Laser Eye Surgery For Astigmatism
What Is Astigmatism?
Astigmatism is a structural disorder of the eye which occurs rather frequently. It transpires when the cornea changes from its natural spherical shape to be more elliptical, like the shape of a rugby ball. The asymmetrical shape caused by astigmatism forces the light that enters the eye to be refracted unevenly and split into two focus points as opposed to a single, clear image on the retina at the back of the eye. It is one of many causes that affect your eyesight, and knowing which condition you have is important if you are looking to compare the potential cost of your laser eye treatment.
In the normal eye the cornea and the lens each have a convex, perfectly spherical surface. This spherical shape helps the eyes refractive qualities better focus on near and far away objects. In astigmatism the eye loses its spherical properties and ends up being more oval shaped, similar to a rugby ball. This means that light that enters the eye is not properly focused on the retina but is actually positioned in front or behind the retina resulting in blurry images.
People suffering from astigmatism will have difficulties with both their long and short sight and the problem can lead to squinting and in some cases severe headaches. Although glasses can help solve the problem in the short term, allowing your eyes to focus, they do not actually cure the disorder and can in some cases make the problem worse.
What Causes Astigmatism?
Astigmatism causes vision problems, and the root of this condition lies with defects that are present in the eye. These are normally hereditary.
The eye is comprised of the optical system, the retina, and the optic nerve. Issues pertaining to the optical system, made up of the cornea and lens, are normally the root cause astigmatism. It is thought that these issues are present from birth, as no one quite knows what causes them. The cornea is a translucent layer of tissue covering the front of the eye, protecting it from dust, dirt and damage. Together with the lens, the cornea is responsible for focussing incoming light in order to create a clear image. In order to do this, the cornea needs to have an ideal shape, which is a perfect curve. When the cornea is shaped irregularly, the light is not focussed properly onto the retina, creating a blurred image instead. This is what is caused corneal astigmatism, and it is a common cause of the condition. When the light bends unevenly in the eye due to an irregularly shaped lens, this is called lenticular astigmatism.
While it is true that most causes of astigmatism are hereditary, there can be other reasons that this condition develops. For example, injuries to the cornea (such as an infection that results in scarring) can alter the shape of it, and changes to the shape of the cornea caused by laser eye surgery can also result in astigmatism. Two eye conditions known as keratoglobus and keratoconus cause the cornea to thin out, bulge and change shape, as can some conditions affecting the eyelids. In essence, anything that alters that shape of the cornea can lead to Astigmatism occurring.
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As Astigmatism is a hereditary condition, it is vital to ensure your children have regular eye tests as they grow older.
Astigmatism may not present itself straight away, and children may be unaware there is anything wrong with their vision if they are not subject to regular testing. This means the condition to go undiagnosed, and if uncorrected could result in them developing a lazy eye. Failing to detect this condition also means children can struggle to read at school, which can lead to issues pertaining to concentration and behaviour.
Testing can start from birth, as a baby will have their eyes examined within 72 hours of being born followed by a follow-up eye examination when they are between six and eight weeks old. By the time they are school age, routine eye tests should be carried out. If any suspected issues pertaining to vision are detected, your child may be referred to a specialist called an orthoptist, a doctor specialising in vision development issues, or an ophthalmologist who specialises in the diagnosis and treatment of eye conditions. If Astigmatism specifically is suspected, one of two tests may be carried out.
A visual acuity test is used to assess the ability of a child or adult to focus on specific objects at different distances. During this test, the patient will be asked to read letters from what is called a Snellen chart. The letters on the rows from top to bottom become progressively smaller and therefore harder to read, helping medical professionals determine the strength and visual acuity of the eyes. During a Keratometer test, a machine called a keratometer measures the degree angle of corneal astigmatism. It can therefore see how the cornea is focussing incoming light, and can detect any irregularities in the curve of the cornea.
Treating Astigmatism With Laser Eye Surgery
While is it accepted that specialised contact lenses can temporarily address the problem, laser eye surgery is still considered a highly effective way of combating astigmatism. LASIK (LASer In situ Keratomileusis) laser eye surgery is the most common and popular form of laser eye surgery for astigmatism. It allows surgeons to correct a wide variety of eye disorders without the discomfort and time associated with other forms of laser eye surgery.
LASIK laser eye surgery involves focusing a laser under the surface of the cornea after an extremely thin layer of the cornea is cut and lifted. Once the exposed tissue has been lasered, the thin layer, the corneal flap, is repositioned and returns to its previous position so as to minimise the healing process. The healing process is typically completed within a couple of hours.
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