Although LASIK vision correction surgery is effective for most individuals who wear glasses or contact lenses, many still believe it’s not appropriate for them. Often, this is based on several misconceptions people have about the procedure. Having bad vision that is not bad enough for LASIK is one of these. It’s not uncommon for a patient to visit us for the first time and say, “My vision is 20/100 (or insert any other visual acuity score here). Is this bad enough for LASIK?”
The simple answer is that LASIK candidacy cannot be determined solely from your visual acuity measurements.
Visual acuity scores, such as 20/100, describe the sharpness of vision and are measured at a specific distance using a standardized method. Normal visual acuity is 20/20. It means you can clearly and accurately see what is reality at 20 feet. Having 20/100 vision means you should be within 20 feet to see what a person with normal vision can see at 100 feet. To determine if your poor eyesight is suitable for LASIK, your laser vision correction doctor will figure out if your refractive error is within the range that can be treated.
You can also help determine your eligibility for LASIK by taking our quick and easy LASIK quiz.
What’s a Refractive Error Within the Treatable Range?
Before we discuss refractive errors that can be corrected by LASIK vision revision, let’s briefly examine how normal vision works.
For 20/20 vision to be possible, the cornea and lens must refract (bend) light rays directed to the very back of the eye, specifically the retina. The retina is a layer of light-sensing photoreceptor cells, rods and cones, that convert light into electrochemical impulses sent to the brain for interpretation.
Refractive errors occur when you have an imperfectly shaped cornea or lens. As a result, not all light rays refract onto 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 that denotes the strength of your lens.
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 as high as -20.0 diopters of nearsightedness, implantable contact lenses are recommended instead of LASIK.
Other Factors that Influence Qualifications for LASIK
Your eye’s prescription is not the sole indicator of whether you are eligible for LASIK. Generally, the following factors also need careful consideration before surgery:
- The thickness of cornea. Performing laser vision correction on a cornea that is too thin or has an extremely irregular, misshapen surface (keratoconus) could compromise outcomes and possibly lead to vision deterioration.
- Pupil size. LASIK done on pupils that are unusually large could increase your risk of side effects such as glare and halos.
- Stability of prescription. Your prescription should be stable for at least 12 months before the procedure. For this reason, teens and younger folks are not good LASIK candidates 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
Although there may be factors that may keep a patient from being a good candidate for LASIK immediately, the good news is that patients who were not deemed good candidates years ago can now enjoy a clearer vision as new techniques are refined and introduced.
Find out if your prescription and overall eye health make you a good laser vision surgery candidate by scheduling a consultation with one of our LASIK specialists across Arizona. A thorough in-person assessment and evaluation is the best way to gauge whether LASIK is right for you.