Eye Health Central

What is Astigmatism? Symptoms, Causes and Treatment

What is astigmatism?

Astigmatism remains one of the most common conditions Optometrists treat on a daily basis. According to research by Johnson and Johnson, 47% of optical patients have astigmatism.

Although astigmatism is quite prevalent, a surprising number of people still don’t know a great deal about this disorder. In this post, we’ll clear up everything you need to know about astigmatism and share a few helpful strategies that you could use to help improve astigmatism symptoms. 

What Is Astigmatism?

Astigmatism is a structural disorder in the eyes that often causes blurry vision. The principal structure that’s affected in most astigmatic patients is the cornea, which refers to the clear layer that sits just above the pupil and iris. 

In non-astigmatic eyes, the corneas will be both smooth and spherical, thus allowing light to enter the eyes evenly. Astigmatic eyes, however, often have unevenly shaped corneas that warp how light penetrates the retina.  It is commonly referred to as a 'rugby ball' shaped eye - however, it is very subtle, and you cannot see it by looking at your eye.

There are two categories of Astigmatism Regular and Irregular.

Regular astigmatism
There is some evidence that suggests that regular astigmatism may be hereditary in nature, passing from parents to their children, but there's not enough information available to know for certain.

Irregular astigmatism
Often caused by damage to the eye, resulting in corneal scarring, or scattering within the crystalline lens inside the eye.

In some cases, astigmatism can be present at the time of birth, although detecting vision problems in very young children is very difficult. In other cases, astigmatism can develop later in life. It's also possible for the condition to either improve or worsen as time passes. Everyone's experience will be different.

Interestingly, doctors believe almost everyone has a slight degree of astigmatism at some point in their lives. Even though you might not notice the symptoms of this disorder, it’s fairly rare for the corneas to remain perfectly even at all times.  

While corneal astigmatism is the most common form of this disorder, there are other potential causes of astigmatism. For instance, some people suffer astigmatic symptoms due to an abnormal lens size which is referred to as lenticular astigmatism. 

No matter whether your astigmatism is caused by abnormal cornea or lens size, the symptoms are the same.

Astigmatism may be annoying, but it’s generally not considered a major threat to a patient’s vision. As long as you put one of the strategies listed below into practice, you shouldn’t have serious issues handling astigmatism symptoms.

Signs And Symptoms Of Astigmatism

For people with very minor levels of astigmatism, there may not be any obvious symptoms at all, aside from requiring a slight change in prescription to match the shape of the eye. Otherwise, there may not be any noticeable issues. For others, a severe case of astigmatism may cause

  • Blurred vision
  • Squinting
  • Headaches
  • Tired eyes

How Is Astigmatism Diagnosed By Optometrists?

A standard comprehensive eye exam is enough to detect astigmatism. The eye exam will consist of several different tests, each designed to measure a different aspect of vision and eye health. The primary tests performed during the exam are:

The Visual Acuity Test

– Probably the most recognizable eye test in the world, where lines of random letters that decrease in size are viewed from a fixed distance of 20 feet (or 6 metres). A person with normal “20/20” vision (or 6/6 in the UK) can see exactly what they are expected to see from 20 feet away. A person with 20/40 vision (6/12 in the UK), for example, can see letters clearly at 20 feet that a person with normal vision could see from 40 feet away.

The Refraction Test

– A vision testing device called a phoropter is used to determine the exact numerical value of someone’s prescription. The phoropter, which looks like a large mask with many dials and lenses, is put in front of the patient's face. While looking at the same lettered chart, different lenses are changed out with one another to find which one provides a clearer image. Through a process of elimination, the best lenses are determined, and the results are used to write a prescription for eyeglass lenses. 

The Keratometry Test

– The tool most relevant to diagnosing the cause of astigmatism in an individual, is a Keratometer. This is a device that shines a light across the surface of the cornea, to measure the exact curvature of the surface of the eye. This is used not only to detect astigmatism, but also for the proper fitting of contact lenses. In some cases, a more complex variation of this test called corneal topography may be used for a more detailed mapping of the cornea. The keratometer can give an insight as to the location of the astigmatism - often it is corneal in nature, but sometimes it can be caused by the lens inside the eye (lenticular astigmatism). This is very important information to determine the best means of correcting it with contact lenses.

Are All Astigmatism Patients Nearsighted?

Astigmatism is often related to other common eye conditions like myopia and hyperopia. Most patients first discover they have astigmatism after visiting the Optometrist for nearsightedness or farsightedness. 

Because astigmatism is so closely linked with other visual disorders, it’s often recommended eye care patients get their corneal sizes checked just to be on the safe side. This is especially true if patients are experiencing significant visual difficulties even with proper eyewear.    

Although there is a close correlation between astigmatism and other vision issues, that doesn’t mean one necessarily causes the other, there are plenty of people who don’t suffer from myopia or hyperopia and still have astigmatism.

There are, however, a few more serious eye care conditions that mimic astigmatism. Here are two severe eye conditions some patients mistakenly believe are astigmatism.   

  1. Keratoconus
    Like astigmatism, keratoconus is a disorder caused by irregularly shaped corneas. In the case of keratoconus, however, the corneas bulge out to a far greater degree than astigmatism. This elongated shape significantly alters the way light enters the patient’s eyes, which often leads to significant nearsightedness, blurred vision, and photophobia.

    Patients with mild keratoconus could potentially be treated with a good pair of eyeglasses or toric contact lenses. Those with more serious cases of keratoconus, however, might require more invasive procedures like corneal transplant surgery or prosthetic lenses to prevent the development of more serious visual difficulties.
  2. Pellucid Marginal Degeneration
    Pellucid marginal degeneration (PMD) refers to an eye disorder that causes the corneas to gradually thin out over time. The hallmark symptom of this disorder is blurred vision, but patients might not experience visual distortion until years after PMD has set in. 

    Unfortunately, since PMD isn’t as common as astigmatism or keratoconus, it’s not as well understood. Patients with PMD are most often prescribed special eyewear or contact lenses to help alleviate symptoms. If these therapies don’t work, then surgery or corneal collagen cross-linking (CXL) therapy might be an effective solution. 

How Is Astigmatism Treated?

The recommended treatment for astigmatism will depend largely on the type and severity of astigmatism in question.

A regular amount of astigmatism can be corrected with any sort of standard corrective lens - contact lenses or spectacles - while irregular astigmatism can only be rectified with special contact lenses. Laser refractive surgery, such as LASIK or PRK, can be beneficial, but can cost quite a bit more than the alternatives, and require a complicated surgical process.

There are many therapies now available for astigmatism patients to try out. Below, we’ll go over the most commonly prescribed correction possibilities for astigmatism and recommend a few natural remedies to keep your eyes healthy.

  • Prescription Eyewear
    Wearing prescription-grade glasses is the least invasive way to correct astigmatism symptoms. While wearing eyeglasses is certainly the easiest way to correct this vision disorder, it usually works best for patients with mild to moderate astigmatism.  
  • Contact lenses
    The type of contact lenses used to correct astigmatism, known as toric lenses, can come in both soft and rigid gas permeable varieties. Which lens is the right one for you will depend on the strength of the prescription, the nature of the astigmatism, as well as personal preference.

    Small amounts of astigmatism (< 0.75D) can often be ignored with soft contact lenses - most people will experience vision only slightly less clear than their glasses.

    However, if you want any astigmatism corrected up to 3.00D there are now soft lenses capable of that - even daily ones. Focus Dailies Aquacomfort Plus Toric can correct up to 2.00D of astigmatism easily and 1 Day Acuvue Moist for Astigmatism can correct up to 3.00D and may be just what you need to sharpen up your vision.
  • Ortho-K Nighttime Contacts
    One of the more exciting treatment options in the astigmatism world is a therapy known as orthokeratology (aka ortho-k). Patients who use ortho-k must wear specially crafted gas-permeable lenses every night and remove these contacts in the morning. 

    Interestingly, ortho-k lenses have the ability to gently even out your corneal size every night so you don’t experience astigmatism symptoms in the morning. Ortho-k has the added benefit of improving other visual disorders such as myopia.

    Ortho-k is one of the biggest innovations in the contact lens market during the last decade, however, there is still a great deal of doctors who don’t know how long the effects of this therapy last. As always, it’s best to ask a certified Optometrist whether ortho-k is a good option for your condition.   
  • Laser Eye Surgery
    If none of the above strategies help manage your astigmatism symptoms, then it might be time to consider a more invasive procedure like laser eye surgery. Doctors can now use laser procedures like LASIK to effectively correct corneal abnormalities.

    As with any other surgical procedure, there are risks associated with using laser eye surgery. Talk with your eye doctor about any concerns you have with laser eye surgery and whether or not you’d be a good candidate. Also, be sure you know all of the potential complications associated with whatever laser surgery you’re interested in.

Home Remedies For Healthy Eyes

While nothing will replace the treatment strategies listed above, there are many lifestyle changes astigmatism people could make to improve their overall eye health. Here, we explain three scientifically proven ways you could boost your overall eye health and potentially reduce the severity of astigmatism.   

Note: none of these strategies are intended to replace a professional treatment protocol prescribed by an Optometrist or doctor. If you have any questions about incorporating these strategies into your daily life, ask your optometrist for guidance. 

  1. Eat More Leafy Greens
    Incorporating more green veggies into your diet is one of the easiest ways to boost your eye health. Nutritionists now know green vegetables have some of the highest concentrations of key nutrients that play a central role in promoting corneal health. Just a few of these eye-healthy compounds in green vegetables include vitamin C, vitamin A, lutein, zeaxanthin, and vitamin D.

    Some of the best greens to consume on a regular basis are as follows:
    • Spinach
    • Kale
    • Collard greens
    • Swiss chard
    • Broccoli  
  2. Consider An Omega-3 Supplement
    On top of all the healthy compounds found in green veggies, eye health experts are excited about the manifold benefits of omega-3 fatty acids. Mostly found in fresh seafood and nuts, this impressive compound has been linked with many eye health benefits including a reduction in dry eye symptoms.

    For those who don’t mind fishy foods, consider adding more salmon, sardines, skipjack tuna, or mackerel to your weekly diet. You might also want to eat more omega-3-rich walnuts, chia seeds, and flaxseeds. 

    Alternatively, you could get your omega-3 from salmon oil capsules or cod liver oil. 
  3. Always Wear UV-Blocking Sunglasses
    Getting plenty of sunshine every day is extremely healthful, but don’t forget to protect your eyes from those harmful UV rays. Yes, UV radiation can significantly damage the cornea over time, which could lead to an increase in astigmatism symptoms.

    Whenever you head outside, put on a pair of UV-blocking sunglasses. Getting in the habit of wearing these sunglasses will save you a great deal of aggravation down the line.

If you are concerned about problems with your vision, the best thing to do is get an eye examination. Your eye care professional will carry out various tests to determine the nature and severity of your condition. They will ask you questions about your lifestyle and working habits to determine the best way to get you to see clearly again. 

Author: John Dreyer Optometrist Bsc(Hons), MCOPTOM, DipCLP
Created: 24 Apr 2015, Last modified: 20 May 2024