Ocular Diagnostic Agents — MCQs

10 questions

A child presents with unilateral white reflex (leukocoria) and raised intraocular pressure, raising suspicion of retinoblastoma. Which of the following investigations is the most appropriate to perform?

All of the following are effective topically except-

Identify the correct sequence of staining in dry eyes? 1. Fluorescein stain 2. Lissamine green 3. Rose Bengal stain

Fluorescein angiography is used to examine -

All of the following are examples of mydriatics except –

What is the commonly used concentration of tetracaine for topical anesthesia in minor ophthalmic procedures?

Fluorescein dye for ophthalmological diagnosis is injected into:

A fundus examination shows 'sunset glow' appearance. Which fluorescein angiography finding would best support Vogt-Koyanagi-Harada disease?

Fluorescein dye study is done to detect:

Q10

1% atropine is given in uveitis to:

Ocular Diagnostic Agents Indian Medical PG Practice Questions and MCQs

Question 1: A child presents with unilateral white reflex (leukocoria) and raised intraocular pressure, raising suspicion of retinoblastoma. Which of the following investigations is the most appropriate to perform?

A. Ultrasound imaging of the eye
B. Measurement of intraocular pressure
C. Detailed examination under anesthesia (Correct Answer)
D. CT imaging of the orbit and head

Explanation: ***Detailed examination under anesthesia*** - A **detailed examination under anesthesia (EUA)** is crucial for accurately assessing the extent of intraocular lesions in children, particularly those with suspected retinoblastoma. It allows for a thorough and precise evaluation of tumor size, location, and multifocality that is otherwise difficult to achieve in an awake child. - EUA often includes fundus photography, ultrasonography, and sometimes anterior segment examination, all performed systematically without the child moving. It is the gold standard for **diagnosing and staging retinoblastoma**. *Ultrasound imaging of the eye* - **Ocular ultrasound** is a key component of the investigation and can help identify the intraocular mass and detect calcifications, which are characteristic of retinoblastoma. - However, ultrasound alone is often insufficient to fully characterize the tumor's extent or for precise staging, and it doesn't replace the need for direct visualization and comprehensive examination. *Measurement of intraocular pressure* - **Raised intraocular pressure** is a symptom that can be present in retinoblastoma but is not a diagnostic tool for the condition itself; it indicates secondary glaucoma due to the tumor. - While important for clinical management, measuring IOP does not directly visualize or characterize the tumor to confirm the diagnosis of retinoblastoma. *CT imaging of the orbit and head* - While **CT imaging** can detect orbital and intracranial extension of retinoblastoma, it involves **ionizing radiation**, which is a significant concern in children, especially those with an increased genetic risk for secondary cancers. - **MRI** is generally preferred over CT for assessing extraocular extension and possible central nervous system involvement due to its superior soft tissue contrast and lack of radiation exposure.

Question 2: All of the following are effective topically except-

A. Amethocaine
B. Procaine (Correct Answer)
C. Lidocaine
D. Cocaine

Explanation: ***Procaine*** - **Procaine** is an ester-type local anesthetic with poor topical penetration due to its **chemical structure and low lipophilicity**. - It is primarily used for **infiltration anesthesia** and nerve blocks, requiring direct injection into tissues to achieve its local anesthetic effects. *Amethocaine* - **Amethocaine** (tetracaine) is a potent ester local anesthetic that is very effective for **topical anesthesia**, particularly on mucous membranes and the eye. - Its high lipophilicity allows for good absorption through the skin and mucous membranes, providing prolonged anesthetic effects. *Lidocaine* - **Lidocaine** is an amide-type local anesthetic that is widely used for **topical anesthesia** due to its excellent penetration and rapid onset of action. - It is available in various forms such as creams, gels, and patches for surface anesthesia. *Cocaine* - **Cocaine** is a naturally occurring ester local anesthetic that is highly effective topically, particularly on **mucous membranes** (e.g., nasal passages). - Besides its local anesthetic properties, it also causes **vasoconstriction**, which helps to reduce bleeding.

Question 3: Identify the correct sequence of staining in dry eyes? 1. Fluorescein stain 2. Lissamine green 3. Rose Bengal stain

A. i, iii, ii
B. i, ii, iii
C. ii, iii, i
D. iii, ii, i (Correct Answer)

Explanation: ***iii, ii, i*** - The correct order for staining in dry eyes is **Rose Bengal, Lissamine Green, and then Fluorescein**. This sequence minimizes the discomfort and potential interference between the dyes. - **Rose Bengal** and **Lissamine Green** stain devitalized or damaged epithelial cells and mucus, while **Fluorescein** stains areas where the epithelium is absent, indicating corneal or conjunctival abrasions or erosions. *i, iii, ii* - This sequence is incorrect because applying fluorescein first could mask the interpretation of epithelial damage by Lissamine Green or Rose Bengal, as it highlights epithelial defects rather than devitalized cells. - The dyes should be applied in an order that optimizes the visualization of different aspects of ocular surface health. *i, ii, iii* - Applying **Fluorescein** first is generally not recommended as it can spread over the ocular surface and potentially interfere with the specific staining patterns of other vital dyes like Lissamine Green or Rose Bengal. - This order does not follow the standard clinical practice for efficient and accurate dry eye assessment. *ii, iii, i* - While Lissamine Green can be used before Fluorescein, placing Rose Bengal after Lissamine Green but still before Fluorescein is not the optimal sequence. - The standard practice aims to assess different layers or types of damage sequentially for a comprehensive evaluation.

Question 4: Fluorescein angiography is used to examine -

A. Ciliary vasculature
B. Retinal vasculature (Correct Answer)
C. Corneal vasculature
D. Conjunctival vasculature

Explanation: ***Retinal vasculature*** - **Fluorescein angiography** involves injecting fluorescein dye into a vein and taking rapid photographs of the retina as the dye perfuses, allowing for detailed visualization of the **retinal blood vessels**. - This technique is crucial for diagnosing and monitoring conditions like **diabetic retinopathy**, **macular degeneration**, and **retinal vascular occlusions** by identifying leaks, non-perfusion areas, and abnormal vessel growth. *Ciliary vasculature* - The **ciliary body vasculature** is not directly visualized by standard fluorescein angiography as it is located anterior to the retina within the uveal tract. - While some dye may perfuse the ciliary body, the primary imaging target and diagnostic utility of fluorescein angiography are the **retinal and choroidal circulations**. *Corneal vasculature* - The normal **cornea is avascular**, meaning it does not contain blood vessels. - **Corneal neovascularization** (new vessel growth) can occur due to pathology, but fluorescein angiography is not the primary or most suitable technique for assessing corneal vessels, which are more readily visible with slit-lamp biomicroscopy. *Conjunctival vasculature* - The **conjunctiva** contains numerous small vessels, but these are superficial and can be directly observed with a slit lamp or even the naked eye. - Fluorescein angiography is an invasive procedure with a higher spatial resolution designed for deeper, more intricate vascular networks like those in the retina, making it overkill and inappropriate for routine assessment of the **conjunctival vasculature**.

Question 5: All of the following are examples of mydriatics except –

A. Tropicamide
B. Atropine
C. Pirenzepine (Correct Answer)
D. Homatropine

Explanation: ***Pirenzepine*** - **Pirenzepine** is an **M1-selective muscarinic antagonist** primarily used to treat peptic ulcers by reducing gastric acid secretion. - It does not significantly affect the **pupil** or cause **mydriasis** as its selectivity is for M1 receptors, which are not predominantly involved in pupillary dilation. *Tropicamide* - **Tropicamide** is a **muscarinic antagonist** that causes rapid and short-acting **mydriasis** and cycloplegia by blocking M3 receptors in the iris sphincter and ciliary body. - It is frequently used for ophthalmic examinations to dilate the pupil. *Atropine* - **Atropine** is a **non-selective muscarinic antagonist** that causes prolonged **mydriasis** and cycloplegia by blocking muscarinic receptors in the eye. - Its effects can last for several days, making it less suitable for routine ophthalmic examinations but useful in treating inflammatory conditions. *Homatropine* - **Homatropine** is a **muscarinic antagonist** with intermediate duration of action, causing **mydriasis** and cycloplegia. - It provides a longer-lasting effect than tropicamide but is shorter than atropine, making it useful in various ophthalmic procedures.

Question 6: What is the commonly used concentration of tetracaine for topical anesthesia in minor ophthalmic procedures?

A. 1%
B. 0.5% (Correct Answer)
C. 2%
D. 0.25%

Explanation: ***0.5%*** - **Tetracaine 0.5%** is the standard and most commonly used concentration for **topical ocular anesthesia** in minor ophthalmic procedures. - This concentration provides effective and rapid onset topical anesthesia for procedures like tonometry, foreign body removal, and gonioscopy with minimal side effects. *1%* - **Tetracaine 1%** is a higher concentration not typically used for routine topical ophthalmic anesthesia due to an increased risk of **epithelial toxicity** and other side effects. - While it would provide more potent anesthesia, its use is generally limited to specific cases where stronger anesthesia is needed and the benefits outweigh the risks. *2%* - **Tetracaine 2%** is an even higher concentration, rarely used in ophthalmology because of a significantly increased risk of **corneal damage** and other ocular surface complications. - This concentration is considered too strong for topical use in the eye and could lead to prolonged epithelial defects. *0.25%* - **Tetracaine 0.25%** is a lower concentration that may not provide sufficient depth or duration of anesthesia for most minor ophthalmic procedures. - While it would have a lower risk of toxicity, its **suboptimal anesthetic effect** makes it less commonly used than 0.5%.

Question 7: Fluorescein dye for ophthalmological diagnosis is injected into:

A. Antecubital vein (Correct Answer)
B. Popliteal vein
C. Femoral vein
D. Subclavian vein

Explanation: ***Antecubital vein*** - Fluorescein angiography requires rapid delivery of the dye into the **systemic circulation** for quick visualization of retinal and choroidal vasculature. - The **antecubital vein** is a readily accessible, large superficial vein that allows for quick and efficient intravenous dye injection. *Popliteal vein* - The popliteal vein is located behind the **knee** and is not a standard or practical site for routine intravenous injections, especially when rapid delivery to the eye is needed. - Its location makes it less accessible and potentially more uncomfortable for the patient compared to an arm vein. *Femoral vein* - The femoral vein is a large, deep vein in the **groin**, typically reserved for central venous access or specific procedures due to the increased risk of complications like infection or hematoma. - It is not routinely used for peripheral intravenous injections such as fluorescein, where a more superficial and accessible vein is preferred. *Subclavian vein* - The subclavian vein is a **central vein** located under the clavicle, accessed via a more invasive procedure, usually for central venous catheters or hemodialysis access. - It carries higher risks compared to peripheral venipuncture and is not chosen for simple diagnostic dye injections like fluorescein.

Question 8: A fundus examination shows 'sunset glow' appearance. Which fluorescein angiography finding would best support Vogt-Koyanagi-Harada disease?

A. Multiple pinpoint leaks (Correct Answer)
B. Cherry red spot
C. Bull's eye maculopathy
D. Cigarette smoke appearance

Explanation: ***Multiple pinpoint leaks*** - **Multiple pinpoint leaks** on fluorescein angiography during the acute inflammatory phase of Vogt-Koyanagi-Harada (VKH) disease reflect areas of **choroidal inflammation** and **serous retinal detachment**. - This finding is highly characteristic of the disease's active stage, signifying widespread inflammation of the **choroidal vasculature**. *Cherry red spot* - A **cherry red spot** is a classic finding in **central retinal artery occlusion** or **lysosomal storage disorders**, not in VKH disease. - It indicates an opaque retina with a fovea that is relatively spared, allowing visualization of the underlying choroidal circulation. *Bull's eye maculopathy* - **Bull's eye maculopathy** is typically associated with drug toxicities, such as **chloroquine** or **hydroxychloroquine**, or certain **inherited retinal dystrophies**. - It describes a ring of atrophy and pigmentary changes around the fovea, which is distinct from the diffuse inflammatory changes of VKH. *Cigarette smoke appearance* - The **cigarette smoke** or **smoke stack** appearance on fluorescein angiography refers to hyperfluorescence with leakage from the **optic disc**, typically seen in conditions like **papillitis** or **optic disc vasculitis**. - While this is a recognized angiographic finding, it is not characteristic of VKH disease, which primarily shows **multiple pinpoint leaks** from choroidal inflammation rather than disc-related leakage.

Question 9: Fluorescein dye study is done to detect:

A. Retinal vascular pathology (Correct Answer)
B. Posterior segment of eye
C. Assess retinal vascular conditions in babies
D. Macular vascular pathology

Explanation: ***Retinal vascular pathology*** - **Fluorescein angiography** is a diagnostic procedure using a fluorescent dye to visualize and study blood flow in the **retinal blood vessels**. - It helps detect and characterize various retinal vascular conditions like **diabetic retinopathy**, **retinal vein occlusions**, and **macular edema**. *Assess retinal vascular conditions in babies* - While fluorescein angiography can be performed in babies, it's generally avoided due to the need for sedation and potential risks, making it less routine than for adult retinal conditions. - The primary purpose is broader than just babies; it's used across all age groups where retinal vascular pathology is suspected. *Macular vascular pathology* - **Macular vascular pathology** is a specific type of retinal vascular pathology, but the dye study assesses the entire retinal vasculature, not just the macula. - Focusing solely on the macula would be an incomplete description of the widespread utility of fluorescein angiography. *Posterior segment of eye* - The **posterior segment** includes structures beyond just the retina, such as the choroid and optic nerve. - While fluorescein angiography provides some information about choroidal circulation, its primary and most detailed application is for evaluating the **retinal vasculature**.

Question 10: 1% atropine is given in uveitis to:

A. Cause miosis and prevent formation of posterior synechiae
B. Cause mydriasis and prevent formation of anterior synechiae
C. Cause mydriasis and prevent formation of posterior synechiae (Correct Answer)
D. Reduce inflammation and relieve pain

Explanation: ***Cause mydriasis and prevent formation of posterior synechiae*** - **Atropine** is a **cycloplegic** and mydriatic agent used in uveitis to dilate the pupil, which helps to separate the iris from the lens. - This dilation is crucial in preventing the formation of **posterior synechiae** (adhesions between the iris and the anterior lens capsule), which can lead to complications such as pupil distortion, secondary glaucoma, and cataracts. *Cause miosis and prevent formation of posterior synechiae* - **Atropine** causes **mydriasis** (pupil dilation), not miosis (pupil constriction). - Miosis would increase the risk of posterior synechiae formation by bringing the iris and lens closer together. *Cause mydriasis and prevent formation of anterior synechiae* - **Anterior synechiae** are adhesions between the iris and the cornea, which are less commonly affected by atropine in uveitis compared to posterior synechiae. - While atropine causes mydriasis, its primary role in preventing synechiae formation in uveitis is directed at **posterior synechiae**. *Reduce inflammation and relieve pain* - While **atropine** can indirectly relieve pain by reducing **ciliary spasm** (a component of uveitic pain), its primary mechanism of action is not to reduce inflammation. - **Corticosteroids** are the main treatment for reducing inflammation in uveitis.

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