If you have high myopia, you may wonder whether SMILE eye surgery can reduce your dependence on glasses or contact lenses. The answer is that it may be an option for some people with high myopia, but eligibility depends on much more than the strength of your prescription.
SMILE, or Small Incision Lenticule Extraction, reshapes the cornea by creating and removing a small piece of corneal tissue called a lenticule. This changes how light is focused inside the eye and can correct myopia, with or without certain levels of astigmatism.
When the prescription is high, however, the amount of correction required becomes an important consideration. The surgeon needs to determine whether the cornea has the appropriate thickness, shape, and structural characteristics to undergo the planned treatment safely.
What Is High Myopia?
High myopia generally refers to a significantly stronger degree of short-sightedness than ordinary myopia. A commonly used clinical definition is a spherical equivalent of -6.00 dioptres (D) or more negative.
However, the definition of high myopia and the prescription range considered suitable for refractive surgery are not the same thing.
Someone can have high myopia but still not be a candidate for SMILE, while another person with a similar prescription may have eye measurements that make treatment possible. This is why the prescription on your glasses or contact-lens prescription is only one part of the assessment.
Can SMILE Correct High Myopia?
Yes. SMILE has been studied extensively for high myopia, including prescriptions above -9.00 D and, in some studies, up to approximately -14.00 D.
Research involving carefully selected patients has reported good visual and refractive outcomes after SMILE for these higher prescriptions. However, there is an important distinction between what has been studied in clinical research and what is included in the approved treatment range of a specific SMILE system.
Why Is High Myopia More Challenging for Laser Eye Surgery?
Correcting a stronger myopic prescription generally requires a greater change in the shape of the cornea. This makes the amount of corneal tissue involved in treatment particularly important. Before considering SMILE for high myopia, your eye specialist may evaluate:
- Corneal thickness: Whether there is sufficient corneal tissue for the planned correction.
- Corneal shape: Whether the cornea has a regular and suitable structure.
- Residual stromal thickness: How much tissue is expected to remain after treatment.
- Prescription strength: The amount of myopia and any associated astigmatism that needs correction.
- Prescription stability: Whether your refractive error has remained stable over time.
- Overall eye health: Whether the cornea, retina, ocular surface, and other structures are healthy enough for refractive surgery.
How Is Eligibility for SMILE Determined in High Myopia?
There is no single prescription number that can determine whether you are suitable for SMILE. Instead, the surgeon considers your complete eye profile.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
1. Your refractive prescription
The amount of myopia and astigmatism determines how much correction is required. The treatment must also fall within the approved range of the specific laser platform being used.
2. Corneal thickness
A corneal thickness measurement helps the surgeon assess whether enough tissue is available for the planned treatment while maintaining an appropriate amount of corneal tissue afterward.
3. Corneal shape
Corneal topography and tomography can identify irregularities that may make laser vision correction unsuitable. This is particularly important when treating larger refractive errors.
4. Prescription stability
If your prescription has continued to change significantly, refractive surgery may need to be postponed. A stable prescription helps make the planned correction more predictable.
5. Overall eye health
Conditions affecting the cornea, tear film, retina, or other parts of the eye can influence whether SMILE is appropriate.
What Tests Are Usually Performed Before SMILE for High Myopia?
A detailed preoperative assessment is especially important when the prescription is high. Depending on your circumstances, the evaluation may include:
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
- Detailed refraction
- Visual-acuity testing
- Corneal topography
- Corneal tomography
- Corneal thickness measurement
- Assessment of the tear film and ocular surface
- Measurement of the pupil under different lighting conditions
- Comprehensive examination of the front and back of the eye
- Retinal evaluation when indicated by the degree of myopia or other findings
These measurements help the surgeon determine whether the planned correction is technically and medically appropriate rather than relying on the prescription alone.
Does Corneal Thickness Affect SMILE Eligibility?
Yes. Corneal thickness is one of the important factors considered before laser vision correction, particularly when a substantial refractive correction is required.
The surgeon needs to estimate how much corneal tissue will be affected by the planned treatment and how much will remain afterward. Corneal thickness is considered together with corneal shape and other structural measurements.
A thicker cornea does not automatically mean that SMILE is safe for someone with high myopia. Similarly, a particular thickness measurement cannot be interpreted without considering the overall shape and health of the cornea.
What About Visual Quality After SMILE for High Myopia?
Seeing clearly on a standard eye chart is not the only measure of visual quality after refractive surgery. Some people may notice glare, halos, difficulty with contrast, or other changes in the way they perceive lights, particularly during the early recovery period.
Research involving high-myopia patients has examined these visual-quality measures in addition to ordinary visual-acuity testing. The likelihood and severity of symptoms can vary between individuals.
This is why a preoperative discussion should cover both the expected improvement in uncorrected vision and the possibility of visual symptoms during or after recovery.
Can High Myopia Affect the Predictability of SMILE?
Higher prescriptions can make refractive correction more demanding. Some research has found slightly lower efficacy in eyes with very high myopia, particularly when high myopia is combined with a thinner cornea.
This does not mean that SMILE is ineffective for high myopia. Rather, it highlights why patient selection and treatment planning are particularly important when larger corrections are being considered.
Your surgeon may also discuss the possibility of residual refractive error or some degree of regression over time. The expected outcome depends on your individual prescription, corneal characteristics, and other eye-related factors.
The Bottom Line
SMILE can be an option for some people with high myopia, but having a high prescription does not automatically make you a candidate. Research has demonstrated that SMILE can provide useful visual and refractive outcomes in carefully selected patients with prescriptions above -9.00 D, including some studies involving corrections beyond -10.00 D.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
At the same time, approved treatment ranges vary by laser system and regulatory setting. The current US FDA indication for the VisuMax system extends to -10.00 D of spherical refractive error, with additional requirements for astigmatism, spherical equivalent, age, and prescription stability.
For high myopia, the most important part of the evaluation is understanding whether your cornea and overall eye health can safely accommodate the planned correction. A detailed examination of corneal thickness, corneal shape, prescription stability, and other eye characteristics is therefore essential before deciding whether SMILE is appropriate.
