Causes, Symptoms And Treatment
As scary as the term may sound, astigmatism is actually a very common vision impairment, accounting for around 13 per cent of refractive errors.1 In an eye with astigmatism, the parts of the eye working to bend light are not spherical or are shaped irregularly. This causes the eye to focus that light in two different places, leading to blurred or distorted vision. Astigmatism can be either regular or irregular. Irregular astigmatism is often caused by eye conditions such as keratoconus or corneal scarring. Regular astigmatism is the more common type, and so, this article refers to regular astigmatism.
The less spherical or more irregular the curvature of the eye, the greater the degree of astigmatism. The condition is often associated with long-sightedness (hyperopia) or short-sightedness (myopia), but it can also occur alone.
There are two common types of astigmatism:
- Corneal astigmatism
When the cornea is not spherical or is irregular in shape, similar to that of a rugby ball or egg, it is called corneal astigmatism. This is the most frequently occurring cause of astigmatism, affecting the ability to see things close up or far away. This type of astigmatism is usually treated with corrective lenses; although surgical options are available to those who wish to do away with glasses or contacts.2
- Lenticular astigmatism
When the eye’s natural lens is distorted it is called lenticular astigmatism. Often when the lens is distorted, the cornea is regular in shape. Lenticular astigmatism is less common than regular corneal astigmatism; however, both types can cause blurry or distorted vision. This type of astigmatism often requires surgical treatment.2
So why does astigmatism affect your vision?
The perfect cornea or other optical surface is spherical; this allows light from all angles to travel evenly onto the retina due to the consistency of the eye’s curvature. With an irregular or oval shaped surface comes difficulty with vision, and light rays are not focussed evenly onto the retina.
The retina’s job is to convert those light rays as they enter the eye into messages. These messages are sent via the optic nerve connecting to the brain. Your brain understands how most things should look and can actually re-adjust to try to improve the image, adapting to the error. This is why it can be difficult to adjust to new spectacles that have a different astigmatic prescription than what you may be used to.
But what if you move around — or move your eyes quickly — or tilt your head?
Performing everyday visual tasks can be somewhat difficult for sufferers of astigmatism, as even the smallest movement can allow your vision to blur.3 Activities such as driving (particularly at night), playing sports and even working at a computer or watching the television, all require a sharp ability to focus on moving objects; so it’s a good idea to have regular eye health checks to ensure adequate visual acuity.
Astigmatism can affect more than just your vision
“...it could very well be responsible for those unsuspecting headaches.”
Not only does astigmatism cause your vision to blur or distort, but it could very well be responsible for those unsuspecting headaches. The eye’s nerves and the brain’s nerves are all interlinked, inflicting headaches, squinting, fatigue and eye strain upon the, often unbeknownst, astigmatism sufferer.
Having these common symptoms does not necessarily mark astigmatism, but they do point towards the need for a visit to see your eye specialist for a full exam. It’s important to treat your condition and avoid any strain you may be placing on your eyes. Your brain may be working harder for your vision impairment, with increasing pressure and blood flow to compensate. Patients are far less likely to experience headaches and other side effects if their vision is corrected properly.4
There is no single cause of astigmatism
“...there have been clues to suggest genetics play a role in its development.”
Though the imperfection of the cornea is observed to some degree in most astigmatism cases, the exact cause is still unknown — despite extensive research on the condition. However, there have been clues to suggest genetics play a role in its development, as well as corneal pressure from the eyelids with various visual tasks.1
Astigmatism affects people of all ages
“Astigmatism is actually a common condition among infants, although many children do grow out of it.”
Anyone is at risk of developing astigmatism, especially those who suffer from short-sighted (myopia) or long-sighted (hyperopia) vision. Your risk of developing an irregularity may be higher if you have a family history of astigmatism.1
Astigmatism is actually a common condition among infants, although many children do grow out of it.5 This prevalent vision impairment often transpires with age, but it can also occur as a result of an injury to the eye or rare complications with certain types of eye surgery, including cataract surgery.
There are many ways to treat astigmatism
“Your ophthalmologist will be the best person to decide upon the treatment suitable for your condition…”
Today, most vision impairments, including astigmatism, can be effectively treated with either corrective lenses or modern laser vision correction methods. Here are the many treatments available to correct your astigmatism. Your ophthalmologist will be the best person to decide upon the treatment suitable for your condition — depending on your individual circumstances.
- Glasses or contact lenses
Correcting your vision can be as simple as wearing your prescription glasses or contact lenses when required. Rigid contact lenses can be used, as well as softer toric lenses. Rigid lenses aren’t usually dependant on the orientation or rotation of the contact lens, whereas toric lenses require precise orientation, depending on the progression of your eye condition.
- Implantable Collamer Lens (ICL)
Permanent lenses, often toric lenses, made precisely to the patient's prescription may be inserted into the eye to treat moderate to severe cases of astigmatism.7 Permanent lenses work much the same as regular contact lenses, and can even be removed if desired.
Laser Eye Surgery
Laser eye surgery is a highly effective means of correcting a host of refractive errors, including astigmatism. Today, there are three advanced laser procedures to achieve accurate focus and allow light rays to focus on the retina in sufferers of astigmatism; all of which are safe, effective, and predictable for the correction.6
A recent type of flapless surgery creates one small incision before removing the lenticule and altering the shape of the cornea. This procedure is minimally invasive and painless, offering a swift recovery time.
The most widely performed laser eye surgery — this procedure creates a hinged flap which is folded back in order to sculpt the cornea. LASIK reports a 96 per cent success rate with little pain or discomfort felt.
Advanced surface ablation prepares the outermost corneal layer before sculpting the tissue. This procedure requires a longer recovery time, but is usually recommended for those with unusually thin or irregular corneas.
In severe cases of astigmatism, a refractive lens exchange can be performed by your ophthalmologist to replace the eye’s natural irregular lens with a toric intraocular lens; this will correct most of the astigmatism. A monovision setup or multifocal intraocular lens can also be used to correct both reading and distance vision in people with astigmatism.
Have regular eye examinations
It’s so important to have regular eye health checks to ensure your vision isn’t getting in the way of doing the things you love. To find out if you’re a suitable candidate for astigmatism treatment, come in for an Eye & Laser Centre consultation where one of our experts will provide a thorough, individual assessment of your eyes.
If you would like further information, we are here to help. Call us on (07) 5555 0800 or fill out an online enquiry form — our friendly team members are ready to discuss your personal needs.
Eye & Laser Centre ophthalmologists specialise in the treatment of many eye conditions, including astigmatism. Our centre employs the latest techniques and equipment to diagnose and treat this common condition.
This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific ophthalmic advice or assistance should consult their optometrist or ophthalmologist.
1. Read, S.A., Collins, M.J. and Carney, L.G., 2007. A review of astigmatism and its possible genesis. Clinical and Experimental Optometry, 90(1), pp. 5-19.
2. Koch, D.D., Jenkins, R.B., Weikert, M.P., Yeu, E. and Wang, L., 2013. Correcting astigmatism with toric intraocular lenses: effect of posterior corneal astigmatism. Journal of Cataract & Refractive Surgery, 39(12), pp. 1803-1809.
3. Beck, J., 1965. Accommodative astigmatism and pattern acuity. JOSA, 55(9), pp. 1139-1142.
4. Harris, W., 1934. Headaches in relation to ocular conditions. British medical journal, 2(3841), p. 298.
5. McKean-Cowdin, R., Varma, R., Cotter, S.A., Tarczy-Hornoch, K., Borchert, M.S., Lin, J.H., Wen, G., Azen, S.P., Torres, M., Tielsch, J.M. and Friedman, D.S., 2011. Risk factors for astigmatism in preschool children: the multi-ethnic pediatric eye disease and Baltimore pediatric eye disease studies. Ophthalmology, 118(10), pp. 1974-1981.
6. Ganesh, S. and Gupta, R., 2014. Comparison of visual and refractive outcomes following femtosecond laser-assisted lasik with smile in patients with myopia or myopic astigmatism. Journal of Refractive Surgery, 30(9), pp. 590-596.
7. Sanders, D.R., Schneider, D., Martin, R., Brown, D., Dulaney, D., Vukich, J., Slade, S. and Schallhorn, S., 2007. Toric Implantable Collamer Lens for moderate to high myopic astigmatism. Ophthalmology, 114(1), pp. 54-61.