Is there a prescription limit for Laser Eye Surgery?
Do you think the numbers on your little prescription card determine whether or not you’re eligible for Laser Eye Surgery?
This is the general idea many people have about being suitable for Laser Eye Surgery. But the reality is, determining eligibility is a lot more involved than that.
This goes to say that if you find yourself thinking your prescription isn’t treatable and that you’re outside of the general limits for Laser Eye Surgery, don’t fret; you probably are suitable. Besides, there are other options available to you.
That being said, it helps to know the limits to get an idea of your suitability. So let’s dive into the prescription limits for the three most common refractive errors: near-sightedness, far-sightedness, and astigmatism.
The prescription limit for near-sighted, or shortsightedness
Myopia, also known as near or short-sightedness, is the most common vision impairment in the world. It’s also becoming more common, with some studies suggesting that by 2050 about half the people on the planet will be myopic.
You know you are near-sighted when you have difficulty seeing objects at a distance, such as a road or street signs.
Myopia is indicated on your prescription card with a negative (-) “diopter” value. A diopter is the unit of measurement for the optical power of the cornea.
Typically, a clinic will qualify patients for LASIK starting from -0.5 D of myopia. Below 0.5 D of myopia, people need glasses only rarely, so LASIK is usually not recommended unless you also have some degree of astigmatism.
The maximum prescription is a little less defined. For instance, most clinics can treat patients with moderate to severe myopia up to about -8.0 D. However, for patients at the high end with severe myopia, you also need thick, healthy corneas. The procedure involves removing more tissue for higher correction.
However, some clinics can treat beyond -8.0 D of myopia using next-generation technology. For example, with ReLEx SMILE, surgeons can treat people with thinner corneas and prescriptions of higher than -10 D.
The prescription limit for far-sighted, or hyperopia
Hyperopia, hypermetropia, long-sightedness, or far-sightedness is another common vision problem that affects about a quarter of the population. In contrast to myopia, you know you have hyperopia because you have difficulty seeing and focusing on objects in your near field of vision.
Other common signs of hyperopia include headaches, eye strain, or feeling fatigued when doing tasks that involve a lot of up-close work like using your phone or computer.
As it presents in young people, hyperopia is different from the type of far-sightedness that appears around the mid-40s. This is a condition called presbyopia and, although it involves many of the same symptoms, requires a different solution.
Hyperopia is measured in positive (+) diopters. Like myopia, most clinics don’t perform LASIK on patients with very mild hyperopia,, i.e. less than +1.00 diopters, unless there is also some degree of astigmatism.
The prescription limit for treating hyperopia with LASIK is typically somewhere around 3 to 4 D. Most clinics don’t treat severely hyperopic patients, +5 or over, as they do not have the technology or expertise to do so safely.
As with other prescriptions, however, your eligibility for Laser Eye Surgery varies according to several other factors, including the clinic you go to. Clinics with access to the leading technology and expertise can treat hyperopic prescriptions up to +7 D.
The prescription limit for astigmatism
Although myopia is considered the most common refractive error, astigmatism takes the official crown because nobody’s eyes are perfectly spherical, so pretty much everyone has some degree of astigmatism.
Astigmatism is when the cornea, the clear front cover of the eye, is curved more like a rugby ball than a football. Having such an irregularly shaped cornea prevents light from focusing perfectly on the retina. Astigmatism may cause blurry vision, eye strain, or headaches.
Astigmatism frequently accompanies myopia or hyperopia. It is shown on your prescription card in positive or negative diopters, though it indicates a different type of error from a myopic or hyperopic prescription.
Whether it appears on its own or alongside other refractive errors, Laser Eye Surgery can typically treat astigmatism of up to 6.0 D.
As with myopia and hyperopia, the treatable range of astigmatism can vary between clinics. As it requires correction in more than one plane, the refractive error is slightly more complex to treat. But with the right technology and level of expertise, virtually all astigmatism symptoms are treatable, high astigmatism cases are routine.
Ultimately, there is no hard and fast line to say what the prescription limit is for Laser Eye Surgery. It all depends on various factors and requires a thorough assessment on an individual basis to know if it is right for you.
The best way to find out if your prescription is suitable for Laser Eye Surgery is through a thorough eye examination. Why not come in and see us.