If you experience a distortion or blurring of images at all distances -- nearby as well as far -- you may have astigmatism. Even if your vision is fairly sharp, headache, fatigue, squinting and eye discomfort or irritation may indicate a slight degree of astigmatism. A thorough eye examination, including tests of near vision, distant vision and vision clarity, can determine if astigmatism is present.
Astigmatism is not a disease nor does it mean that you have "bad eyes." It simply means that you have a variation or disturbance in the shape of your cornea.
What is astigmatism?
Astigmatism is one of a group of eye conditions known as refractive errors. It is caused when the front surface of your eye, called the cornea, is not perfectly round. So instead of having equal curvatures like a basketball, it has several different curvatures like a football. As a result, light is focused differently in your eye. Astigmatism often occurs with nearsightedness and farsightedness, conditions also resulting from refractive errors.
Farsightedness
If you can see objects at a distance clearly but have trouble focusing well on objects close up, you may be farsighted.
Your eye care practitioner may refer to farsightedness as longsightedness, or its medical names, hypermetropia or hyperopia. Hypermetropia causes the eye to exert extra effort to see close up. After viewing nearby objects for an extended period, you may experience blurred vision, headaches and eyestrain. Children who are farsighted may find reading difficult.
Hypermetropia is not a disease, nor does it mean that you have "bad eyes." It simply means that you have a variation in the shape of your eyeball. The degree of variation will determine whether or not you will need corrective lenses.
What causes farsightedness?
In normal vision, light rays from an object entering the eye are focused by the lens (transparent tissue that changes shape to help focus incoming light) on the retina (the membrane at the back of the eye that transmits images of external objects to the optic nerve). In people with farsightedness, the distance between the lens and the retina is too short. As a result, light rays from near objects strike the retina before they are in focus, which causes blurred vision. Distant objects appear clearly because light rays from them focus correctly on the retina.
Farsightedness is present at birth and tends to run in families. The condition usually is not severe in young children, and mild cases sometimes correct naturally-as these children grow, eye muscles adjust the distortion of the lens until light rays from near objects focus correctly on the retina, resulting in sharp vision. With age, this natural ability to accommodate the condition is lost.
Persons with farsightedness frequently suffer from eyestrain and headaches in addition to defective vision. Farsightedness usually can be corrected with eyeglasses or contact lenses. The age at which a person requires eyeglasses for this condition depends on its degree of severity. However, almost everyone requires at least reading glasses by the time they are in their 60s to help them see objects that are small but near.
Nearsightedness
If you can see objects nearby with no problem, but reading road signg sor making out out the writing on the board at school is more difficult, you may be near- or shortsighted.
Your eye care professional may refer to the condition as myopia, a term that comes from a Greek word meaning "closed eyes." Use of the word "myopia" for this conditon may have grown out of one of the main indications of nearsightedness: Squinting to see distant objects clearly.
Myopia is not a disease, nor does it bean you have "bad eyes." It simply refers to a variation in the shape of your eyeball. The degree of variation determines whether or not you will need corrective eyewear.
What causes nearsightedness?
Myopia most often occurs because the eyeball is too long, rather than the normal, more rounded shape. Another less frequent cause of myopia is that cornea, the eye's clear outer window, is too curved. There is some evidence that nearsightedness may also be caused by too much close vision work.
Presbyopia
Hold the book up close and the words appear blurred. Push the book farther away, and the words snap back into sharp focus.
That's how most of us first recognize a condition that eye care professionals call presbyopia, a name derived from Greek words meaning "old eye." Eye fatigue or headaches when doing close work, such as sewing, knitting or painting, are also common symptoms. Because it is associated with aging, presbyopia is often met with a groan -- and the realization that reading glasses or bifocals are inevitable.
What causes presbyopia?
As we age, body tissues normally lose their elasticity. As skin ages, it becomes less elastic and we develop wrinkles. Similarly, as the lenses in our eyes lose some of their elasticity, they lose some of their a bility to change focus for different distances. The loss is gradual. Long before we become aware that seeing close up is becoming more difficult, the lenses in our eyes have begun losing their ability to flatten and thicken. Only when the loss of elasticity impairs our vision to a noticeable degree do we recognize the change
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If you are experiencing the symptoms described above please call one of our offices to discuss any further questions you may have or to schedule an appointment.
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