Astigmatism

Astigmatism occur due to an irregularity in the curvature of the cornea or lens of the eyes. The function of the cornea and the lens is to focus the light ray on the retina where visual images are formed.

A normal cornea and lens are smooth and properly curved equally in all directions. This uniform curvature helps to focus light rays precisely and sharply onto the centre of the retina. This process is called refraction.

An abnormal curvature of the cornea and the lens results in an improper refraction of light rays. This causes a distortion of the images as they form on the retina. Astigmatism is hence known as a type of refractive error. In astigmatism the images are formed either in front of or behind the retina.

The other common types of refractive errors are myopia or near-sightedness or short-sightedness and hypermetropia or far-sightedness or long-sightedness. Astigmatism can occur in combination with any of these errors or independently.

It is easy to detect astigmatism in the elderly since they know that the images are getting blurred. But children are less likely to complain, as they are naïve to treat this as a natural thing to happen. Since astigmatism is known to run in families, parents who suffer from or have suffered from astigmatism should get their children’s eyes tested regularly to help in early correction. Untreated astigmatism can hinder the performances of a child in both academics as well as sports.

In adults, astigmatism may develop as a result of certain diseases of the eye, injury to the eye and as a complication of some eye surgeries. 

Astigmatism is a refractive error that causes distortion or blurring of images in the eyes. Astigmatism may occur both in children as well as adults.

Astigmatism usually occurs due to abnormal curvatures of the cornea as well as the lens. The most common reason is the asymmetry of the anterior portion of the cornea followed by the posterior cornea and the lens. Certain abnormalities of the retina may also contribute to astigmatism also, but it’s rare.

The irregularity of the curvature of the cornea and the retina diminishes their refractive power. This prevents the proper focusing of the light rays on the retina. This results in either blurring or distortion of the images as they form in the retina causing astigmatism.

In children astigmatism may be present at birth. But for a vast majority of those born with astigmatism, it corrects by itself before the child reaches one year of age. But in certain children with other refractive errors like myopia or hypermetropia, astigmatism may remain uncorrected.

Astigmatism is known to run in families. Hence there is ample support for the part played by heredity in causing astigmatism.  

 Certain disease of the eye may also cause astigmatism.

      ·       Keratoconus, a condition where the cornea thins off resulting in a change of shape from the normal round to a conical shape is one of the main causes of astigmatism in adults.

      ·       Cataracts where there is a clouding of lens due to deposition of certain proteins is another major cause for astigmatism in adults.

      ·       Traumatic injuries to the eyes that damage the cornea, or the lens can also cause astigmatism. Surgeries to correct eye injuries may also alter the refractive power of the cornea or the lens causing astigmatism

In adults, astigmatism may occur as an after effect of certain eye surgeries. Some of the eye surgeries that can contribute to astigmatism are

     ·       cataract surgeries,

     ·       lamellar keratoplasty

     ·       retinal repair surgeries

     ·       trabeculectomy.

Astigmatism is a condition that cannot be cured completely. But there are various treatments available to bring better clarity of vision for those suffering from the condition.

Astigmatism occurs due to an abnormality in the curvature of the cornea or the lens. The cornea and the lens are parts of the eyes that helps focus the light rays in the retina where visual images are formed.

Eyeglasses - Eyeglasses are the primary treatment for astigmatism. Special cylindrical eyeglasses that provide additional power to certain areas are used. They are easy to wear and carries no risk of an infection unlike contact lenses. Those who have presbyopia may require bifocal or progressive lenses.

Contact lenses- Standard soft contact lenses cannot correct astigmatism. Special toric lenses are necessary to correct astigmatism. Contact lenses may offer a wider range of vision as compared to eyeglasses. Since these lenses are worn directly on the eyes, they require proper cleaning and changing to keep up the eye hygiene.

Orthokeratology- Orthokeratology, is a treatment modality, where special rigid contact lenses are used to alter the curvature of the cornea to normal levels. The lenses are used only for limited periods of time and the effect will be retained for a considerable period of time. The lenses are usually worn in the night which helps the wearer to go about his day activities without glasses. The problem with this type of treatment is that the effectiveness diminishes as soon as one stops wearing the lens in the nights.

Astigmatic keratotomy eye surgery or AK-In this type of eye surgery, one or two relieving incisions are made in the steepest part of the cornea. These relieving incisions help to make the cornea more rounded. This helps to improve the refractory power of the cornea, thereby helping correct astigmatism. Those who undergo astigmatic keratotomy, will have to wear eyeglasses or contact lenses for better clarity of vision. This type of surgery is very safe and well tolerated. The side effects if at all they happen are fluctuation of vision, weakening of the cornea, sensitivity to bright light etc.

Refractive surgeries-Astigmatism can be corrected with refractive surgeries. These surgeries aim to reshape portions of the cornea where the curvature is improper, to make it smooth and symmetrical. The helps to focus the images clearly on the retina. cornea.

Refractive surgery might be a good option for those

• Want to avoid using eyeglasses or contact lenses
• Who do not have a pre-existing eye disease
• Accept the risks and potential complications associated with the surgery
• Have an appropriate refractive error that can be corrected through surgery.

Certain persons may have to wear eyeglasses or contact lenses even after surgery for clearer vision. This fact should be thoroughly understood before taking a decision to undergo the surgery.

There are various types of refractive surgeries that are done to correct astigmatism

Laser- Assisted in-situ keratomileusis or LASIK

LASIK surgery for astigmatism not only offers a high rate of success but is also easy to undergo. The surgery is a minimally invasive one as it uses Lasers to correct the shape of the cornea. During the surgery a flap is created in the cornea to alter its shape and make it more rounded.

The reshaping of the cornea helps to properly focus the light on the retina. Lasik may also be done to correct other eye disorders like myopia or short-sightedness and hypermetropia or long sightedness.

The normal duration of a Lasik surgery is about an hour. Most of the patients feel very little or no pain during or after the surgery. There is no need for placing any sutures after the surgery. The effect of Lasik surgery can be felt within a day after surgery.

But certain complications like loss of vision or a deterioration of existing vision is also reported with Lasik surgery.

Some of the other side effects include

·       increased glare,

·       presence of a halo around images,

·       dryness of the eyes

·       difficulty in driving at night,

·       sudden changes in vision etc.

Lasik surgery is not recommended for those with

·       Thin corneas

·       Very high refractive error

·       An age below eighteen

Other surgeries for astigmatism are

     •        Laser-assisted sub-epithelial keratectomy (Lasek)- In Lasek, the outer epithelial covering of the cornea is loosened to reshape it with laser. The surgery takes about an hour for completion.

     •        Photorefractive keratectomy- In this surgery the epithelial portion of the cornea is surgically removed before correcting its shape. Once reshaped, the epithelium is allowed to grow back on the cornea naturally.

     •        Epi-Lasik- A refractory surgery almost similar to Lasek, but the corneal flap raised is thinner. The surgery is very effective for those with thin corneas, which is a contra-indication for Lasik.

Various alternative treatments are also offered for astigmatism. Ayurveda the ancient Indian system of medicine offers various treatment methods for correcting astigmatism. They include the use of medicinal herbs to specific ayurvedic treatments. There are some highly specialised ayurvedic hospitals for eye disorders in India, that offer various comprehensive treatments for astigmatism.

Astigmatism is a refractive error of the eyes that occurs due to imperfection in the curvature of the cornea and the lens. This leads to improper refraction of light rays by the cornea or the lens. The light rays focus either in front of the cornea or way beyond it.

If you have astigmatism, the visual images formed in the retina will be blurred or distorted. This happens to images of the object located close by or far away.

Since the vision is blurred or distorted, you may strain your eyes to properly focus on the images. This may lead to squinting of the eyes. If you develop a squint that was not present before, it is better to consult an ophthalmologist and check for astigmatism.

Straining of your eyes can also lead to headaches. The intensity of the headaches may increase when you read or watch television for longer periods of time. Driving especially in the nights can become a problem.

Astigmatism in adults can occur as a result of injuries to the cornea. It may also occur as a result of certain surgeries of the eyes. Some of the common eye surgeries that may lead to astigmatism are:

     •        cataract removal surgeries,

     •        lamellar keratoplasty

     •        retinal repair surgeries

     •        trabeculectomy

If you had any of these surgeries of late and, have problems with focusing even after a considerable period after surgery, you need to rule out astigmatism

Astigmatism in children is difficult to identify initially than adults. This is mainly because, children may fail to understand that, the images they see are blurred or distorted. In most children astigmatism may be present at birth and the first images they see itself may be blurred. This makes them think it to be natural and fail to complain about it.

Astigmatism in children may hinder their progress in academic, extra- curricular and sporting activities. This is due to the fact that they are not able to see things as clearly as they should do.

More often, teachers and parents may feel that these children may have some learning disorder. Parents who had astigmatism as children should periodically test the eyes of their children for presence of astigmatism.

Since astigmatism has various treatment options, the cost of treating astigmatism will depend on the type of procedure selected. In cases where patients opt for lenses or eyeglasses, this will be an ongoing cost.

The cost of the surgeries will vary depending on the type of the surgery selected, the hospital selected, the city where the hospital is located and the duration of the treatment.

The clinical condition of the patient also contributes to the variation in the total cost.

Apart from this patients will also need to factor in additional costs, such as travel fare, hotel stay, food and medications.

Astigmatism is a condition where images get blurred or distorted due to changes in the shape of the cornea. A normal cornea is round, and the curvature is uniform in nature. Certain conditions cause imperfections in the curvature of the cornea making it cone shaped.

This results in changes in the refractive power of the cornea. The changes in refraction causes the cornea or the lens to focus the image improperly in the retina.

The images may be formed in front of the retina, making them appear blurred or beyond the retina, making them appear distorted.

Astigmatism may be present at birth in a lot of children. Most of the cases of astigmatism in children are self-corrective and usually resolves before they are a year old.

In certain children the astigmatism may persist for the rest of their lives. There is always a possibility for the astigmatism to worsen as they grow older.

Certain diseases like keratoconus and cataracts may cause astigmatism in adults. The astigmatism so developed may worsen as the underlying eye disease worsens.

Having an astigmatism treated is no guarantee that the condition may not worsen at a later stage.

Wearing of eyeglasses can correct astigmatism, but not cure the condition. Eyeglasses may help only to bring more clarity to vision. Not wearing eyeglasses, may or may not worsen the degree of astigmatism.

There is a misconception that straining the eyes may worsen astigmatism, but it is not true. Continuous reading or watching of television has nothing to do with the worsening of astigmatism. Only thing that may happen as a result of these actions is a bad headache.

It is said that astigmatism may or may not worsen as age progresses and have nothing to do with having treatment or no treatment. Treatments help to bring clarity of vision than usual.