Refractive Surgery

Refractive Surgery Indian Medical PG Question 1: Presently, the surgical treatment of choice in a 22-year-old male with 10D myopia is

• A. Phakic intraocular lens (Correct Answer)
• B. Refractive lens exchange
• C. Wavefront guided LASIK
• D. Femtosecond laser LASIK

Refractive Surgery Explanation: ***Phakic intraocular lens*** - For high myopia such as **10D in a young patient**, phakic intraocular lenses are often preferred as they provide superior optical quality and are reversible, preserving the natural lens. - This procedure avoids removing the natural lens, which is important for maintaining **accommodation** [1] in a young individual. *Refractive lens exchange* - This procedure involves removing the natural lens and replacing it with an artificial intraocular lens, similar to cataract surgery. - It is generally reserved for older patients with high refractive errors or those already developing **cataracts**, as it sacrifices the eye's natural ability to accommodate. *Wavefront guided LASIK* - LASIK (Laser-Assisted In Situ Keratomileusis) involves reshaping the cornea and is less effective and may carry higher risks for very high myopia (typically above **-8 to -10 diopters**). - It can thin the cornea excessively in cases of high myopia [1], potentially leading to **ectasia**. *Femtosecond laser LASIK* - While using a femtosecond laser for flap creation improves safety in LASIK, the fundamental limitations of corneal reshaping for **high myopia (e.g., thinning of the cornea)** still apply. - It does not overcome the issues of insufficient tissue for correction or potential long-term corneal stability concerns in severe myopia.

Refractive Surgery Indian Medical PG Question 2: Which of the following lasers is NOT used in laser trabeculoplasty?

• A. Argon laser
• B. Diode laser
• C. Nd: YAG laser, 532nm
• D. Nd: YAG laser, 1064nm (Correct Answer)

Refractive Surgery Explanation: ***Nd: YAG laser, 1064nm*** - The **1064nm wavelength Nd:YAG laser** is primarily used for procedures like **posterior capsulotomy** or **iridotomy**, where its photodisruptive effect is desired. - This wavelength is not absorbed by the pigmented cells of the trabecular meshwork, making it ineffective for **trabeculoplasty**. *Nd: YAG laser, 532nm* - The **frequency-doubled Nd:YAG laser (532nm)**, also known as a **green laser**, is effectively used in **selective laser trabeculoplasty (SLT)**. - It targets **melanin-containing cells** in the trabecular meshwork, causing selective photothermolysis without coagulating adjacent non-pigmented tissue. *Argon laser* - The **argon laser** is historically significant and is used in **argon laser trabeculoplasty (ALT)**. - It creates **thermal coagulation** of the trabecular meshwork, leading to tissue contraction and increased outflow. *Diode laser* - **Diode lasers** are used in **diode laser trabeculoplasty (DLT)**. - They also utilize a **thermal effect** on the trabecular meshwork to improve aqueous outflow.

Refractive Surgery Indian Medical PG Question 3: In a case of myopia, LASIK can correct up to how many diopters?

• A. -4D
• B. -12D (Correct Answer)
• C. -20D
• D. -6D

Refractive Surgery Explanation: ***-12D*** - LASIK can effectively correct myopia up to approximately **-12 diopters** in suitable candidates, though this can vary slightly based on individual corneal thickness and health. - The excimer laser reshapes the **cornea** to reduce its curvature, thereby decreasing the focusing power of the eye and correcting the myopic error. *-20D* - While some highly myopic individuals might desire such a correction, LASIK is generally not recommended or effective for myopia higher than **-12 to -14 diopters** due to limitations in corneal tissue removal and potential for complications. - Correcting very high myopia with LASIK would require removing too much corneal tissue, potentially leading to **corneal instability** or vision-threatening complications like **ectasia**. *-6D* - This is a common and highly successful range for LASIK correction, but it represents only a **moderate level of myopia** and not the maximum correctable range. - Patients with myopia of -6D typically achieve excellent visual outcomes with very low complication rates after LASIK. *-4D* - This is a relatively low level of myopia, and LASIK is very effective for this amount of correction, but it is far from the **upper limit** of what LASIK can achieve. - This level of correction requires minimal corneal reshaping and typically results in a very high success rate and predictable outcomes.

Refractive Surgery Indian Medical PG Question 4: A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?

• A. LASIK
• B. Spherical Specs
• C. Contact lenses (Toric) (Correct Answer)
• D. FEMTO Lasik

Refractive Surgery Explanation: ***Contact lenses (Toric)*** - **Toric contact lenses** are specifically designed to correct **astigmatism**, along with myopia or hyperopia, by having different refractive powers in different meridians. - They offer a non-surgical alternative to glasses, addressing the patient's desire not to wear spectacles, and are generally safe and effective for teenagers. *LASIK* - **LASIK (Laser-Assisted In Situ Keratomileusis)** is a surgical procedure to correct refractive errors, but it is not typically recommended for individuals under **18-21 years of age** due to continued eye growth and refractive changes. - The patient's age of 15 makes her an unsuitable candidate for LASIK at this time. *Spherical Specs* - **Spherical spectacles** are designed to correct myopia or hyperopia but cannot adequately correct **astigmatism**, which is a significant component of this patient's refractive error. - The patient also explicitly states she does not want to wear glasses, making this option undesirable. *FEMTO Lasik* - **FEMTO LASIK** is an advanced form of LASIK that uses a femtosecond laser to create the corneal flap, offering higher precision and safety. - However, similar to traditional LASIK, it is a **refractive surgical procedure** and typically not performed on patients younger than **18 years old** due to ongoing eye development.

Refractive Surgery Indian Medical PG Question 5: Gold standard procedure to reduce recurrence of pterygium after surgical excision is

• A. Thiotepa
• B. Amniotic membrane grafting
• C. Conjunctival autograft (Correct Answer)
• D. Beta-radiation

Refractive Surgery Explanation: ***Conjunctival autograft*** - **Conjunctival autografting** involves transplanting a piece of healthy conjunctiva from the superior bulbar conjunctiva to the bare scleral bed after pterygium excision, acting as a barrier to fibrovascular proliferation. - This technique has consistently shown the **lowest recurrence rates** in comparative studies, making it the **gold standard** for preventing pterygium recurrence due to its high success rate and safety profile. *Thiotepa* - **Thiotepa** is an **antimetabolite** that inhibits DNA synthesis and cell proliferation, used topically post-excision to reduce recurrence by suppressing fibroblast activity. - While it can lower recurrence rates compared to simple excision, its efficacy is generally **less than conjunctival autografting**, and it carries risks of corneal toxicity and limbal stem cell deficiency. *Amniotic membrane grafting* - **Amniotic membrane grafting** involves placing processed amniotic membrane over the scleral bed, which has anti-inflammatory, anti-scarring, and pro-epithelialization properties. - It is an effective option, especially for **large pterygia** or for patients at high risk of recurrence, but its recurrence rates are generally **not as low as those achieved with conjunctival autografting**, and the graft can sometimes detach. *B- radiation* - **Beta-radiation** (strontium-90) is a form of adjuvant therapy applied to the scleral bed immediately after pterygium excision to inhibit fibroblast proliferation and reduce recurrence. - It is effective but associated with potential complications such as **scleral melt**, corneal scarring, and cataract formation, making it a less preferred option than conjunctival autografting, especially in primary cases.

Refractive Surgery Flashcard 1 of 5

Question: ICRS implantation is used for treatment of _____

Answer: myopia (hypermetropia/myopia)

Refractive Surgery Flashcard 2 of 5

Question: ReLEx or SMILE is used for treatment of _____

Answer: myopia (hypermetropia/myopia)

Refractive Surgery Flashcard 3 of 5

Question: What is the most frequent post-op complication of LASIK?_____

Answer: Punctate epithelial dystrophy (dry eye)

Refractive Surgery Flashcard 4 of 5

Question: _____ laser is used in the treatment of myopia.

Answer: Excimer

Refractive Surgery Flashcard 5 of 5

Question: Flap _____ can occur 24 hours after LASIK sx

Answer: displacement