Astigmatism is an eye disorder that results in blurred (unclear) vision, irrespective of whether the object being viewed is near or at a distance. It is often present at birth and is a type of refractive error. Astigmatism is considered the most common refractive error in children and adults around the world. Let’s see what a refractive error is, and understand astigmatism, its causes, symptoms, diagnosis, and treatment in Pune.
Astigmatism is an eye disorder that results in the individual having blurred vision, both close-up and of objects farther away. This usually happens when the shape of your eye (either the cornea or the lens) is more curved than it should be.
The main types of astigmatism are:
- Corneal Astigmatism: It is usually caused by your cornea (the clear dome-shaped front part of the eye) having an irregular shape. This is the most common type of astigmatism.
- Lenticular Astigmatism: This type of astigmatism occurs when the lens (the curved structure in the eye that bends light and focuses it for the retina) in your eye has an irregular shape.
- Myopic Astigmatism: This type of astigmatism happens when astigmatism occurs with nearsightedness or myopia.
- Hyperopic Astigmatism: This type occurs when astigmatism combines with farsightedness or hyperopia.
Additionally, astigmatism can be categorized as regular and irregular astigmatism based on the pattern of irregularity in the cornea or lens.
The reason behind astigmatism is a refractive error. A refractive error is an eye condition in which the eye does not refract or bend light properly, resulting in problems with clear vision formation.
In astigmatism, the cornea or the lens is curved differently than normal. Instead of having a perfect round curve, the surface or the cornea or the lens may be egg- or oval-shaped.
Thus, light rays entering the eyes are not bent properly and result in the formation of two different images. These two images overlap or combine and result in blurry vision, and sometimes, double vision.
Astigmatism may be present from birth. However, some factors may increase your risk of developing the condition:
- Family history of astigmatism
- Preterm birth
- Eye injury that may result in scarring of the cornea
- Eye disease
- Complications after eye surgery such as cataract surgery
- Excessive nearsightedness or myopia
- Excessive farsightedness or hyperopia
- Keratoconus, a condition in which the cornea bulges outward into a cone shape
Symptoms of astigmatism include:
- Blurred vision at all distances
- Eyestrain or irritation
- Headache
- Difficulty seeing things at night
- Squinting to see clearly
- Seeing a glare or halos around lights
- Fatigue
Since young children may not be able to explain the symptoms of astigmatism, consult an eye doctor if you notice your child squinting, rubbing eyes, or complaining of frequent headaches.
An eye care specialist will perform a complete eye examination to diagnose astigmatism. The tests generally included in the diagnosis of astigmatism are:
- Visual Acuity Test: This test checks your near and distance vision based on how well you can see different-sized symbols on a chart. You will be made to cover one eye while the other is being tested.
- Refraction Test: This test is meant to measure how much your eye focuses and bends light as it enters. It involves placing an instrument called a phoropter on your eyes and adding different lenses to it. You are then asked to read an eye chart with each lens to determine the appropriate prescription to correct your vision. Another instrument called a retinoscope may also be used to shine a special light into your eyes and see how it reflects off the retina.
- Keratometry: This test uses a device called a keratometer to measure reflected light from the surface of the cornea. This helps the doctor determine the shape and curvature of the cornea.
- Corneal Topography: This is a type of photography technique that maps the surface of the cornea. This helps the eye doctor find distortions in the curvature of the cornea.
- Slit Lamp Exam: This exam uses a microscope with a bright light that the eye doctor shines into your eye. This helps the doctor get a closer look at the different structures at the front of the eye and inside the eye.
The treatment for astigmatism depends on the severity of the condition. Treatment for astigmatism includes:
- Corrective Eyeglasses: Eyeglasses, the most popular option to treat astigmatism, work by compensating for the uneven shape of the eye with corrective lenses. The lenses make the light bend into the eye properly and correctly project images onto the retina.
- Corrective Contact Lenses: Contact lenses are small clear discs worn directly on the eyes. Just like eyeglasses, prescription contact lenses help improve vision sharpness by bending light correctly. Consult an eye doctor to know if contact lenses are a good treatment option in Pune for you based on your specific symptoms.
- Orthokeratology: Also called corneal refractive therapy, orthokeratology involves wearing a specially fitted, rigid contact lens during sleep to even out the curvature of the cornea. However, if treatment is discontinued, the eye returns to its former shape and refractive error.
- Refractive Surgery: Refractive surgery is an option for those with astigmatism who do not want to use eyeglasses or contact lenses. As the name suggests, in this surgery, the eye surgeon corrects the refractive error by reshaping the curves of the cornea using a laser beam.
The types of refractive surgery for astigmatism include:
- Laser-Assisted In-Situ Keratomileusis: LASIK employs a laser beam with which the eye surgeon makes a thin, hinged flap in the cornea. The laser is used to change the shape of the cornea and the corneal flap is repositioned.
- Laser-Assisted Subepithelial Keratectomy: Also called LASEK, this procedure uses a special alcohol to loosen and remove the top protective layer (epithelium) of the cornea instead of making a flap in the cornea itself. A laser beam is used to change the curvature of the cornea and the loosened epithelium is repositioned.
- Epi-LASIK: This procedure is a variation of LASEK wherein, instead of alcohol, a special mechanized blunt blade is used to separate a very thin sheet of the epithelium. A laser beam is used to reshape the cornea and the loosened epithelium is repositioned.
- Photorefractive Keratectomy: Also called PRK, this procedure is similar to LASEK, except for one major difference. In PRK, the epithelium is removed and then not replaced. After using a laser beam to reshape the cornea, a temporary contact lens is used to cover and protect it until the epithelium grows back naturally.
- Small-Incision Lenticule Extraction: Also called SMILE, this newer type of surgery reshapes the cornea by using a laser to cut a lens-shaped bit of tissue (lenticule) below the cornea's surface, which is removed through a small incision.
If left untreated, astigmatism can cause:
- Amblyopia, or “lazy eye”, if the astigmatism is present in only one eye
- Severe eye strain and headaches
- Significant reduction in visual acuity
- Higher risk of developing other eye problems such as glaucoma and cataracts
Unfortunately, astigmatism cannot be prevented. However, there are some steps you can take to maintain good eye health and reduce your risk of developing other eye problems that can worsen astigmatism.
- Opt for regular eye checkups for prompt diagnosis and resolution of issues with eye health.
- Protect your eyes from injuries by wearing protective eyewear while playing sports, mowing the lawn, etc.
- Maintain a healthy lifestyle by spending time outdoors and adopting a balanced diet with eye-health-promoting foods.
- Rest your eyes regularly when working on a computer or reading to reduce eyestrain.
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