which of the following?
Cataract is NOT seen with which of the following conditions?
Ectopia lentis is seen in which of the following conditions?
What is the equatorial diameter of the lens?
Ectopia lentis in a child is seen in which of the following diseases?
Sunflower cataract is seen in which condition?
What is the earliest stage in the development of senile cortical cataract?
In extra-capsular cataract surgery, which part of the lens is excised?
Bilateral inferior dislocation of the lens is seen in which condition?
Diseases of the Lens Indian Medical PG Practice Questions and MCQs
Question 161: A 60-year-old man, who underwent phacoemulsification surgery one year back, presents with a one-month history of gradual blurring of vision in the operated eye. The condition is not associated with pain, redness, or watering. He reports clear vision immediately following the surgery. What is the most common cause of this delayed visual impairment?
- A. Posterior capsular opacification (Correct Answer)
- B. Neovascular glaucoma
- C. Chorioretinitis
- D. Cystoid macular edema
Explanation: ### Explanation The patient presents with a classic case of **Posterior Capsular Opacification (PCO)**, also known as "After-Cataract." **1. Why Posterior Capsular Opacification (PCO) is correct:** PCO is the **most common late complication** of extracapsular cataract extraction (ECCE) and phacoemulsification. It occurs due to the proliferation, migration, and differentiation of residual lens epithelial cells (LECs) from the equatorial region onto the posterior capsule. This creates an opaque membrane that obstructs the visual axis, leading to a gradual, painless decrease in vision months or years after an initially successful surgery. **2. Why the other options are incorrect:** * **Neovascular Glaucoma:** This is a secondary glaucoma characterized by pain, redness, and high intraocular pressure, usually following ischemic retinal conditions (like CRVO or Diabetic Retinopathy), not standard cataract surgery. * **Chorioretinitis:** This is an inflammatory/infectious condition of the uvea and retina. It typically presents with floaters and blurred vision but is often associated with signs of inflammation (cells in the vitreous) and is not a standard "delayed" complication of lens surgery. * **Cystoid Macular Edema (CME):** While CME (Irvine-Gass Syndrome) causes painless visual loss after surgery, it typically peaks at **6–10 weeks** post-operatively. A presentation one year later is much more characteristic of PCO. **Clinical Pearls for NEET-PG:** * **Morphological types of PCO:** 1. **Elschnig’s pearls:** Vacuolated subcapsular cells (most common). 2. **Fibrosis:** Myofibroblastic differentiation of LECs. 3. **Soemmering’s ring:** A ring of lens fibers trapped between the two layers of the capsule. * **Treatment:** The gold standard is **ND:YAG Laser Capsulotomy**. * **Prevention:** Use of square-edge intraocular lenses (IOLs) and thorough cortical aspiration during surgery significantly reduces PCO incidence.
Question 162: Ectopia lentis is caused by which of the following?
- A. Marfan syndrome
- B. Trauma
- C. Ehlers-Danlos syndrome
- D. All of the above (Correct Answer)
Explanation: **Explanation:** **Ectopia lentis** refers to the displacement or malposition of the crystalline lens from its normal anatomical location in the patellar fossa. This occurs due to the weakness or disruption of the **ciliary zonules** (Zonules of Zinn) that hold the lens in place. 1. **Trauma (Option B):** This is the **most common cause** of lens subluxation overall. Blunt trauma to the eye causes rapid equatorial expansion, leading to the stretching and tearing of zonular fibers. 2. **Marfan Syndrome (Option A):** This is the **most common systemic/hereditary cause**. It is an autosomal dominant disorder involving a mutation in the **FBN1 gene** (fibrillin-1), which is a major component of zonules. Classically, the displacement is **superotemporal** (upward and outward). 3. **Ehlers-Danlos Syndrome (Option C):** This is a connective tissue disorder characterized by collagen deficiency. Since zonules are composed of fibrillin and collagen-like glycoproteins, they become fragile, leading to lens instability. **Clinical Pearls for NEET-PG:** * **Homocystinuria:** The second most common systemic cause. Unlike Marfan, the displacement is typically **inferonasal** (downward and inward), and patients have a high risk of thromboembolism. * **Weill-Marchesani Syndrome:** Characterized by **microspherophakia** (small, spherical lens) and downward subluxation. * **Iridodonesis:** A clinical sign where the iris trembles upon eye movement, indicating a lack of posterior support from a displaced lens. * **Management:** Surgical intervention (Pars Plana Lensectomy) is indicated if there is lens-induced glaucoma, uveitis, or uncorrectable visual impairment.
Question 163: Cataract is NOT seen with which of the following conditions?
- A. Steroids
- B. Vitamin B12 deficiency (Correct Answer)
- C. Diabetes mellitus
- D. Homocystinuria
Explanation: **Explanation:** The correct answer is **Vitamin B12 deficiency**. While Vitamin B12 deficiency is associated with optic neuropathy (tobacco-alcohol amblyopia) and retinal hemorrhages, it is **not** a recognized cause of cataract. **Why the other options are associated with Cataract:** * **Steroids (Option A):** Long-term use of systemic or topical corticosteroids is a classic cause of **Posterior Subcapsular Cataract (PSC)**. This occurs due to the interference with lens fiber differentiation and glucose metabolism within the lens. * **Diabetes Mellitus (Option C):** Hyperglycemia leads to the accumulation of **sorbitol** via the polyol pathway (aldose reductase enzyme). Sorbitol acts as an osmotic agent, drawing water into the lens, leading to "Snowflake cataracts" in juveniles or early-onset senile cataracts in adults. * **Homocystinuria (Option D):** This metabolic disorder is characterized by a deficiency of cystathionine beta-synthase. It leads to **ectopia lentis** (downward and inward subluxation) and frequently results in early-onset cataracts. **NEET-PG High-Yield Pearls:** 1. **True Diabetic Cataract:** Characterized by bilateral "Snowflake" opacities. 2. **Steroid-Induced Cataract:** Most commonly presents as Posterior Subcapsular Cataract (PSC). 3. **Galactosemia:** Associated with "Oil droplet" cataracts. 4. **Myotonic Dystrophy:** Associated with "Christmas tree" cataracts. 5. **Wilson’s Disease:** Associated with "Sunflower" cataracts (though this is technically a copper deposition in the capsule, not a true lenticular opacity). 6. **Hypocalcemia:** Can lead to punctate, polychromatic "Zonular" cataracts.
Question 164: Ectopia lentis is seen in which of the following conditions?
- A. Hyperlysinemia
- B. Weill-Marchesani syndrome
- C. Sulfite oxidase deficiency
- D. All of the above (Correct Answer)
Explanation: **Explanation:** **Ectopia lentis** refers to the displacement or malposition of the crystalline lens from its normal anatomical location, typically due to the dysfunction or disruption of the ciliary zonules. **Why "All of the above" is correct:** Ectopia lentis is a hallmark feature of several systemic metabolic and genetic disorders. * **Hyperlysinemia:** An autosomal recessive metabolic disorder where an enzyme deficiency leads to elevated lysine levels. It is a rare but recognized cause of lens subluxation. * **Weill-Marchesani Syndrome:** A connective tissue disorder characterized by short stature, brachydactyly (short fingers), and **microspherophakia** (small, spherical lens). The abnormal lens shape often leads to downward subluxation and secondary angle-closure glaucoma. * **Sulfite Oxidase Deficiency:** A rare error of sulfur metabolism. It presents early in life with severe neurological impairment, seizures, and characteristic ectopia lentis. **High-Yield Clinical Pearls for NEET-PG:** To differentiate these conditions in clinical vignettes, remember the direction of displacement: 1. **Marfan Syndrome:** Most common cause; displacement is typically **Superotemporal** (Upward and Outward). 2. **Homocystinuria:** Second most common; displacement is **Inferonasal** (Downward and Inward). Associated with intellectual disability and a high risk of thromboembolism. 3. **Weill-Marchesani:** Displacement is usually **Inferior** (Downward). 4. **Trauma:** The most common cause of *acquired* (non-hereditary) ectopia lentis. **Summary:** Since Hyperlysinemia, Weill-Marchesani, and Sulfite Oxidase deficiency are all established systemic causes of lens displacement, the correct answer is **All of the above**.
Question 165: What is the equatorial diameter of the lens?
- A. 7 mm
- B. 8 mm
- C. 9 mm
- D. 10 mm (Correct Answer)
Explanation: **Explanation:** The crystalline lens is a transparent, biconvex structure located behind the iris. Understanding its dimensions is crucial for NEET-PG, as these parameters change with age and clinical conditions. **Why Option D is Correct:** In an adult, the **equatorial diameter** of the lens is approximately **9–10 mm**. At birth, it is about 6.5 mm and grows rapidly during the first few years of life, reaching its adult size by the second decade. The equator is the widest part of the lens where the anterior and posterior surfaces meet and where the zonules of Zinn attach. **Analysis of Incorrect Options:** * **Option A (7 mm):** This is closer to the equatorial diameter at birth (approx. 6.5 mm). * **Option B (8 mm):** This represents an intermediate growth stage in childhood. * **Option C (9 mm):** While 9 mm is the lower limit of the adult range, **10 mm** is the standard value cited in most ophthalmic textbooks (like Khurana) for a fully developed adult lens. **High-Yield Clinical Pearls for NEET-PG:** * **Anteroposterior (AP) Diameter:** At birth, it is roughly 3.5–4 mm. In an adult, it increases to about **4–5 mm**. * **Radius of Curvature:** The anterior surface is flatter (**10 mm**) compared to the more convex posterior surface (**6 mm**). * **Refractive Power:** The lens contributes approximately **15–18 Diopters** to the total refractive power of the eye (60D). * **Weight:** The lens weighs about 135 mg at birth, increasing to roughly **250 mg** in old age. * **Microphakia:** A condition where the equatorial diameter is abnormally small, often seen in Lowe syndrome or as part of Microspherophakia (associated with Weill-Marchesani syndrome).
Question 166: Ectopia lentis in a child is seen in which of the following diseases?
- A. Sarcoidosis
- B. Homocystinuria (Correct Answer)
- C. Alkaptonuria
- D. Urea cycle defects
Explanation: **Explanation:** **Ectopia lentis** refers to the displacement or subluxation of the crystalline lens from its normal position due to the disruption of the ciliary zonules. **Why Homocystinuria is correct:** Homocystinuria is an autosomal recessive metabolic disorder caused by a deficiency of the enzyme **cystathionine beta-synthase**. This leads to an accumulation of homocysteine, which interferes with the cross-linking of fibrillin, a key component of the lens zonules. In Homocystinuria, the lens typically undergoes **inferonasal subluxation** (downward and inward). It is the second most common cause of hereditary ectopia lentis after Marfan syndrome. **Analysis of Incorrect Options:** * **Sarcoidosis:** This is a multisystem granulomatous disease. Ocular involvement typically manifests as granulomatous uveitis, dry eyes, or retinal vasculitis, but not primary lens displacement. * **Alkaptonuria:** This is a disorder of tyrosine metabolism (deficiency of homogentisic acid oxidase). It causes **ochronosis** (dark pigmentation of sclera and cartilage) and arthritis, but does not affect the lens zonules. * **Urea Cycle Defects:** These disorders (e.g., Ornithine transcarbamylase deficiency) lead to hyperammonemia and neurological symptoms but are not associated with structural ocular defects like ectopia lentis. **High-Yield Clinical Pearls for NEET-PG:** * **Direction of Subluxation:** * **Marfan Syndrome:** Superotemporal (Upward and Outward) - *Most common cause.* * **Homocystinuria:** Inferonasal (Downward and Inward). * **Accommodation:** In Homocystinuria, accommodation is lost because the zonules are completely disintegrated, whereas in Marfan’s, some zonules remain intact. * **Other Causes:** Weill-Marchesani syndrome (microspherophakia with inferior subluxation), Sulfite oxidase deficiency, and trauma (most common cause of *acquired* ectopia lentis).
Question 167: Sunflower cataract is seen in which condition?
- A. Galactosemia
- B. Diabetes mellitus
- C. Copper Chalocosis (Correct Answer)
- D. Hereditary polyposis
Explanation: **Explanation:** **Sunflower cataract** is a classic clinical sign of **Chalcosis**, which refers to the intraocular deposition of copper. This occurs due to an intraocular copper-containing foreign body or systemic conditions like **Wilson’s disease** (Hepatolenticular degeneration). The copper ions deposit in the **anterior lens capsule** and subcapsular epithelium, radiating outward in a petal-like configuration, resembling a sunflower. **Analysis of Options:** * **Galactosemia (Option A):** Characterized by an **"Oil droplet" cataract**. This is due to the accumulation of dulcitol (galactitol) within the lens, causing osmotic swelling. * **Diabetes Mellitus (Option B):** Associated with **"Snowflake" cataracts** (subcapsular opacities) in young diabetics due to sorbitol accumulation. In adults, it typically leads to the early onset of senile nuclear cataracts. * **Hereditary Polyposis (Option D):** This is not typically associated with specific lens opacities. However, Gardner’s syndrome (a variant of FAP) is associated with **CHRPE** (Congenital Hypertrophy of Retinal Pigment Epithelium). **High-Yield Clinical Pearls for NEET-PG:** * **Wilson’s Disease:** Look for the triad of Sunflower cataract, **Kayser-Fleischer (KF) ring** (copper deposition in the Descemet’s membrane of the cornea), and neurological/hepatic symptoms. * **Christmas Tree Cataract:** Seen in Myotonic Dystrophy. * **Rosette-shaped Cataract:** Classic sign of Concussive Ocular Trauma. * **Shield Cataract:** Associated with Atopic Dermatitis. * **Posterior Subcapsular Cataract (PSC):** Most commonly associated with prolonged **Steroid use** or ionizing radiation.
Question 168: What is the earliest stage in the development of senile cortical cataract?
- A. Lamellar separation
- B. Intumescent cataract
- C. Incipient cataract (Correct Answer)
- D. Mature senile cataract
Explanation: **Explanation:** Senile cortical cataract is a common age-related condition characterized by the hydration of lens fibers. The progression occurs in four distinct stages: 1. **Incipient Cataract (Correct Answer):** This is the **earliest stage**. It is characterized by the appearance of "cuneiform opacities" (wedge-shaped) in the periphery of the lens. While **lamellar separation** (hydration of sutures) is the very first pathological change, it is often considered a sub-stage or precursor. In the context of standard clinical staging, the **Incipient stage** is the recognized starting point of clinical cataract formation. 2. **Intumescent Cataract (Incorrect):** This is a progression of the incipient stage where the lens continues to absorb water, becoming swollen and "intumescent." This stage is clinically significant because the swollen lens can shallow the anterior chamber, potentially leading to secondary angle-closure glaucoma. 3. **Mature Senile Cataract (Incorrect):** In this stage, the entire lens becomes opaque (pearly white). The lens loses the excess water and returns to its normal size. Vision is typically reduced to "Hand Movements" or "Projection of Rays." 4. **Hypermature Cataract (Incorrect):** This is the final stage where the lens cortex liquefies (Morgagnian cataract) or the lens becomes shrunken and wrinkled due to water leakage (Sclerotic type). **High-Yield NEET-PG Pearls:** * **Cuneiform opacities:** Wedge-shaped opacities seen in cortical cataracts (start in the periphery). * **Cupuliform opacities:** Characteristic of Posterior Subcapsular Cataracts (start centrally). * **Iris Shadow Test:** Positive in the Immature stage; Negative in the Mature stage (because no clear cortex remains between the iris and the opacity). * **Most common cause of cataract worldwide:** Age-related (Senile).
Question 169: In extra-capsular cataract surgery, which part of the lens is excised?
- A. Anterior capsule
- B. Posterior capsule
- C. Nucleus (Correct Answer)
- D. Whole lens
Explanation: In **Extracapsular Cataract Extraction (ECCE)**, the surgical principle is to remove the lens material while leaving the **posterior capsule** and the peripheral part of the anterior capsule (the capsular bag) intact. ### Why the Correct Answer is Right: * **Nucleus (C):** In ECCE, a large incision is made, an opening is created in the anterior capsule (capsulotomy), and the hard **nucleus** is expressed or delivered out of the eye. This is followed by the aspiration of the remaining cortex. Since the nucleus is the primary bulk of the cataractous lens being removed, it is the correct choice among the components listed. ### Why the Other Options are Wrong: * **Anterior capsule (A):** Only a portion of the anterior capsule (usually a central circular part) is removed to access the lens material. The peripheral rim is preserved to support the Intraocular Lens (IOL). * **Posterior capsule (B):** This is intentionally left **intact** in ECCE. It serves as a barrier between the anterior and posterior segments, preventing vitreous loss and providing a platform for "in-the-bag" IOL implantation. * **Whole lens (D):** Removal of the whole lens (including the entire capsule) is termed **Intracapsular Cataract Extraction (ICCE)**. This technique is largely obsolete due to higher risks of retinal detachment and cystoid macular edema. ### NEET-PG High-Yield Pearls: * **ECCE vs. Phacoemulsification:** Phacoemulsification is a form of ECCE where the nucleus is emulsified using ultrasound energy through a smaller incision. * **Primary Advantage of ECCE:** Preservation of the posterior capsule allows for **Posterior Chamber IOL (PCIOL)** placement, which is the physiological gold standard. * **Common Complication:** The most common late complication of ECCE/Phaco is **Posterior Capsular Opacification (PCO)**, also known as "After Cataract," treated with YAG laser capsulotomy.
Question 170: Bilateral inferior dislocation of the lens is seen in which condition?
- A. Marfan syndrome
- B. Homocystinuria (Correct Answer)
- C. Weill-Marchesani syndrome
- D. Trauma
Explanation: **Explanation:** The direction of lens subluxation/dislocation is a high-yield diagnostic marker in ophthalmology. In **Homocystinuria**, the lens typically undergoes **inferior or inferonasal dislocation**. This occurs due to a deficiency in the enzyme *cystathionine beta-synthase*, leading to high systemic levels of homocysteine. This metabolic derangement results in the disintegration of the zonular fibers (which are rich in cysteine), causing them to become brittle and eventually snap, leading to a downward displacement of the lens. **Analysis of Options:** * **Marfan Syndrome:** This is the most common cause of hereditary lens subluxation. However, the dislocation is characteristically **superior and temporal (upward and outward)**. The zonules remain intact but are stretched. * **Weill-Marchesani Syndrome:** This condition is associated with **microspherophakia** (small, spherical lens). While dislocation can occur, it is typically **inferior**, but the presence of a small, round lens is the primary distinguishing feature. * **Trauma:** This is the most common cause of *unilateral* lens dislocation. While it can occur in any direction, it is rarely bilateral or symmetrical unless the mechanism of injury is specific to both eyes. **NEET-PG High-Yield Pearls:** * **Marfan vs. Homocystinuria:** Remember "Marfan is UP, Homocystinuria is DOWN." * **Accommodation:** In Marfan, accommodation is often preserved because zonules are stretched; in Homocystinuria, accommodation is lost because zonules are broken. * **Systemic Clue:** If the question mentions a "fair-complexioned child with mental retardation and a history of thromboembolism," always suspect **Homocystinuria**. * **Ectopia Lentis et Pupillae:** A rare condition where the lens and pupil are displaced in opposite directions.
Practice by Chapter
Lens Anatomy and Physiology
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Age-Related Cataract
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Congenital and Developmental Cataracts
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Traumatic Cataract
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Metabolic Cataracts
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Drug-Induced Cataracts
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Cataract Surgery Techniques
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Intraocular Lens Implants
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Complications of Cataract Surgery
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Posterior Capsular Opacification
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Lens Subluxation and Dislocation
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Specialty IOLs
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