Doctors use LASIK to correct a number of vision issues, including farsightedness, nearsightedness and astigmatism. However, like all medical procedures, LASIK isn’t for everyone and cannot treat all vision-related conditions. Read on to learn about conditions commonly treated with LASIK and talk to your doctor about your specific case.
Farsightedness, or hyperopia, means that up-close objects tend to be blurry, but distant objects are clear. Under normal circumstances, light is focused on the retina, but with this issue, it is focused behind the retina. This occurs as a result of weak focusing power or a small eyeball. The lack of focus also occurs if the cornea isn’t curved enough.
Laser vision correction treats farsightedness by creating more curvature in the cornea. The laser targets the central corneal tissue and changes the profile of the curve. Corneal tissue is removed to create greater curvature, which improves the way light focuses on the retina.
Nearsightedness, or myopia, is the opposite of farsightedness. Nearby objects may be clear, while distant objects are blurry. Again, this is caused by improperly focused light hitting the retina — the eye’s optical length is not as long as its physical length. To correct this, doctors make the corneal tissue less curved.
LASIK for nearsightedness works by removing tissue from the inner layers of the cornea. The doctor removes a precise amount of tissue from the cornea with a laser, reshaping the cornea to flatten out excessive curvature.
Presbyopia starts affecting most people when they reach middle age. It is characterized by difficulty focusing on objects that are nearby, making it hard to read or do close-up tasks. This occurs as a result of a loss of flexibility of the crystalline lens of the eye. Presbyopia is a normal result of aging and is not a disease.
Some surgeons have used the same LASIK procedure that corrects nearsightedness to treat presbyopia. Some consider this controversial, because the surgery may improve distance vision while possibly making up-close vision worse. Another option is a LASIK procedure called monovision. This treatment optimizes one eye for close-up vision and optimizes the other eye for distance vision.
As with other LASIK procedures, monovision is not for everyone. It takes time for patients to become accustomed to the “unbalanced” vision. In fact, patients wanting monovision must do a trial run with contacts to ensure they can adapt to this new way of seeing.
Patients with astigmatism have corneas shaped like a football instead of a baseball. This prevents light from being able to properly focus on the retina, and distance vision is blurry as a result. Most people have some degree of astigmatism, but the condition is so slight, treatment isn’t necessary.
Many people with astigmatism are also farsighted or nearsighted. This combination is referred to as a refractive error, because the eyes cannot properly refract (or bend) light when it enters the eye. It is not fully known what causes this eye condition — it can be present at birth and can also be hereditary. When it’s present at birth, astigmatism can get better or worse over time.
LASIK corrects astigmatism by flattening the abnormal corneal curve. This causes the cornea to become more spherical, so it properly refracts light entering the eye.
Talk to your doctor about your specific condition and ask if there are possible treatments that can improve your vision.