What is Astigmatism?
Astigmatism is an eye condition that causes blurring of vision. Blurring of vision occurs due to a refractive error in the cornea. This leads to the inability of the cornea to properly focus the light on the retina. In astigmatism, the cornea takes a kind of oval shape rather than its more rounded natural shape. This type of astigmatism is referred to as corneal astigmatism. Astigmatism can also occur due to an improper curvature of the lens and this is referred to as lenticular astigmatism.
Astigmatism may be present at birth or may develop later in life. Astigmatism may occur as a side effect of certain eye injuries or eye surgeries. Astigmatism can occur alone or along with other eye conditions like short sightedness or long sightedness.
The exact cause of astigmatism is not clearly understood. In majority of cases it is present at birth. It may also occur later in life due to eye disorders like keratoconus where there is a thinning of the cornea. Some of the predisposing factors of astigmatism are-
• A family history of astigmatism
• Presence of keratoconus
• Injury or scarring of the cornea
• Excessive short sightedness or long sightedness
• A history of eye surgery including cataract
The common symptoms of astigmatism are
• Blurred vision at all distances
• Hazy vision
• Increase stress and strain on the eyes
• Development of a squint
• Difficulty in seeing at night
A complete eye examination is necessary to assess the extent of astigmatism. Various tests are performed during the eye examination. They include
• Visual acuity assessment test-for assessing vision
• Refraction test- For assessing the refractory error
• Keratometry- to assess the curvature of the cornea
There are various methods for correcting astigmatism. The most simple and effective way is wearing eye glasses. Contact lens is an option if one does not want to wear glasses. Orthokeratology, where contact lenses are worn for a specific time period every day is also a favoured option in certain situation. Refractive surgeries that reshape the cornea is a curative treatment that eliminates the need to wear glasses.
Wearing special eye glasses that helps to focus the images on the retina is the most common mode of treatment. Astigmatism is corrected by using cylindrical lenses. The power of the lenses is adjusted according to the extent of the refractive error. A single vision lens that allows clear eye sight at all distances is usually prescribed in a majority of the cases. A bifocal or progressive lens is suggested for those with other eye conditions like myopia. presbyopia etc. A disadvantage of glasses is the effect it has on ones looks. A thick cylindrical lens can become an issue for some and for them contact lenses are prescribed.
Contact lenses are ideal for those who prefer not to wear glasses. Instead of the normal soft contact lens, a specially designed toric contact lens is prescribed for astigmatism. These toric lenses help to maintain the rigidity and the shape of the cornea which allows for better focussing. A major disadvantage of contact lenses is the irritation that they cause to the eye in certain persons. Contact lenses also need proper cleaning and maintenance.
This treatment involves the use of a series of contact lenses over a period of time to reshape the cornea. The lenses are to be worn for a specific period of time every day for a particular time frame. After this the patient goes on to wear the next set and so on. The lenses help to retain the proper shape of the cornea for the rest of the day. Hence these lenses are referred to as retainer lenses.
Surgery for astigmatism
Surgery is the only curative treatment for astigmatism. Most cases of astigmatism can be corrected by surgery. Minimally invasive laser astigmatism surgery is the most common choice. Being very precise surgeries, it needs an experienced surgeon to conduct the procedure.
Types of astigmatism surgeries
There are various types of surgeries called refractive surgeries recommended for astigmatism. The type of surgery depends on the extent of refractive error as well as various other factors. A refractive surgery can eliminate the need of wearing glasses or contact lenses. The success rates of refractive surgeries are high but like any other surgeries certain complications may arise.
The most common types of refractive surgeries are -
Laser- Assisted in-situ keratomileusis or LASIK
LASIK surgery for astigmatism not only offers a high rate of success but also is 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. 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 short and long sights.
Lasik surgery duration is about one hour. A vast majority of the patients feel very little or no pain at all. There is no need for 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 vision is also reported with Lasik surgery. Some of the side effects include increased glare, presence of a halo around images, dryness of the eyes etc. Other complaints include a 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 kerectomy (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.
Astigmatism treatment in India
All types of Laser astigmatism surgery are available in various speciality hospitals in India. The duration of surgery is about an hour and there is no need for hospitalisation. The effect of the surgery is obvious soon after completion of the procedure. A patient coming to India for a Lasik surgery for astigmatism has to come one day before to undergo the relevant tests. The patients can go back to their native countries a day or two after surgery. So a period of four five days is enough for those coming from foreign countries.
Alternate treatments for Astigmatism:
Various alternative treatments are 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.