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This book describes Astigmatism, Diagnosis and Treatment and Related Diseases
Why is Astigmatism so important?
It is to me because I develop astigmatism after my cataract operation.
It affects my night vision to the extent that I have wear eye glasses when driving at night.
Astigmatism is a disorder in which the cornea of the eye is curved differently leading to blurred and distorted vision at all distances.
The eyeball is flattened normally from above downwards or occasionally sideways or along an oblique axis.
It is different from near or far sightedness.
It is therefore important to recognize Astigmatism and seek the correct treatment for it.
Astigmatism is a frequent form of refractive error that produces blurred vision
It appears when the cornea (the clear front cover of the eye) is irregularly shaped (more oval than round) or occasionally due to the curvature of the lens inside the eye.
Astigmatism is induced by an irregularly shaped cornea or lens that stops light from focusing properly to a single point on the retina, the light-sensitive surface at the back of the eye.
In this instance, the vision becomes out of focus at any distance.
Also, the curvature of the lens inside the eye can alter, resulting in a rise or reduction of the degree in astigmatism.
This change often happens in adulthood and can happen before the development of naturally happening cataracts.
Astigmatism often happens with other vision disorders like myopia (nearsightedness) and hyperopia (farsightedness).
Together these vision disorders are regarded as refractive error disorders since they influence how the eyes bend or "refract" light.
Astigmatism is normally an inherited disorder where the curvature of the cornea of the eye is different from a normal person.
Due to the curvature the eye is seeing the objects in front of it at a different angle.
The light is entering the eye at a different angle which cast shadows and induces blurred vision.
Other causes of Astigmatism are from:
1. Eye surgery or
2. Sport injuries
Astigmatism appears when the light is bent differently depending on where it reaches the cornea and passes through the eyeball.
It can happen due to a relatively rare disorder called keratoconus in which the cornea becomes progressively thinner and cone-shaped
The astigmatism can decrease or increase over time.
Astigmatism can involve both children and adults.
Some patients with slight astigmatism will not observe much change in their vision.
It is essential to have eye examinations at regular intervals in order to detect any astigmatism early on for children.
The most important symptom is blurred vision at any distance, unlike near or far sightedness.
Other symptoms are:
1. Blurred and distorted vision of near and distant objects
2. Blurring of vertical, horizontal and diagonal lines
3. Eye strain and fatigue
4. Sensitivity to light
5. Tired and dry eyes
8. Difficulty seeing and driving at night
An eye examination is accompanied by vision tests and computerized testing of the curvature of eye, nearsightness, farsightness and any other abnormality of eye vision.
A keratometer measures the curvature of the cornea.
The treatment of astigmatism can be done with eyeglasses, contact lenses, or surgery.
The person’s lifestyle affects the way the astigmatism is treated.
Orthokeratology requires the fitting of a series of rigid contact lenses to reshape the cornea.
Refractive Surgery aims to alter the shape of the cornea permanently.
Astigmatism can also be treated by reshaping the cornea through LASIK (laser in situ keratomileusis) or PRK (photorefractive keratectomy).
TABLE OF CONTENT
Chapter 1 Astigmatism
Chapter 2 Causes
Chapter 3 Symptoms
Chapter 4 Diagnosis
Chapter 5 Treatment
Chapter 6 Prognosis
Chapter 7 Farsightedness
Chapter 8 Nearsightedness