Understanding LASIK Surgery and its Limitations

What is LASIK surgery?

LASIK (Laser-Assisted in Situ Keratomileusis) surgery is a popular refractive eye surgery used to correct vision problems like nearsightedness (myopia), farsightedness (hyperopia), and astigmatism. During LASIK, a laser is used to reshape the cornea, allowing light to properly focus onto the retina, thus improving vision. This procedure can reduce or eliminate the need for glasses or contact lenses for many people.

What is the difference between function of Cornea and Lens in our eyes ?

The cornea and lens are both essential parts of the eye's optical system, contributing to the focusing of light onto the retina, which allows us to see clearly. The cornea primarily provides the initial focusing power by bending incoming light, while the lens fine-tunes and adjusts the focus to allow for clear vision at various distances. Both structures work together to ensure that light rays are properly focused onto the retina, facilitating clear and sharp vision. The cornea bends (refracts) incoming light and accounts for approximately two-thirds of the eye's total optical power. The lens contributes the remaining one-third of the eye's focusing power.

What happens during LASIK Surgery ?

LASIK Surgery is performed on Cornea which consists of following layers:

• Epithelium: This is the outermost layer of the cornea, acting as a protective barrier against foreign particles and contributing to the overall health of the cornea. 
• Stroma: The stroma is the thickest layer of the cornea, composed of collagen fibers and other supportive structures. 
• Descemet's membrane: This layer is located beneath the stroma and acts as a basement membrane for the corneal endothelium.
• Endothelium: The endothelium is the innermost layer of the cornea, consisting of specialized cells that help maintain the clarity of the cornea by regulating fluid levels and transporting nutrients to the cornea from the aqueous humor in the eye.

Following steps are performed during LASIK Surgery:

• Step 1: A thin flap of the epithelium is carefully created and folded back to expose the underlying stroma. 
• Step 2: The laser is used to precisely reshape stroma by removing small amounts of tissue, altering the curvature of the cornea to correct refractive errors like nearsightedness, farsightedness, or astigmatism. The laser works by either vaporizing or ablating microscopic amounts of tissue to alter the curvature of the cornea.
• Step 3 :The epithelial flap is then repositioned back into its original place, where it typically heals naturally without the need for stitches.

What is the success rate of LASIK Surgery ?

The success rate of LASIK surgery is generally quite high, with a significant majority of patients experiencing improved vision without the need for glasses or contacts. The success rate can vary based on several factors, including the patient's initial vision prescription, eye health, surgeon's expertise, and post-operative care.

Most studies suggest that around 90% to 95% of patients who undergo LASIK achieve their desired vision correction, typically reaching 20/20 vision or better after the procedure. However, it's important to note that success rates can differ based on individual circumstances.

What are the limitations of LASIK surgery?

LASIK surgery is highly effective for many individuals, but it does have some limitations and potential risks:

• Not Suitable for Everyone: Not everyone is a good candidate for LASIK. Factors like unstable vision, certain eye conditions, or health issues might disqualify someone from undergoing the procedure.
• Possible Complications: Though uncommon, LASIK can have complications such as dry eyes, glare, halos, under-correction, over-correction, or even loss of vision in rare cases.
• Age-Related Changes: Vision changes due to aging can still occur after LASIK, potentially requiring additional vision correction later in life.
• Corneal Thickness: Individuals with thin corneas might not be suitable candidates for LASIK.
• Temporary Discomfort: Some people might experience temporary discomfort, such as dry eyes or glare, during the healing process after surgery.
• No Guarantee of Perfect Vision: While LASIK can significantly improve vision, it might not always achieve perfect vision for everyone. Some people might still need glasses or contacts, though with a reduced prescription.

It's crucial to consult with an experienced eye surgeon to determine whether LASIK is suitable for your specific vision needs and to understand the potential risks and limitations associated with the procedure.

Why LASIK surgery is  not recommended for individuals under the age of 18?

LASIK surgery is generally not recommended for individuals under the age of 18 because their eyes are still developing and changing. The eyes tend to stabilize in prescription and structure by early adulthood, usually around the age of 18 or older. Performing LASIK on younger individuals whose eyes are still changing significantly might lead to unpredictable results.

Furthermore, the stability of the refractive error (such as nearsightedness, farsightedness, or astigmatism) needs to be confirmed before undergoing LASIK. Prescriptions for glasses or contact lenses can fluctuate during adolescence, making it challenging to determine the accurate and stable prescription needed for the surgery.

Therefore, waiting until the eyes have fully matured and stabilized helps ensure a more predictable outcome and reduces the chances of needing additional vision correction surgeries in the future.

Which factors influence the success of LASIK Surgery ?

• Initial Prescription: Patients with lower prescriptions often have a higher chance of achieving 20/20 vision after LASIK compared to those with higher degrees of nearsightedness, farsightedness, or astigmatism.
• Eye Health: Patients with healthy eyes and corneas tend to have better outcomes compared to those with certain eye conditions or irregularities.
• Surgeon's Skill and Experience: The expertise of the surgeon performing the procedure significantly impacts the success of LASIK. Experienced surgeons who use advanced technology tend to have better outcomes.
• Post-operative Care: Following the surgeon's post-operative instructions diligently can contribute to successful healing and vision correction.

While LASIK has a high success rate, it's important for individuals considering the procedure to discuss potential risks, limitations, and expected outcomes with their eye care professional to make an informed decision. Additionally, some patients might still require glasses for certain activities or experience minor visual disturbances like glare or halos, especially in low-light conditions, even after a successful LASIK surgery.

Why LASIK can't be performed on patients with high levels of myopia ?

Performing LASIK on patients with high levels of myopia (nearsightedness) exceeding -8 diopters can pose certain challenges and risks. While advancements in LASIK technology have expanded the range of treatable refractive errors, there are limitations, especially for individuals with very high myopia. Here are some reasons why LASIK might not be recommended for those with myopia exceeding -8 diopters:

• Tissue Removal: High myopia requires more corneal tissue to be removed to reshape the cornea adequately. Removing too much tissue can compromise the structural integrity of the cornea, increasing the risk of post-operative complications like corneal ectasia (a condition where the cornea bulges outward) or reduced corneal thickness.
• Risk of Over-Correction or Under-Correction: Achieving precise correction becomes more challenging with higher levels of myopia. There's a risk of over-correction (resulting in farsightedness) or under-correction (not fully correcting the myopia), leading to less than optimal visual outcomes.
• Corneal Stability: Individuals with high myopia may have thinner corneas, making them more susceptible to changes or irregularities after LASIK surgery. This could affect the long-term stability of the cornea and the success of the procedure.
• Alternative Treatments: For patients with very high myopia, alternative procedures like implantable collamer lenses (ICLs) or refractive lens exchange (RLE) may be more suitable options to correct their vision while avoiding excessive corneal tissue removal.

While LASIK might not be recommended for individuals with myopia exceeding -8 diopters, advancements in technology continue to expand the range of treatable refractive errors. Surgeons may consider alternative procedures or techniques to address high myopia while minimizing the risk of complications and ensuring better visual outcomes. Consulting with an experienced eye surgeon can help determine the most suitable and safest treatment option for each individual's specific needs and eye characteristics.

Has LASIK surgery technology improved in past few years ?

Yes, LASIK surgery technology has seen significant advancements and improvements in recent years, leading to enhanced precision, safety, and better outcomes for patients. Some of the notable advancements include:

• Wavefront-guided LASIK: This technology uses detailed mapping of the eye's unique irregularities, allowing for a more customized treatment that addresses higher-order aberrations, potentially improving visual quality beyond just correcting basic refractive errors.
• Femtosecond Lasers: These lasers have replaced the traditional microkeratome blade in creating the corneal flap during LASIK surgery. Femtosecond lasers offer greater precision, allowing for thinner and more precise flaps, reducing the risk of complications and improving healing.
• Customized Treatments: Modern LASIK platforms offer treatments tailored to individual eye characteristics, allowing surgeons to customize procedures based on each patient's unique vision imperfections.
• Improved Tracking and Eye-Tracking Technology: Advanced eye-tracking systems track eye movements during surgery, adjusting the laser in real-time to ensure accurate treatment even if the eye moves slightly.
• Topography-Guided LASIK: This approach utilizes corneal topography to guide the laser, addressing irregular corneal surfaces and improving visual outcomes, particularly for patients with corneal irregularities or prior refractive surgeries.
• Better Safety Profiles: Technological advancements have contributed to increased safety during LASIK procedures, reducing the risk of complications such as dry eyes, glare, halos, and other visual disturbances.

These advancements have collectively contributed to improving the accuracy, predictability, and safety of LASIK surgery. As technology continues to evolve, LASIK procedures are becoming increasingly precise and customized, leading to better visual outcomes and higher patient satisfaction. Patients considering LASIK surgery are encouraged to consult with experienced eye care professionals who utilize the latest technology to achieve the best possible results.