Atanas Bogoev M.D.
Astigmatism — Symptoms, causes, treatment
Updated: Feb 19
If you're experiencing a blurry or distorted vision, especially when looking at objects from a distance or up close, you may be suffering from astigmatism.
Astigmatism is caused by an irregularly shaped cornea, which can cause light to focus unevenly on the retina, resulting in vision problems. While astigmatism can be concerning, the good news is that it can often be easily corrected with the right treatment. In this post, we will provide a detailed explanation of what astigmatism is, its causes, symptoms, and various treatment options available to help you better understand this condition and how to manage it.
Table of contents: 1. Intro 2. Symptoms 3. Causes 4. When do I see an eye doctor? 5. Treatment 5.1. Glasses 5.2. Contact lenses
5.3 Orthokeratology 5.4. Laser correction (refractive surgery)
5.5. Implantable lenses 6. Astigmatism in Children
Astigmatism is measured in Diopters (cylindrical diopters).
Astigmatism occurs quite often and sometimes even goes unnoticed. There was a large population study in the USA, Canada, and the UK that concluded that only 11% of all people have 0.00 diopters of astigmatism.
Data on the general population
People with astigmatism of −0.25 to −0.75D (Diopters)
People with astigmatism in one eye that is worse than the other eye
People with astigmatism, the difference between their eyes is less than −0.75D
Astigmatism is likely to be symmetrical. If someone has an astigmatism of more than −1.00D in one eye, there is an 80.8% chance that their other eye will have it too.
Symptoms of Astigmatism
Here are some of the most frequent symptoms of astigmatism:
Blurred or distorted vision
Eye strain and discomfort
Reduced night vision
Astigmatism can cause objects to appear blurry or out of focus, especially at night or in low-light conditions. People with astigmatism may experience frequent eye strain and headaches, especially when reading, working on a computer for longer periods of time, or engaging in other activities that require a lot of visual focus.
The images demonstrate me holding an astigmatism glass in front of a screen, showing the different blurriness and distortions of the number 4. Note how the blurriness changes when you rotate the glass 90 degrees.
Some people with astigmatism may experience double vision or the perception of two images instead of one. In addition, astigmatism could make it difficult to focus on fine details or to see the small print clearly. That is why most people with this condition squint their eyes quite often.
Astigmatism is very obvious at night, especially when driving, as the pupil is dilated and it lets in more light to the retina. In that case, the refractive imperfections are more obvious and one notices 2 spikes of light in opposite directions coming from a direct light source like car lights, street lights, and traffic lights. This is very well illustrated in the following video:
Causes of Astigmatism
Our eyes have two structures with curved surfaces that bend (refract) light and allow us to see clearly:
Cornea - The clear structure in the front part of your eye, covered by the tear film
Lens - the transparent structure in the eye that can change shape to focus on near objects
In a perfectly shaped eye, each of these elements has a circular curvature similar to the surface of a smooth ball.
If those curves on the cornea or the lens are mismatched, then light rays fail to bend correctly, causing a refraction error (refractive error). All of this causes an unfocused image to form on the retina. So overall, astigmatism is actually a type of impaired refraction of light.
Blurred vision may appear more in one direction - horizontally, vertically, or diagonally.
Astigmatism is NOT a disease and is NOT caused does not get worse by reading in poor light, sitting too close to the TV, or squinting.
Astigmatism can also occur in combination with other refractive errors — nearsightedness (myopia) or farsightedness (hypermetropia).
The condition can be present from birth, or it can develop after an eye disease, eye injury, or surgery.
When do I have to see an eye doctor?
As we discussed in the beginning, many people have astigmatism. But this does not mean that correction with glasses is absolutely necessary. We advise you to make an appointment with an eye doctor if your complaints interfere with your ability to perform daily activities (seeing blurry when working on your laptop, having frequent headaches, and eyestrain).
An eye doctor or optician will perform a special test called auto-refractometry, which will help to determine the optical error of your eye. The device works by shining a light beam and analyzing the returned light rays reflected by the back of your eye.
On the left image, we show a standard auto-refractometer (a device that measures the refractive error of your eye). On the right of the image, you see a printout. In this case, the printout demonstrates that the patient has +0.75 D (hyperopia or farsightedness) combined with -0.75 D astigmatism of the right eye, and +0.75 D (hyperopia or farsightedness), combined with -0.50 D astigmatism of the left eye. You may notice that a minimum of 3 measurements per eye is performed and the final result is their average.
After the refractometry, patients undergo an examination called a refraction test where he puts different glasses with different power to correct it.
The examiner can determine if you have astigmatism or another refraction disorder (nearsightedness or farsightedness) and proceed to correct it if necessary. Have in mind that small degrees of refractive error do not need to be corrected if you have no symptoms or complaints.
High degrees of astigmatism, as well as astigmatism that is progressing, or hard to correct with glasses may be caused by a condition called keratoconus which is a disease of the cornea and should be investigated further.
Stay tuned for a detailed article about keratoconus soon. We will put a link for you here.
What are the astigmatism treatment options?
After undergoing a complete examination, there are several treatment options for correcting astigmatism (and refractive error of the eye in general):
Correction with eyeglasses:
Eyeglasses are the most common treatment for astigmatism. The lenses that correct astigmatism have different powers in different meridians to compensate for the irregular shape of the cornea. Glasses are easy to keep clean and provide good-quality of vision. The negative sides include Limited field of vision, discomfort, and high costs.
Correction with contact lenses:
Soft contact lenses can also be used to correct astigmatism. Contact lenses that correct astigmatism are called toric contact lenses. Contacts are ideal for people with active lifestyles, playing sports, having professions that require clear vision, or having certain eye conditions that cannot be corrected with glasses. There are some negatives as well, like a higher risk of infection, eye irritation, dry eye restricted activities such as swimming and showering while wearing contact lenses, maintenance, and costs.
Detailed article about correction with glasses v.s. contact lenses coming soon.
Orthokeratology or Ortho-K is a type of special rigid gas permeable contact lens that you put in your eyes before you go to bed and wear at night while you sleep at night. It reshapes the curvature of the cornea temporarily and improves vision during the day. While it can be a great option for some patients, there are a lot of limitations and negatives in this treatment method as well. Some of them are high costs (most types of insurance do not cover Ortho-K contact lenses), Limited effectiveness (meaning the effect carries on how much hours you sleep and wears off during the day), and last but not least - the risk of corneal infections, irritations, and dry eye.
Laser refractive surgery:
Refractive surgery, also known as LASIK, SMILE, or PRK, can also be used to correct astigmatism. This procedure uses a special type of laser to reshape the cornea, thus improving vision.
Detailed article about laser refractive surgery with glasses v.s. contact lenses coming soon.
Eye surgery with implantation of an implantable lens, called phakic intraocular lens, can be performed correct astigmatism. These lenses are implanted in front of or behind the iris and in front of the eye's natural lens.
Which is the best option for you? It is important to consult an eye specialist to determine which treatment option is best for you, based on the degree of your astigmatism, your lifestyle, your eye health, and other factors.
Astigmatism in Children
Why is diagnosing and correcting astigmatism in children so important?
If not corrected in time, high astigmatism in children can lead to "lazy eye".
Unlike adults, children do not realize or complain that their vision is blurry. Uncorrected astigmatism can seriously affect a child's ability to recognize small details clearly and perform in school or in sports.
Imagine being a child who sees the world blurry. You just cannot know that there is a possibility to see things more clearly as you may have a refractive error in your eyes. Luckily your parents read this article on www.ophthalmology24.com and know when and why to take you to the prophylactic eye examinations, recommended for children.
We at Ophthalmology24 advise you to take your child for prophylactic eye examinations:
Immediately after birth
At 6 months old
At 3 years old
At 7 years old
During the school years (ages 7–18)
If you have any comments or questions on the topic of Astigmatism, feel free to leave us a comment down below. For more eye health advice, visit the Ophthalmology24 eye care blog for patients now.
Astigmatism, Atanas Bogoev M.D. for Ochno Zdrave
All medical facts were checked by Atanas Bogoev M.D.
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