What is farsightedness?
Farsightedness is a defect in the eye's focusing (refractive) mechanism, which makes nearby objects difficult to see.
What causes farsightedness?
Light rays from distant objects enter the lens at the front of the eye. Light rays from nearby objects are bending (diverging) as they enter the eye. When
- Reading and other close tasks are difficult.
- The printed page or TV screen seem blurry.
vision is normal, light rays from both near and far objects converge precisely on the retina, the tissue at the back of the eyeball, which is made up of light-sensitive nerve cells that carry light signals to the brain for processing as an image. Thus, the retina is like the film in a camera; in order for the image to be sharp, light rays streaming through the lens must focus on this focal plane.
In farsightedness, instead of converging precisely on the retina, the light rays from near objects converge too far back, behind the retina. Thus, when they actually strike the retina they are not in sharp focus.
Farsightedness that starts early in life tends to be a genetic trait and is referred to as hyperopia. With age, people develop a certain degree of farsightedness, a condition called presbyopia. This is caused by a stiffening of the lenses, which reduces their ability to focus sharply on close objects.
How is farsightedness diagnosed and treated?
Farsightedness is easily diagnosed during a routine eye examination in which the patient reads an eye chart or looks at objects through a special viewing machine.
Squinting can help sharpen the
focus, but this can lead to headaches and eyestrain. The better way is to be fitted for corrective glasses or contact lenses that employ a refractive lens of plastic or glass directly in front of each eye. These artificial lenses work in tandem with the natural lens, bending light rays so that they are focused on the retina.
What can I do myself?
Contrary to popular belief, neither far- nor nearsightedness is caused by overworking the eyes or reading in a dim light. Similarly, there are no exercises or other maneuvers that correct farsightedness. Avoid the nonprescription eyeglasses that are sold in pharmacies or variety stores. Each person's eyes are different, and corrective lenses should be tailored to individual needs.
When should I see my doctor?
Everyone should have periodic eye examinations, beginning in early childhood. In addition, an eye specialist should be consulted if there is difficulty reading, driving, or performing other tasks because of faulty vision.
Eyes can be tested by either an ophthalmologist, a medical doctor who has advanced training in eye disorders, or an optometrist, a health professional who is trained to test eyes for refractive problems and prescribe corrective lenses. In any event, eyes should be examined regularly by an ophthalmologist or an
optometrist for signs of serious disorders, such as diabetes, cataracts, or glaucoma.
What will the doctor do?
He or she examines the eyes carefully, using special lights and equipment. If the person is farsighted, the doctor uses a set of supplementary lenses to determine the corrective formulas that are needed for glasses. When the patient can read the lower lines of the eye chart and can also read small print of a sampler held at reading distance from the face, the proper lens correction has been determined. A prescription can then be prepared that an optometrist or optician uses to make the eyeglasses or contact lenses.
It may be difficult or impossible to provide one set of corrections that allow an older person to see both close and distant objects cleanly and sharply. This can be remedied by bifocals, which have lens corrections for both close and far objects, or even trifocals, which provide multiple corrections. There are also bifocal contact lenses.
The course of farsightedness
This condition usually worsens gradually with age.
Is farsightedness dangerous?
It is not a threat to health, but it can be dangerous if it hinders a person's ability to see while driving or operating dangerous machinery.
What can I do to avoid farsightedness ?
Farsightedness cannot be prevented, but it can be corrected by wearing properly fitted glasses or contact lenses.