LASIK vision correction surgery is effective for most individuals who wear glasses or contact lenses; however, many still believe it’s not suitable for them. Often, this is based on several misconceptions people have about the procedure. Having impaired vision that is not “bad enough” for LASIK is one such misconception. At Vantage Eye Center, it’s not uncommon for a patient to visit us for the first time and say, “My vision is 20/100. Is this bad enough for LASIK?”
Our response to this is that LASIK candidacy cannot be verified solely based on your visual acuity measurements.
Why Visual Acuity Isn’t the Whole Story
Visual acuity measurements, such as 20/20 or 20/100, describe how clearly you see at a specific distance compared to a standardized baseline.
20/20 vision means you can clearly see at 20 feet what should normally be seen at 20 feet.
20/100 vision means you must be within 20 feet to see what someone with normal vision can see at 100 feet.
While this helps describe how blurry your vision is, it does not explain why your vision is blurry. LASIK candidacy depends on the underlying cause of your vision problem, not just how poor your eyesight feels on a day-to-day basis.
To determine whether LASIK is an option, your surgeon evaluates whether your refractive error falls within a safe and treatable range.
What’s a Refractive Error Within the Treatable Range?
Before we delve into refractive errors that can be corrected by LASIK vision revision, let’s take a quick look at how normal vision works.
For 20/20 vision to be possible, the cornea and the lens must refract (bend) light rays directed to the very back of the eye, or specifically the retina. The retina is a layer of light-sensing photoreceptor cells – rods and cones – that convert light rays into electrochemical impulses that are sent to the brain for interpretation.
Refractive errors occur when you have an imperfectly shaped cornea or lens. As a result, light rays do not all refract from the retina. Sometimes, as in the case of aging men and women, it’s the lens that can’t change shape enough to focus on nearby objects (presbyopia).
Refractive errors include the following:
- Nearsightedness (nearby objects are the only ones that are clear or distinct)
- Farsightedness (far objects are the only ones that are clear or distinct)
- Astigmatism (objects are blurred whether far or near)
- Presbyopia (difficulties seeing up close due to the loss of elasticity in the lens)
A refractive error is measured in diopters — a unit used to denote the strength of your lens.
LASIK Prescription Ranges
To qualify for the newest LASIK technology (topography-guided LASIK), your refractive prescription should fall within the following:
- Up to -8.0 diopters of nearsightedness, or
- Up to -3.0 diopters of astigmatism, or
- Up to -9.0 diopters nearsightedness with astigmatism; and,
- The amount of nearsightedness with or without astigmatism in your eye did not change by more than 0.5 diopters during the year before your pre-operation examination.
If your prescription is for vision measured as high as -20.0 diopters of nearsightedness, implantable contact lenses are recommended instead of LASIK.
There is no minimum prescription required to have refractive surgery. If you have a combination of nearsightedness and astigmatism, and you see better when it is corrected with glasses or contacts, you may be a good candidate for LASIK.
Other Factors that Influence Qualifications for LASIK
Your eye prescription is not the sole indicator of your eligibility for LASIK. Generally, the following factors also need careful consideration before surgery:
- The thickness of the cornea. Performing laser vision correction on a cornea that is too thin can compromise outcomes. A highly irregular or misshapen cornea, such as in keratoconus, may also increase the risk of vision deterioration.
- Pupil size. LASIK performed on large pupils may increase your risk of side effects, such as glare and halos.
- Stability of prescription. Your prescription should remain stable for at least 12 months prior to the procedure. For this reason, teens and younger individuals are not good candidates for LASIK until their eyes have “settled down” into a stable prescription.
- Overall eye health. You don’t suffer from dry eye syndrome, cataracts, or glaucoma.
- Pregnancy or lactation. Medications used during and after LASIK may pose a risk to your child while you’re pregnant or nursing. Hormonal shifts during pregnancy can also trigger dry eye symptoms.
Poor Eyesight is Not the Only Factor for LASIK
Find out if your prescription and overall eye health make you a good LASIK candidate by scheduling a consultation! A thorough in-person assessment and evaluation are the most effective ways to determine whether LASIK is right for you.