Diseases of the Lens Practice Questions

Q: Lens dislocation can occur in all of the following conditions except:

Wilson's disease. **Explanation:** The correct answer is **Wilson’s Disease** because it is characterized by copper deposition in the eye, but it does not cause ectopia lentis (lens dislocation). The classic ocular finding in Wilson’s disease is the **Kayser-Fleischer (KF) ring** (copper deposition in Descemet’s membrane) and, occasionally, a **Sunflower cataract** (anterior subcapsular copper deposition). **Analysis of Options:** * **Homocystinuria:** This is a common cause of lens dislocation. Characteristically, the dislocation is **downward and inward** (inferonasal). It is associated with a deficiency of cystathionine beta-synthase and carries a high risk of thromboembolism. * **Marfan’s Syndrome:** This is the most common hereditary cause of ectopia lentis. The dislocation is typically **upward and outward** (superotemporal). The zonules are stretched but often remain intact. * **Trauma:** This is the **most common overall cause** of lens dislocation. Blunt trauma leads to the mechanical rupture of zonular fibers, resulting in subluxation or complete luxation of the lens. **High-Yield Clinical Pearls for NEET-PG:** 1. **Directionality Matters:** * Marfan’s = Upward (M**up**fan) * Homocystinuria = Downward (**Low**mocystinuria) 2. **Weill-Marchesani Syndrome:** Another high-yield cause where the lens is small and spherical (**Microspherophakia**) and typically dislocates **downward**. 3. **Ectopia Lentis et Pupillae:** A rare autosomal recessive condition characterized by lens dislocation and iris coloboma/pupil displacement in opposite directions. 4. **Sulfite Oxidase Deficiency:** A rare cause of lens dislocation associated with severe neurological impairment in infancy.

Q: Anterior polar cataract develops in which of the following conditions?

Penetrating corneal injury. **Explanation:** **Anterior polar cataract** is a type of congenital or acquired developmental cataract involving the central part of the anterior lens capsule and the underlying subcapsular cortex. **Why Penetrating Corneal Injury is Correct:** The primary mechanism for an acquired anterior polar cataract is a **penetrating corneal ulcer or injury**. When the cornea is perforated, the aqueous humor escapes, causing the anterior chamber to collapse. This leads to prolonged contact between the lens and the inflamed/damaged cornea. This contact, often associated with the formation of an inflammatory exudate, interferes with the nutrition of the lens fibers and stimulates the proliferation of the subcapsular epithelium, resulting in a localized opacity (cataract). **Analysis of Incorrect Options:** * **A. Diabetes Mellitus:** Typically presents with "Snowflake cataracts" (bilateral, subcapsular) or early onset of senile nuclear sclerosis. * **C. Irradiation:** Radiation exposure (X-rays, Gamma rays) classically leads to **Posterior Subcapsular Cataracts (PSC)**, as the damaged epithelial cells migrate to the posterior pole. * **D. Barbiturates:** These are not classically associated with cataract formation. Drugs like Steroids (PSC), Chlorpromazine (Stellate/Star-shaped), and Amiodarone are more common pharmacological causes. **High-Yield Clinical Pearls for NEET-PG:** * **Pyramidal Cataract:** If an anterior polar cataract projects forward into the anterior chamber as a conical opacity, it is termed a pyramidal cataract. * **Associated Findings:** Often associated with **persistent pupillary membrane** or microphthalmos. * **Visual Impact:** These are usually small, stationary, and rarely interfere significantly with vision unless they are large or associated with other ocular defects. * **Cupuliform Cataract:** Another name for Posterior Subcapsular Cataract, often seen in steroid use or ionizing radiation.

Q: What is a known cause of cataract?

All of the above. **Explanation:** Cataractogenesis is a multifactorial process where various forms of electromagnetic radiation cause oxidative stress and protein denaturation within the crystalline lens. * **Infrared Radiation (Option A):** Chronic exposure to infrared rays (IR) leads to **"Glass-blower’s cataract"** or **"Furnace-worker’s cataract."** The mechanism involves the absorption of IR by the iris, which converts it into heat. This heat is transferred to the lens epithelium, causing true exfoliation of the anterior lens capsule and subsequent opacification. * **Microwaves (Option B):** Microwave radiation causes cataracts primarily through **dielectric heating.** The lens is particularly vulnerable because it is avascular and cannot dissipate heat efficiently. This thermal injury leads to the denaturation of lens proteins. * **Ultraviolet Rays (Option C):** UV-B radiation (290–320 nm) is a well-documented risk factor for **senile cortical cataracts.** UV light generates free radicals and reactive oxygen species (ROS), which damage lens cell membranes and lead to the photo-oxidation of amino acids. **Clinical Pearls for NEET-PG:** 1. **Ionizing Radiation (X-rays/Gamma rays):** Characteristically causes **Posterior Subcapsular Cataract (PSC)**. The most sensitive part of the lens to radiation is the germinal epithelium at the equator. 2. **Electric Cataract:** Occurs following a high-voltage lightning strike or electric shock; typically presents as milky white subcapsular opacities. 3. **Glass-blower’s Cataract:** Look for the keyword **"True Exfoliation"** (separation of the lamellae of the anterior capsule), distinguishing it from Pseudoexfoliation syndrome. 4. **UV Radiation:** Associated specifically with **Cortical** cataracts, while smoking is more strongly linked to **Nuclear** cataracts.

Q: Laser capsulotomy is the treatment of choice for which of the following conditions?

Posterior capsular opacification after cataract surgery. **Explanation:** **Posterior Capsular Opacification (PCO)**, also known as "After-Cataract," is the most common late complication of extracapsular cataract surgery (ECCE/Phacoemulsification). It occurs due to the proliferation and migration of residual lens epithelial cells (LECs) across the posterior capsule. The treatment of choice is **Nd:YAG Laser Capsulotomy**, a non-invasive procedure where the laser creates a central opening in the opacified posterior capsule to clear the visual axis. **Analysis of Incorrect Options:** * **Primary Open-Angle Glaucoma (POAG):** The primary treatment is medical (Prostaglandin analogues). If laser is used, it is **Selective Laser Trabeculoplasty (SLT)** or Argon Laser Trabeculoplasty (ALT) to increase aqueous outflow. * **Phacolytic Glaucoma:** This is a lens-induced glaucoma caused by a hypermature cataract. The definitive treatment is urgent **cataract extraction** (surgical removal of the lens), not a laser procedure. * **Closed-Angle Glaucoma:** The definitive laser treatment for primary angle-closure is **Laser Peripheral Iridotomy (LPI)**, which bypasses pupillary block. **High-Yield Clinical Pearls for NEET-PG:** * **Elschnig’s Pearls:** Large, vacuolated cells (LECs) seen in PCO that resemble a "bunch of grapes." * **Soemmering’s Ring:** A ring-shaped PCO formed when lens fibers are trapped between the anterior and posterior capsule. * **Complication of Nd:YAG Capsulotomy:** The most common serious complication is a transient rise in **Intraocular Pressure (IOP)**. Other risks include cystoid macular edema (CME) and retinal detachment.

Q: What is the treatment of choice for congenital cataract?

Cataract surgery with IOL implant. **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.

Q: Which of the following is NOT a cause of congenital cataract?

Marfan's syndrome. **Explanation:** The correct answer is **Marfan’s syndrome**. In the context of NEET-PG, it is crucial to distinguish between lens **opacification** (cataract) and lens **dislocation** (ectopia lentis). **1. Why Marfan’s Syndrome is the correct answer:** Marfan’s syndrome is a connective tissue disorder caused by a mutation in the **FBN1 gene** (fibrillin-1). It is the most common cause of heritable **ectopia lentis** (typically superior-temporal subluxation). While patients may develop early-onset presbyopia or secondary cataracts later in life, Marfan’s is **not** a classical cause of congenital cataract. **2. Analysis of Incorrect Options:** * **Trisomy 21 (Down Syndrome):** Frequently associated with various types of congenital cataracts (often punctate or flake-like) along with Brushfield spots and keratoconus. * **Lowe’s Syndrome (Oculocerebrorenal syndrome):** An X-linked recessive disorder characterized by aminoaciduria, mental retardation, and **100% incidence of bilateral congenital cataracts** (often discoid/microphakic). * **Stickler Syndrome:** A collagenopathy (Types II/XI) that presents with high myopia, vitreoretinal degeneration, and "sunflower" or cortical congenital cataracts. **Clinical Pearls for NEET-PG:** * **Most common metabolic cause** of congenital cataract: Galactosemia (Oil droplet cataract). * **Most common intrauterine infection** causing cataract: Rubella (Pearly white nuclear cataract). * **Ectopia Lentis Mnemonic:** Marfan’s = **Up**ward (Superior-temporal); Homocystinuria = **Down**ward (Inferior-nasal). * **Lowe’s Syndrome** is a high-yield association for "Total Cataract" and glaucoma in male infants.

Question 1

Lens dislocation can occur in all of the following conditions except:

Accepted Answer

Wilson's disease

Answer

Homocystinuria

Answer

Marfan's syndrome

Answer

Trauma

Question 2

Anterior polar cataract develops in which of the following conditions?

Accepted Answer

Penetrating corneal injury

Answer

Diabetes Mellitus

Answer

Irradiation

Answer

Barbiturates

Question 3

Ascorbate and a-tocopherol are maintained in a reduced state in the lens by:

Accepted Answer

Glutathione

Answer

Glucose

Answer

Glycoprotein

Answer

Fatty acid

Question 4

Which of the following is true regarding Mittendorf dot?

Accepted Answer

An obliterated hyaloid vessel remnant running forward into the vitreous

Answer

Glial tissue projecting from the optic disc

Answer

Associated with posterior polar cataract

Question 5

What is a known cause of cataract?

Accepted Answer

All of the above

Answer

Infrared radiation

Answer

Microwaves

Answer

Ultraviolet rays

Question 6

What is the standard power of an intraocular lens implanted in the posterior chamber?

Accepted Answer

20 dioptres

Answer

18 dioptres

Answer

23 dioptres

Answer

25 dioptres

Question 7

Which of the following is NOT a treatment for pediatric cataract?

Accepted Answer

Intracapsular cataract extraction

Answer

Phaco-aspiration

Answer

Corneo-scleral tunnel technique

Answer

Intraocular lens implantation

Question 8

Laser capsulotomy is the treatment of choice for which of the following conditions?

Accepted Answer

Posterior capsular opacification after cataract surgery

Answer

Primary open-angle glaucoma (POAG)

Answer

Phacolytic glaucoma

Answer

Closed-angle glaucoma

Question 9

What is the treatment of choice for congenital cataract?

Accepted Answer

Cataract surgery with IOL implant

Answer

Pharmacotherapy

Answer

Combined cataract surgery and goniotomy

Answer

Pars plana lensectomy with no IOL implant

Question 10

Which of the following is NOT a cause of congenital cataract?

Accepted Answer

Marfan's syndrome

Answer

Trisomy 21

Answer

Stickler syndrome

Answer

Lowe's syndrome

Diseases of the Lens — MCQs

Diseases of the Lens — MCQs

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