Astigmatism is a common structural eye disorder, which can affect both adults and children. In fact, it impacts millions of people around the world of various ages. Astigmatism occurs when the cornea changes shape, from a natural spherical shape to something that resembles more of a rugby ball. This results in the light that enters the eye not being correctly focused on the retina, which can cause problems with short and long sight.
What causes astigmatism?
What causes astigmatism is generally unknown, although it tends to occur due to an irregular-shaped lens or cornea. Genetics plays a vital role, as the condition tends to be present at birth. However, it can also occur later in life, as well as after eye surgery or because of an injury.
There are two forms of astigmatism; irregular and regular. The former is the most common and it occurs when the cornea is curved more in one direction than the other. Irregular astigmatism is when the cornea’s curvature is not even across the eye’s surface. This tends to happen because of an eye injury that results in scarring on the cornea.
There are people that are at a greater risk of developing astigmatism than others, and this includes the following:
- People with a history of specific types of eye surgery, for example, cataract surgery.
- People with far-sightedness.
- People with near-sightedness.
- People that experience thinning or scarring of their cornea.
- People with a family history of astigmatism or other eye disorders, for example, keratoconus.
The symptoms of astigmatism can differ from person to person, with some people not experiencing any symptoms at all. Common symptoms are as follows:
- Eye irritation
- Difficulty seeing at night
- Fuzzy, distorted, or blurry vision at all distances (far away and up close)
If you experience any of the symptoms mentioned above, you should book an appointment with a doctor or ophthalmologist as soon as possible and they will be able to diagnose it for you.
An astigmatism will usually be diagnosed via a routine eye test. However, there are also two types of eye test for astigmatism diagnosis.
As most people are born with astigmatism, it is important to make sure your children have routine eye tests because most children will not recognise that there is anything wrong with your vision.
If astigmatism is suspected, the two most common tests used are the keratometer test and the visual acuity test. The former involves using a keratometer, which is a device that can measure the degree of corneal astigmatism. This is done through measuring how the cornea is focusing the light, enabling the person conducting the test to detect irregularities in the cornea’s curve.
A visual acuity test is used to determine your ability to focus on objects at a variety of distances. This is usually going to involve letters being read on a Snellen chart, whereby they get progressively smaller on every line of the chart.
How to treat astigmatism
In a lot of cases, astigmatism does not need to be treated, as it does not always cause detriment to a person’s vision. However, if it does need to be treated, the type of treatment you will need will depend on the type of astigmatism you have. The most common astigmatism correction options are as follows:
Glasses And Contact Lenses for Astigmatism
Corrective lenses, known as toric contact lenses, can be used to correct astigmatism. These lenses work by compensating for the cornea’s irregular curve. This means that the light will pass through the corrective lens and focus on the retina properly. Both glasses, sunglasses, and astigmatism contact lenses are effective, and your decision will depend on the advice you have received from your optometrist and your own personal preference.
Laser Eye Surgery
Can laser eye surgery correct astigmatism? It can. This involves utilising lasers to remould the cornea’s tissue to alter the curve. This is an outpatient procedure, meaning you do not need to stay in hospital overnight. Most forms of laser eye surgery take roughly 15 minutes per eye. However, laser eye surgery and astigmatism treatment options are varied, and include:
- LASIK – During LASIK surgery, a specially trained ophthalmologist will use a microkeratome to create a thin and precise, hinged corneal flap. The surgeon then exposes the underlying corneal tissue by pulling back the flap. He or she will then use an excimer laser to reshape the cornea in a unique pre-specified pattern for each patient.
- PRK – As is the case with most laser eye treatments, an excimer laser is used to reshape the cornea. However, the difference with PRK is that the outer layer of the cornea is completely removed, rather than a flap being created.
- LASEK – Again, LASEK differs in the way the eye is prepared. The treatment involves a little of both PRK and LASIK. Like PRK, the thin outer layer is separated, but it is simply pushed to one side of the eye, rather than being discarded altogether.
- IntraLASIK – This procedure is similar to LASIK. However, a precision laser is used to create the flap, rather than a mechanical device. This is for a more precise flap.
- EpiLASIK – This procedure is very similar to LASEK. However, a blunt, plastic blade is used to separate the epithelial sheet from the eye, rather than alcohol. This eradicates the possibility of a reaction to the alcohol.