SMILE eye surgery can reduce dependence on glasses or contact lenses for people with suitable myopia, with or without certain types of astigmatism. But having a glasses prescription within a particular range does not automatically make you eligible.
SMILE eligibility depends on several factors, including your age, whether your prescription is stable, the health and shape of your cornea, the condition of your eyes, and whether you have any medical conditions that could affect healing.
A detailed eye examination is therefore essential before deciding whether SMILE is appropriate. For a broader overview of the procedure, see the SMILE Eye Surgery guide.
What Makes Someone a Suitable Candidate for SMILE?
A suitable candidate generally has a stable refractive error that falls within the applicable treatment range and otherwise healthy eyes. Your ophthalmologist will usually consider:
- Your age
- The type and strength of your refractive error
- Whether your prescription has remained stable
- The thickness and shape of your cornea
- The health of the ocular surface
- The presence of other eye conditions
- Your general health and medications
- Your expectations from refractive surgery
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Does My Glasses Prescription Need to Be Stable?
Yes. A stable prescription is one of the most important considerations before refractive surgery. If your glasses or contact lens prescription has changed significantly during the previous year, your eyes may not yet be ready for permanent refractive correction.
Requirements can differ between devices and countries, so your ophthalmologist will review your previous prescriptions and examination records rather than relying on your current prescription alone.
Why Does Corneal Health Matter?
SMILE changes the cornea, so the cornea must have sufficient strength and a suitable shape before surgery. During the preoperative assessment, your ophthalmologist may evaluate:
- Corneal thickness
- Corneal curvature
- Corneal topography or tomography
- Corneal symmetry and regularity
- Signs of corneal weakness or abnormal shape
- The amount of tissue that would remain after treatment
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Can Someone With Thin Corneas Have SMILE?
Not necessarily. Having a relatively thin cornea does not automatically answer whether SMILE is safe. The surgeon also considers the corneal shape, the amount of tissue that would need to be removed, and how much structurally adequate cornea would remain after treatment.
A cornea with an abnormal shape may be a more important concern than thickness alone. This is why corneal mapping and detailed measurements are an essential part of the eligibility assessment.
What If I Have Keratoconus or an Abnormal Cornea?
Conditions such as keratoconus and other forms of corneal ectasia can make SMILE unsuitable. These conditions involve abnormalities or progressive changes in the shape and structure of the cornea.
Since SMILE intentionally removes corneal tissue, treating an already structurally abnormal cornea can increase the risk of an undesirable outcome. Abnormal findings on corneal topography or tomography therefore need to be carefully assessed before refractive surgery is considered.
Can You Have SMILE If You Have Dry Eyes?
It depends on the severity of the dry-eye condition. Mild symptoms do not necessarily rule out SMILE, but significant or uncontrolled ocular-surface disease may need to be treated before surgery or may make the procedure inappropriate.
This is important because the tear film contributes to the quality of the eye's optical surface. Dryness can also cause discomfort and fluctuating vision after refractive surgery. Your surgeon may therefore assess tear production, the ocular surface and the severity of any existing dry-eye symptoms before making a decision.
Can People With Diabetes Have SMILE?
Diabetes requires additional consideration because it can affect healing and may be associated with eye complications.
Uncontrolled diabetes or significant diabetic eye disease can make elective refractive surgery unsuitable. Even when diabetes is controlled, the ophthalmologist may need to consider your overall health, eye findings and healing risk.
The important point is that having diabetes does not lead to an automatic yes or no. The decision depends on your individual health and eye examination.
Can You Have SMILE During Pregnancy or Breastfeeding?
Elective refractive surgery is generally postponed during pregnancy and breastfeeding. Hormonal changes can temporarily affect refraction and the ocular surface, which may make measurements and treatment planning less predictable.
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
It is usually preferable to wait until the eyes and prescription have returned to a stable state before considering permanent refractive correction.
What Tests Are Done Before SMILE?
The preoperative assessment usually involves considerably more than checking your glasses prescription.
Your ophthalmologist may perform:
- Visual acuity testing
- Detailed refraction
- Corneal topography or tomography
- Corneal thickness measurement
- Assessment of the tear film and ocular surface
- Eye-pressure measurement
- Examination of the front and back of the eye
- Retinal and optic-nerve assessment
- Pupil assessment when appropriate
*AI-generated image - for illustration only. Clinical accuracy is not guaranteed.
Your previous glasses or contact lens prescriptions may also be reviewed to establish whether your refractive error has remained stable.
SMILE Eligibility: A Simple Checklist
| Factor | What the doctor assesses |
|---|---|
| Age | Whether you meet the applicable age requirement |
| Prescription | Whether your myopia or myopic astigmatism falls within the approved range |
| Stability | Whether your prescription has remained sufficiently stable |
| Cornea | Thickness, shape, regularity and structural suitability |
| Eye health | Whether there are conditions that could make surgery unsafe |
| Ocular surface | Whether dry eye or other surface problems are absent or adequately controlled |
| General health | Whether medical conditions or medications could affect healing |
| Expectations | Whether you understand the benefits, limitations and possible visual symptoms |
The Bottom Line
Being eligible for SMILE depends on much more than the strength of your glasses prescription. A stable refractive error, suitable corneal thickness and shape, healthy eyes, and appropriate expectations are all important parts of the assessment.
Conditions such as significant corneal abnormalities, severe dry eye, active eye disease, uncontrolled diabetes or certain systemic conditions can make SMILE unsuitable. Pregnancy and breastfeeding are also generally reasons to postpone elective refractive surgery.
The final decision should come after a detailed eye examination that evaluates the cornea, prescription, ocular surface and overall eye health. If SMILE is not appropriate, another form of vision correction—or continuing with glasses or contact lenses—may be safer.
In other words, the goal of the eligibility assessment is not simply to determine whether you can have SMILE, but whether it is a safe and appropriate choice for your individual eyes.
