What is a Cataract?
A cataract is a clouding of the normally clear and transparent lens of the eye. It is not a tumor
or a new growth of skin or tissue over the eye, but a fogging of the lens itself. Normally the lens
of the eye is clear. When a cataract develops, the lens becomes cloudy as a frosted window. Located
near the front of the eye, the lens focuses light on the retina at the back of the eye. Light passes
through it to produce a sharp image on the retina. When a cataract forms, the lens can become so
opaque and unclear that light cannot easily be transmitted to the retina. Often, however, a cataract
covers only a small part of the lens and, if sight is not greatly impaired, there is no need to
remove the cataract. If a large portion of the lens becomes cloudy, sight can be partially or
completely lost until the cataract is removed. There are many misconceptions about cataracts. For
instance, cataracts do not spread from eye to eye, though they may develop in both eyes at the same
time. A cataract is not a film visible on the outside of the eye, is not caused from overuse of the
eyes, and using the eye does not make it worse. Cataracts usually develop gradually over many years;
rarely they develop over a few months. Finally, cataracts are not related to cancer and having a
cataract does not mean a patient will be permanently blind.
Causes and Symptoms.
There are many types of cataracts. Most are caused by a change in the chemical composition of the lens
resulting in a loss of transparency. These changes can be caused by aging, injuries to the eye, certain
diseases and conditions of the eye and body, and heredity or birth defects. The normal process of
aging may cause the lens to harden and turn cloudy. These are called senile cataracts and are the
most common type. They can occur as early as age 40. Children as well as adults of any age can
develop cataracts. When cataracts appear in children they are sometimes hereditary or can be
caused by infection or inflammation which affect the pregnant mother and the unborn baby. These are
called congenital cataracts and are present at birth. Eye injuries can cause cataracts in patients
of any age. A hard blow, puncture, cut, intense heat or chemical burn can damage the lens
resulting in a traumatic cataract. Certain infections or diseases of the eye such as diabetes, can
also cause the lens to cloud and form a secondary cataract. Depending on the size and location of
the cloudy areas in a lens, a person may or may not be aware that a cataract is developing. If the
cataract is located on the outer edge of the lens, no change may be noticed in vision, but if the
cloudiness is located near the center of the lens, it usually interferes with sight. As cataracts
develop there may be hazy, fuzzy, and blurred vision. Double vision may also occur when a cataract
is beginning to form. The eyes may be more sensitive to light and glare, making night driving
difficult. There may be a need to change eyeglass prescriptions frequently. As the cataract worsens,
stronger glasses no longer improve sight. It may help to hold objects closer to the eye to read and
do close-up work. The pupil, which is normally black, may undergo noticeable color changes and
appear to be yellowish or white.
Detection and Diagnosis.
Usually cataracts cannot be viewed from the outside of the eye without proper instruments. If blurred
vision or other symptoms are noticed, an eye doctor (Optometrist, Optometric Physician or Ophthalmologist)
should be visited as soon as possible for a comprehensive medical eye examination. The eye doctor examines
the eye with a variety of instruments to determine the type, size and location of the cataract. The
interior of the ye is also viewed with an instrument called an ophthalmoscope.
When cataracts cause enough loss of sight to interfere with the patient's work or life-style, it is
probably time to remove them. Depending on individual needs, the patient and the eye doctor decide
together when removal is necessary. Surgery is the only effective way to remove the cloudy lens.
Cataracts cannot be removed with a laser, an intense beam of light energy. Ophthalmologic laser
surgery can, however, be used to open part of the lens membrane (capsule)which may become cloudy
after cataract surgery. Though rapidly changing technology and ongoing research in recent years has
improved the treatment of cataracts, eye drops, ointments, pills, special diets or eye exercises
have not been proven to dissolve or reduce a cataract. Ultraviolet rays have been shown to hasten
cataract formation so ultraviolet protection glasses is recommended whenever outside. Fortunately,
cataract surgery is highly successful and over 90% of patients who undergo surgery regain useful
vision. It is important to understand that complications can occur. As with any surgery, a good
result cannot be guaranteed. Once the cloudy, natural lens of the eye is removed, the patient needs
a substitute lens to focus the eye. Medical advances have provided new ways to restore vision after
the lens is removed. These include:
There are advantages and disadvantages to each type of lens replacement. The eye doctor helps the
patient decide which lens or combination of lenses will be best suited to each person's life-style
and will help provide the best vision. The implanted IOL is certainly the most common correction
done as it generally provides more benefit than the other options.
- Somewhat thinner and lighter cataract glasses. They may still be thicker, however,
than most ordinary glasses.
- Rigid Gas Permeable or Soft contact lenses that can be worn all day, but are taken
out at night.
- Special extended-wear Rigid Gas Permeable or Soft contact lenses that can be left in
the eye up to 30 days.
- Intraocular lenses (IOLs) that are permanent lenses implanted inside the eye by
surgery in place of the natural lenses.