LASIK Isn't for Everyone | The Real Conditions, According to an Optometrist

Am I a Candidate for LASIK? Essential Requirements from a BGN Eye Clinic Optometrist

Hello, this is BGN Eye Clinic at Jamsil Lotte Tower.

Greeting you through our blog is a first for us.

While wondering what topic to start with, the most frequently asked question immediately came to mind: "Doctor, am I a candidate for LASIK?"

We truly hear this question multiple times a day. With so many people undergoing vision correction surgeries like LASIK, LASEK, and SMILE, it is natural to wonder, "Can I finally take off my glasses too?"

However, not every eye is suitable for LASIK. Every eye has a different corneal thickness, refractive power, and level of dryness.

Today, just like the conversations we have with our patients in the consultation room, we will easily break down the "conditions for eyes that can undergo LASIK."

Corneal Thickness: The Foundation of LASIK

LASIK is a surgery that corrects vision by creating a very thin flap on the surface of the cornea and reshaping the underlying layer with a laser. Simply put, it involves slightly opening the surface of the eye and adjusting the inner refractive power. Therefore, you must have sufficient corneal thickness for the surgery to be safe.

Generally, if it is over 500㎛, LASIK is often possible. If it is thinner, we recommend methods that cause less corneal damage, such as LASEK or SMILE. However, thinking "I only need to check the thickness" is a misconception. The depth of the laser ablation changes depending on the prescription required, meaning the degree of myopia or astigmatism.

For example, a patient with a -2.00 myopia and another with a -7.00 myopia require entirely different correction amounts, which inevitably affects the 'remaining corneal thickness.' That is why the most critical factor checked during pre-surgery examinations is the Residual Thickness. We must calculate whether "enough cornea remains for the eye to withstand pressure post-surgery" to secure a safety margin. The cornea is not just a thin membrane; it acts as a 'pillar' that supports the shape of the eye.

In short, "Only when the cornea is strong can we open the door called LASIK." It is absolutely true that the eyes need physical stamina, too.

Vision & Prescription Range: The Limits of Correction

LASIK is not an option for "all eyes." It is safest and yields the most satisfactory results when performed within an effective vision correction range.

General Safe Correction Range

• Mild to moderate myopia: -1.00D to -8.00D
• Astigmatism: Up to -4.00D
• Hyperopia: Up to +4.00D

You can consider this the 'safety line.' Beyond this range, refractive errors might remain after surgery, or the cornea could become too thin, compromising stability. In cases of irregular astigmatism or high myopia, alternatives like SMILE Pro or Implantable Collamer Lens (ICL) surgery are often more suitable than LASIK. This is not merely about the numbers on a vision test; it is about respecting the 'range your eyes can handle.'

"LASIK shines brightest when performed within the limits of correction." Ultimately, knowing exactly "where your eyes stand right now" is what matters. During an optometry exam, we verify this with exact figures and work with the doctor to find the safest direction for you.

Age: Ensuring Vision Stability

"At what age can I get LASIK?"

We hear this question countless times every single day. LASIK is generally considered for individuals over 18 years old whose vision has remained stable for at least the past year. The reason is simple: during the growth period, the eyes grow as well. Just as you grow taller, the axial length of the eye can slightly increase, meaning your vision has not yet stabilized.

If you undergo surgery while your prescription is still changing, myopia may return after the correction. Conversely, after the age of 40, the lens inside the eye slowly hardens, initiating 'presbyopia' symptoms, and early signs of cataracts may appear. During this period, presbyopia correction surgery or lens replacement surgery is often more appropriate than LASIK.

Simply put, the "age of your eyes" determines the timing of LASIK. When you are young, your eyes are still growing; as you age, the structure of your eye begins to change. The key is "how stable your eyes are right now." Confirming this is the first step toward LASIK.

Dry Eyes: Evaluating Tear Health Before LASIK

There is an unavoidable question during every LASIK consultation: 

"Doctor, my eyes are naturally a bit dry... Will I be okay?"

This is a crucial point. Because LASIK involves making microscopic incisions in the corneal nerves, your eyes can temporarily become dry in the early recovery stages. Therefore, we meticulously check the condition of your tears before surgery. We evaluate how much tear fluid is produced, how long it lasts, and whether the meibomian glands (oil glands) in your eyelids are functioning properly.

Standard Dry Eye Tests

• Tear Break-Up Time (TBUT)
• Schirmer Test (Tear volume test)
• Meibography (Meibomian gland function test)

If tests reveal severe dryness, we do not automatically say surgery is "impossible." Instead, we first stabilize the eye condition through dry eye treatments and management before proceeding with the surgery. In other words, "For dry eyes, management comes first, and surgery follows." Having a successful surgery is important, but a healthy tear environment is essential for a comfortable recovery.

For those who stare at computers for long hours or wear contact lenses frequently, eyes can easily become dry. Maintaining habits like using artificial tears and applying warm compresses is highly beneficial. Ultimately, the moisture in your eyes is the invisible core factor that determines the outcome of LASIK.

Other Important Checkpoints

The conditions for LASIK are not determined solely by vision numbers or corneal thickness. The overall health of the eye must be evaluated together.

Additional Factors to Consider

• If there is inflammation or scarring (opacity) on the cornea
• If you are pregnant or breastfeeding
• If your recovery ability is compromised due to immune disorders

In such situations, we may temporarily postpone the surgery or consider alternative correction methods. LASIK is not simply a "vision-fixing surgery"; it is a sophisticated process that must account for the eye's structure and recovery capacity. This is why we scrutinize every detail of your eye data during the comprehensive pre-surgery exam.

Conclusion

Ultimately, having eyes suitable for LASIK is not just about "having bad eyesight," but rather, "are your eyes ready to accept the surgery?" Corneal thickness, tear condition, vision stability, and lifestyle habits must all harmonize for LASIK to be performed safely and comfortably.

We always tell our patients in the consultation room:

"LASIK is a surgery you can only have if your eyes permit it."

Thank you for reading our post.

We will return with more stories about the eyes from inside our consultation room.