What is a cataract?
A cataract is a clouding of the eye's lens, which lies behind the iris and the pupil. It works much like
a camera lens, focusing light onto the retina at the back of the eye. The lens also adjusts the eye's focus, letting us
see things clearly both up close and far away.
A cataract at first has little effect on your vision. You may notice that your vision is blurred a little,
like looking through a cloudy piece of glass. A cataract may cause glare. You may notice when you drive at night that the
oncoming lights cause glare or starursts. Colors may not appear as bright as they once did.
No one knows for sure why the eye's lens changes as we age, forming cataracts. Researchers are gradually
identifying factors that may increase risk of developing cataracts, such as ultraviolet light, steroids, diabetes, and
cigarette smoke.
What will happen during cataract surgery?
Many poeple consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively
painless procedure to regain vision. Cataract surgery is very successful in restoring vision; in fact, it is one of the
most frequently performed surgeries in the United States, with over 1.5 million cataract surgeries done every year. Nine
out of ten people who have cataract surgery regain very good vision, somewhere between 20/20 and 20/40.
Once you and your eyecare practitioner have decided that you will have cataract surgery, the eye surgeon
will examine you. Ask the surgeon if you should continue your usual medications. Your eye will be measured to determine
the proper power of the intraocular lens that will be placed in your eye during surgery. Cataract surgery is usually done
on an outpatient basis. You may be asked to skip breakfast, depening on the time of your surgery. Upon arrival for surgery,
you will be given eye drops and perhaps medications to help you relax. A local anesthetic will make the operation painless.
The skin around your eye will be thoroughly cleansed, and sterile coverings will be placed around your head.
Under an operating microscope, a small incision will be made into the eye. Microsurgical instruments will be used to fragment
and suction the cloudy lens from the eye. The black membrane of the lens (called the posterior capsule) will be left in place.
A plastic IOL will be placed inside the eye to replace the natural lens that was removed. The incision will
then be closed. When stitches are used, they rarely need to be removed. When the operation is over, the surgeon will usually
place a shield over your eye. After a short stay in the recovery area, you will be ready to go home. You should plan to have
someone else drive you home.
What is nearsightedness (myopia)?
Nearsightedness, or myopia, is a vision problem experienced by up to one-third of the population. Nearsighted
people have difficulty reading highway signs and seeing other objects at distance, but can see for up-close tasks such as
reading or sewing. Myopic people often have headaches or eyestrain, and might squint or feel fatigued when driving or playing
sports. If you experience these symptoms while wearing your glasses or contact lens, you may need a comprehensive eye
examination.
Myopia occurs when the eyeball is slightly longer than usual from front to back. This causes light rays to
focus at a point in front of the retina, rather than directly on its surface. Myopia is not a disease, nor does it mean that
you have "bad eyes". It simply means that you have a normal variation in the shape of your eyeball. The degree of variation
determines the need for corrective wear.
Myopia usually begins between the ages of 8 and 12 years and nearly always before the age of 20. Often the
degree of myopia increases as the body grows rapidly, then levels off in adulthood. During the years of rapid growth,
frequent changes in prescription eyewear may be needed to maintain clear vision.
What is farsightedness (hyperopia)?
Farsightedness, or hyperopia, is a common vision problem, affecting about a fourth of the population. People
with hyperopia can see distant objects very well, but have difficulty seeing objects that are up close. This vision problem
occurs when light rays entering the eye focus behind the retina, rather than directly on it. The eyeball of a farsighted
person is shorter than normal.
Many children are born with hyperopia, and some of them outgrow it as the eyeball lengthens with normal growth.
Farsighted people sometimes have headaches or eyestrain, and may squint or feel fatigued when performing work at close range.
If you get these symptoms while wearing your glasses or contact lenses, you may need an eye exam and a new prescription.
What is presbyopia?
During middle age, usually beginning in the 40s people experience blurred vision at near points, such as when
reading, sewing, or working at the computer. There's no getting around it - this happens to everyone at some point in their
life, even if they never had a vision problem before. When people develop presbyopia, they find they need to hold books,
magazines, newspapers, menus, and other reading materials at arm's length in order to focus properly. When they perform
near work, they may have headaches or eyestrain, or feel fatigued.
Presbyopia is caused by an age-related process, rather than the way light is refracted, or bent, by the eye
(which causes astigmatism, nearsightedness, and farsightedness). Presbyopia is caused by a slow loss of flexibility within
the lens inside your eye.
These age-related changes occur within the proteins in the lens, making the lens harder and less elastic as
you age. Age-related changes also take place in the muscle fibers surrounding the lens. Glasses with bifocal or progressive
addition lenses (PALs) are the most common correction for presbyopia. Bifocal means two points of focus: the main
part of the spectacle lens contains a prescription for nearsightedness or farsightedness, while the lower portion of the lens
holds the stronger near prescription for close work.
Progressive Addition Lenses are similar to bifocal lenses, but they offer a more gradual visual
transition between the two prescriptions.
Reading glasses are another choice. They may be worn just while doing close work, and may even be prescribed
to wear over the top of contact lenses (usually worn for distance correction). These glasses may be purchased over-the-counter
at a retail store, or higher-quality versions may be prescribed by your eyecare professional.
There are contact lenses for presbyopes, called multifocal lenses. You can obtain multifocal contact
lenses in gas permeable or soft lens materials. Another type of contact lens correction for presbyopia is monovision,
in which one eye wears a distance prescription, and the other wears a prescription for near vision. The brain learns to
favor one eye or the other for different tasks. Some people are delighted with this solution, while others miss the depth
perception they once had.
Because the human lens continues to change as you grow older, your presbyopic prescription will change over
time as well. You can expect your eyecare practitioner to prescribe a stronger correction for near work as you need it.
Read more about presbyopia at http://www.varilux.com/.
What is astigmatism?
Astigmatism is the most common vision problem. Sometimes incorrectly called a "stigmatism", astigmatism may
accompany nearsightedness or farsightedness. It is caused by an irregularly shaped cornea and is corrected with glasses or
contact lenses. If you have only a small amount of astigmatism, you may not notice it or have just slightly blurred vision.
Sometimes uncorrected astigmatism can give you headaches or eyestrain, and distort or blur your vision.
If your eyeglass or contact lens prescription contains three parts rather than one, you have some amount of
astigmatism. A prescription with three parts looks like this:
-2.75 +1.25 x180
The first part contains your main spherical correction, while parts two and three show the extent and location
of your astigmatism.
Astigmatism occurs when the cornea is shaped more like an oblong football than a spherical baseball, which is
the normal shape. The oblong shape causes light rays to focus on two points at the back of your eye, instead of just one.
Astigmatism can be corrected with glasses or contact lenses. Many people with astigmatism believe that they
cannot wear contact lenses, or that only rigid lenses can correct astigmatism, but this is no longer true. Now there are
soft lens designs that correct astigmatism; they are called toric lenses. Toric lenses have a special correction
built into them and may also contain a prescription for nearsightedness or farsightedness if you need it.
|
