Ocular Lubricants — MCQs
Commonest complication of topical corticosteroids is -
Which of the following is Iso-osmolar agent?
Which of the following is a contraindication to topical steroids?
What does the Phenol red thread test assess in relation to dry eye?
In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?
It is essential to lubricate dam before applying it. Which of these is the MOST suitable lubricant?
A young 23-year-old black African man presents with a hyphema in the right eye after blunt injury. All of the following are acceptable initial treatments except?
Distichiasis is a condition characterized by:
Internal hordeolum is due to inflammation of-
What is the most likely complication of the condition shown in the image below?
Ocular Lubricants Indian Medical PG Practice Questions and MCQs
Question 1: Commonest complication of topical corticosteroids is -
- A. Ptosis
- B. Proptosis
- C. Glaucoma (Correct Answer)
- D. Cataract
Explanation: ***Glaucoma*** - **Topical corticosteroids** are well-known to increase **intraocular pressure** by reducing the outflow of aqueous humor, leading to **steroid-induced glaucoma**. - This complication can result in irreversible **optic nerve damage** and vision loss if not managed properly. *Ptosis* - **Ptosis** is a drooping of the upper eyelid and is not a common complication directly associated with topical corticosteroid use. - It is more often linked to issues like **muscle weakness**, nerve damage, or age-related changes. *Proptosis* - **Proptosis** refers to the bulging of the eye and is typically associated with conditions like **Graves' ophthalmopathy** or orbital tumors. - It is not a common or direct side effect of topical corticosteroid application. *Cataract* - While **steroid-induced cataracts** (specifically **posterior subcapsular cataracts**) are a known complication of chronic systemic corticosteroid use, they are less common with topical corticosteroids and usually require prolonged, high-dose therapy. - In contrast, a rise in intraocular pressure (leading to glaucoma) can occur more acutely and with lower doses of topical corticosteroids.
Question 2: Which of the following is Iso-osmolar agent?
- A. Non-ionic Dimer contrast media (Correct Answer)
- B. Ionic Monomer - High osmolality contrast media
- C. Non-ionic Monomer - Low osmolality contrast media
- D. Ionic Dimer - Low osmolality contrast media
Explanation: ***Non-ionic Dimer contrast media*** - **Iodixanol** is the only available non-ionic dimer contrast agent, and it is **iso-osmolar** with blood plasma (290 mOsm/kg). - Its iso-osmolality contributes to a lower incidence of adverse reactions, particularly in patients at high risk. *Ionic Monomer - High osmolality contrast media* - These agents have an osmolality significantly higher than that of blood plasma, often 6-8 times greater. - High osmolality leads to a higher incidence of adverse effects due to cellular fluid shifts and direct endothelial damage. *Non-ionic Monomer - Low osmolality contrast media* - These agents have an osmolality lower than ionic monomers but are still hyperosmolar compared to blood plasma (typically 2-3 times higher). - While generally safer than high-osmolality agents, they can still cause discomfort and adverse reactions due to their hyperosmolality. *Ionic Dimer - Low osmolality contrast media* - Ionic dimers, such as **ioxaglate**, are considered low-osmolality agents but are still hyperosmolar relative to plasma. - They feature two benzene rings with iodine atoms and are salts, contributing to their osmolality.
Question 3: Which of the following is a contraindication to topical steroids?
- A. Dendritic ulcer (Correct Answer)
- B. Herpetic stromal keratitis without epithelial defect
- C. Elevated intraocular pressure
- D. Non-infectious anterior uveitis
Explanation: ***Dendritic ulcer*** - A **dendritic ulcer** is characteristic of **herpes simplex keratitis**, which is an active viral infection of the cornea. - **Topical steroids** are contraindicated because they can suppress the immune response, leading to viral replication, corneal melt, and potentially severe vision loss or perforation. *Herpetic stromal keratitis without epithelial defect* - In cases of **stromal keratitis**, where the infection is deeper and an intact epithelium is present, topical steroids may be used cautiously in conjunction with antiviral agents to reduce inflammation and scarring. - The primary concern with steroids in herpes simplex keratitis is activating viral replication in the presence of an **epithelial defect**, which is not present here. *Elevated intraocular pressure* - **Elevated intraocular pressure** is a known side effect of topical steroid use, especially with prolonged administration, but it is not an absolute contraindication in itself. - It necessitates careful monitoring and may require concurrent glaucoma treatment, but the primary condition needing steroids may still warrant their use. *Non-infectious anterior uveitis* - **Topical corticosteroids** are the **mainstay of treatment** for non-infectious anterior uveitis to reduce inflammation and prevent complications such as synechiae and vision loss. - The benefits of controlling inflammation in uveitis generally outweigh the risks associated with judicious steroid use.
Question 4: What does the Phenol red thread test assess in relation to dry eye?
- A. Colour change on contact with tears to assess the volume of tears (Correct Answer)
- B. Uses a pH meter for measurement and interpretation
- C. Measures ocular surface mucin deficiency if thread colour changes to blue
- D. Requires instillation of topical anesthesia before the procedure
Explanation: ***Colour change on contact with tears to assess the volume of tears*** - The Phenol red thread test measures the **volume of aqueous tears** by observing how far a thread changes color when moistened by reflex tearing. - The thread is impregnated with a **pH-sensitive dye** that changes from yellow to red-orange in contact with the alkaline pH of tears. *Uses a pH meter for measurement and interpretation* - The Phenol red thread test relies on a **visual color change** of the thread itself, not a separate pH meter. - The color change directly indicates the extent of wetting by tears, not a precise pH value for interpretation. *Measures ocular surface mucin deficiency if thread colour changes to blue* - The Phenol red thread test primarily assesses **aqueous tear production**, not mucin deficiency. - The dye changes to shades of **red or orange** in the presence of tears, not blue. *Requires instillation of topical anesthesia before the procedure* - The Phenol red thread test is designed to be a **non-irritating** and **unstimulated** tear test. - Topical anesthesia **should not be used** as it can interfere with natural tear production and lead to inaccurate results.
Question 5: In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?
- A. Procaine
- B. Cocaine
- C. Prilocaine (Correct Answer)
- D. Tetracaine
Explanation: **Local anesthetics are classified into two chemical groups: esters (aminoesters) and amides. Allergies to esters typically do not cross-react with amides.** ***Prilocaine*** - **Prilocaine** is an **amide-type local anesthetic**, and allergies to **aminoesters** typically do not cross-react with **amides**. - It is a safe alternative in patients with a known allergy to **ester-type local anesthetics**. *Cocaine* - **Cocaine** is an **ester-type local anesthetic**, sharing a similar chemical structure with **aminoesters**. - Patients allergic to **aminoesters** are likely to experience a **cross-reaction** with **cocaine**. *Procaine* - **Procaine** is a classic **ester-type local anesthetic** (an aminoester). - An allergy to aminoesters directly implies an allergy to **procaine** due to its chemical classification. *Tetracaine* - **Tetracaine** is also an **ester-type local anesthetic** (an aminoester). - It is contraindicated in patients with an allergy to **aminoesters** due to the high risk of **allergic reaction**.
Question 6: It is essential to lubricate dam before applying it. Which of these is the MOST suitable lubricant?
- A. Liquid soap (Correct Answer)
- B. Vaseline
- C. Scrub gel
- D. Shaving cream
Explanation: ***Liquid soap*** - A small amount of **water-soluble lubricant** like liquid soap or a commercial water-based lubricant is ideal for lubricating the dental dam. - This type of lubricant allows the dam to **slide easily over teeth** and through contacts, ensuring a proper seal without interfering with the bonding agents. *Vaseline* - **Petroleum-based products** like Vaseline can degrade latex and neoprene rubber, potentially compromising the integrity of the dental dam. - It can also interfere with the **setting or bonding of dental materials** if it comes into contact with the prepared tooth surface. *Scrub gel* - Scrub gels often contain **abrasive particles** or exfoliating agents, which are entirely unsuitable for lubricating a dental dam. - These particles could not only cause **patient discomfort** but also damage the dam or interfere with dental procedures. *Shaving cream* - Shaving cream contains various chemicals, emollients, and fragrances that are **not intended for intraoral use** and could cause irritation or adverse reactions. - Its consistency and chemical composition are **not optimal for lubricating a dental dam**, as it may impede visibility or proper placement.
Question 7: A young 23-year-old black African man presents with a hyphema in the right eye after blunt injury. All of the following are acceptable initial treatments except?
- A. Sleep with the head elevated
- B. Cyclopentolate dilating drops
- C. Carbonic anhydrase inhibitor pressure drops (Correct Answer)
- D. Prednisolone steroid eye drops
Explanation: ***Carbonic anhydrase inhibitor pressure drops*** - **Carbonic anhydrase inhibitors** are generally avoided in patients with **sickle cell trait or disease** because they can cause **acidosis**, which may induce RBC sickling within the anterior chamber and worsen secondary hemorrhage or complications like **increased intraocular pressure (IOP)**. - The patient's presentation as a **young black African man** increases the suspicion for **sickle cell trait/disease**, making this treatment potentially harmful. *Sleep with the head elevated* - Elevating the head of the bed helps to settle red blood cells and debris inferiorly in the anterior chamber, which can prevent them from obstructing vision and potentially **reduce rebleeding rates**. - This position can also contribute to **reducing intraocular pressure** by promoting aqueous outflow and preventing pooling of blood. *Cyclopentolate dilating drops* - **Cyclopentolate** is a **cycloplegic agent** that helps to relieve ciliary spasm and pain associated with trauma. - It also dilates the pupil, which helps to prevent **posterior synechiae formation** (adhesions between the iris and lens) and allows for better examination of the fundus. *Prednisolone steroid eye drops* - **Topical corticosteroids** like prednisolone are used to reduce intraocular inflammation that often accompanies a hyphema. - Anti-inflammatory effects help to decrease the risk of **secondary hemorrhage** and improve overall healing by stabilizing damaged blood vessels.
Question 8: Distichiasis is a condition characterized by:
- A. Abnormal inversion of eyelashes
- B. Abnormal extra row of cilia (Correct Answer)
- C. Abnormal eversion of eyelashes
- D. Misdirected cilia
Explanation: ***Abnormal extra row of cilia*** - **Distichiasis** is a congenital or acquired condition characterized by the presence of a double row of eyelashes, where the extra row emerges from the **Meibomian gland orifices**. - These accessory eyelashes can be the same length as normal lashes or appear finer and shorter, often causing **ocular irritation**, corneal abrasion, and epiphora due to their abnormal growth direction. *Abnormal inversion of eyelashes* - This description typically refers to **trichiasis**, where normally positioned eyelashes grow inwards towards the eye. - While both can cause irritation, **trichiasis** involves misdirection of existing lashes, whereas distichiasis involves an *extra* row. *Abnormal eversion of eyelashes* - Eversion of eyelashes is not a recognized abnormality in this context; rather, **ectropion** refers to the outward turning of the eyelid margin, which may expose the eyelashes but is not a primary cilial abnormality. - This condition is more about eyelid positioning than the eyelashes themselves. *Misdirected cilia* - While distichiasis does involve cilia growing in an abnormal direction, the key feature of distichiasis is the presence of an *additional* row of lashes, not just misdirection of the primary row. - **Trichiasis** is the more appropriate term for misdirected cilia from the normal lash line.
Question 9: Internal hordeolum is due to inflammation of-
- A. Meibomian glands (Correct Answer)
- B. Moll's gland
- C. Lacrimal gland
- D. Zeis gland
Explanation: ***Meibomian glands (Correct)*** - An **internal hordeolum** results from acute **bacterial infection** (usually *Staphylococcus aureus*) and inflammation of a **Meibomian gland**, which are modified sebaceous glands located within the tarsal plate of the eyelid. - These glands produce the **lipid layer** of the tear film, and their blockage and infection lead to a painful, red lump on the **inner surface of the eyelid**. *Moll's gland (Incorrect)* - **Moll's glands** are modified apocrine sweat glands located near the base of the eyelashes. - Inflammation or infection of a Moll's gland would more commonly contribute to an **external hordeolum (stye)**, not an internal one. *Lacrimal gland (Incorrect)* - The **lacrimal gland** produces the watery component of tears and is located in the superotemporal orbit. - Inflammation of the lacrimal gland is called **dacryoadenitis**, which presents with swelling in the outer part of the upper eyelid and is distinct from a hordeolum. *Zeis gland (Incorrect)* - **Zeis glands** are sebaceous glands associated with the hair follicles of the eyelashes. - Similar to Moll's glands, infection of a Zeis gland is a common cause of an **external hordeolum (stye)**, which appears on the eyelid margin.
Question 10: What is the most likely complication of the condition shown in the image below?
- A. Exposure Keratitis (Correct Answer)
- B. Difficulty in eye movement
- C. Cataract
- D. Glaucoma
Explanation: ***Exposure Keratitis*** - The image shows **proptosis** (exophthalmos) of the right eye, where the eyeball protrudes forward. This condition often leads to incomplete eyelid closure (lagophthalmos). - **Exposure keratitis** occurs when the cornea is inadequately covered by the eyelids, leading to drying and damage due to constant exposure to air and environmental factors. *Difficulty in eye movement* - While **proptosis** can sometimes be associated with restricted eye movements (e.g., in severe Graves' ophthalmopathy due to muscle swelling), it is not the **most likely direct complication** of the exposure itself. - The image primarily depicts the physical displacement of the globe, which predisposes to corneal issues, not necessarily oculomotor dysfunction as the primary complication. *Cataract* - **Cataracts** are opacities of the lens and are typically associated with aging, trauma, or certain systemic conditions (e.g., diabetes, steroid use). - They are not a direct or common complication of **proptosis** or the resulting **exposure of the ocular surface**. *Glaucoma* - **Glaucoma** is a group of conditions characterized by damage to the optic nerve, often due to elevated intraocular pressure. - While severe **proptosis** leading to orbital congestion can theoretically increase intraocular pressure, it is not the most direct or prevalent complication compared to **exposure keratitis**, which is a direct consequence of inadequate globe protection.
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