Astigmatism – Symptoms, Causes and Risk factors

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Astigmatism

This is a very common and generally treatable imperfection in the curvature of the eye which is causing blurred distance and near vision. It happens when either the front surface of the eye (also called cornea) or the lens, inside the eye, has mismatched curves. You should have one curve like a round ball but you have surface which is egg shaped. This is causing blurred vision at all distances.

This condition is often present at birth and it can happen in combination with farsightedness or nearsightedness. In many cases, it is not pronounced enough to require corrective action. When it is pronounced enough, then there are different treatment options like corrective lenses or surgery.

Contents

Symptoms

Astigmatism

Here are some signs and symptoms of astigmatism

  • Squinting
  • Difficulty with night vision
  • Headaches
  • Eyestrain or discomfort
  • Blurred or distorted vision

You should talk with your doctor if your symptoms detract you from your enjoyment of activities or interfere with your ability to do daily tasks. Your eye doctor can determine if you have astigmatism and if you have what is your degree. Your doctor will give you advice about some options to correct your vision. Children may not realize that their vision is blurry and they need to be screened for eye disease. Also, their pediatrician, an ophthalmologist or optometrist, or another trained screener to make tests on your children. He or she will make tests during the newborn period. Also, the doctor will do eye tests at well – child visits until school age. When your child is during the school years, then you should take your child every 1 – 2 years at well – child visits, at the eye doctor or through public or school screenings.

Causes

We know that our eyes have 2 structures with curved surfaces which bend light onto the retina and this makes the images:

  • The lens: This is a clear structure inside the eye which changes shape to help focus on near objects.
  • The cornea: This is the clear front surface of the eye along with the tear film.

When the eye is perfectly shaped, then each of these elements has a round curvature which is like the surface of a smooth ball. The cornea and lens with such curvature refract all incoming light to make a sharply focused image directly on the retina, at the back of the eye. If the cornea or the lens is egg shaped with 2 mismatched curves, then the light rays are not bent properly and this is causing a refractive error. This is causing a blurry image and the astigmatism is a type of refractive error.

This condition is happening when your cornea or lens is curved more steeply in one direction than in another. If your cornea has mismatched curves, then you have corneal astigmatism. If your lens has mismatched curves, then you have lenticular astigmatism. Both types of astigmatism can cause blurred vision. Blurred vision can happen in one direction, either vertically, horizontally or diagonally. Astigmatism can be present from birth. Also, it can happen after an eye injury, disease or surgery. You should know that the astigmatism is not caused or made worse by sitting too close to the TV or squinting or by reading in a poor light.

Other refractive errors

It is known that astigmatism can happen in a combination with other refractive errors, such as

  • Farsightedness (hyperopia): It happens when the corena is curved too little or when your eye is shorter than normal. The effect in the farsightedness is opposite of nearsightedness. When your eye is in relaxed state, then the light never comes to a focus on the back of the eye and this is making nearly objects to seem blurry.
  • Nearsightedness (myopia): This condition is happening when your cornea is curved too much or when your eye is longer than normal. The light is not precisely focused on your retina and it is focused in front of your retina which is making distant objects to seem blurry.

Risk factors

Here are some factors which can increase your risk of astigmatism

  • A history of certain types of eye surgery, such as cataract surgery
  • Excessive farsightedness, which creates blurry close – up vision
  • Excessive nearsightedness, which creates blurry vision at a distance
  • Scarring or thinning of your cornea
  • A family history of astigmatism or other eye disorder, such as keratoconus

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