If your glasses prescription has barely changed for several years, it is reasonable to think you have cleared one of the biggest hurdles for LASIK. Stable vision does matter. But it tells the surgeon only one part of the story.
LASIK changes the shape of the cornea, so candidacy depends on the structure and health of the eye as well as the prescription being corrected.
Josh Ford, M.D., from Eyecare Associates of New Orleans, practices ophthalmology at the Metairie clinic, where the practice evaluates patients considering LASIK in Metairie. A refractive-surgery evaluation may uncover issues that have never affected how well you see with glasses but still matter when deciding whether to operate.
Prescription stability is only the starting point
Surgeons want evidence that your refractive error has stopped changing before they plan a permanent corneal correction.
A prescription that is still shifting can make the result less predictable. Current refractive-surgery guidance therefore treats the absence of refractive stability as an important reason not to proceed until the eye has settled.
That is why a surgeon may ask for previous glasses or contact-lens prescriptions rather than relying only on the measurement taken that day.
Stable refraction, though, does not answer questions about corneal strength, surface health or how much tissue a particular correction would require. Someone can have worn the same prescription for years and still have another finding that changes the recommendation.
Corneal shape can reveal risks you cannot feel
A routine prescription measures how much focusing correction you need. Corneal topography and tomography answer a different question.
These imaging tests map the contour and structure of the cornea. They can reveal asymmetry or irregular shape patterns that may be difficult or impossible for a patient to notice.
That matters because LASIK removes microscopic amounts of corneal tissue to alter focusing power. If the cornea already has structural characteristics associated with weakness, additional reshaping may increase the risk of postoperative ectasia, a condition in which the cornea progressively thins or bulges.
Research on refractive-surgery screening has consistently identified abnormal preoperative corneal topography as an important ectasia risk factor. Tomography can add information about corneal thickness patterns and subtle abnormalities that may not be obvious from the front surface alone.
So clear vision with glasses does not necessarily mean the cornea is a good candidate for laser reshaping.
Why surgeons look for signs of keratoconus
Keratoconus is one of the conditions surgeons specifically try to detect before LASIK.
In keratoconus, the cornea becomes thinner and develops an increasingly irregular shape. Early disease may not always produce dramatic symptoms, especially when glasses or contact lenses are still providing useful correction.
Performing LASIK on a cornea with keratoconus or signs of ectatic weakness can make the structural problem worse. FDA patient guidance therefore lists keratoconus among the conditions that need to be considered during LASIK screening.
This is one reason a detailed corneal scan can change the conversation even when the prescription itself looks uncomplicated.
A suspicious scan does not automatically tell a patient what treatment they need next. It tells the surgeon that the cornea deserves closer evaluation before an elective procedure permanently alters it.
Corneal thickness has to fit the treatment plan
Patients sometimes hear that LASIK candidacy depends on having corneas that are “thick enough.”
Thickness matters, but there is no useful universal number that can be interpreted without the rest of the treatment plan.
LASIK removes tissue, and the amount removed depends partly on the correction being attempted. Surgeons therefore consider the starting corneal thickness, the planned flap and ablation, and how much load-bearing tissue will remain afterward.
Research into ectasia risk suggests that the proportion of tissue altered can provide important information beyond central corneal thickness alone.
A patient with a stronger prescription may require more tissue reshaping than someone with a mild correction. Likewise, an irregularly shaped cornea may raise concern even when its central thickness does not initially seem unusual.
The practical question is not simply, “Are my corneas thin?” It is, “Do my corneal measurements fit safely with the correction being planned?”
Dry eye may need attention before surgery
Dry eye is another reason a stable prescription does not necessarily mean surgery should happen immediately.
LASIK affects corneal nerves involved in ocular-surface sensation and tear regulation. A 2023 review identified dry eye as a common complication of corneal laser refractive surgery and emphasized preoperative screening and optimization of the ocular surface.
Symptoms can include burning, irritation, fluctuating clarity or contact lenses becoming uncomfortable as the day goes on. Some people have relatively subtle symptoms despite measurable ocular-surface problems.
When significant dry eye is present, treatment may come before another LASIK measurement or surgical decision.
That delay allows the clinician to reassess the eye after the ocular surface is healthier.
Your overall health can change the recommendation
A LASIK consultation should include more than an eye history.
Systemic illnesses, medications, pregnancy and other health factors can affect refractive stability or healing. A recent review of contraindications to corneal laser refractive surgery identifies active autoimmune disease and poorly controlled diabetes among important concerns. It also describes pregnancy, lactation and certain medications as situations that may require postponement or additional caution.
This does not mean every diagnosis automatically rules out refractive surgery.
Disease activity, control, medications and the individual eye examination all matter. The important point is that elective eye surgery should not be planned in isolation from the rest of the patient’s health.
Bringing an accurate medication list and medical history to the consultation is therefore part of LASIK screening, not administrative paperwork.
Being a candidate also means having realistic expectations
An anatomically suitable eye is only part of candidacy.
LASIK can reduce dependence on glasses or contact lenses, but it does not guarantee perfect uncorrected vision. Some patients may still need correction afterward, and normal age-related changes such as presbyopia can create a later need for reading glasses.
Potential side effects also belong in the conversation. FDA guidance discusses glare, halos, dry eye, under- or overcorrection and reduced visual quality in some low-light situations among the risks patients should understand before surgery.
A good consultation should therefore consider how you actually use your vision.
Someone who drives long distances after dark may have different priorities from someone mainly hoping to exercise without contact lenses. A patient approaching the age when near focusing begins to decline also needs a different expectations discussion from a younger adult.
For patients evaluated at Eyecare Associates of New Orleans, the practice documents corneal topography, corneal-thickness measurement, retinal evaluation and dedicated dry-eye testing, with refractive procedures performed through its co-located Eye Laser Institute. Those resources are relevant because LASIK screening works best when the decision is built from several findings rather than from a stable prescription alone.
A useful evaluation should leave you understanding why the eye is suitable for surgery, which risks were considered and what result is reasonable to expect.
