Metabolic Cataracts — MCQs

10 questions

Intumescent cataract is associated with which type of glaucoma?

An infant with intolerance to breast milk, vomiting, and diarrhea develops cataracts. Which of the following is the most likely diagnosis?

What can be prevented by inhibiting aldose reductase in diabetes mellitus?

Which of the following statements is false about phacolytic glaucoma?

A neonate was brought to the hospital with chief complaints of poor feeding, vomiting, acidosis, and cataract. Benedict's test on urine was positive, but urinary glucose was negative. What is the defective enzyme in the above-mentioned disorder?

All are manifestation of dengue virus infection in eye except?

Consider the following causes of visual loss : 1. Obstruction of the central retinal artery 2. Vitreous and retinal haemorrhage 3. Cataract 4. Retinal detachment Which of the above causes are associated with acute visual loss in a patient?

Vision 2020 "The right to sight" includes all except-

Rosette cataract is seen after:

Q10

Which of the following is NOT a cause of posterior subcapsular cataract?

Metabolic Cataracts Indian Medical PG Practice Questions and MCQs

Question 1: Intumescent cataract is associated with which type of glaucoma?

A. Phacolytic glaucoma
B. Phacotopic glaucoma
C. Pseudophakic glaucoma
D. Phacomorphic glaucoma (Correct Answer)

Explanation: ***Phacomorphic glaucoma*** - **Intumescent cataract** refers to a mature or hypermature cataract that has absorbed water, leading to a swollen lens. - This swelling can cause the lens to push the iris forward, leading to secondary **angle closure glaucoma** due to pupillary block, which is characteristic of phacomorphic glaucoma. *Phacolytic glaucoma* - This type of glaucoma is caused by leakage of **high-molecular-weight lens proteins** from a mature or hypermature cataract into the aqueous humor, triggering a macrophagic response and obstruction of the trabecular meshwork. - It results in an **open-angle glaucoma** and anterior chamber inflammation, unlike the angle closure seen with intumescent cataracts. *Phacotopic glaucoma* - This is a rare term and not a recognized distinct category of glaucoma related to lens swelling. It may refer loosely to glaucoma associated with **lens dislocation** or subluxation. - It does not specifically describe glaucoma caused by an **intumescent cataract**. *Pseudophakic glaucoma* - This refers to glaucoma that develops in patients who have undergone **cataract surgery** and have an **intraocular lens (IOL)** implant (pseudophakia). - It can be caused by various mechanisms post-surgery, such as inflammation, steroid response, or IOL-related issues, but it is not directly associated with the presence of an intumescent natural lens.

Question 2: An infant with intolerance to breast milk, vomiting, and diarrhea develops cataracts. Which of the following is the most likely diagnosis?

A. Galactosemia (Correct Answer)
B. Fabry disease
C. Lowe syndrome
D. Congenital hypoglycemia
E. Homocystinuria

Explanation: **Galactosemia** - **Galactosemia** is an inborn error of metabolism where the body is unable to process **galactose**, leading to its build-up. - Symptoms such as **vomiting**, **diarrhea**, **failure to thrive** (intolerance to breast milk containing lactose, which is broken down into glucose and galactose), and **cataracts** are classic signs of galactosemia in infants. *Lowe syndrome* - Also known as **oculocerebrorenal syndrome**, Lowe syndrome is an X-linked disorder characterized by **congenital cataracts**, **renal tubular dysfunction**, and **intellectual disability**. - While cataracts are present, it primarily presents with **kidney and brain abnormalities**, not predominantly with GI symptoms like vomiting and diarrhea upon feeding. *Fabry disease* - **Fabry disease** is an X-linked lysosomal storage disorder caused by a deficiency of the enzyme **alpha-galactosidase A**. - It is characterized by **neuropathic pain**, **angiokeratomas**, **renal disease**, and **cardiac involvement**, and is not typically associated with infantile vomiting, diarrhea, or early onset cataracts from breast milk intolerance. *Homocystinuria* - **Homocystinuria** is an inherited disorder of methionine metabolism due to **cystathionine beta-synthase deficiency**. - It presents with **lens dislocation** (ectopia lentis), **intellectual disability**, **skeletal abnormalities** (marfanoid habitus), and **thromboembolism**, typically becoming apparent in later infancy or childhood, not with acute feeding intolerance and GI symptoms in early infancy. *Congenital hypoglycemia* - **Congenital hypoglycemia** refers to abnormally low blood glucose levels at birth or shortly after. - Symptoms include **poor feeding**, **lethargy**, **irritability**, and **seizures**, but it is not typically associated with cataracts or specific intolerance to breast milk causing vomiting and diarrhea as seen in metabolic disorders.

Question 3: What can be prevented by inhibiting aldose reductase in diabetes mellitus?

A. Diabetic nephropathy
B. Diabetic cataract (Correct Answer)
C. Deafness
D. Diabetic neuropathy

Explanation: ***Diabetic cataract*** - **Aldose reductase** is the key enzyme in the **polyol pathway**, which converts glucose to **sorbitol**. - In diabetes, high glucose levels lead to excessive sorbitol accumulation in the **lens**, causing **osmotic stress** and contributing to cataract formation. - **Aldose reductase inhibitors are most effective** in preventing diabetic cataracts, as the lens has limited sorbitol metabolism capacity. *Deafness* - While diabetes can affect **hearing**, the primary mechanism is often related to **microvascular damage** rather than the direct action of aldose reductase. - Aldose reductase inhibition is not a primary strategy for preventing diabetic hearing loss. *Diabetic nephropathy* - This kidney complication of diabetes is primarily caused by **glomerular hypertrophy**, **basement membrane thickening**, and **mesangial expansion**. - While the polyol pathway might play a minor role, it's not the main driver of nephropathy, and aldose reductase inhibitors have not shown significant benefit in preventing it clinically. *Diabetic neuropathy* - The **polyol pathway does contribute** to diabetic neuropathy through sorbitol accumulation in peripheral nerves, causing osmotic stress and **myoinositol depletion**. - However, neuropathy is **multifactorial**, involving **microvascular ischemia**, **oxidative stress**, and **advanced glycation end products (AGEs)**. - While aldose reductase inhibitors have shown **some benefit** for neuropathy, they have had **limited clinical success** compared to their effectiveness in preventing cataracts, making diabetic cataract the **best answer** to this question.

Question 4: Which of the following statements is false about phacolytic glaucoma?

A. Open angle glaucoma
B. Lens induced glaucoma
C. Primarily caused by iris-lens contact (Correct Answer)
D. Seen in hypermature stage of cataract

Explanation: ***Primarily caused by iris-lens contact*** - This statement is **FALSE** because **phacolytic glaucoma** is caused by the leakage of **lens proteins** from a **hypermature cataract** into the **anterior chamber**, not by iris-lens contact. - **Iris-lens contact** is the mechanism in **pupillary block glaucoma** and **acute angle-closure glaucoma**, not in phacolytic glaucoma. - The pathophysiology involves **macrophages** engulfing leaked lens proteins and obstructing the **trabecular meshwork**. *Open angle glaucoma* - This statement is true because **phacolytic glaucoma** is definitively an **open-angle glaucoma**. - It involves obstruction of the **trabecular meshwork** by **macrophages** laden with **lens proteins**, which is an open-angle mechanism. - The angle remains anatomically open but functionally blocked. *Seen in hypermature stage of cataract* - This statement is true because **phacolytic glaucoma** develops when the **lens capsule** of a **hypermature (Morgagnian) cataract** becomes permeable. - This permeability allows **high-molecular-weight lens proteins** to leak into the **aqueous humor**. *Lens induced glaucoma* - This statement is true as **phacolytic glaucoma** is a specific type of **lens-induced glaucoma**, arising from the toxic effects of **leaked lens material**. - Other forms of **lens-induced glaucoma** include **phacomorphic glaucoma**, **lens-particle glaucoma**, and **phacoanaphylactic glaucoma**.

Question 5: A neonate was brought to the hospital with chief complaints of poor feeding, vomiting, acidosis, and cataract. Benedict's test on urine was positive, but urinary glucose was negative. What is the defective enzyme in the above-mentioned disorder?

A. Galactose 1-phosphate uridyl transferase (Correct Answer)
B. Fructokinase
C. Lactase
D. Sucrase
E. Aldolase B

Explanation: ***Galactose 1-phosphate uridyl transferase*** - This enzyme deficiency leads to **classic galactosemia**, characterized by the accumulation of **galactose-1-phosphate**, which is toxic. - Clinical features like **poor feeding, vomiting, acidosis, and cataracts** are typical, and a positive **Benedict's test** (detecting reducing sugars like galactose) with negative urinary glucose confirms the presence of another reducing sugar. *Fructokinase* - Deficiency of fructokinase causes **essential fructosuria**, a benign condition where **fructose** accumulates in the urine. - Unlike classic galactosemia, it does not present with severe symptoms like **acidosis** or **cataracts**. *Aldolase B* - **Aldolase B deficiency** causes hereditary fructose intolerance, presenting with **vomiting, hypoglycemia, and hepatomegaly** after fructose ingestion. - It does not cause **cataracts**, and Benedict's test would detect fructose, but the clinical context (symptoms with fructose/sucrose intake) differs from galactosemia. *Lactase* - **Lactase deficiency** (lactose intolerance) results in gastrointestinal symptoms such as **bloating, diarrhea, and abdominal pain** upon lactose consumption. - It does not typically cause **acidosis, cataracts**, or a positive Benedict's test in urine unless secondary bacterial fermentation leads to other reducing substances. *Sucrase* - **Sucrase-isomaltase deficiency** leads to the malabsorption of sucrose, causing symptoms similar to lactose intolerance like **diarrhea and abdominal cramping**. - It does not result in the systemic, severe metabolic derangements or signs like **cataracts** seen in classic galactosemia.

Question 6: All are manifestation of dengue virus infection in eye except?

A. Cataract (Correct Answer)
B. Vitreous hemorrhage
C. Maculopathy
D. Optic neuritis

Explanation: ***Cataract*** - **Cataracts** are primarily associated with aging, congenital factors, trauma, or long-term steroid use, not directly with acute dengue virus infection. - While dengue can cause various ocular manifestations, the formation of cataracts is a **chronic process** that does not fit the typical acute or subacute presentation of dengue-related eye complications. *Vitreous hemorrhage* - **Vitreous hemorrhage** can occur in dengue due to associated **thrombocytopenia** and coagulation abnormalities, leading to bleeding in the eye. - Severe dengue can induce systemic vasculopathy and bleeding tendencies, which may manifest as intraocular hemorrhage. *Maculopathy* - **Dengue maculopathy** is a recognized complication, often presenting as macular edema, hemorrhage, or foveolitis, leading to visual impairment. - This is thought to be due to direct viral effects, immune-mediated responses, or vasculitis affecting the retinal microvasculature. *Optic neuritis* - **Optic neuritis** following dengue infection has been reported, characterized by inflammation of the optic nerve, causing acute vision loss. - This is considered to be an **immune-mediated post-infectious complication** rather than a direct viral cytopathic effect on the nerve.

Question 7: Consider the following causes of visual loss : 1. Obstruction of the central retinal artery 2. Vitreous and retinal haemorrhage 3. Cataract 4. Retinal detachment Which of the above causes are associated with acute visual loss in a patient?

A. 1, 3 and 4
B. 1, 2 and 3
C. 2, 3 and 4
D. 1, 2 and 4 (Correct Answer)

Explanation: ***1, 2 and 4*** - **Obstruction of the central retinal artery**, **vitreous and retinal haemorrhage**, and **retinal detachment** all present as sudden, acute vision loss. - **Central retinal artery occlusion** causes complete, sudden, painless monocular vision loss. **Vitreous hemorrhage** is acute, painless, and can present with floaters or red haze. **Retinal detachment** is acute, painless vision loss, often preceded by flashes and floaters, and can present as a "curtain" coming across the vision. *1, 3 and 4* - While **central retinal artery obstruction** and **retinal detachment** cause acute vision loss, **cataracts** typically cause gradual, progressive vision loss over months to years. - Cataracts primarily affect lens clarity, leading to blurry vision, glare, and dull colors rather than an abrupt onset of blindness. *1, 2 and 3* - **Central retinal artery obstruction** and **vitreous/retinal hemorrhage** lead to acute vision loss, but **cataracts** are a cause of *chronic* and *gradual* vision impairment. - The onset and progression of a **cataract** are distinctly different from the sudden nature of acute vision loss conditions. *2, 3 and 4* - **Vitreous and retinal haemorrhage** and **retinal detachment** are causes of acute vision loss, but a **cataract** is not. - The defining characteristic of acute vision loss is its rapid onset, which does not align with the slow development of a cataract.

Question 8: Vision 2020 "The right to sight" includes all except-

A. Measles induced blindness (Correct Answer)
B. Onchocerciasis
C. Trachoma
D. Cataract

Explanation: ***Measles induced blindness*** - Vision 2020 primarily targets conditions that are either preventable or treatable with *cost-effective interventions* and contribute significantly to *avoidable blindness*. - While measles can cause blindness, the specific program focuses on a defined list of priority diseases for intervention, and measles-related blindness is generally addressed through broader public health initiatives (vaccination) rather than direct "right to sight" surgical or direct medical interventions for established blindness. *Onchocerciasis* - **Onchocerciasis** (river blindness) is a major focus of Vision 2020 due to its profound impact on sight, particularly in endemic areas. - It is a **preventable** and **treatable** cause of blindness through mass drug administration. *Trachoma* - **Trachoma** is recognized as one of the leading infectious causes of blindness globally and is explicitly targeted by Vision 2020 through the **SAFE strategy** (Surgery, Antibiotics, Facial cleanliness, Environmental improvement). - It is a highly **preventable** and **treatable** condition, fitting the program's objectives. *Cataract* - **Cataract** is the leading cause of blindness worldwide and is highly **treatable** through a relatively simple and cost-effective surgical procedure. - Providing cataract surgery is a cornerstone of the Vision 2020 initiative to restore sight.

Question 9: Rosette cataract is seen after:

A. Infection
B. Penetrating injury to eye
C. Copper foreign body in eye
D. Blunt trauma to eye (Correct Answer)

Explanation: ***Blunt trauma to eye*** - **Rosette cataract** is a classic finding following **blunt ocular trauma**, often due to the concussive force on the lens. - The characteristic **flower-petal or star-shaped opacity** forms in the anterior and/or posterior subcapsular regions of the lens. *Infection* - Ocular infections can lead to various complications like **uveitis** or **endophthalmitis**, but **rosette cataract** is not a typical direct sequela. - While inflammation can cause cataracts, they usually present as **inflammatory cataracts** rather than the specific rosette pattern. *Penetrating injury to eye* - **Penetrating injuries** to the eye often lead to **traumatic cataracts** due to direct lens capsule rupture. - These cataracts are typically focal and can progress rapidly, but the morphology is not usually described as a **rosette pattern** unless secondary to significant blunt force component. *Copper foreign body in eye* - A **copper foreign body** in the eye can cause **chalcosis oculi**, leading to a characteristic greenish-brown discoloration and a **sunflower cataract**. - This type of cataract has a distinct appearance from a **rosette cataract**, with a diffuse radial pattern rather than a focal star shape.

Question 10: Which of the following is NOT a cause of posterior subcapsular cataract?

A. Ionizing radiation
B. Wilson's Disease
C. Myotonic dystrophy
D. Congenital cataract (Correct Answer)

Explanation: ***Congenital cataract*** - **Congenital cataract** is the correct answer because it is **not an etiological cause** but rather a **temporal classification** describing cataracts present at birth or within the first year of life. - The question asks for **causes** (risk factors or etiological agents) of posterior subcapsular cataracts, whereas "congenital cataract" describes **when** the cataract occurs, not **what causes** it. - While congenital cataracts can have various morphologies (including posterior polar types), they arise from developmental abnormalities, genetic factors, or intrauterine infections—not from acquired causes like the other options listed. *Myotonic dystrophy* - **Myotonic dystrophy** is a well-established systemic disorder associated with **posterior subcapsular cataracts**, often with a characteristic **"Christmas tree" or polychromatic appearance**. - This is an **acquired cause** due to the genetic defect (CTG repeat expansion) affecting lens metabolism and protein structure. *Wilson's Disease* - **Wilson's disease**, a disorder of copper metabolism, causes the characteristic **"sunflower cataract"**, which is a type of **posterior subcapsular cataract** with a polychromatic, petal-like appearance. - Copper deposition in the lens capsule and epithelium is the underlying **etiological mechanism**. *Ionizing radiation* - Exposure to **ionizing radiation** (radiotherapy, occupational exposure) is a well-known **acquired cause** of **posterior subcapsular cataracts**. - Radiation damages lens epithelial cells, particularly in the posterior region, leading to migration and opacification in the posterior subcapsular zone.

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