Astigmatism: Causes, Symptoms, and Treatment Options
Understanding Astigmatism and What Causes It
Understanding what astigmatism is and where it comes from can help you make sense of your symptoms and feel confident in your care. Astigmatism is a refractive error, meaning it affects how your eye focuses light rather than being a disease or injury to the eye itself. Knowing the type and cause of your astigmatism helps us recommend the most effective treatment plan for you.
In a healthy eye, the cornea is round and smooth, like a basketball. With astigmatism, the cornea is shaped more like a football, curved more steeply in one direction than another. This uneven shape scatters light as it enters the eye, sending it to multiple points on the retina instead of one. The result is blurry, distorted, or smeared vision at all distances, not just up close or far away.
People with astigmatism often squint to try to see more clearly. This extra effort taxes the eye muscles and can lead to persistent eye strain, headaches, and fatigue, especially after reading or extended screen time.
Most people are born with some degree of astigmatism because of the natural shape of their cornea or lens. The condition tends to run in families, so if one or both parents have it, there is a higher chance their children will too. In some cases, astigmatism can develop or change after an eye injury, certain eye conditions, or eye surgery that alters the shape of the cornea.
- Genetic factors inherited from parents
- The natural, slightly uneven curve of the cornea present from birth
- Eye injury or trauma that changes the cornea's shape
- Keratoconus, a condition where the cornea gradually thins and bulges outward
- Scarring from prior eye infections or surgeries
We classify astigmatism based on which part of the eye has an irregular shape. Corneal astigmatism means the front surface of the eye is unevenly curved. Lenticular astigmatism occurs when the lens inside the eye, rather than the cornea, has an irregular shape.
You may also hear the terms regular and irregular astigmatism. Regular astigmatism, the most common type, can typically be corrected with standard eyeglasses or contact lenses. Irregular astigmatism often results from corneal scarring or conditions like keratoconus and may require specialty lenses or other treatments.
Astigmatism can develop in anyone, but some people are at higher risk. Children with a family history of the condition may need correction early in life. Astigmatism also frequently occurs alongside other refractive errors such as nearsightedness (difficulty seeing far away) or farsightedness (difficulty seeing up close).
- Individuals with a parent or sibling who has astigmatism
- Those who also have nearsightedness or farsightedness
- People who have experienced eye trauma or corneal scarring
- Patients with keratoconus or other corneal conditions
Recognizing the Signs of Astigmatism
Astigmatism does not always cause obvious symptoms, especially when it is mild. When symptoms are present, they often overlap with other vision problems, which is why a comprehensive eye exam is the only reliable way to confirm a diagnosis. Being aware of common signs can help you know when to seek care.
The most telling sign of astigmatism is blurry or distorted vision that does not improve simply by moving closer to or farther from an object. You might notice that letters look tilted, edges appear fuzzy, or straight lines seem wavy or curved. This happens because light entering your eye is not focusing to a single sharp point on your retina.
Unlike nearsightedness (where only distant objects blur) or farsightedness (where close-up tasks are harder), astigmatism can affect your sharpness at every distance. Many people are unaware they have it until a routine eye exam reveals the problem.
Your eyes work constantly to compensate for the distorted images caused by astigmatism. This ongoing effort can leave your eyes feeling tired, achy, or sore, particularly after reading, working at a computer, or driving. Frequent headaches around the forehead or temples are another common complaint, especially after tasks that require sustained visual focus.
- Burning or aching sensation in or around the eyes
- Headaches after reading or extended screen use
- Difficulty concentrating on detailed work
- Feeling unusually tired after visual tasks
Many people with astigmatism find their vision worsens in low-light conditions. Streetlights, car headlights, and other bright points of light may appear to have starbursts, streaks, or halos radiating outward. This happens because pupils widen in dim light, allowing more unfocused light to enter the eye and making the effects of astigmatism more noticeable.
Night driving can become particularly challenging when oncoming headlights cause glare and visual distortion. If you experience these symptoms, let our team know so we can evaluate your prescription and discuss options to improve your night vision.
Most astigmatism develops gradually and does not require urgent attention. However, sudden changes in vision, severe eye pain, flashes of light, or a curtain-like shadow spreading across your field of view are warning signs of more serious conditions. If you experience any of these symptoms, contact an eye care provider right away.
Rapid worsening of blurry vision or new blurriness in one eye may signal a problem beyond astigmatism. Our team can evaluate your symptoms and determine whether you need immediate care or additional testing.
How We Diagnose Astigmatism
Diagnosing astigmatism is straightforward and comfortable during a comprehensive eye exam. We use several tools and tests to measure not just whether you have astigmatism, but how much you have and exactly where the irregular curve is located. This detail guides us in creating the most accurate prescription for your needs.
Your exam begins with a conversation about your symptoms, family eye history, and any changes you have noticed in your vision. From there, we check how clearly you can see at different distances, evaluate how your eyes work together, and examine the front and back of each eye for signs of disease or damage.
- Reviewing your personal and family eye health history
- Measuring visual acuity at multiple distances using an eye chart
- Assessing eye alignment and how well both eyes work as a team
- Examining the cornea, lens, and retina for any signs of underlying conditions
A refraction test is the key step for measuring astigmatism precisely. You will look through a device called a phoropter while we rotate different lenses in front of your eyes and ask which option makes letters on the chart appear clearest. This process identifies how much astigmatism you have and determines the exact prescription strength needed to correct your vision.
The refraction test also reveals whether nearsightedness or farsightedness is present alongside your astigmatism. A single pair of eyeglasses or contact lenses can correct all three refractive errors at once.
To map the exact contours of your cornea, we use an instrument called a keratometer or corneal topographer. This device shines a ring of light onto the cornea and measures how the reflection returns, revealing where the surface is steeper or flatter than a normal, evenly rounded shape. The measurement is quick and completely painless.
Corneal mapping is especially useful if you are considering contact lenses or refractive surgery, because it shows us the precise shape of your eye and helps us determine the best correction method for your unique anatomy.
Your eyeglass or contact lens prescription includes three main numbers for each eye. The first number (the sphere) indicates the degree of nearsightedness or farsightedness. The second number (the cylinder) measures the amount of astigmatism. The third number (the axis) identifies the angle of the irregular curve in degrees.
- Sphere value for nearsightedness or farsightedness correction
- Cylinder value for the degree of astigmatism present
- Axis number indicating the direction of the astigmatic curve
- Additional values for reading correction if multifocal lenses are needed
Treatment Options for Astigmatism
Astigmatism is highly treatable, and most patients have several options to choose from depending on their lifestyle, the severity of their condition, and their long-term vision goals. Our team works with you to find the correction method that best fits your daily life. Whether you prefer the simplicity of glasses, the convenience of contacts, or a more permanent solution, we can help.
Eyeglasses are the most straightforward way to correct astigmatism. Your lenses are made with a special cylindrical curve that compensates for the irregular shape of your cornea or lens, allowing light to focus properly on your retina. Most patients notice an immediate improvement in sharpness and clarity after putting on their corrective lenses for the first time.
Modern lens technology can address even higher levels of astigmatism while keeping lenses thin and lightweight. Anti-glare coatings, blue light filters, and photochromic (light-adjusting) lenses can all be added for extra comfort depending on your needs.
If you prefer contact lenses, toric lenses are designed specifically to correct astigmatism. Unlike standard contact lenses, toric lenses have different powers in different zones and are weighted or shaped to stay correctly positioned on your eye throughout the day. We carefully measure your cornea to ensure the best possible fit and comfort.
- Soft toric lenses for mild to moderate astigmatism
- Rigid gas permeable lenses for higher or irregular astigmatism
- Hybrid lenses with a rigid center and soft outer edge for added comfort
- Scleral lenses that vault over the cornea for complex or irregular cases
Laser vision correction can permanently reshape the cornea to reduce or eliminate astigmatism. Procedures such as LASIK and PRK use a precision laser to remove small amounts of corneal tissue, smoothing out the irregular curve. Advanced wavefront imaging allows us to create highly customized treatment plans tailored to the specific shape of each patient's eye.
Not every patient is a candidate for laser surgery. We carefully evaluate corneal thickness and health, prescription stability, and overall eye health before recommending any refractive procedure. For patients who are not good candidates for laser treatment, alternatives such as implantable lenses may be considered.
If your astigmatism is very mild and does not affect your comfort or daily activities, we may recommend monitoring your vision over time rather than prescribing correction right away. Many people have small amounts of astigmatism that cause no noticeable symptoms and do not interfere with their quality of life.
We will schedule regular eye exams to track whether your astigmatism changes or begins to affect your vision. If you develop blurry vision, headaches, or eye strain, we can prescribe glasses or contact lenses at that point to restore your comfort and clarity.
Managing Astigmatism Day to Day
Living well with astigmatism is manageable once you have the right prescription and understand how to care for your eyes and your correction. Small daily habits can protect your vision and help you get the most out of your glasses or contact lenses. Our team is here to support you through every step, from your first fitting to long-term follow-up care.
It may take several days for your eyes and brain to adapt to a new prescription, particularly if this is your first time wearing correction for astigmatism. You might temporarily notice that straight lines look slightly off or that your depth perception feels different. These sensations are normal and typically resolve within one to two weeks as your visual system adjusts.
Wearing your new glasses or contacts consistently during the adjustment period helps speed up the process. If blurry vision, dizziness, or discomfort continues beyond two weeks, contact our office so we can check the accuracy and fit of your prescription.
Proper contact lens care is essential for keeping your eyes healthy and your vision clear. Always wash and dry your hands thoroughly before handling lenses, and use only the lens solution recommended by your eye care provider. Never rinse lenses with tap water or sleep in your contacts unless they are specifically approved for overnight wear.
- Clean and store lenses with fresh solution every day
- Replace your lens storage case at least every three months
- Follow the replacement schedule for your specific lens type (daily, biweekly, or monthly)
- Remove lenses immediately if your eyes become red, painful, or irritated
- Never use saliva or tap water on your contact lenses
For adults with stable astigmatism, we typically recommend comprehensive eye exams every one to two years. Children and teenagers often need more frequent visits because their eyes are still growing and prescriptions can change quickly during these years. Contact lens wearers benefit from annual exams so we can monitor corneal health and update the lens fit as needed.
Patients with certain eye conditions, rapidly changing prescriptions, or those considering refractive surgery may need more frequent monitoring. We will create a personalized follow-up schedule based on your age, eye health, and vision goals.
Even with correction in place, astigmatism can change gradually as you age. Pay attention to any new blurriness, increased sensitivity to glare, or difficulty with tasks that used to feel easy. If your current glasses or contacts no longer provide clear vision, schedule an appointment so we can update your prescription.
Sudden changes in vision can sometimes signal conditions beyond astigmatism. Let our team know right away if you notice new flashes of light, floating spots, or a loss of peripheral (side) vision so we can evaluate your eyes promptly.
Frequently Asked Questions
Here are answers to questions we hear often about astigmatism. These address specific situations and decisions that go beyond the general information covered above.
Astigmatism can shift throughout your life, though many adults find it stays relatively stable for long periods. Hormonal changes, aging of the lens, or a progressive corneal condition like keratoconus can cause it to increase more noticeably. This is one reason we emphasize regular exams, because catching a change early allows us to update your correction before it begins to affect your daily vision or quality of life.
Most children do not fully outgrow astigmatism, though small amounts may change as the eyes develop. Leaving significant astigmatism uncorrected in childhood can interfere with visual development and contribute to amblyopia, commonly called lazy eye, where one eye does not develop normal visual strength. Early correction with glasses protects your child's vision during the critical learning years and gives us the opportunity to monitor any changes as they grow.
Astigmatism itself is a refractive error and does not damage the eye or cause blindness. However, when left uncorrected in young children, it can lead to amblyopia, which involves reduced vision in one eye that can become harder to treat if not caught early. In adults, uncorrected astigmatism does not cause structural damage, but it does affect quality of life and functional vision. Wearing your prescribed correction consistently keeps your vision sharp and prevents unnecessary strain.
No. Nearsightedness and farsightedness are caused by the overall length of the eyeball being too long or too short. Astigmatism is caused by an uneven curve in the cornea or lens, regardless of eye length. The conditions are separate but very commonly occur together. A single pair of correctly prescribed glasses or contact lenses can address all three refractive errors at once, so having astigmatism alongside another refractive error does not necessarily mean more complicated treatment.
The uneven corneal surface scatters incoming light in multiple directions rather than focusing it cleanly. At night, your pupils dilate (open wider) to let in more light, which amplifies this scattering effect and makes starbursts, streaks, and halos around lights more pronounced. Correcting your astigmatism with glasses, contact lenses, or laser surgery typically reduces or eliminates these visual disturbances, which can make nighttime driving significantly more comfortable and safer.
Standard spherical contact lenses are not designed to correct the directional irregularity of astigmatism and typically will not provide clear vision on their own. Toric contact lenses, which are built with the precise orientation needed to compensate for your specific astigmatism, are usually the appropriate choice. For irregular astigmatism, rigid or scleral lenses may offer better clarity. Our optometry team will measure your cornea carefully and fit you with the lens type that gives you the sharpest, most comfortable vision for your level of astigmatism.
See Clearly With Expert Astigmatism Care
If blurry vision, eye strain, or difficulty seeing clearly at any distance is affecting your daily life, we encourage you to schedule a comprehensive eye exam with our team at Rhode Island Eye Institute. Our specialists have the training, technology, and experience to accurately diagnose your astigmatism and recommend the treatment option best suited to your vision, lifestyle, and long-term eye health. We are proud to serve patients throughout Rhode Island and southeastern Massachusetts and are committed to helping you see your world clearly and comfortably.