Excimer Laser Therapy — MCQs
Which of the following are side effects of using argon laser?
All of the following are used in systemic therapy of psoriasis except
A 54-year-old man presents with well-demarcated, erythematous plaques covered with silvery-white scales on the extensor surfaces of his elbows and knees. What is the most likely diagnosis?
Which drug is least likely to cause exanthematous skin eruptions?
Which of the following statements about conjunctival lesions is NOT true?
For a neonate with threshold retinopathy of prematurity, the most appropriate treatment would be:
What is the first-line treatment for melasma?
Which of the following are correct for managing hypertrophic scars? 1. Silicone gel sheeting 2. Intralesional steroid injections 3. Vitamin A gel applications 4. Laser treatment Select the answer using the code given below.
PUVA therapy is used in all except:
What is the most effective treatment for central nebular corneal opacity?
Excimer Laser Therapy Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following are side effects of using argon laser?
- A. Hypopigmentation
- B. Crusting
- C. Keloid formation
- D. All of the options (Correct Answer)
Explanation: ***All of the options*** - **Argon laser** targets hemoglobin and melanin, making it effective for vascular lesions but also carries a risk of pigmentary changes, scar formation, and local tissue reactions. - **Hypopigmentation**, **crusting**, and **keloid formation** are all recognized potential side effects due to its thermal destructive mechanism. *Hypopigmentation* - This side effect occurs due to the **non-selective absorption** of argon laser energy by **melanin** in the epidermis, leading to destruction of melanocytes. - It results in lighter patches of skin in the treated area, especially problematic in darker skin types. *Crusting* - **Crusting** is a common immediate post-treatment effect following argon laser therapy, caused by tissue damage and subsequent inflammation and exudation. - It indicates surface epithelial damage and typically resolves as the skin heals, but proper wound care is essential to prevent infection. *Keloid formation* - **Keloid formation** is a risk with argon laser treatment, particularly in individuals prone to abnormal scarring. - The thermal injury caused by the laser can trigger an exaggerated wound healing response, leading to raised, fibrous scars that extend beyond the original treated area.
Question 2: All of the following are used in systemic therapy of psoriasis except
- A. Methotrexate
- B. Cyclosporine
- C. Oral glucocorticoids (Correct Answer)
- D. Acitretin
Explanation: ***Oral glucocorticoids*** - **Oral glucocorticoids** are generally avoided in psoriasis because they can precipitate severe **rebound flares** upon discontinuation or during dose tapering. - While they can temporarily suppress inflammation, the risk of worsening psoriasis and other systemic side effects makes them unsuitable for long-term systemic therapy. *Methotrexate* - **Methotrexate** is a commonly used systemic agent for psoriasis due to its **immunosuppressive** and **anti-proliferative effects**, targeting rapidly dividing cells. - It works by inhibiting dihydrofolate reductase and is typically given once weekly for chronic plaque psoriasis. *Cyclosporine* - **Cyclosporine** is an effective systemic immunosuppressant used for severe, resistant psoriasis, particularly when rapid control is needed. - It primarily acts by inhibiting **T-cell activation** and proliferation, thereby reducing the inflammatory response in psoriasis. *Acitretin* - **Acitretin** is an oral retinoid derivative of vitamin A, used in severe forms of psoriasis, especially **pustular** and **erythrodermic** types. - It works by modulating **keratinocyte differentiation** and proliferation, helping to normalize skin cell growth.
Question 3: A 54-year-old man presents with well-demarcated, erythematous plaques covered with silvery-white scales on the extensor surfaces of his elbows and knees. What is the most likely diagnosis?
- A. Pityriasis rosea
- B. Psoriasis (Correct Answer)
- C. Eczema
- D. Lichen planus
Explanation: ***Psoriasis*** - **Psoriasis** classically presents with **scaly plaques** that often appear on the **extensor surfaces** such as the elbows and knees. - The scales are typically silvery-white and can be itchy or painful, consistent with the characteristic presentation of chronic plaque psoriasis. *Pityriasis rosea* - This condition presents with a **herald patch** followed by smaller, oval, pinkish-red patches with fine scales, often distributed in a **Christmas tree pattern** on the trunk. - It primarily affects the trunk and proximal extremities, rarely involving the extensor surfaces in the same way as psoriasis. *Eczema* - **Eczema**, particularly atopic dermatitis, typically presents with **itchy, erythematous patches** that are often ill-defined and can be dry or weeping. - While it can occur on extensor surfaces, it is more commonly found on flexural surfaces in adults and lacks the distinct, thick silvery scales characteristic of psoriasis. *Lichen planus* - **Lichen planus** is characterized by **pruritic, purple, polygonal, planar papules and plaques** (**the 6 P's**). - It usually affects the flexural surfaces, wrists, ankles, and oral mucosa, rather than predominantly presenting as scaly plaques on extensor surfaces.
Question 4: Which drug is least likely to cause exanthematous skin eruptions?
- A. Phenytoin
- B. Ampicillin
- C. Phenylbutazone
- D. Hydrocortisone (Correct Answer)
Explanation: ***Hydrocortisone*** - **Corticosteroids** like hydrocortisone are **anti-inflammatory** and immunosuppressive agents. - They are commonly used to **treat allergic reactions** and skin eruptions, making them highly unlikely to cause exanthematous eruptions themselves. *Phenytoin* - **Anticonvulsant** medications like phenytoin are frequently associated with various **drug-induced skin reactions**, including exanthematous eruptions. - It is a common cause of **drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome**, which manifests with a widespread rash. *Ampicillin* - **Antibiotics**, particularly **aminopenicillins** like ampicillin, are well-known triggers for **maculopapular rashes** and other exanthematous eruptions. - The incidence of ampicillin-induced rash is notably higher, especially in patients with **viral infections** like infectious mononucleosis. *Phenylbutazone* - This **non-steroidal anti-inflammatory drug (NSAID)** has a documented history of causing severe cutaneous adverse reactions, including **exanthematous eruptions**. - Due to its potential for serious side effects, such as **aplastic anemia** and severe skin reactions, its use is now highly restricted.
Question 5: Which of the following statements about conjunctival lesions is NOT true?
- A. Arise from any part of conjunctiva
- B. Can cause Astigmatism
- C. Surgery is treatment of choice (Correct Answer)
- D. UV exposure is risk factor
Explanation: ***Surgery is treatment of choice*** - While surgery can be used to treat conjunctival lesions, it is not always the **treatment of choice**, especially for smaller, asymptomatic lesions like **pinguecula** which may only require observation and lubrication. - Many conjunctival lesions, such as uncomplicated **pterygium** or **pinguecula**, are managed conservatively unless they cause significant symptoms, vision impairment, or cosmetic concerns. *Arise from any part of conjunctiva* - **Conjunctival lesions** can indeed arise from various parts of the conjunctiva, including the palpebral, bulbar, and forniceal conjunctiva. - For example, **pterygium** typically arises from the bulbar conjunctiva, while **pinguecula** also originates in the bulbar conjunctiva, specifically in the interpalpebral fissure. *Can cause Astigmatism* - Larger **conjunctival lesions**, particularly a **pterygium** that encroaches onto the cornea, can induce or alter astigmatism. - The growth of the lesion can change the **curvature of the cornea**, leading to optical distortion and astigmatism. *UV exposure is risk factor* - **Ultraviolet (UV) light exposure** is a well-established risk factor for the development of many conjunctival lesions, including **pterygium** and **pinguecula**. - Chronic UV exposure leads to **elastotic degeneration** of the conjunctival collagen and is thought to play a key role in the pathogenesis of these growths.
Question 6: For a neonate with threshold retinopathy of prematurity, the most appropriate treatment would be:
- A. Photocoagulation (Correct Answer)
- B. Antioxidants
- C. Oxygen therapy adjustment
- D. Cryotherapy
Explanation: ***Photocoagulation*** - **Laser photocoagulation** is the most effective treatment for **threshold ROP**, as it ablates the avascular retina, preventing the growth of abnormal vessels. - This procedure aims to halt the progression of **retinal neovascularization** and reduce the risk of retinal detachment and vision loss. *Oxygen therapy adjustment* - While careful **oxygen management** is crucial in preventing and managing ROP, simply adjusting oxygen therapy is not a definitive treatment for established **threshold ROP**. - **Oxygen therapy** primarily influences the initial development of the disease rather than treating advanced stages. *Cryotherapy* - **Cryotherapy**, involving freezing of the peripheral avascular retina, was historically used but has largely been replaced by **laser photocoagulation** due to better precision and reduced collateral damage. - While effective, it is less commonly used today for **threshold ROP** compared to laser treatment. *Antioxidants* - **Antioxidants** have been investigated for their potential role in preventing ROP, but there is insufficient evidence to support their use as a primary treatment for **established threshold ROP**. - Their role is more in **prophylaxis** rather than active treatment of advanced disease.
Question 7: What is the first-line treatment for melasma?
- A. Laser therapy
- B. Topical hydroquinone (Correct Answer)
- C. Chemical peels
- D. Microdermabrasion
Explanation: ***Topical hydroquinone*** - **Topical hydroquinone** (2-4%) is the **most effective single-agent treatment** among the given options, serving as the gold standard for melasma by inhibiting **tyrosinase enzyme** and melanin production. - Demonstrates **highest efficacy rates** (60-80% improvement) when combined with strict sun protection, making it both first-line and most effective monotherapy choice. *Laser therapy* - Carries **high risk of paradoxical darkening** and post-inflammatory hyperpigmentation, especially in darker skin types common in melasma patients. - Requires **specialized expertise** and should only be considered as adjunctive therapy after optimizing topical treatments, not as primary treatment. *Chemical peels* - Provide **variable and inconsistent results** as monotherapy, typically requiring multiple sessions with unpredictable outcomes. - Risk of **post-inflammatory hyperpigmentation** particularly in Fitzpatrick skin types IV-VI, making them less reliable than hydroquinone. *Microdermabrasion* - Offers only **superficial exfoliation** with minimal clinical improvement in melasma pigmentation. - May actually **worsen pigmentation** through mechanical irritation and is not recommended in evidence-based treatment guidelines.
Question 8: Which of the following are correct for managing hypertrophic scars? 1. Silicone gel sheeting 2. Intralesional steroid injections 3. Vitamin A gel applications 4. Laser treatment Select the answer using the code given below.
- A. 1, 3 and 4
- B. 1, 2 and 3
- C. 1, 2 and 4 (Correct Answer)
- D. 2, 3 and 4
Explanation: ***1, 2 and 4*** - **Silicone gel sheeting**, **intralesional steroid injections**, and **laser treatment** are all established and effective methods for managing hypertrophic scars. - Silicone gel helps to hydrate the scar, reduce collagen synthesis, and decrease itching, while steroids reduce inflammation and collagen production, and lasers can help to improve scar texture and color. *1, 3 and 4* - This option incorrectly includes **Vitamin A gel applications** as a primary treatment. While retinoids can have some skin benefits, they are not a first-line or well-established treatment for hypertrophic scars. - **Silicone gel sheeting** and **laser treatment** are indeed effective, but the inclusion of Vitamin A makes this option less accurate. *1, 2 and 3* - This option also incorrectly includes **Vitamin A gel applications**. While **silicone gel sheeting** and **intralesional steroid injections** are effective, Vitamin A is not a standard treatment for hypertrophic scars. - The primary methods for managing hypertrophic scars focus on reducing collagen production and inflammation, which Vitamin A gel does not effectively address in this context. *2, 3 and 4* - This option correctly includes **intralesional steroid injections** and **laser treatment**, but it again incorrectly includes **Vitamin A gel applications** and omits **silicone gel sheeting**, which is a widely recommended and often first-line treatment. - Omitting **silicone gel sheeting** significantly weakens the effectiveness of this combination as a comprehensive management strategy.
Question 9: PUVA therapy is used in all except:
- A. Psoriasis
- B. Vitiligo
- C. Mycosis fungoides
- D. Melasma (Correct Answer)
Explanation: ***Melasma*** - **PUVA (Psoralen plus UVA) therapy** is contraindicated in melasma due to its potential to worsen hyperpigmentation and cause paradoxical darkening. - Melasma is best managed with topical agents like **hydroquinone**, **tretinoin**, and chemical peels, along with strict **sun protection**. *Psoriasis* - **PUVA therapy** is a well-established and effective treatment for moderate to severe psoriasis, especially for patients with widespread plaques. - It works by inhibiting DNA synthesis and cell proliferation in rapidly dividing keratinocytes, leading to a reduction in psoriatic lesions. *Vitiligo* - **PUVA therapy** is a common treatment for vitiligo, stimulating melanocyte activity and promoting repigmentation in affected areas. - Psoralen sensitizes melanocytes to UVA light, which then encourages melanin production. *Mycosis fungoides* - In its early stages, **mycosis fungoides**, a cutaneous T-cell lymphoma, can be effectively treated with **PUVA therapy**. - PUVA induces apoptosis of malignant T-cells in the skin, leading to remission of skin lesions.
Question 10: What is the most effective treatment for central nebular corneal opacity?
- A. Phototherapeutic keratectomy (Correct Answer)
- B. Penetrating keratoplasty
- C. Gas permeable contact lens
- D. Soft contact lens
Explanation: ***Phototherapeutic keratectomy*** - **Phototherapeutic keratectomy (PTK)** is the most effective treatment for superficial **central nebular corneal opacities** as it uses an excimer laser to remove anterior corneal tissue with precision. - This **surgical procedure** aims to improve visual acuity by reducing the opacity's density while preserving the main corneal structure. - PTK is preferred over more invasive procedures for superficial opacities. *Penetrating keratoplasty* - **Penetrating keratoplasty (PK)**, or full-thickness corneal transplant, is reserved for **deep stromal opacities** or those that significantly impair vision beyond the scope of PTK. - This **surgical procedure** involves replacing the entire central cornea, which carries higher risks such as graft rejection and requires longer recovery compared to PTK. *Gas permeable contact lens* - **Gas permeable (GP) contact lenses** are used for correcting irregular astigmatism and improving visual acuity in cases of mild corneal surface irregularities. - They provide a smooth refracting surface but do not address the underlying pathology of the opacity and are not effective for treating dense central opacities. *Soft contact lens* - **Soft contact lenses** are primarily used for correcting refractive errors like myopia, hyperopia, and astigmatism, or for therapeutic purposes such as protecting the ocular surface. - They are generally not effective in improving vision significantly in the presence of a central corneal opacity, as they conform to the corneal shape and do not mask the opacity.
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