SMILE LASIK for High Myopia: Precise Corneal Design and Safety Criteria

Pre-Surgery Essentials: Ocular Structure Analysis and Residual Corneal Thickness Guidelines

Q. "I have high myopia with a very strong prescription. Is it safe for me to undergo SMILE LASIK? I am worried that my cornea might become too thin or that I might experience severe side effects."

Hello, I am Dr. Min-kyung Kim, an ophthalmologist at BGN Eye Clinic Jamsil.

Patients with severe myopia often rely heavily on strong glasses for everyday life and long for visual freedom. At the same time, because higher prescriptions require removing a larger volume of corneal tissue, concerns regarding potential side effects are naturally heightened. Based on real questions gathered during patient consultations, I would like to explain the essential safety criteria needed to make an informed and confident choice.

Definition of High Myopia and Ocular Structural Vulnerabilities

In clinical ophthalmology, high myopia is defined as a refractive error of -6.00D (diopters) or worse, while conditions exceeding -9.00D are categorized as extreme myopia. High myopia involves more than just a strong prescription; it is accompanied by structural changes where the axial length (the front-to-back length of the eye) stretches significantly compared to a normal eye.

As the eye stretches forward and backward, internal structures such as the retina and optic nerve tissue become taut and thin, similar to an overinflated balloon. Consequently, the risks for peripheral retinal degeneration, retinal tears, retinal detachment, and glaucoma become substantially higher than in eyes with normal vision.

Therefore, when designing vision correction procedures for high myopia, surgeons must evaluate both the refractive error and the structural vulnerabilities of the inner eye multidimensionally.

LASIK vs. LASEK vs. SMILE LASIK for High Myopia

Traditional LASIK for high myopia creates a corneal flap approximately 100–120 µm thick, folds it back to reshape the inner tissue, and reposition it. Because this technique requires a wide corneal incision, maintaining structural stability in eyes with high myopia can be challenging. On the other hand, LASEK gently removes the outer epithelial layer. While it avoids flap-related complications, it involves a longer recovery period and postoperative discomfort.

SMILE LASIK addresses these limitations by utilizing a femtosecond laser that passes through the corneal surface to separate a precise piece of stromal tissue inside the cornea. Because the separated tissue fragment (lenticule) is extracted through a tiny 2mm micro-incision, the structural integrity and tensile strength of the corneal surface are preserved, making it an ideal option for safe vision recovery in high myopia patients.

3 Core Safety Metrics for High Myopia SMILE LASIK

• 1. Strict Adherence to Residual Corneal Thickness Guidelines: To prevent corneal ectasia (keratoconus), a condition where the weakened cornea bulges under intraocular pressure, maintaining a safe post-surgery residual corneal thickness of at least 380 µm is the top structural priority.
• 2. Precise Visual Axis and Astigmatism Alignment: Patients with high myopia frequently present with accompanying astigmatism. If the visual axis (refractive center) and the astigmatism axis are slightly misaligned during correction, post-operative night glare and halos can increase. Precise alignment techniques during surgery are imperative.
• 3. Healing Control to Prevent Myopic Regression: When large amounts of tissue are reshaped, natural cellular healing responses may cause the tissue to regrow slightly, leading to myopic regression. To prevent this, corneal collagen cross-linking (corneal strengthening) may be performed concurrently when necessary.

The Evolution: SMILE LASIK vs. SMILE Pro

Recent medical advancements introduced the SMILE Pro system using the ultra-fast VisuMax 800 laser, delivering greater accuracy and stability during corneal correction for high myopia patients.

• 1. Ultra-Fast VisuMax 800 Laser Delivery: SMILE Pro operates at significantly higher speeds, creating the refractive lenticule in just 7 to 9 seconds. Reducing laser exposure time dramatically lowers the risk of suction loss caused by microscopic eye movements or patient tension.
• 2. OcuLign Digital Axis Alignment System: The OcuLign system automatically compensates for cyclotorsion (eye rotation when lying down) and aligns the line of sight in real time. This ensures accurate correction of complex astigmatism axes associated with high myopia, minimizing blur and residual refractive errors.

📌 Note: Suitable treatment plans vary based on individual corneal thickness and refractive profiles identified during clinical evaluation.

Comprehensive Diagnostic Standards at BGN Eye Clinic Jamsil

Achieving long-term satisfaction in high myopia correction requires adjusting for the subtle curvature and structural nuances of each eye. While advanced laser technology is critical, the surgeon's clinical expertise and rigorous multidimensional diagnostic screening are equally vital.

BGN Eye Clinic Jamsil utilizes advanced diagnostic protocols including anterior/posterior corneal topography, corneal elasticity testing, high-resolution optic nerve analysis (OCT), and AI-driven predictive modeling to craft personalized vision correction plans.

We promise to recommend only the safest, data-driven treatments for your eyes. Discover your ideal treatment plan through our comprehensive pre-operative eye evaluation.

Thank you.