About Your Vision FAQ
If you don't see your question or topic addressed here, check with your doctor.
What kinds of vision problems can traditional LASIK correct?
Depending on which laser system is used, LASIK surgery can help if you are nearsighted, farsighted, or have a condition known as astigmatism. Surgery can treat these vision problems in most cases, but certain health problems may exclude you from being a good candidate. Your eye specialist can evaluate and diagnose your vision problems, and can tell you whether or not traditional LASIK surgery is for you.
What are lower order aberrations?
Lower order aberrations are the common vision problems that affect over half the population of the United States, including nearsightedness (myopia), farsightedness (hyperopia), and astigmatism.
What is nearsightedness, or myopia?
When you have more trouble seeing distant images clearly than close-up images, you may be nearsighted (myopia). If you are nearsighted, light rays from distant images do not focus to a precise point on the retina. It can also occur in combination with astigmatism. For more information, see common vision problems. LASIK can help correct these conditions.
What is farsightedness, or hyperopia?
When you have more trouble seeing close-up images clearly, you may be farsighted (hyperopia). If you are farsighted, light rays from distant images focus behind the retina. It can also occur in combination with astigmatism. For more information, see common vision problems. LASIK can help correct these conditions.
What is astigmatism?
When images focus on different points in front of or behind your retina, images both near and far may appear blurry. This condition is astigmatism. When astigmatism is combined with farsightedness, or hyperopia, it is called hyperopic astigmatism. When combined with nearsightedness, or myopia, it is called myopic astigmatism. Mixed astigmatism occurs when the astigmatism is both hyperopic and myopic or when the eye has characteristics of both nearsightedness and farsightedness. For more information, see common vision problems. LASIK can help correct all these conditions.
What are higher order aberrations?
Higher order aberrations are a range of common vision problems that affect the quality of your vision. Ophthalmic experts believe these problems affect visual quality, especially in low-light situations. They believe higher order aberrations can contribute to night vision problems like glare and halos.
What is coma?
Coma is a higher order aberration that makes objects appear to have a comet-shaped pattern, which creates blurring in your vision.
What is spherical aberration?
Spherical aberration reflects a change in curvature between the center and edge of the pupil. This can cause halos in your vision.
What is secondary astigmatism?
Secondary astigmatism is a higher order aberration that can create multiple focal points and blurs your vision.
What is presbyopia?
Presbyopia, a natural phenomenon caused by aging, occurs due to the physiological stiffening of the lens inside the eye. (It's the reason so many people start to need reading glasses around the age of 40.)
Glossary Entries
LASIK: An acronym for Laser In-Situ Keratomileusis. LASIK is a type of laser surgery in which the cornea is reshaped to improve vision. A device called a microkeratome is used to surgically create a thin, hinged flap of corneal tissue. The flap is folded back, the laser is directed to the corneal surface exposed beneath the flap and the flap is brought back into place.
nearsightedness: A common term for myopia. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance.
farsightedness: A common term for hyperopia, a vision problem that most commonly results in blurred close vision. Moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly on, the retina.
astigmatism: A vision problem that results in blurred distance and/or near vision. Light rays entering the eye are bent unequally, which prevents the formation of a sharp point of focus on the retina. This creates a blurring of parts of objects you see.
lower order aberrations: A collective term for a series of common vision problems including myopia, hyperopia and astigmatism.
myopia: Another term for nearsightedness. A condition of the eye that results in blurred distance vision. The cornea and lens focus light rays from distant objects in front of the retina. This incorrect focusing of light results in blurred images of objects at a distance.
hyperopia: A vision problem, commonly called farsightedness, that results in blurred close vision although moderate to severe hyperopia may also result in blurred distance vision. The cornea and lens focus light rays behind, rather than directly onto, the retina.
ophthalmic: Pertaining to the eye.
coma: A higher order aberration which makes items appear to have a comet-shaped ”tail”, creating blurring in your vision.
spherical aberration: A visual disorder reflecting a change in curvature between the center and edge of the pupil. This creates multiple focal points and can cause halos in your vision.
Glossary
Confused on LASIK jargon? Click on terms in bold to pull up the glossary tab.
Myopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 18 years of age or older for the reduction or elimination of myopic refractive errors up to -12.0 diopters (D) of sphere with and without astigmatic refractive errors up to -6.0 D; and in patients with documented evidence of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 901 eyes treated, of which 813 of 866 eligible eyes were followed for 12 months. Accountability at 3 months was 93.8%, at 6 months was 91.9%, and at 12 months was 93.9%.
d. The studies found that of the 844 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 3-month stability time point, 98.0% were corrected to 20/40 or better, and 84.4% were corrected to 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months posttreatment: visual fluctuations (12.8% at baseline versus 28.6% at 3 months).
f. Long-term risks of LASIK for myopia with and without astigmatism beyond 12 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of myopic refractive errors up to -12.0 diopters (D) of sphere with and without astigmatic refractive errors up to -6.0 D at the spectacle plane.”
Hyperopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 18 years of age or older for the reduction or elimination of hyperopic refractive errors up to +6.0 diopters (D) of sphere with and without astigmatic refractive errors up to 5.0 D at the spectacle plane, with a maximum manifest refraction spherical equivalent (MRSE) of +6.0 D; and in patients with documented evidence of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery, exclusive of changes due to unmasking latent hyperopia.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 290 eyes treated, of which 100 of 290 eligible eyes were followed for 12 months. Accountability at 3 months was 95.2%, at 6 months was 93.9%, and at 12 months was 69.9%.
d. The studies found that of the 212 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point, 95.3% were corrected to 20/40 or better, and 67.5% were corrected to 20/20 or better without spectacles or contact lenses.
e. The study showed that the following subjective patient adverse events were reported as “much worse” by at least 1% of the subjects (in order of increasing frequency) at 6 months post final treatment: glare from bright lights (3.0%); night driving glare (4.2%) light sensitivity (4.9%); visual fluctuations (6.1%); and halos (6.4%).
f. Long term risks of LASIK for hyperopia with and without astigmatism beyond 12 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of hyperopic refractive errors up to +6.0 diopters (D) of sphere with and without astigmatic refractive errors up to 5.0 D with a maximum manifest refraction spherical equivalent (MRSE) of +6.0 D.”
Mixed Astigmatism:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System to perform LASIK treatments in patients 21 years of age or older for the reduction or elimination of naturally occurring mixed astigmatism of up to 6.00 D at the spectacle plane; and in patients with documentation of a stable manifest refraction defined as less than or equal to 0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), and other refractive surgeries.
c. Approval of the application is based on clinical trials in the United States with 162 eyes treated, of which 111 were eligible to be followed at 6 months. Accountability at 1 month was 99.4%, at 3 months was 96.0%, and at 6 months was 100.0%.
d. The studies found that of the 142 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 3-month stability time point, 95.8% achieved acuity of 20/40 or better, and 67.6% achieved acuity of 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months post-treatment: sensitivity to light (43.3% at baseline versus 52.9% at 3 months); visual fluctuations (32.1% at baseline versus 43.0% at 3 months); and halos (37.0% at baseline versus 42.3% at 3 months).
f. Long term risks of LASIK for mixed astigmatism beyond 6 months have not been studied.
g. The safety and effectiveness of LASIK surgery has ONLY been established with an optical zone of 6.0 - 7.0 mm and an ablation zone of 9.0 mm.
h. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System for laser assisted in-situ keratomileusis (LASIK) treatments of naturally occurring mixed astigmatism of up to 6.00 D at the spectacle plane.”
Wavefront-Guided Treatment of Myopia:
a. Approval of the premarket approval application is for the WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System used in conjunction with the WaveLight® ALLEGRO Analyzer® device. The device uses a 6.5 mm optical zone, a 9.0 mm ablation/treatment zone, and is indicated for wavefront-guided (WFG) laser assisted in-situ keratomileusis (LASIK): 1) for the reduction or elimination of up to -7.00 diopters (D) of spherical equivalent myopia or myopia with astigmatism, with up to -7.00 D of spherical component and up to 3.00 D of astigmatic component at the spectacle plane; 2) in patients who are 18 years of age or older; and 3) in patients with documentation of a stable manifest refraction defined as ≤0.50 D of preoperative spherical equivalent shift over one year prior to surgery.
b. LASIK is an elective procedure with the alternatives including but not limited to eyeglasses, contact lenses, photorefractive keratectomy (PRK), traditional LASIK and other refractive surgeries.
c. Approval of the application is based on a randomized clinical trial in the United States with 374 eyes treated; 188 with wavefront-guided LASIK (Study Cohort) and 186 with Wavefront Optimized® LASIK (Control Cohort). 178 of the Study Cohort and 180 of the Control Cohort were eligible to be followed at 6 months. In the Study Cohort, accountability at 1 month was 96.8%, at 3 months was 96.8%, and at 6 months was 93.3%. In the Control Cohort, accountability at 1 month was 94.6%, at 3 months was 94.6%, and at 6 months was 92.2%.
d. The studies found that of the 180 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point in the Study Cohort, 99.4% were corrected to 20/40 or better, and 93.4% were corrected to 20/20 or better without spectacles or contact lenses. In the Control Cohort, of the 176 eyes eligible for the uncorrected visual acuity (UCVA) analysis of effectiveness at the 6-month stability time point, 99.4% were corrected to 20/40 or better, and 92.8% were corrected to 20/20 or better without spectacles or contact lenses.
e. The clinical trials showed that the following subjective patient adverse events were reported as “moderate to severe” at a level at least 1% higher than baseline of the subjects at 3 months post-treatment in the Study Cohort, light sensitivity (37.2% at baseline versus 47.8% at 3 months) and visual fluctuations (13.8% at baseline versus 20.0% at 3 months). In the Control Cohort, halos (36.6% at baseline versus 45.4% at 3 months) and visual fluctuations (18.3% at baseline versus 21.9% at 3 months).
f. Long term risks of wavefront-guided LASIK for myopia with and without astigmatism beyond 6 months have not been studied.
g. Note that the complete name for this ophthalmic laser is “WaveLight® ALLEGRETTO WAVE® / ALLEGRETTO WAVE® Eye-Q Excimer Laser System used in conjunction with the WaveLight® ALLEGRO Analyzer® device. The device uses a 6.5 mm optical zone, a 9.0 mm ablation/treatment zone, and is indicated for wavefront-guided (WFG) laser-assisted in-situ keratomileusis (LASIK): 1) for the reduction or elimination of up to -7.00 diopters (D) of spherical equivalent myopia or myopia with astigmatism, with up to -7.00 D of spherical component and up to 3.00 D of astigmatic component at the spectacle plane; 2) in patients who are 18 years of age or older; and 3) in patients with documentation of a stable manifest refraction defined as ≤0.50 D of preoperative spherical equivalent shift over one year prior to surgery.”