Diseases of the Lens — MCQs

Diseases of the Lens Indian Medical PG Practice Questions and MCQs

Question 111: What type of intraocular lens (IOL) is preferred in children?

A. Foldable acrylic lens (Correct Answer)
B. Foldable silicone lens
C. Three-piece PMMA lens
D. Single-piece PMMA lens

Explanation: ### Explanation **Correct Option: A. Foldable acrylic lens** The primary challenge in pediatric cataract surgery is the intense inflammatory response and the high rate of **Posterior Capsular Opacification (PCO)**. Hydrophobic acrylic lenses are the gold standard for children because: 1. **Biocompatibility:** They are highly inert, leading to minimal postoperative uveitis. 2. **Square-edge Design:** Most modern foldable acrylic IOLs feature a sharp "square edge" that acts as a physical barrier, significantly reducing the migration of lens epithelial cells and thus lowering the incidence of PCO. 3. **Small Incision:** Being foldable, they can be inserted through a small incision (2.2–2.8 mm), which ensures a self-sealing wound, reduces astigmatism, and allows for faster visual rehabilitation in the amblyogenic age group. **Why other options are incorrect:** * **B. Foldable silicone lens:** These are avoided in children because they are associated with a higher rate of "calcification" and increased inflammatory response. Furthermore, if the child requires vitreoretinal surgery later in life, silicone oil can adhere permanently to a silicone IOL. * **C & D. PMMA lenses:** Polymethylmethacrylate (PMMA) lenses are rigid (non-foldable). They require a much larger incision (5–6 mm), which necessitates sutures. Large incisions in children increase the risk of wound leak, iris prolapse, and high postoperative astigmatism. **High-Yield Clinical Pearls for NEET-PG:** * **IOL Power Calculation:** In children, we aim for **initial hypermetropia** (under-correction) to account for the "myopic shift" that occurs as the eye grows. * **Primary Posterior Capsulotomy (PPC) + Anterior Vitrectomy:** This is mandatory in children under 5–6 years of age to prevent PCO, as the visual axis obscures rapidly otherwise. * **Heparin-coated IOLs:** Sometimes used in pediatric cases to further reduce postoperative inflammation. * **Ideal Site:** The **Capsular Bag** is the preferred site for IOL implantation in children.

Question 112: Rubella cataract is seen as which of the following types?

A. Posterior polar cataract
B. Nuclear cataract (Correct Answer)
C. Blue dot cataract in young
D. Cuneiform cataract

Explanation: **Explanation:** **Congenital Rubella Syndrome (CRS)** typically presents with a dense **Nuclear cataract**. This occurs because the Rubella virus crosses the placenta and directly invades the embryonic lens vesicle before the lens capsule develops (around the 8th week of gestation). The virus persists within the lens fibers, leading to necrosis and opacification of the central embryonic and fetal nuclei. * **Why Nuclear Cataract is Correct:** In CRS, the cataract is usually pearly-white and central (nuclear). The virus can remain live within the lens for several years post-natally, which is a critical surgical consideration as it can cause severe post-operative endophthalmitis if the lens cortex is not thoroughly aspirated. **Analysis of Incorrect Options:** * **A. Posterior polar cataract:** This is typically an autosomal dominant inherited condition or associated with persistent hyperplastic primary vitreous (PHPV), not viral infections. * **C. Blue dot cataract (Punctate cataract):** These are the most common type of congenital cataracts but are usually stationary, asymptomatic, and not specifically linked to Rubella. * **D. Cuneiform cataract:** This is a type of age-related (senile) cortical cataract characterized by wedge-shaped opacities in the periphery. **High-Yield Clinical Pearls for NEET-PG:** * **Gregg’s Triad of CRS:** Cataract, Sensorineural hearing loss (most common), and Cardiac defects (Patent Ductus Arteriosus). * **Ocular signs of Rubella:** "Salt and pepper" retinopathy (most common ocular sign), microphthalmos, and glaucoma. * **Surgical Note:** In Rubella cataract surgery, complete removal of the lens material is mandatory to prevent virus-induced uveitis.

Question 113: Rosette-shaped cataract is seen in which of the following conditions?

A. Trauma (Correct Answer)
B. Radiation
C. Diabetes Mellitus
D. Iridocyclitis

Explanation: **Explanation:** **Rosette-shaped cataract** is a classic clinical sign of **mechanical trauma** to the eye, most commonly occurring after blunt injury. The mechanism involves the disruption of lens fibers along their natural suture lines. When the eye is struck, the concussive force causes fluid to accumulate between the lens fibers (hydrodissection), typically in the subcapsular region. This fluid collection follows the anatomical pattern of the lens sutures, resulting in a characteristic "flower-shaped" or "rosette" appearance. **Analysis of Options:** * **Trauma (Correct):** Blunt trauma leads to the **Vossius ring** (pigment on the anterior capsule) and the **Rosette cataract** (usually posterior subcapsular). It can be "early" (appearing shortly after injury) or "late" (developing years later). * **Radiation:** Typically causes **Posterior Subcapsular Cataract (PSC)**, often described as having a "saucer-shaped" or "polychromatic luster" appearance, but not a rosette pattern. * **Diabetes Mellitus:** Classically associated with **Snowflake cataracts** (bilateral, subcapsular opacities) in young patients with uncontrolled Type 1 DM, or early onset of senile cataracts in Type 2 DM. * **Iridocyclitis:** Chronic intraocular inflammation (complicated cataract) typically results in a **Polychromatic luster** or "bread-crumb" appearance at the posterior pole. **High-Yield Clinical Pearls for NEET-PG:** * **Sunflower Cataract:** Seen in Wilson’s Disease (Copper deposition). * **Snowflake Cataract:** Seen in Diabetes Mellitus. * **Christmas Tree Cataract:** Seen in Myotonic Dystrophy. * **Oil Droplet Cataract:** Seen in Galactosemia. * **Shield Cataract:** Seen in Atopic Dermatitis. * **Vossius Ring:** A circular ring of iris pigment on the anterior lens capsule, pathognomonic for blunt trauma.

Question 114: Laser capsulotomy is the treatment of choice for which of the following conditions?

A. Primary open-angle glaucoma (POAG)
B. Phacolytic glaucoma
C. Posterior capsular opacification after cataract surgery (Correct Answer)
D. Closed-angle glaucoma

Explanation: **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.

Question 115: The lens contains the oldest cells in which region?

A. Nucleus (Correct Answer)
B. Anterior surface of the lens
C. Posterior surface of the lens
D. Nucleo-cortical junction

Explanation: **Explanation:** The lens is a unique biological structure because it never sheds its old cells. Throughout life, new lens fibers are continuously produced by the mitotic division of epithelial cells at the **equator**. As these new fibers are formed, they are laid down peripherally in the **cortex**, while the older fibers are progressively compressed and pushed toward the center. **1. Why the Nucleus is Correct:** The **Nucleus** represents the central core of the lens. Since the lens grows from the outside in (centripetal growth), the fibers formed during embryonic and fetal development remain trapped in the center for the individual's entire life. Therefore, the embryonic nucleus contains the oldest cells in the human body. **2. Why the other options are Incorrect:** * **Anterior and Posterior surfaces:** These represent the subcapsular regions where the youngest, most recently formed fibers are located. * **Nucleo-cortical junction:** This is a transition zone. While older than the outer cortex, it is significantly younger than the central embryonic and fetal nuclei. **Clinical Pearls for NEET-PG:** * **Lens Protein:** The lens has the highest protein content (33%) of any organ in the body, primarily **Crystallins**. * **Metabolism:** The lens is avascular and derives its nutrition from the **aqueous humor** via anaerobic glycolysis (90%). * **Sutures:** The meeting points of lens fibers form the characteristic **Y-sutures** (Erect 'Y' anteriorly, Inverted 'Y' posteriorly). * **Hardness:** As the nucleus ages, it undergoes "nuclear sclerosis" (dehydration and compaction), which is the physiological basis for age-related nuclear cataracts.

Question 116: To avoid amblyopia, a congenital cataract should ideally be operated within what age?

A. 6 weeks (Correct Answer)
B. 6 months
C. 12 months
D. 24 months

Explanation: **Explanation:** The correct answer is **6 weeks**. The management of congenital cataracts is a time-sensitive emergency in pediatric ophthalmology due to the risk of **stimulus-deprivation amblyopia**. **1. Why 6 weeks is correct:** The first few months of life are the "critical period" for visual development. If a dense cataract obstructs the visual axis, the brain does not receive clear images, leading to permanent neural atrophy in the visual cortex (amblyopia). Clinical studies and the Infant Aphakia Treatment Study (IATS) suggest that operating on unilateral or bilateral dense congenital cataracts by **4 to 6 weeks of age** provides the best chance for achieving functional vision and preventing nystagmus. **2. Why other options are incorrect:** * **6 months (B):** By this age, the critical period for rapid visual development is already peak-passing. Delaying surgery until 6 months often results in irreversible amblyopia and sensory nystagmus. * **12 months (C) & 24 months (D):** These timeframes are far beyond the window for optimal visual rehabilitation. Surgery at this stage may clear the visual axis, but the "lazy eye" (amblyopia) will likely be permanent, resulting in poor legal vision. **Clinical Pearls for NEET-PG:** * **Unilateral vs. Bilateral:** Unilateral cataracts are more urgent (ideally <4–6 weeks) because of the intense competition between the eyes. Bilateral cataracts can sometimes be managed up to 8–10 weeks, but 6 weeks remains the gold standard. * **IOL Implantation:** Generally avoided in infants **<6 months** due to the high rate of inflammatory complications and changing axial length; these patients are managed with aphakic glasses or contact lenses. * **Most common cause:** Most bilateral cases are idiopathic, but the most common systemic association is **Galactosemia** (Oil droplet cataract) or **Lowe Syndrome**. * **Surgical Technique:** Lens aspiration + Posterior Capsulotomy + Anterior Vitrectomy (to prevent Posterior Capsular Opacification).

Question 117: Which of the following is NOT a cause of congenital cataract?

A. Trisomy 21
B. Stickler syndrome
C. Lowe's syndrome
D. Marfan's syndrome (Correct Answer)

Explanation: **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 118: Rapid change of presbyopic glass is a feature of –

A. Senile cataract
B. Retinal detachment
C. Intumescent cataract
D. Open angle glaucoma (Correct Answer)

Explanation: **Explanation:** The correct answer is **Open angle glaucoma (OAG)**. **Why it is correct:** In Primary Open Angle Glaucoma (POAG), there is a progressive increase in intraocular pressure (IOP) which leads to **pressure-induced weakness of the ciliary muscle**. This results in a premature or rapid loss of accommodative power. Since presbyopia is the physiological loss of accommodation, any pathological weakening of the ciliary body necessitates a frequent increase in the strength of near-vision (presbyopic) glasses. Therefore, a history of "frequent change of presbyopic glasses" is a classic early clinical symptom of POAG. **Why other options are incorrect:** * **Senile cataract:** Typically causes a "second sight" phenomenon (myopic shift) due to nuclear sclerosis, where a patient may actually stop needing presbyopic glasses for a while. It does not cause a rapid *increase* in presbyopic power. * **Retinal detachment:** Presents with sudden flashes (photopsia), floaters, or a "curtain-like" vision loss. It does not affect the accommodative apparatus or refractive error in a way that mimics presbyopia. * **Intumescent cataract:** This is a stage where the lens becomes swollen. While it can cause a myopic shift or lead to secondary angle-closure glaucoma, it is not characterized by the gradual, repetitive change in presbyopic glasses seen in chronic OAG. **Clinical Pearls for NEET-PG:** * **Triad of POAG:** Raised IOP, Optic disc cupping, and Visual field defects. * **Early symptoms of POAG:** Often asymptomatic ("Silent thief of sight"), but may present with frequent change of reading glasses or delayed dark adaptation. * **Differential Diagnosis:** Rapid change in *distal* refractive error (myopia) is seen in nuclear cataract, while rapid change in *presbyopic* error is a hallmark of POAG.

Question 119: Which of the following is true regarding the concentration of proteins in senile cataract?

A. More insoluble protein, less soluble protein (Correct Answer)
B. More soluble protein, less insoluble protein
C. Equal concentration of soluble and insoluble protein
D. None of the above

Explanation: In the normal human lens, proteins account for approximately 33% of its weight, the highest concentration in any body tissue. These are divided into **water-soluble proteins (Crystallins: alpha, beta, and gamma)** and **water-insoluble proteins (Albuminoids).** ### Why Option A is Correct As a senile cataract develops, the lens undergoes significant biochemical changes. The primary mechanism involves the **denaturation and aggregation** of soluble crystallins. Through processes like oxidative stress, non-enzymatic glycosylation, and proteolysis, the low-molecular-weight soluble proteins transform into high-molecular-weight **insoluble aggregates**. Consequently, in a cataractous lens, the concentration of **insoluble protein increases** while the **soluble protein decreases**. This shift disrupts lens transparency, leading to opacification. ### Why Other Options are Incorrect * **Option B:** This describes a healthy, young lens where soluble crystallins predominate to maintain transparency. * **Option C:** There is no physiological or pathological state where these proteins remain in equal concentration; the progression of cataract is characterized by a definitive shift toward insolubility. ### High-Yield Clinical Pearls for NEET-PG * **Alpha-crystallins** act as molecular chaperones, preventing the precipitation of other proteins; their depletion or dysfunction is a key factor in cataractogenesis. * **Amino Acid Changes:** There is a decrease in the levels of **Glutathione** (the main antioxidant) and **Potassium**, while **Sodium, Calcium, and hydration** (in cortical cataracts) increase. * **Nuclear vs. Cortical:** Nuclear cataracts are primarily associated with protein denaturation and pigment accumulation (urochrome), whereas cortical cataracts involve electrolyte imbalance and hydration.

Question 120: Polychromatic lustre is seen in which of the following conditions?

A. Complicated cataract (Correct Answer)
B. Diabetes mellitus
C. Post-radiation cataract
D. Congenital cataract

Explanation: **Explanation:** **1. Why Complicated Cataract is Correct:** A complicated cataract refers to opacification of the lens secondary to intraocular diseases (e.g., chronic uveitis, high myopia, or retinal detachment). The hallmark early sign is **polychromatic lustre**, which is a characteristic **iridescent play of colors** (red, green, and blue) seen at the posterior pole of the lens. This occurs due to the accumulation of metabolic debris and inflammatory byproducts in the **posterior subcapsular region**, leading to light interference patterns. Over time, this progresses to a "bread-crumb" appearance. **2. Why the Other Options are Incorrect:** * **B. Diabetes Mellitus:** Typically presents with "Snowflake cataracts" (subcapsular opacities) in young diabetics or earlier onset of senile nuclear sclerosis in older patients. * **C. Post-radiation Cataract:** Characteristically presents as a posterior subcapsular opacity, often described as a "discoid" or "saucer-shaped" opacity, but it lacks the classic polychromatic lustre associated with intraocular inflammation. * **D. Congenital Cataract:** These present in various morphologies (e.g., Zonular/Lamellar, Blue dot, or Total) depending on the genetic or metabolic trigger, but they do not exhibit polychromatic lustre. **3. High-Yield Clinical Pearls for NEET-PG:** * **Earliest sign of Complicated Cataract:** Polychromatic lustre at the posterior pole. * **Most common cause:** Chronic Anterior Uveitis. * **Bread-crumb appearance:** A later stage of complicated cataract. * **Snowflake cataract:** Pathognomonic for Diabetes Mellitus. * **Sunflower cataract:** Seen in Wilson’s Disease (Copper deposition). * **Oil droplet cataract:** Seen in Galactosemia. * **Christmas tree cataract:** Seen in Myotonic Dystrophy.

Practice by Chapter

Lens Anatomy and Physiology

Practice Questions

Age-Related Cataract

Practice Questions

Congenital and Developmental Cataracts

Practice Questions

Traumatic Cataract

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Metabolic Cataracts

Practice Questions

Drug-Induced Cataracts

Practice Questions

Cataract Surgery Techniques

Practice Questions

Intraocular Lens Implants

Practice Questions

Complications of Cataract Surgery

Practice Questions

Posterior Capsular Opacification

Practice Questions

Lens Subluxation and Dislocation

Practice Questions

Specialty IOLs

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