Diseases of the Lens — MCQs

Diseases of the Lens Indian Medical PG Practice Questions and MCQs

Question 181: Which of the following is NOT a feature of mature senile cataract?

A. Pearly white colored
B. Diminution of vision
C. Glare
D. Iris shadow (Correct Answer)

Explanation: In a **Mature Senile Cataract (MSC)**, the entire cortex becomes opaque. The absence of an **iris shadow** is the hallmark clinical feature that distinguishes it from an Immature Senile Cataract (ISC). ### Why "Iris Shadow" is the Correct Answer An iris shadow is formed when there is still a layer of clear (transparent) cortex between the iris and the opaque part of the lens. In an **Immature Cataract**, light passing through the pupil casts a shadow of the iris onto the underlying opacification. In a **Mature Cataract**, the opacification reaches the anterior capsule (the surface of the lens). Since there is no clear space left, no shadow can be cast. Therefore, the iris shadow is **absent** in MSC. ### Explanation of Other Options * **Pearly white colored:** This is the characteristic appearance of a mature cataract. The lens appears totally opaque and chalky or pearly white. * **Diminution of vision:** In MSC, vision is significantly reduced, usually to the level of **Hand Movements (HM)** or **Perception of Light (PL)**, as light cannot pass through the totally opaque lens. * **Glare:** While most prominent in early stages (like cortical or posterior subcapsular cataracts), patients with developing or mature cataracts experience significant glare due to the scattering of light by lens opacities. ### High-Yield Clinical Pearls for NEET-PG * **Immature Senile Cataract (ISC):** Lens is partially opaque; **Iris shadow is present.** * **Hypermature Cataract:** Characterized by a shrunken, wrinkled capsule (Morgagnian type involves a liquefied cortex where the nucleus settles at the bottom). * **Intumescent Cataract:** The lens becomes swollen due to osmotic water intake, often leading to a shallow anterior chamber and secondary angle-closure glaucoma. * **Best Surgical Approach:** Phacoemulsification with Posterior Chamber Intraocular Lens (PCIOL) implantation is the gold standard.

Question 182: Which type of cataract is associated with the minimum vision loss?

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

Explanation: **Explanation:** The correct answer is **Blue dot cataract (Punctate cataract)**. This is the most common type of congenital cataract. It is characterized by small, discrete, bluish-white opacities scattered throughout the lens. Because these opacities are small, peripheral, and do not involve the visual axis or the entire lens thickness, they rarely interfere with the light path significantly. Consequently, they are usually asymptomatic, non-progressive, and associated with **minimum or no vision loss**. **Analysis of Incorrect Options:** * **Zonular (Lamellar) Cataract:** This is the most common type of congenital cataract *requiring surgery*. It involves a specific "zone" or layer of the lens (usually around the nucleus) with linear opacities called "riders." It typically causes significant visual impairment. * **Anterior Polar Cataract:** These are small, central opacities on the anterior capsule. While often compatible with good vision, they can cause more significant blurring than blue dot cataracts if they are large or associated with persistent pupillary membranes. * **Posterior Polar Cataract:** These are located at the posterior pole of the lens, very close to the nodal point of the eye. Even small opacities here cause **significant visual loss** and glare. They are also surgically challenging due to an associated weak or absent posterior capsule. **High-Yield Clinical Pearls for NEET-PG:** * **Blue dot cataract** is also known as *Cataracta Punctata Caerulea*. * **Zonular cataract** is classically associated with maternal Vitamin D deficiency or hypocalcemia. * **Posterior polar cataract** carries a high risk of **Posterior Capsular Rupture (PCR)** during surgery (the "White Star" or "Onion skin" appearance). * For any congenital cataract, the most critical period for surgery to prevent **amblyopia** is within the first 4–6 weeks of life.

Question 183: Which among the following is the commonest type of congenital cataract?

A. Nuclear
B. Zonular (Correct Answer)
C. Capsular
D. Coralliform

Explanation: **Explanation:** **Zonular (Lamellar) cataract** is the most common type of congenital cataract, accounting for approximately 50% of cases. It is characterized by opacification of a specific layer (lamella) of the lens fibers, usually occurring due to a transient genetic or environmental insult during lens development. A classic clinical feature is the presence of **"riders"**—linear opacities extending from the equator of the opacity into the clear cortex. It is typically bilateral and often results in significant visual impairment. **Analysis of Incorrect Options:** * **Nuclear Cataract:** This involves the embryonic or fetal nucleus. While common, it is less frequent than the zonular type. It is often associated with microphthalmos and rubella. * **Capsular Cataract:** These are small, stationary opacities involving the anterior or posterior capsule. They are usually unilateral and rarely affect vision significantly. * **Coralliform Cataract:** This is a rare morphological variant characterized by irregular, coral-shaped opacities radiating from the center of the lens. It is genetically determined but not the most common clinical presentation. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of treatable blindness in children:** Congenital Cataract. * **Most common etiology:** Idiopathic (followed by genetic/autosomal dominant). * **Most common infection:** Congenital Rubella Syndrome (classically presents with "pearly white" nuclear cataract). * **Galactosemia:** Associated with **"Oil droplet"** cataracts. * **Diabetes Mellitus:** Associated with **"Snowflake"** cataracts. * **Myotonic Dystrophy:** Associated with **"Christmas tree"** cataracts.

Question 184: What is the best treatment for after cataract?

A. Argon laser
B. Nd-YAG laser (Correct Answer)
C. Excimer laser
D. Holmium laser

Explanation: **Explanation:** **After-cataract**, also known as **Posterior Capsular Opacification (PCO)**, is the most common late complication of extracapsular cataract extraction (ECCE) or Phacoemulsification. It occurs due to the proliferation and migration of residual lens epithelial cells (LECs) across the posterior capsule. **Why Nd-YAG laser is the correct answer:** The gold standard treatment for PCO is **Nd-YAG laser capsulotomy**. The Neodymium-doped Yttrium Aluminum Garnet (Nd-YAG) laser is a solid-state laser that operates at a wavelength of 1064 nm. It works on the principle of **photodisruption** (optical breakdown). It creates a small opening in the central part of the opacified posterior capsule, clearing the visual axis and restoring vision without the need for invasive surgery. **Why other options are incorrect:** * **Argon laser:** This is a gas laser used primarily for **photocoagulation** (e.g., in diabetic retinopathy or sealing retinal tears). It requires pigment to be absorbed and is not effective for cutting transparent or white membranes like the posterior capsule. * **Excimer laser:** This is an ultraviolet laser used for **photoablation**. It is the mainstay of refractive surgeries like LASIK and PRK to reshape the cornea. * **Holmium laser:** This is used primarily in urology (lithotripsy) or sometimes in glaucoma surgery (sclerostomy), but it has no role in treating after-cataract. **Clinical Pearls for NEET-PG:** * **Most common type of PCO:** Elschnig’s pearls (vacuolated cells) are more common than the fibrous type. * **Timing:** Usually performed at least 3 months post-surgery to allow the IOL to stabilize. * **Complications of Nd-YAG capsulotomy:** Transient rise in Intraocular Pressure (IOP) (most common), cystoid macular edema (CME), retinal detachment, and IOL pitting. * **Contraindication:** Active intraocular inflammation (uveitis).

Question 185: What is the diagnosis in a patient who presented with sudden painful vision impairment after vigorous exercise?

A. Central retinal artery occlusion
B. Corneal ulcer
C. Dislocation of the lens (Correct Answer)
D. Episcleritis

Explanation: **Explanation:** The correct answer is **Dislocation of the lens (C)**. In the context of NEET-PG, the combination of **vigorous exercise** (or minor trauma) and **sudden painful vision loss** is a classic presentation for lens subluxation or dislocation. When the lens dislocates into the anterior chamber, it can cause an acute rise in intraocular pressure (secondary angle-closure glaucoma) due to pupillary block, leading to sudden pain and blurred vision. This is particularly common in patients with underlying zonular weakness (e.g., Marfan syndrome or Homocystinuria). **Analysis of Incorrect Options:** * **A. Central Retinal Artery Occlusion (CRAO):** While it causes sudden vision loss, it is characteristically **painless**. The classic finding is a "cherry-red spot" on the macula. * **B. Corneal Ulcer:** This presents with pain and redness, but the onset is typically gradual (over days) rather than sudden following physical exertion, and it is usually associated with discharge or a visible white infiltrate. * **D. Episcleritis:** This causes localized redness and mild discomfort, but it does **not** cause significant vision impairment. **Clinical Pearls for NEET-PG:** * **Ectopia Lentis:** The most common cause of non-traumatic lens dislocation is **Marfan syndrome** (typically bilateral, superior-temporal displacement). * **Homocystinuria:** Lens dislocation is typically **inferior-nasal** and associated with intellectual disability and prothrombotic states. * **Phacolytic vs. Phacomorphic Glaucoma:** Remember that a dislocated lens can lead to **Phacomorphic glaucoma** (lens-induced angle closure), a high-yield surgical emergency. * **Iridodonesis:** Tremulousness of the iris is a key clinical sign of a subluxated or absent lens.

Question 186: Secondary cataract is an opacity of which of the following?

A. The lens after extracapsular extraction (Correct Answer)
B. The lens after Nd:YAG laser iridotomy
C. The lens after peripheral iridectomy
D. The lens due to nutritional deficiency

Explanation: **Explanation:** **Secondary Cataract**, also known as **After-Cataract**, refers to the opacification that develops in the remaining lens components following an **Extracapsular Cataract Extraction (ECCE)** or Phacoemulsification. In these surgeries, the posterior capsule and parts of the anterior capsule are left intact to support the Intraocular Lens (IOL). The opacity arises due to the proliferation and migration of residual lens epithelial cells (LECs) across the posterior capsule. The most common clinical presentation is **Posterior Capsular Opacification (PCO)**. **Analysis of Options:** * **Option A (Correct):** As explained, it occurs post-ECCE due to the proliferation of residual subcapsular epithelium. * **Option B & C (Incorrect):** Nd:YAG laser iridotomy and peripheral iridectomy are procedures performed on the **iris** (usually for glaucoma). While intraocular surgery can technically accelerate cataract formation, "Secondary Cataract" is a specific pathological term reserved for post-ECCE opacification. * **Option D (Incorrect):** Opacity due to nutritional deficiency or metabolic disorders is classified under **Complicated Cataract** or metabolic cataract, not secondary cataract. **High-Yield Clinical Pearls for NEET-PG:** * **Morphological Types:** 1. **Elschnig’s Pearls:** Round, vacuolated cells (common in children). 2. **Soemmering’s Ring:** A ring-shaped opacity formed when residual cortex is trapped between the two layers of the capsule. * **Treatment of Choice:** **Nd:YAG laser capsulotomy** (painless, outpatient procedure to create a central opening in the opacified capsule). * **Prevention:** Use of IOLs with **square-edge designs** and thorough cortical washing during surgery significantly reduces PCO incidence.

Question 187: Which of the following is the only reversible cataract?

A. Senile Cataract
B. Cataract in Galactosemia (Correct Answer)
C. Congenital Cataract
D. None of the above

Explanation: **Explanation:** **Cataract in Galactosemia** is considered the only reversible cataract if detected and treated in the very early stages. **Why it is the correct answer:** Galactosemia is an inborn error of metabolism, most commonly due to a deficiency of the enzyme **Galactose-1-phosphate uridyltransferase (GALT)**. This leads to an accumulation of galactose, which is converted into **Dulcitol (Galactitol)** by the enzyme aldose reductase. Dulcitol is osmotically active and draws water into the lens fibers, causing swelling and the characteristic **"Oil Droplet" appearance**. If a lactose-free/galactose-free diet is initiated early (before permanent protein denaturation and lens fiber rupture occur), the osmotic changes can resolve, and the lens can regain its clarity. **Why other options are incorrect:** * **Senile Cataract:** This is an age-related degenerative process involving irreversible protein denaturation (aggregation of crystallins) and lens fiber sclerosis. It cannot be reversed by medical therapy. * **Congenital Cataract:** Most congenital cataracts (e.g., Rubella, hereditary) involve structural malformations or irreversible protein damage during development. Once the lens fibers are opacified, surgical intervention is the only treatment. **High-Yield Clinical Pearls for NEET-PG:** 1. **Oil Droplet Cataract:** Classic sign of Galactosemia. 2. **Sunflower Cataract:** Seen in Wilson’s Disease (Copper deposition). 3. **Snowflake Cataract:** Seen in Juvenile Diabetes Mellitus. 4. **Christmas Tree Cataract:** Seen in Myotonic Dystrophy. 5. **Rosette-shaped Cataract:** Characteristic of blunt trauma to the eye.

Question 188: All of the following are true about Morgagnian cataract, EXCEPT:

A. It is an immature cataract (Correct Answer)
B. Lens becomes a bag of milky fluid
C. Calcium deposits are seen on the lens capsule
D. Brown nucleus settles at the bottom

Explanation: **Explanation:** A **Morgagnian cataract** is a specific form of **Hypermature Senile Cataract (HMSC)**, not an immature one. This distinction is the key to identifying the correct answer. 1. **Why Option A is the correct answer (The Exception):** An immature cataract (IMS) is one where the lens is only partially opaque. A Morgagnian cataract occurs when a mature cataract is left untreated, leading to the total liquefaction of the cortex. Therefore, it is classified as **Hypermature**, making Option A false. 2. **Analysis of other options:** * **Option B:** Due to the degeneration of lens fibers and enzymatic breakdown, the cortex transforms into a **milky white fluid**. The lens essentially becomes a bag containing this fluid. * **Option C:** In the hypermature stage, the lens capsule becomes thickened, and **calcium deposits** (calcific spots) are frequently seen on the anterior capsule. * **Option D:** As the cortex liquefies, it loses its structural support. The heavy, dense, and often brownish-colored nucleus **sinks to the bottom** of the capsular bag due to gravity. **Clinical Pearls for NEET-PG:** * **Iridodonesis:** In Morgagnian cataracts, the lack of cortical support can lead to "tremulousness of the iris." * **Complications:** If the liquefied cortex leaks through the capsule, it can lead to **Phacolytic Glaucoma** (macrophages clog the trabecular meshwork). * **Visual Acuity:** Usually reduced to "Hand Movements" or "Projection of Rays." * **Surgical Note:** During surgery (SICS/Phaco), the "milky" cortex can obscure the view, making the Continuous Curvilinear Capsulorhexis (CCC) challenging (often requiring Trypan Blue dye).

Question 189: Cataract associated with convulsions is seen in which condition?

A. Toxoplasmosis
B. Tay-Sachs disease
C. Galactosemia (Correct Answer)
D. Birth asphyxia with prematurity

Explanation: **Explanation:** **Galactosemia** is the correct answer because it is a metabolic disorder characterized by the deficiency of the enzyme **Galactose-1-phosphate uridyltransferase (GALT)**. This leads to the accumulation of galactose and its metabolite, **dulcitol (galactitol)**, in the lens. Dulcitol is osmotically active, drawing water into the lens fibers and causing the classic **"Oil droplet cataract."** Systemically, the accumulation of toxic metabolites leads to liver failure, mental retardation, and **hypoglycemic convulsions** (due to inhibition of glycogenolysis). **Analysis of Incorrect Options:** * **Toxoplasmosis:** Typically presents with the triad of chorioretinitis, hydrocephalus, and intracranial calcifications. While it causes seizures, it does not typically cause congenital cataracts. * **Tay-Sachs Disease:** A lysosomal storage disorder characterized by a **"Cherry-red spot"** at the macula and progressive neurodegeneration. It does not cause cataracts. * **Birth Asphyxia with Prematurity:** This is a major risk factor for **Retinopathy of Prematurity (ROP)** and hypoxic-ischemic encephalopathy (causing seizures), but it is not a primary cause of congenital cataract. **High-Yield Clinical Pearls for NEET-PG:** * **Oil Droplet Cataract:** Pathognomonic for Galactosemia. * **Reversibility:** Galactosemic cataracts are among the few types that can be **reversed** if a lactose-free diet is initiated early. * **Sunflower Cataract:** Seen in Wilson’s Disease (Copper deposition). * **Snowflake Cataract:** Seen in Diabetes Mellitus. * **Christmas Tree Cataract:** Seen in Myotonic Dystrophy.

Question 190: Polychromatic lustre is seen in:

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

Explanation: **Explanation:** **Polychromatic lustre** is a pathognomonic clinical sign of **Complicated Cataract**. It refers to a multi-colored (rainbow-like) sheen observed at the posterior pole of the lens during a slit-lamp examination. 1. **Why Complicated Cataract is correct:** A complicated cataract occurs due to intraocular inflammation (e.g., chronic uveitis) or degenerative conditions (e.g., high myopia, retinitis pigmentosa). These conditions lead to the accumulation of inflammatory debris and metabolic byproducts in the **posterior subcapsular region**. The "lustre" is caused by the interference of light reflecting off these irregular deposits and opacities just beneath the posterior capsule. 2. **Why other options are incorrect:** * **Diabetes Mellitus:** Typically presents with "Snowflake cataracts" (subcapsular opacities) or early-onset senile nuclear sclerosis. * **Post-radiation Cataract:** Characteristically presents as a posterior subcapsular cataract, often with a "saucer-shaped" appearance, but lacks the classic polychromatic lustre of inflammatory cataracts. * **Congenital Cataract:** Presents with various morphologies (e.g., Zonular/Lamellar, Blue dot, or Total) depending on the genetic or metabolic trigger, but not with polychromatic lustre. **High-Yield Clinical Pearls for NEET-PG:** * **Breadcrumb Appearance:** Complicated cataracts often show a "breadcrumb" appearance in the posterior subcapsular cortex. * **Most Common Cause:** Chronic anterior uveitis is the most frequent cause of complicated cataracts. * **Differential Diagnosis:** While polychromatic lustre is classic for complicated cataracts, it can occasionally be seen in early **Sunflower Cataracts** (Wilson’s Disease) due to copper deposition, though the location and clinical context differ.

Practice by Chapter

Lens Anatomy and Physiology

Practice Questions

Age-Related Cataract

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Congenital and Developmental Cataracts

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Traumatic Cataract

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Metabolic Cataracts

Practice Questions

Drug-Induced Cataracts

Practice Questions

Cataract Surgery Techniques

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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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