Diseases of the Lens — MCQs

Diseases of the Lens Indian Medical PG Practice Questions and MCQs

Question 121: Which of the following statements regarding galactosemic cataract is NOT true?

A. Irreversible (Correct Answer)
B. Due to deficiency of galactose-1-phosphate uridyl transferase
C. Oil droplet cataract is seen
D. Avoid milk products for the child

Explanation: **Explanation:** Galactosemia is an autosomal recessive metabolic disorder characterized by the body's inability to metabolize galactose. The classic form is caused by a deficiency of the enzyme **galactose-1-phosphate uridyl transferase (GALT)**. **Why "Irreversible" is the correct (False) statement:** Galactosemic cataracts are unique because they are **reversible** in their early stages. If the condition is diagnosed early and the child is placed on a strict galactose-free diet (eliminating milk and milk products), the lens opacities can regress completely. This makes early screening crucial. **Analysis of other options:** * **Option B (Deficiency of GALT):** This is the most common cause of classic galactosemia. The accumulation of galactose leads to its conversion into **dulcitol (galactitol)** by the enzyme aldose reductase. Dulcitol is osmotically active, drawing water into the lens fibers, causing swelling and opacity. * **Option C (Oil droplet cataract):** This is the classic morphological description of the cataract seen in galactosemia. It appears as a central refractive change in the lens resembling a drop of oil when viewed with an ophthalmoscope. * **Option D (Avoid milk products):** Dietary modification is the primary treatment. Since lactose in milk is broken down into glucose and galactose, all milk products must be strictly avoided to prevent further damage to the lens, liver, and brain. **High-Yield Clinical Pearls for NEET-PG:** * **Enzyme Deficiency:** Classic Galactosemia = GALT deficiency; Galactokinase deficiency also causes cataracts but without systemic involvement. * **Morphology:** "Oil droplet" = Galactosemia; "Sunflower" = Wilson’s Disease; "Snowflake" = Diabetes Mellitus; "Christmas Tree" = Myotonic Dystrophy. * **Reversibility:** Galactosemic and Diabetic cataracts are potentially reversible in early stages with metabolic control.

Question 122: A perforated corneal ulcer gives rise to which of the following?

A. Anterior capsular cataract (Correct Answer)
B. Posterior subcapsular cataract
C. Vossius ring
D. Rosette shaped cataract

Explanation: **Explanation:** The correct answer is **Anterior capsular cataract**. **Mechanism:** When a central corneal ulcer perforates, there is a sudden escape of aqueous humor, leading to the collapse of the anterior chamber. This causes the lens to move forward and come into direct contact with the inflamed cornea and the site of perforation. The resulting mechanical irritation and the presence of inflammatory toxins trigger the proliferation of the anterior lens epithelium. This leads to the formation of a localized, white, opaque plaque known as an **anterior capsular (or polar) cataract**. **Analysis of Incorrect Options:** * **Posterior subcapsular cataract:** This is typically associated with chronic intraocular inflammation (uveitis), prolonged topical/systemic steroid use, or ionizing radiation. It is not a direct complication of corneal perforation. * **Vossius ring:** This is a circular ring of pigment deposits on the anterior lens capsule. It is a sign of **blunt trauma**, where the iris pigment is "stamped" onto the lens due to the force of the impact. * **Rosette-shaped cataract:** This is a classic feature of **concussive (blunt) ocular trauma**, occurring due to fluid accumulation along the lens suture lines. **High-Yield Clinical Pearls for NEET-PG:** * **Pyramidal Cataract:** If the anterior capsular opacity is particularly thick and projects forward into the anterior chamber, it is termed a pyramidal cataract. * **Adherent Leucoma:** A common sequel of a perforated corneal ulcer where the iris becomes incarcerated in the corneal scar. * **Most common cause of complicated cataract:** Chronic anterior uveitis (usually presents as posterior subcapsular opacities). * **Sunflower Cataract:** Associated with Wilson’s disease (copper deposition).

Question 123: Cataract is a cause of:

A. Painful sudden vision loss
B. Painless sudden vision loss
C. Painful gradual vision loss
D. Painless gradual vision loss (Correct Answer)

Explanation: **Explanation:** **1. Why Option D is Correct:** Cataract is defined as the opacification of the crystalline lens. This process is typically a slow, degenerative change (especially in senile cataracts) that leads to a progressive decrease in visual acuity. Because the lens is an avascular and non-innervated structure, its opacification does not trigger an inflammatory response or stimulate pain fibers, resulting in a **painless, gradual loss of vision.** **2. Why Other Options are Incorrect:** * **Option A (Painful sudden):** This is characteristic of **Acute Angle Closure Glaucoma** or Endophthalmitis. * **Option B (Painless sudden):** This suggests vascular catastrophes like **Central Retinal Artery Occlusion (CRAO)**, Central Retinal Vein Occlusion (CRVO), or Retinal Detachment. * **Option C (Painful gradual):** This is typical of chronic inflammatory conditions like **Chronic Uveitis** or Corneal Dystrophies with recurrent erosions. **3. Clinical Pearls for NEET-PG:** * **Second Sight (Myopic Shift):** In nuclear cataracts, the refractive index of the lens increases, causing a shift toward myopia. This allows elderly patients to read without glasses temporarily. * **Early Symptoms:** Patients often complain of **glare (nyctalopia)**, especially while driving at night, and halos around lights. * **Exceptions:** While cataracts are generally painless, a **Phacolytic or Phacomorphic glaucoma** (complications of a hypermature or intumescent cataract) can present with sudden, painful vision loss due to secondary rise in intraocular pressure. * **Gold Standard Treatment:** Phacoemulsification with Foldable Intraocular Lens (IOL) implantation.

Question 124: Which is the commonest congenital cataract that presents as visual impairment?

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

Explanation: **Explanation:** **Zonular (Lamellar) cataract** is the most common type of congenital cataract that results in significant visual impairment. It typically involves a specific "zone" or layer of the lens fibers (usually the fetal nucleus), while the layers internal and external to the opacity remain clear. 1. **Why Zonular is Correct:** It is the most frequent variety of hereditary cataract. Because the opacity is often large and centrally located within the visual axis, it significantly obstructs light, leading to early visual impairment. A classic diagnostic feature is the presence of **"riders"** (linear opacities extending from the equator of the opacity into the clear cortex). 2. **Why other options are incorrect:** * **Nuclear:** While it involves the central core and causes visual loss, it is less common than the zonular type. * **Capsular:** These are usually small, polar opacities (anterior or posterior). Unless they are very large, they rarely cause significant visual impairment compared to zonular cataracts. * **Coralliform:** This is a rare variety of sutural cataract with a characteristic "coral-like" shape. It is much less common in clinical practice. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of congenital cataract:** Idiopathic (followed by genetic/hereditary factors). * **Most common infection:** Rubella (presents as a "pearly white" nuclear cataract). * **Galactosemia:** Associated with "Oil droplet" cataracts. * **Diabetes Mellitus:** Associated with "Snowflake" cataracts. * **Treatment:** If the cataract is visually significant, the surgery of choice is **Lens Aspiration with IOL implantation** (usually performed after 1 year of age for better outcomes, though surgery may be earlier if bilateral and dense).

Question 125: What is the ideal site for intraocular lens implantation?

A. Anterior to the pupil
B. Behind the cornea
C. In the lens capsule (Correct Answer)
D. Behind the lens capsule

Explanation: The ideal site for intraocular lens (IOL) implantation is the **capsular bag (in the lens capsule)**. ### Why the Capsular Bag is Ideal Modern cataract surgery (Phacoemulsification or SICS) involves creating a circular opening in the anterior capsule (capsulorhexis) and removing the lens matter while leaving the peripheral capsule and posterior capsule intact. Placing the IOL "in the bag" is preferred because: * **Anatomical Position:** It mimics the natural position of the crystalline lens (posterior chamber), maintaining the normal anatomy of the eye. * **Stability:** The capsular bag provides excellent centration and prevents the IOL from tilting or shifting. * **Safety:** It keeps the IOL away from sensitive structures like the corneal endothelium and the uveal tissue (iris and ciliary body), minimizing complications like inflammation or glaucoma. ### Why Other Options are Incorrect * **Anterior to the pupil (Option A):** Refers to the anterior chamber. IOLs here (ACIOLs) are used only when capsular support is inadequate. They carry a higher risk of corneal endothelial damage and secondary glaucoma. * **Behind the cornea (Option B):** This is a vague anatomical description of the anterior chamber; placing a lens directly against the cornea would cause immediate corneal decompensation and blindness. * **Behind the lens capsule (Option D):** This would place the lens in the vitreous cavity. Without capsular support, the lens would sink (dislocate) into the posterior segment. ### High-Yield NEET-PG Pearls * **Preferred IOL Site:** Capsular bag (In-the-bag). * **Second Best Site:** Ciliary Sulcus (between the iris and the lens capsule), used if the posterior capsule is ruptured but peripheral support remains. * **Uveitis-Glaucoma-Hyphema (UGH) Syndrome:** A classic complication of poorly positioned or ill-fitting anterior chamber IOLs. * **Material of Choice:** Foldable hydrophobic acrylic is currently the most popular for "in-the-bag" implantation.

Question 126: Which type of cataract is associated with Myotonic dystrophy?

A. Posterior subcapsular (Correct Answer)
B. Anterior subcapsular
C. Nuclear cataract
D. Corical cataract

Explanation: **Explanation:** **Myotonic Dystrophy (Steinert’s Disease)** is a multisystem disorder characterized by muscle wasting and delayed relaxation. In the early stages, it is classically associated with **"Christmas Tree Cataracts"**—polychromatic, iridescent crystals in the lens cortex. As the disease progresses, these opacities evolve into a **Posterior Subcapsular Cataract (PSC)**, which is the most common definitive cataractous change seen clinically in these patients. **Why the correct answer is right:** * **Posterior Subcapsular Cataract (PSC):** While the "Christmas Tree" appearance is pathognomonic, the standard morphological type of cataract that develops and eventually impairs vision in Myotonic Dystrophy is the PSC (often appearing in a star-like or stellate distribution). **Why the other options are wrong:** * **Anterior Subcapsular:** These are typically associated with trauma, Atopic Dermatitis, or Amiodarone use, rather than muscular dystrophies. * **Nuclear Cataract:** This is primarily an age-related (senile) change caused by sclerosis of the lens nucleus; it is not a specific feature of Myotonic Dystrophy. * **Cortical Cataract:** While early crystals appear in the cortex, "Cortical Cataract" usually refers to wedge-shaped (cuneiform) opacities seen in senile cataracts or diabetes, which differ from the specific PSC/Christmas tree morphology of Myotonic Dystrophy. **High-Yield Clinical Pearls for NEET-PG:** 1. **Christmas Tree Cataract:** The earliest sign; consists of cholesterol crystals. 2. **Inheritance:** Myotonic Dystrophy follows **Autosomal Dominant** inheritance with **Anticipation** (CTG triplet repeat expansion). 3. **Other Ocular Signs:** Ptosis, pigmentary retinopathy, and low intraocular pressure (IOP). 4. **Systemic Associations:** Frontal balding, "hatchet" facies, cardiomyopathy, and testicular atrophy.

Question 127: Cataract brunescens results due to deposition of?

A. Urochrome (Correct Answer)
B. Copper
C. Iron
D. Silver

Explanation: **Explanation:** **Cataract brunescens** is an advanced stage of nuclear senile cataract. The correct answer is **Urochrome** because the characteristic dark brown or amber discoloration of the lens nucleus is primarily due to the progressive accumulation of **urochrome-like pigments** and amino acid oxidation products (such as melanin precursors and oxidized tyrosine/tryptophan). As a nuclear cataract matures, the lens fibers become increasingly dehydrated and compressed (sclerosis). This process is accompanied by a chemical change where the soluble crystallins convert into insoluble proteins, leading to the deposition of these brown pigments. If the process continues, the lens may turn almost black, a condition known as **Cataract nigra**. **Why other options are incorrect:** * **Copper:** Deposition of copper in the lens leads to **Sunflower Cataract** (Chalcosis), typically seen in Wilson’s disease or intraocular copper foreign bodies. * **Iron:** Deposition of iron leads to **Siderosis Bulbi**, which can cause a yellowish-brown discoloration of the lens epithelium but is not the cause of brunescent cataracts. * **Silver:** Deposition of silver results in **Argyrosis**, which typically causes a slate-grey discoloration of the ocular tissues, not a brown nuclear cataract. **High-Yield Clinical Pearls for NEET-PG:** * **Nuclear Cataract:** Associated with **"Second Sight"** (myopic shift due to increased refractive index, allowing elderly patients to read without glasses temporarily). * **Grading:** Brunescent cataracts are considered "Hard" cataracts (Grade 4+), requiring higher phacoemulsification energy. * **Morgagnian Cataract:** A hypermature stage where the cortex liquefies and the heavy, brown nucleus sinks to the bottom of the capsular bag.

Question 128: Which of the following is responsible for presenile cataract?

A. Atopic dermatitis
B. Blue dot congenital cataract
C. Dystrophica myotonica
D. All of the above (Correct Answer)

Explanation: **Explanation:** **Presenile cataract** refers to the development of lens opacification before the age of 50. While senile cataracts are age-related, presenile cataracts are typically associated with systemic diseases, metabolic disorders, or genetic syndromes. **Breakdown of Options:** * **Atopic Dermatitis (Option A):** This is a well-known cause of presenile cataracts. It typically presents as a bilateral, **Shield-like anterior subcapsular cataract** that matures rapidly. It is often seen in the second to fourth decade of life. * **Blue Dot Congenital Cataract (Option B):** Also known as *Cataracta Punctata Caerulea*, these are small, bluish, harmless opacities. While they are congenital, they often remain stationary or progress very slowly, frequently being diagnosed during a routine presenile eye examination. * **Dystrophica Myotonica (Option C):** This is a high-yield association for NEET-PG. It presents with a characteristic **"Christmas Tree Cataract"** (polychromatic luster) in the early stages, which eventually progresses to a subcapsular stellate opacity. **Conclusion:** Since all three conditions are established causes or associations of lens opacities occurring in younger age groups, **Option D (All of the above)** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** 1. **Diabetes Mellitus:** The most common metabolic cause; presents as "Snowflake cataracts." 2. **Wilson’s Disease:** Associated with "Sunflower cataracts." 3. **Hypocalcemia:** Presents as punctate, multicellular subcapsular opacities. 4. **Galactosemia:** Classic "Oil droplet" appearance. 5. **Steroid use:** Most commonly leads to **Posterior Subcapsular Cataract (PSC)**.

Question 129: Foldable IOL is made of:

A. PMMA
B. HEMA
C. Polypropylene
D. Acrylic (Correct Answer)

Explanation: **Explanation:** The choice of material for an Intraocular Lens (IOL) depends on its flexibility and biocompatibility. **1. Why Acrylic is Correct:** Foldable IOLs are designed to be inserted through small incisions (2.2 to 2.8 mm) during phacoemulsification. **Acrylic** (both hydrophobic and hydrophilic) and **Silicone** are the primary materials used for foldable lenses because they possess high elasticity and "shape memory," allowing the lens to be folded, injected, and then unfolded safely within the capsular bag. Hydrophobic acrylic is currently the gold standard due to its low rate of Posterior Capsular Opacification (PCO). **2. Why Other Options are Incorrect:** * **PMMA (Polymethylmethacrylate):** This is a **rigid**, non-foldable material. It was the first material used for IOLs (by Sir Harold Ridley). Because it cannot be folded, it requires a larger incision (5-6 mm), typically used in ECCE or SICS. * **HEMA (Hydroxyethylmethacrylate):** While HEMA is a hydrogel used in soft contact lenses, it is not the standard material for foldable IOLs, which require specific refractive indices and stability provided by acrylic polymers. * **Polypropylene (Prolene):** This material is used for the **haptics** (the side arms) of some 3-piece IOLs or for stay sutures, but not for the optic (the lens body) itself. **High-Yield Clinical Pearls for NEET-PG:** * **Ideal Material for PCO prevention:** Hydrophobic Acrylic (due to its square-edge design and bio-adhesion). * **Smallest Incision:** Micro-incision cataract surgery (MICS) uses ultra-thin foldable acrylic lenses. * **First IOL Material:** PMMA. * **Haptic Material:** Usually PMMA or Polypropylene.

Question 130: Lens sutures are formed in which part of the lens?

A. Foetal nucleus (Correct Answer)
B. Embryonic nucleus
C. Infantile nucleus
D. Adult nucleus

Explanation: **Explanation:** The lens develops from the surface ectoderm. The formation of lens sutures is a result of the meeting points of lens fibers that are too long to span from pole to pole. **Why Option A is Correct:** The **Foetal nucleus** is formed from the 3rd month of gestation until birth. During this period, the lens fibers meet in a specific pattern to form the **Y-sutures**. On the anterior aspect, the suture is an upright 'Y', while on the posterior aspect, it is an inverted 'Y' (λ). These sutures are a hallmark of the foetal nucleus and serve as a vital landmark during slit-lamp biomicroscopy. **Analysis of Incorrect Options:** * **B. Embryonic nucleus:** This is the innermost core formed during the first 1-3 months of gestation. It consists of primary lens fibers that elongate from the posterior vesicle wall to the anterior wall. Since these fibers fill the cavity directly, no sutures are formed. * **C. Infantile nucleus:** This layer is formed from birth until puberty. While it surrounds the foetal nucleus, the characteristic Y-sutures are already established within the foetal layer. * **D. Adult nucleus:** This refers to the fibers formed from puberty until later life. It lies peripheral to the infantile nucleus. **High-Yield Clinical Pearls for NEET-PG:** * **Suture Landmark:** The Y-sutures are used by surgeons to demarcate the boundaries of the foetal nucleus during cataract surgery. * **Lens Growth:** The lens is the only structure in the body that continues to grow throughout life. * **Congenital Cataract:** Sutural cataracts are a specific type of congenital cataract that affects these Y-shaped meeting points, usually without significantly affecting vision.

Practice by Chapter

Lens Anatomy and Physiology

Practice Questions

Age-Related Cataract

Practice Questions

Congenital and Developmental Cataracts

Practice Questions

Traumatic Cataract

Practice Questions

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

Practice Questions

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