What Is Astigmatism?


Astigmatism is a refractive error of the eye and is present in almost all people to some degree. Such limited amount of astigmatism neither impacts the vision of a person nor requires any treatment. The distinguishing feature of astigmatism is the uneven curvature of the lens or cornea of the eye which results in unclear vision. The problem in most people is because of some genetic reason and is present from the time of birth. Vision problem caused by the optical condition can be corrected by the use of glasses, contact lenses and laser eye surgery.

What Is Astigmatism?

Naturally, eye is shaped like a sphere which allows light entering the eye to refract evenly. This uniform refraction of light results in a clear picture of the object. On the other hand, a person whose eye is affected by astigmatism has a blurred vision of all near and far objects. The reason for such vision is the cornea of such person which is more like the back of a spoon. When light enters, rather than forming a sharp image, it gets refracted more in one direction resulting in an unfocused image.

Types for Astigmatism

Astigmatism has two types: corneal and lenticular astigmatism. The corneal astigmatism is because of the abnormal shape of the cornea, whereas lenticular astigmatism is because of the abnormal shape of the lens. The result of both types of astigmatism is the same—an unclear and distorted image.

What Are the Signs & Symptoms of Astigmatism?

The main indication and symptoms of astigmatism are:

  • Fuzzy vision for both near and far objects
  • Not easy to drive during nights
  • Pain in head
  • Squinting to see properly
  • Eyes feel stressed

When to See a Doctor

In case you find it difficult to carry out your day to day responsibilities because of your vision, you must consult an ophthalmologist. The eye doctor will examine your eye to diagnose whether you have astigmatism or not. Moreover, he will also identify the degree of astigmatism in your eye and will prescribe a mean to correct your vision.

People who have an optical problem like astigmatism need to get their eyes checked more consistently than usual. More frequent visits to an eye specialist are also important in case you have an eye problem like glaucoma or a disease like diabetes. The frequency of your visits should in any case be decided by your specialist.

What Are the Causes & Risk Factors of Astigmatism?

There is no identified reason for astigmatism. It is basically an imperfection of the cornea or the lens and is present in most people at the time of birth. Little amount of imperfection of cornea or the lens is common in a number of people and they do not require any corrective measures for their vision. Almost all people with astigmatism have some hereditary reason for the eye defect, even though in some cases, the optical problem appears in childhood or early adulthood and not at the time of birth. Most people with the problem have it in both their eyes.

Astigmatism can be also caused by a condition called keratoconus. In addition to the disease, some injuries and infections can also results in astigmatism. In such conditions, astigmatism is asymmetrical.

How Is Astigmatism Diagnosed?

In order to diagnose astigmatism in a patient, a number of measures are required to be determined which are found through a complete examination of the eye. The important aspects of eye examination include:

  • Sharpness of vision
  • Refractive ability of the lens
  • Finding the curvature of surface of cornea using keratometer

The tests examine a number of things and the information obtained from the tests is used by the optometrist to determine the degree of astigmatism in your eye. In addition, they also enable the optometrist to find out the power of lens to make your vision correct and clear.

What Are the Treatments for Astigmatism?

In most cases of astigmatism, the degree of the problem is so less that there is no corrective measure required if there is no nearsightedness or farsightedness. In cases where astigmatism affects the routine life of a person, lenses or glasses can fix any degree of astigmatism and make the vision of the person clear and correct.

Corrective Lenses

The use of lens or glass support clarity of vision by refracting the light to cancel out the effect of refractive error caused by astigmatism. The corrective lens used can both be in the form of a contact lens or a glass as both can equally solve the vision problem.

There is a certain degree of precaution that must be ensured while using contact lenses. First of all, contact lenses are not supposed to be used for a consistently long duration of time. Moreover, contact lens should always be cleaned properly before using.

Laser Eye Surgery

Laser surgery treats astigmatism by correcting the shape of cornea. Your eye specialist will examine you to decide whether you can have a laser surgery or not. There are three different types of laser surgery being used today:

  • LASIK (Laser in situ keratectomy). Keratome or a laser is used to make a hinged cut into the cornea. Cornea is then reshaped using excimer laser. Since LASIK vision recovers in a few days and it causes the least amount of pain, it is the most used method. It still takes almost one month for vision to become completely correct and stable.
  • LASEK (Laser epithelial keratomileusis). Alcohol makes the surface of cornea loose so that it can be removed. A laser then reshapes the cornea which is then placed back. Since only a small layer is affected in this procedure, there is less dangerous for damage of the eye. The procedure causes less pain than PRK and is better suited for patients with a thinner cornea. The vision starts to recover after one week.
  • PRK (Photorefractive keratectomy). In this process, an excimer laser is used to make the cornea spherical by removing tissues of cornea. It takes up a month before vision becomes clear while the surgery causes a fair amount of pain.

It is not appropriate to perform laser surgery if:

  • The age of patient is less than 21. Before the age of 21, eye structure is varying and it should not be reshaped externally.
  • Vision is still transforming. In some cases, vision of even people aged more than 21 is still not stable and continues to vary. Eye specialists argue that a patient’s vision must be stable for 3 years before laser surgery can be performed.
  • Diabetic patients. In some diabetes patients, optical problems will increase after undergoing laser surgery.
  • Pregnant women and breastfeeding mothers. Hormone levels in eye keep on varying during pregnancy and while breastfeeding. This is the reason performing an accurate surgery during this time is not possible
  • People with compromised immunity. Such people will have a difficult time in recovering from the surgical procedure. Conditions including rheumatoid arthritis, HIV and lupus compromise immune system in people.
  • Other eye problems. In case a person has other eye problems like cataracts or glaucoma, they need to get treatment of those conditions before getting their surgery.
  • A person on specific medications. Going through laser surgery is not an option for people on oral prednisone or Accutane.
 
 
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