Diseases of the Lens — MCQs

Diseases of the Lens Indian Medical PG Practice Questions and MCQs

Question 271: What is the type of cataract associated with Galactosemia?

A. Oil drop (Correct Answer)
B. Snowflake cataract
C. Blue dot cataract
D. Polychromatic lustre cataract

Explanation: ***Oil drop*** - This characteristic appearance is caused by the accumulation of **galactitol** in the lens, leading to changes in refractive index. - The "oil drop" cataract is a classic sign of **galactosemia**, often appearing as an early manifestation of the disease. *Snowflake cataract* - This type of cataract is more commonly associated with **diabetes mellitus** rather than galactosemia. - It presents as **fluffy white opacities** that can lead to rapid vision loss. *Blue dot cataract* - This is typically a **congenital stationary cataract** with small, bluish opacities in the peripheral lens. - It is usually **benign** and non-progressive, and not specifically linked to metabolic disorders like galactosemia. *Polychromatic lustre cataract* - This describes the varied, iridescent colors seen in certain types of cataracts, often associated with **complicated cataracts** or those near the lens sutures. - It does not specifically refer to the unique "oil drop" appearance of galactosemic cataracts.

Question 272: In senile nuclear cataract what type of myopia is seen?

A. Curvature myopia
B. Axial myopia
C. Index myopia (Correct Answer)
D. Lenticular myopia

Explanation: **Index myopia** - **Senile nuclear cataract** involves opacification and hardening of the lens nucleus, which increases the **refractive index** of the lens. - This results in a stronger refractive power of the eye, causing light to focus in front of the retina, characteristic of **myopia**. *Curvature myopia* - Occurs when there is an increase in the **curvature of the cornea** or lens, leading to increased refractive power. - While lens curvature can change, the primary mechanism in nuclear cataracts is refractive index change, not solely curvature. *Axial myopia* - Arises from an **elongation of the eyeball**, making the axial length too long relative to the refractive power. - This is a structural change in the eye's shape, not directly caused by changes within the lens itself due to cataract. *Lenticular myopia* - This term is a broader category that refers to myopia caused by changes in the lens, which **index myopia** falls under. - However, "index myopia" is more specific and accurately describes the underlying mechanism in senile nuclear cataracts.

Question 273: "Bread-crumb" appearance is seen in ?

A. Cataract due to CMV infection
B. Complicated cataracts (Correct Answer)
C. Cataract due to diabetes
D. Cataract due to Toxoplasmosis

Explanation: ***Complicated cataracts*** - A "bread-crumb" appearance, specifically referring to small, refractile opacities in the posterior capsule, is a characteristic finding in **complicated cataracts**. - These cataracts often develop due to chronic intraocular diseases such as **uveitis**, **retinal detachment**, or **intraocular tumors**, leading to secondary lens changes. *Cataract due to diabetes* - Diabetic cataracts typically present as "snowflake" opacities in younger patients or accelerated nuclear/cortical sclerosis in older patients, not a "bread-crumb" appearance. - They are often associated with poor glycemic control and metabolic changes affecting lens hydration and protein structure. *Cataract due to CMV infection* - Cataracts associated with **cytomegalovirus (CMV) infection** are more common in congenital infections and can manifest as varying degrees of lens opacification, but "bread-crumb" is not a typical description. - Congenital CMV can cause a spectrum of ocular abnormalities, including microphthalmia, chorioretinitis, and optic atrophy, in addition to cataracts. *Cataract due to Toxoplasmosis* - **Toxoplasmosis** primarily causes **chorioretinitis**, especially in congenital cases, with lens involvement being less common and not typically described as having a "bread-crumb" appearance. - If a cataract develops, it's usually secondary to inflammation or direct lens invasion, but the characteristic morphology differs.

Question 274: Polyopia/diplopia is seen in which type of cataract?

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

Explanation: ***Cortical cataract*** - **Cortical cataracts** cause spokes or vacuoles that refract light in multiple directions, leading to **polyopia** or **diplopia**. - The irregular opacities disrupt the light path, causing the brain to perceive **multiple images**. *Nuclear cataract* - **Nuclear cataracts** primarily affect central vision and cause **myopic shift**, not typically polyopia or diplopia. - They cause **blurry vision** and difficulty seeing in dim light as the lens nucleus hardens and yellows. *Posterior subcapsular cataract* - **Posterior subcapsular cataracts** are characterized by glare and difficulty with reading, mainly affecting near vision. - They form at the back of the lens, close to the nodal point, causing earlier onset of **visual symptoms** with less impact on polyopia. *Anterior polar cataract* - **Anterior polar cataracts** are usually small, well-demarcated opacities at the front of the lens that typically do not cause significant visual impairment. - They rarely cause **polyopia** unless they are very large or dense, which is uncommon.

Question 275: Foldable lens is made up of?

A. PMMA
B. Hydrogel
C. Silicone (Correct Answer)
D. None of the options

Explanation: ***Silicone*** - **Silicone** was one of the **first materials** used for foldable intraocular lenses (IOLs) and remains widely used today. - Its excellent **elastomeric properties** allow the lens to be folded or rolled for insertion through a **small incision** (typically 2.8-3.2 mm) in modern cataract surgery. - Silicone IOLs are **hydrophobic** and have high biocompatibility with minimal inflammatory response. - **Clinical advantage**: Silicone's flexibility enables **sutureless small-incision cataract surgery**, reducing astigmatism and recovery time. *PMMA* - **PMMA (Polymethyl methacrylate)** is a **rigid material** and was the standard for IOLs before the development of foldable lenses. - Its rigidity requires a **large incision** (5.5-7 mm) for insertion, resulting in more induced astigmatism and longer recovery. - PMMA is not foldable and therefore is not used in modern small-incision cataract surgery. *Hydrogel* - **Hydrophilic acrylic (hydrogel)** is actually another material used for foldable IOLs, along with hydrophobic acrylic. - However, in the context of this question, **silicone** is the most recognized answer as it was the **first foldable material** introduced. - Hydrogel IOLs can absorb water and require different handling during insertion. *None of the options* - This is incorrect as **silicone** is definitively a material used for foldable IOLs.

Question 276: Elschnig's pearls are a clinical sign of which condition?

A. Chronic uveitis
B. Secondary cataract (Correct Answer)
C. Cystoid macular oedema
D. None of the options

Explanation: ***Secondary cataract*** - **Elschnig's pearls** are bladder-like cells formed by **proliferation of residual equatorial lens epithelial cells** following extracapsular cataract extraction (ECCE) or phacoemulsification - They migrate posteriorly along the posterior capsule, contributing to **posterior capsular opacification (PCO)** - PCO is commonly called **"secondary cataract"** or **"after-cataract"** and is the most common complication of cataract surgery - Presents with **gradual visual decline** months to years after initially successful cataract surgery - Treated with **Nd:YAG laser capsulotomy** *Chronic uveitis* - While chronic uveitis causes various ocular complications (**synechiae**, **band keratopathy**, **cataract formation**, **macular edema**), **Elschnig's pearls are not a sign of uveitis** - They are specifically a **post-surgical complication** of cataract extraction, not an inflammatory finding - Uveitis patients may develop cataracts requiring surgery, which could subsequently lead to Elschnig's pearls, but this is an indirect relationship *Cystoid macular oedema* - **CME** involves fluid accumulation in the macula forming **cyst-like spaces**, causing decreased central vision - Can occur after cataract surgery (Irvine-Gass syndrome) or with uveitis - Has **completely different pathophysiology and clinical appearance** from Elschnig's pearls - CME affects the **retina**, while Elschnig's pearls involve the **lens capsule** *None of the options* - Incorrect because **secondary cataract (PCO)** is the established correct answer for Elschnig's pearls

Question 277: What is the most common cause of cataract?

A. Lifestyle factors
B. Environmental exposures
C. Physiological changes (Correct Answer)
D. Endocrine disorders

Explanation: ***Physiological changes*** - The most common cause of cataracts is **age-related changes** in the eye, where proteins in the lens denature and clump together, causing it to become cloudy. - This is a **natural process** that occurs with aging and is a primary reason for the development of senile cataracts. *Endocrine disorders* - Certain endocrine disorders like **diabetes mellitus** can increase the risk of cataract formation, particularly metabolic cataracts. - However, they are not the most common cause compared to age-related physiological changes. *Lifestyle factors* - Factors such as **smoking** and **excessive alcohol consumption** can contribute to cataract development. - While these can be modifiable risk factors, they are secondary to the primary physiological process of aging in causing cataracts. *Environmental exposures* - **Prolonged exposure to ultraviolet (UV) radiation** from the sun is a known environmental risk factor for cataracts. - However, like lifestyle factors, this is not the leading direct cause when compared to the inevitable physiological changes of aging.

Question 278: Which type of congenital cataract is commonly associated with significant visual defects?

A. Punctate Cataract
B. Blue dot cataract
C. Fusiform cataract
D. Nuclear cataract (Correct Answer)

Explanation: ***Nuclear cataract*** - It involves the **nucleus** of the lens, which is the central and most visually critical part. - This type of cataract can cause **significant visual impairment** due to its central location and density, impacting early visual development. *Punctate Cataract* - These are **small, dot-like opacities** that are usually clinically insignificant and do not typically cause significant visual defects. - They are often **peripheral** or very fine, thus not obstructing the central visual axis. *Blue dot cataract* - Also known as **cerulean cataract**, this type consists of small, bluish opacities in the lens cortex. - While congenital, it often has **minimal impact on vision** and is frequently observed incidentally. *Fusiform cataract* - This cataract forms in the shape of a **spindle or needle**, usually along the visual axis. - While it can sometimes cause minor visual compromise, its impact is generally **less severe** compared to a dense nuclear cataract.

Question 279: In the context of homocystinuria, which direction does the lens typically subluxate?

A. Inferotemporal
B. Inferonasal (Correct Answer)
C. Superonasal
D. Superotemporal

Explanation: ***Inferonasal*** - In **homocystinuria**, the **ectopia lentis** (lens subluxation) often occurs due to weakening of the **zonular fibers**. - The classic direction for lens subluxation in homocystinuria is **inferior and nasal**. *Inferotemporal* - While lens subluxation can occur in various directions, **inferotemporal** is not the classic or most common presentation in homocystinuria. - This direction is less specific and does not strongly point to homocystinuria as the underlying cause. *Superonasal* - **Superonasal** dislocation of the lens is more characteristic of **Marfan syndrome**, which is important to differentiate from homocystinuria. - This direction helps distinguish different causes of lens ectopia. *Superotemporal* - **Superotemporal** lens subluxation is the hallmark of **Marfan syndrome**, a genetic connective tissue disorder. - This specific finding is crucial for differential diagnosis in patients presenting with lens ectopia.

Question 280: What is the most common type of congenital cataract?

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

Explanation: ***Blue dot*** - **Blue dot (punctate) cataracts** are the **most common type of congenital cataract overall**. - They appear as **multiple small, blue-white opacities** scattered throughout the lens cortex. - These cataracts are typically **bilateral, non-progressive, and asymptomatic**, rarely affecting visual acuity. - Often considered **physiological variants**, they usually do not require surgical intervention. *Zonular (Lamellar)* - **Zonular (lamellar) cataracts** are the **most common visually significant** congenital cataract. - They feature **opacities arranged in layers or lamellae** within the lens, classically with alternating clear and opaque zones. - Unlike blue dot cataracts, these **often require surgical intervention** due to visual impairment. *Capsular* - **Capsular cataracts** involve the anterior or posterior lens capsule and are relatively uncommon. - They appear as **small, well-circumscribed opacities** on the lens capsule. - Visual impact depends on size and location relative to the visual axis. *Coralliform* - **Coralliform cataracts** are a rare type characterized by **coral-like branching opacities**. - This distinctive morphology makes them one of the less common congenital cataract types.

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

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