Condition Library
Astigmatism
Astigmatism gets treated as an exotic diagnosis by patients and it is nothing of the sort. Most people have some. It simply means the eye's surface is not perfectly spherical, so light entering it focuses at more than one point rather than one.
The practical consequence is blur and distortion at all distances rather than only near or far, often with a stretched or smeared quality rather than a simple softness.
Symptoms
- Blurred or distorted vision at all distances
- Eye strain and fatigue, particularly after sustained visual work
- Headaches
- Squinting
- Difficulty seeing at night, with streaking around lights
- Frequently, no symptoms at all when the amount is small
Causes and risk factors
- Naturally occurring corneal shape, which is by far the most common
- Genetics, since it commonly runs in families
- Keratoconus and other corneal conditions, in irregular astigmatism
- Eye injury or scarring
- Complications following eye surgery
Treatment
- Glasses with a cylindrical correction
- Toric soft contact lenses, designed to stay in a stable rotational orientation
- Rigid gas permeable lenses for higher amounts
- Scleral lenses for irregular astigmatism from keratoconus or surgery
- Orthokeratology for suitable low to moderate amounts
- Refractive surgery in adults with a stable prescription
- Toric lens implants during cataract surgery
Getting the most from your correction
- Have the axis rechecked if your vision seems slightly off, since astigmatism correction is orientation-dependent and a few degrees matters.
- Have your frames adjusted when they drift, because a tilted frame changes the effective axis of your correction.
- Ask about toric contact lenses if you have been told astigmatism rules them out, since that advice is frequently out of date.
- Ask for corneal topography if your astigmatism is increasing or the axis keeps shifting, to rule out keratoconus.
- Consider anti-reflective coating, which noticeably improves night vision where astigmatism causes streaking around lights.
- Do not assume small amounts need correcting. If it is not affecting your vision or comfort, it may not be worth treating.
Common misunderstandings about astigmatism
- That it rules out contact lenses. It does not, and it has not for many years. Toric soft lenses correct most astigmatism well, including in daily disposables. If you were told otherwise more than a few years ago, the advice is out of date.
- That it is caused by reading in bad light or sitting too close to a screen. It is not. Astigmatism is the natural shape of the cornea in most cases and it commonly runs in families.
- That it is rare or unusual. Most people have some. Small amounts are so common as to be unremarkable, and it is only clinically interesting when it is large enough to affect vision or is changing.
- That any amount is worth correcting. Small amounts frequently cause no symptoms and correcting them changes nothing. What matters is whether it is affecting your vision or comfort, not the number on the prescription.
Regular versus irregular astigmatism
This distinction matters more than the amount, and it rarely gets explained. Regular astigmatism means the cornea is curved unevenly but in a predictable, symmetrical way, like the back of a spoon. It is fully correctable with a cylindrical lens in glasses or a toric contact lens.
Irregular astigmatism means the surface is distorted unpredictably, which happens in keratoconus, after corneal injury or scarring, and sometimes after surgery. A cylindrical lens cannot correct it, because a cylindrical lens is itself regular. This is why some patients with high astigmatism are corrected easily and others are never satisfied with any pair of glasses.
Corneal topography distinguishes the two immediately. If your astigmatism is high, increasing, or your glasses have never quite worked, that is the test worth asking for.
Getting the correction right
Astigmatism correction is axis-dependent, which means the orientation of the correction has to match the orientation of your cornea. A few degrees off and the correction degrades noticeably, which is why fitting accuracy matters more with astigmatism than with a simple spherical prescription.
In contact lenses this is why toric designs are engineered to stay in a stable rotational position rather than spinning freely, and why the fitting focuses on rotational stability rather than only on power. A toric lens that rotates on blink gives fluctuating vision, and that is a fitting problem rather than a reason to give up on lenses.
In glasses it is why the fitting measurements and the frame adjustment matter. A frame that sits tilted changes the effective axis of your correction, which is one reason a technically correct prescription can still feel wrong.
When to see an optometrist
Book an exam if vision is blurred at all distances, if you get eye strain after visual work, or if your astigmatism has been increasing, which warrants corneal topography to rule out keratoconus. If you are being examined because your vision has changed, bring your current and previous glasses. Comparing prescriptions over time tells us whether the astigmatism is stable or moving, and a moving axis is the finding that prompts corneal topography to rule out keratoconus. That distinction changes the whole management plan, so it is worth establishing early rather than after several more prescription updates.
Related conditions
- Myopia (Nearsightedness)Nearsightedness is the eye growing too long. Why the final prescription matters for lifetime eye health, and how progression is slowed in children.
- KeratoconusKeratoconus thins and bulges the cornea, distorting vision glasses cannot fix. Why early detection and cross-linking matter so much.
This page is general educational information, not medical advice or a diagnosis. It is not a substitute for an examination. If you are experiencing sudden vision loss, eye pain or an eye injury, contact us immediately or go to an emergency room.
Astigmatism questions
Can I wear contact lenses with astigmatism?
Almost certainly yes. Toric soft lenses correct most astigmatism well. If you were told years ago that astigmatism ruled you out, that advice is out of date.
Does astigmatism get worse?
It usually stays fairly stable in adults and can change gradually. Astigmatism that is increasing noticeably, particularly with a shifting axis, warrants corneal topography to rule out keratoconus.
What causes astigmatism?
Most commonly it is simply the natural shape of the cornea, and it often runs in families. It is not caused by reading in low light or sitting close to a screen.
Can astigmatism be corrected permanently?
In adults with a stable prescription, refractive surgery can correct regular astigmatism. During cataract surgery, a toric implant corrects it at the same time.
Book an appointment with a doctor who has time for you
We schedule 2 patients an hour, so your exam is unhurried and your questions get answered. Most patients are seen within a few days.