Ocular Toxicity of Systemic Medications — MCQs
Which antituberculosis drug most commonly causes optic neuritis?
A 45 year old male, known case of Rheumatoid arthritis is on a monotherapy since many years. Symptoms of RA are controlled but suddenly patient develops blurring of vision. Which of the following drug is responsible for sudden effect on vision?
Most serious injury to the eye is caused by:
Bulls-eye retinopathy is seen in toxicity of:
Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?
Which drug does NOT cause optic neuropathy?
A patient on amiodarone is diagnosed to have cornea verticillata. What should be the management?
Which of the following anesthetics is known to increase intraocular pressure?
Abrus precatorius poisoning resembles which poison?
Most common cause of death in diphtheria is due to
Ocular Toxicity of Systemic Medications Indian Medical PG Practice Questions and MCQs
Question 1: Which antituberculosis drug most commonly causes optic neuritis?
- A. Rifampicin
- B. Isoniazid
- C. Ethambutol (Correct Answer)
- D. Pyrazinamide
Explanation: ***Ethambutol*** - **Ethambutol** is well-known for its dose-dependent ocular toxicity, specifically causing **optic neuritis** [3]. - Symptoms include decreased visual acuity, red-green color blindness, and central scotoma due to damage to the **optic nerve** [3]. *Rifampicin* - **Rifampicin** can cause several side effects, including hepatotoxicity and a reddish-orange discoloration of bodily fluids, but **optic neuritis** is not a common or characteristic side effect [2]. - While it can rarely be associated with ocular disturbances, these are typically less severe and uncommon compared to **ethambutol**. *Isoniazid* - **Isoniazid (INH)** is primarily associated with **peripheral neuropathy**, often reversible with **pyridoxine (vitamin B6)** supplementation [1]. - While it can rarely cause optic neuropathy, this is far less common and less severe than the **optic neuritis** caused by **ethambutol** [1]. *Pyrazinamide* - **Pyrazinamide** is known for causing **hepatotoxicity** (liver damage) and **hyperuricemia**, which can lead to gout [3], [4]. - It does not commonly cause **optic neuritis** or other significant ocular side effects.
Question 2: A 45 year old male, known case of Rheumatoid arthritis is on a monotherapy since many years. Symptoms of RA are controlled but suddenly patient develops blurring of vision. Which of the following drug is responsible for sudden effect on vision?
- A. Methotrexate
- B. Hydroxychloroquine (Correct Answer)
- C. Sulfasalazine
- D. Leflunomide
Explanation: ***Hydroxychloroquine*** - **Hydroxychloroquine** [1] is known to cause **retinal toxicity** (maculopathy) as a dose-dependent, long-term side effect, leading to **blurring of vision** and other visual disturbances. - Patients on long-term hydroxychloroquine therapy require regular **ophthalmological screening** to detect and prevent irreversible vision loss. *Methotrexate* - **Methotrexate** is a common DMARD used in RA [1], but its ocular side effects are typically rare and less severe, usually involving **conjunctivitis** or **periorbital edema**. - It does not commonly cause **maculopathy** or sudden profound blurring of vision. *Sulfasalazine* - **Sulfasalazine** [1] can cause a range of side effects, including gastrointestinal issues and various hypersensitivity reactions. - Ocular side effects are infrequent and generally mild, such as **conjunctivitis** or **periorbital edema**, and not severe blurring of vision due to retinal damage. *Leflunomide* - **Leflunomide** is an immunosuppressive DMARD [1] whose common adverse effects include hepatotoxicity, gastrointestinal upset, and hypertension. - Significant **ocular toxicity** leading to blurring of vision, particularly retinal damage, is not a characteristic side effect of **leflunomide**.
Question 3: Most serious injury to the eye is caused by:
- A. Nitric acid
- B. Hydrochloric acid
- C. Lime (Correct Answer)
- D. Sulphuric acid
Explanation: ***Lime*** - **Lime (calcium hydroxide)** is an **alkali** that causes **liquefactive necrosis** of ocular tissues, leading to deep penetration and severe, progressive damage. - Alkaline burns saponify cell membranes, resulting in continuous tissue destruction and potentially **corneal opacification**, **limbal ischemia**, and **perforation**. *Nitric acid* - **Nitric acid** is a strong acid that causes **coagulation necrosis**, which tends to create a protective barrier on the tissue. - While serious, this barrier often limits deeper penetration and tissue destruction compared to alkalis. *Hydrochloric acid* - **Hydrochloric acid** is also a strong acid and causes **coagulation necrosis**, similar to nitric acid. - This type of injury typically results in superficial damage to the eye, as the denatured proteins form a physical barrier. *Sulphuric acid* - **Sulphuric acid**, another strong acid, also primarily causes **coagulation necrosis**. - Although it can dehydrate tissues and cause significant superficial damage, its effect is generally less severe and penetrating than strong alkalis.
Question 4: Bulls-eye retinopathy is seen in toxicity of:
- A. Quinine
- B. Tobacco
- C. Ethanol
- D. Chloroquine (Correct Answer)
Explanation: ***Chloroquine*** - **Bulls-eye maculopathy** is a classic and severe manifestation of retinal toxicity associated with **chloroquine** and **hydroxychloroquine** use. - This pattern involves central macular damage with a surrounding ring of preserved photoreceptors, affecting **visual acuity** and **color vision**. *Quinine* - Quinine toxicity primarily affects the **optic nerve** and **retinal vessels**, leading to **vasoconstriction** and **ischemia**, which can cause **optic neuropathy** and **sudden vision loss**. - It does not typically cause the characteristic bulls-eye maculopathy pattern. *Tobacco* - **Tobacco amblyopia** is a form of **toxic optic neuropathy** associated with chronic tobacco use, particularly smoking or chewing. - It is characterized by **progressive, painless vision loss**, often with **central or centrocecal scotomas**, and typically affects the **optic nerve** rather than the macula in a bulls-eye pattern. *Ethanol* - **Ethanol** (alcohol abuse) can lead to **nutritional optic neuropathy**, especially when combined with poor diet and vitamin deficiencies (e.g., **B vitamins**). - This condition affects the **optic nerve** and causes **gradual vision loss** and **central scotomas**, but not the specific bulls-eye retinopathy seen with chloroquine.
Question 5: Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?
- A. Cyclophosphamide
- B. Methotrexate
- C. Cisplatin (Correct Answer)
- D. Dacarbazine
Explanation: ***Cisplatin*** - **Cisplatin** is a platinum-based chemotherapy drug that forms **DNA cross-links**, inhibiting DNA synthesis and leading to the death of rapidly dividing cells, making it highly effective against **ovarian carcinoma**. - It is a cornerstone of chemotherapy regimens for ovarian cancer, often used in combination with other agents such as paclitaxel. *Methotrexate* - **Methotrexate** is an **antimetabolite** that inhibits dihydrofolate reductase, thereby interfering with DNA synthesis. - While it is used in various cancers like leukemia, lymphoma, and some solid tumors (e.g., breast cancer, gestational trophoblastic disease), it is **not a primary recommended drug for ovarian carcinoma**. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** that causes DNA damage, leading to cell death. - It is used in many cancers, including lymphoma, breast cancer, and some leukemias, but it is **not a first-line or primary agent for ovarian carcinoma** in contemporary treatment guidelines. *Dacarbazine* - **Dacarbazine** is an **alkylating agent** primarily used in the treatment of **malignant melanoma** and Hodgkin lymphoma. - It is **not indicated for the treatment of ovarian carcinoma**.
Question 6: Which drug does NOT cause optic neuropathy?
- A. Chloramphenicol
- B. Penicillin (Correct Answer)
- C. Ethambutol
- D. INH
Explanation: ***Penicillin*** - Penicillin is a widely used antibiotic that is **not associated with optic neuropathy** - Its primary side effects are **allergic reactions and hypersensitivity** - Visual disturbances or optic nerve damage are **not characteristic** of penicillin therapy *Chloramphenicol* - Known to cause **dose-dependent and duration-dependent optic neuropathy**, especially with prolonged use - Can lead to visual impairment, including reduced visual acuity and color vision defects - May be **irreversible** in some cases *Ethambutol* - **Most notorious** antitubercular drug for causing optic neuritis - Causes **dose-dependent bilateral visual loss** and **red-green color blindness** - Requires regular visual monitoring during therapy - Potentially **irreversible** optic nerve damage *INH (Isoniazid)* - Can cause optic neuropathy, though **less frequently** than ethambutol - Usually associated with **high doses** or prolonged therapy - Risk increases in slow acetylators and those with nutritional deficiencies
Question 7: A patient on amiodarone is diagnosed to have cornea verticillata. What should be the management?
- A. Observation (Correct Answer)
- B. Stop the drug
- C. Penetrating keratoplasty
- D. Lamellar keratoplasty
Explanation: ***Observation*** - **Cornea verticillata** (vortex keratopathy) is a **common and benign side effect** of amiodarone therapy, occurring in **>90% of patients** on chronic treatment. - The corneal deposits are typically **asymptomatic** and **do not significantly impair vision** in most cases. - **Standard management is observation** with regular monitoring, as the deposits are reversible but stopping amiodarone (a critical antiarrhythmic drug) is **not routinely indicated** for this benign finding. - The **cardiac benefits of amiodarone** for life-threatening arrhythmias typically **outweigh the ocular side effects**. *Stop the drug* - Discontinuation of amiodarone should **only be considered** if: - There is **significant visual impairment** (rare) - The cardiac condition allows for **safe alternative therapy** - Stopping amiodarone solely for asymptomatic cornea verticillata is **inappropriate** given its critical role in managing serious arrhythmias. - While deposits do resolve after discontinuation (over months), the risk of cardiac complications from stopping the drug outweighs the benign corneal findings. *Penetrating keratoplasty* - This is a **full-thickness corneal transplant**, which is **completely unnecessary** for amiodarone-induced cornea verticillata. - The deposits are **superficial epithelial** and **benign**, requiring no surgical intervention. *Lamellar keratoplasty* - This **partial-thickness corneal surgery** is also **not indicated** for drug-induced vortex keratopathy. - Surgical intervention is **excessive** for a condition that is asymptomatic and can be managed with observation.
Question 8: Which of the following anesthetics is known to increase intraocular pressure?
- A. Thiopental
- B. Alfentanil
- C. Ketamine (Correct Answer)
- D. Propofol
Explanation: ***Ketamine*** - **Ketamine** is known to increase **intraocular pressure (IOP)**, making it generally avoided in patients with **glaucoma** or those undergoing ocular surgery. - This effect is due to its influence on sympathetic nervous system activity and extraocular muscle tone. *Thiopental* - **Thiopental**, a barbiturate, typically causes a **reduction in intraocular pressure**, which can be beneficial in certain ocular procedures. - Its mechanism involves decreasing cerebral blood flow and metabolic rate, indirectly leading to a decrease in IOP. *Alfentanil* - **Alfentanil**, an opioid, generally has **minimal to no significant effect on intraocular pressure**. - Its primary actions are analgesia and sedation, without direct impact on oculomotor tone or fluid dynamics. *Propofol* - **Propofol** is known to **decrease intraocular pressure**, making it a favorable agent for ophthalmic surgery. - This effect is attributed to a reduction in cerebral blood flow and an inhibition of aqueous humor production.
Question 9: Abrus precatorius poisoning resembles which poison?
- A. Arsenic
- B. Ricin (Correct Answer)
- C. Cyanide
- D. Thallium
Explanation: ***Ricin*** - The toxic protein in *Abrus precatorius* seeds, **abrin**, is structurally and functionally similar to **ricin** from *Ricinus communis* seeds. - Both abrin and ricin are **ribosome-inactivating proteins**, leading to similar clinical presentations of multi-organ failure. *Arsenic* - Arsenic poisoning primarily affects the GI tract, cardiovascular system, and nervous system, causing symptoms like **rice-water stools** and **garlic odor** on breath. - It works through enzyme inhibition, specifically targeting **pyruvate dehydrogenase**, unlike the ribosome-inactivating mechanism of abrin. *Cyanide* - Cyanide poisoning rapidly impairs **cellular respiration** by inhibiting cytochrome c oxidase, leading to cellular hypoxia and lactic acidosis. - Clinical features include **rapid onset of symptoms**, bright red venous blood, and **almond odor**, which are distinct from abrin poisoning. *Thallium* - Thallium poisoning is characterized by **neurological symptoms** (e.g., severe peripheral neuropathy), **alopecia**, and gastrointestinal distress. - It interferes with potassium channels and ATPase pumps, a different mechanism of toxicity compared to abrin.
Question 10: Most common cause of death in diphtheria is due to
- A. Airway obstruction
- B. Septic shock
- C. Toxic cardiomyopathy (Correct Answer)
- D. Descending polyneuropathy (rare)
Explanation: ***Toxic cardiomyopathy*** - Diphtheria toxin primarily targets and damages the **myocardium**, leading to heart failure, arrhythmias, and ultimately death. - Myocardial damage can occur even in mild cases and is the most frequent cause of **fatality** in both treated and untreated diphtheria. *Airway obstruction* - While significant **pharyngeal and laryngeal pseudomembrane formation** can cause severe respiratory distress and obstruction, it is not the most common cause of death overall. - Prompt medical intervention, such as **tracheostomy** or antitoxin administration, can often alleviate acute airway issues. *Septic shock* - Diphtheria itself is a **toxin-mediated disease**, not typically characterized by overwhelming bacterial sepsis leading to septic shock as the primary cause of death. - While secondary infections can occur, direct **toxin-induced organ damage** is the main concern. *Descending polyneuropathy (rare)* - **Neurological complications**, such as polyneuropathy, can occur later in the course of diphtheria due to toxin effects. - However, these are generally less common and less immediately life-threatening than **cardiac complications**, and rarely the direct cause of death.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free