Laser eye surgery can treat nearsightedness, farsightedness and astigmatism. However, LASIK eligibility depends on the severity of your visual errors. LASIK can treat most people in the standard range for common refractive errors, but not some people with extreme conditions. There may be other options available if you are outside the recommended limits for LASIK correction.
Prescription by Diopters
Common refractive errors like myopia, hyperopia, and astigmatism are measured in diopters (D). A prescription of 0.0 D, also called "plano" would be very good vision; the further from 0, the stronger the error in your vision. A prescription of + or -5.0 D is stronger than + or -3.0 D.
Myopia, or Nearsightedness
Myopia is the most common type of refractive error and makes it hard to focus on objects at a distance. Myopic prescriptions are indicated with negative diopter values. If a patient is otherwise a good candidate, Woodhams Eye Clinic will consider LASIK for patients starting with -0.5 D nearsightedness. Below this, most patients need glasses only rarely, so LASIK is usually not recommended unless there is also some degree of astigmatism as well.
Woodhams can treat patients with moderate to severe myopia up to about -8.0 D. For patients with severe myopia, LASIK eligibility requires thick, healthy corneas, as the procedure involves removing more tissue for higher correction.
Hyperopia, or Farsightedness
Hyperopia is a refractive error that is present in young patients, which makes it difficult to focus on objects up close. In patients who develop this symptom at about the age of 40, this is a condition called Presbyopia. LASIK can not restore the ability to see up close in patients over 40 without giving up the ability to see well at a distance.
Hyperopic lenses are measured in positive diopter prescriptions. As with myopia, Woodhams does not usually perform LASIK on patients with very mild farsightedness less than 0.5 D unless there is some degree of astigmatism as well. Also, patients who are extremely hyperopic +5 or over would not usually be considered candidates for LASIK surgery.
Woodhams Eye Clinic will consider treating hyperopia up to about 3 to 4 D with LASIK. Above this level, the results may be more mixed and less predictable, according to a meta study by the American Academy of Ophthalmology. As with other errors, however, LASIK eligibility for hyperopia varies by individual based on other characteristics of the eye.
Astigmatism
Characterized by an eye that is slightly football-shaped rather than perfectly round, most people have some degree of astigmatism, which causes blurry vision. As a result, astigmatism often accompanies myopia or hyperopia. Astigmatic prescription can be expressed in positive or negative diopters, though it indicates a different type of error from the similar myopic or hyperopic prescription.
Alone or alongside other refractive errors, astigmatism up to about 3.0 D can usually be treated effectively with LASIK. Above about 3.0 D, astigmatism tends to return to some degree, after treatment.
Ultimately, your LASIK eligibility depends on the health and qualities of your unique eyes-the only way to know for sure if you are a candidate is to see an experienced LASIK surgeon.
Would you like to talk to someone here at Woodhams about LASIK? Enter your information below and one of our patient care advocates will reach out to you or you can call us at 770-394-4000.
Image source: Flickr
