Cataracts
If the lens becomes cloudy, the light reaching the retina is blurred and distorted, and your vision is affected. This clouded lens is called a cataract, and it must be removed before vision can be restored. A clouded lens can be compared to a window that is frosted or "fogged" with steam. Cataracts are not cancerous. They can be treated with a surgical procedure that has become a fairly common procedure in the United States.The two most common types of cataracts are: the cortical cataract and a posterior subcapsular cataract. Depending on the type of cataract, a patient will experience different vision problems, but the most common cataract symptoms include:
blurring vision
sensitivity to light or glare
double vision in one eye
poor night vision
needing brighter light to read
experiencing fading or yellowing of colors.
If the cloudiness is not near the center of the lens, you may not be aware that you have a cataract.
Age-Related Cataracts
Other Types of Cataracts
Treatment of Cataracts
Cloudiness of the Capsule
Restoring Sight After a Cataract is Removed
Development of Intraocular Lens Implants
Your Cataract Surgery
Frequently Asked Questions>
Cataract and Primary Eye Care Service
[font=黑体][size=3]Age-Related Cataracts[/size][/font]
Many cataracts take years to develop to the point where vision is seriously affected. Most occur as a result of the normal aging process. The types of age-related cataract are usually described by their location in the lens. They are: nuclear cataracts, cortical cataracts and subcapsular cataracts.
Nuclear cataracts occur in the center of the lens and may induce other eye problems, such as myopia. A cortical cataract, which tends to occur more in persons with diabetes, begins at the outer portion of the lens, then slowly moves inward. Subcapsular cataracts develops under the capsule, often at the back of the lens. This type of cataract also occurs more in persons with diabetes, but it is also found in persons with high myopia, adults with retinitis pigmentosa and in people who take steroids.
[font=黑体][size=3]Other Types of Cataracts [/size][/font]
There are other kinds of cataracts not related to the aging process. Traumatic cataracts develop as a result of an eye injury. Others can develop from metabolic blood disorders, eye infections and inflammations and certain types of medications.
Another type, called congenital cataract, occurs at birth, particularly if the mother has had rubella (German measles) during pregnancy. A nuclear cataract occurs in the center of the lens.
Research continues to look for ways to prevent cataracts. Until then, useful vision can be restored in 98 percent of all patients who have normal, healthy eyes.
[font=黑体][size=3]Treatment for Cataracts[/size][/font]
Cataracts can be removed at any age. You no longer have to wait until the cataract "ripens" or until you lose your sight before surgery can be performed. In fact, the placement of an intraocular lens (IOL) implant to restore vision is best done in an eye when the cataract interfers with your daily activities or causes a decrease in vision.
In removing cataracts, the clouded lens (cataract) must be removed surgically. Cataracts cannot be removed via laser.
A common surgical procedure used today is extracapsular cataract extraction. The surgeon makes an incision in the eye and the front (anterior) capsule of the lens to remove the clouded lens. The lens tissue within the capsule is removed. The sac-like capsule that surrounds the lens remains in place. This capsule is left intact for two reasons: to avoid disturbing the gel, or vitreous, that fills most of the eye, and to support an intraocular lens.
After the cataract has been removed, the incision is closed. Often the sutures, which are finer than human hair, do not need to be removed. Some patients, in fact, don't even need sutures, and the "no suture" surgery is popular today.
Another common type of extracapsular cataract extraction is phacoemulsification (often just called "phaco"), where the surgeon removes the cataract through an even smaller incision than the one used in conventional surgery. In this procedure, the surgeon uses a computerized instrument consisting of a needle about the size of a ballpoint pen tip which vibrates at about 40,000 times a second.
This ultrasonic vibration dissolves the cataract into fine particles, which are then vacuumed through an opening in the instrument.
The benefits of the phaco approach include an early restoration of vision and return to normal activities. Phaco is well suited for patients with a less-advanced cataract, when an earlier return to activity is required or when increased physical activity is part of the convalescent period.
[font=黑体][size=3]Cloudiness of the Capsule[/size][/font]
In about 10 to 50 percent of patients who have a cataract removed, the capsule becomes cloudy several months or years after the original surgery. Often this condition is referred to as a "secondary cataract." However, this does not mean that the patient has another cataract; it is only the capsule — not the artificial lens — that has become cloudy.
If this cloudiness blurs your vision, a clear opening can be painlessly made in the center of the posterior capsule membrane with a YAG laser. This procedure is done on an outpatient basis in about 15 minutes, without injections. This is the only instance in which a laser can be used for a cataract-related treatment.
[font=黑体][size=3]Restoring Sight After a Cataract is Removed[/size][/font]
Because the clouded lens is removed in cataract surgery, some type of substitute or replacement lens is needed to restore vision. There are three ways of doing this:
Intraocular Lens Implant
An intraocular lens implant, or IOL, is an artificial lens made of plastic, silicone, acrylic or other material that is implanted inside the eye during cataract surgery. The IOL is implanted within the capsule, which provides permanent support for the lens. This is the most natural and preferred way of restoring vision.
Because the IOL lies safely inside the eye, it is never handled or adjusted as one would for a contact lens. Most patients are good candidates for the implant.
Most patients have the device implanted during their surgery. Those who have had cataract surgery without the IOL implant, and who later discover they cannot tolerate contact lenses or cataract glasses, have to be evaluated very carefully before a second operation for a lens implant is recommended.
Contact Lenses
Contact lenses are another alternative to IOL implants. However, handling them is sometimes cumbersome, and not everyone is a good candidate. Patients with tremors, extreme nervousness, or dry eyes, for example, are not likely to wear contact lenses with much success.
Today, hard contact lenses, soft lenses and extended wear soft lenses are available for persons who have had cataract surgery.
Cataract Eyeglasses
Years ago, cataract eyeglasses were the only option for patients who required cataract surgery. They are still used today but seldomly because they are the least-preferred option. These are recommended only when a patient cannot have another IOL implant or when they cannot wear contact lenses.
A cataract glass is a thick magnifying glass that may provide perfect vision. However, the glass provides clear vision only through the center of the lens, magnifying everything to about one-third larger than normal.
There are several disadvantages with cataract eyeglasses.
Because of the thickness of the glass, you must turn your entire head 支持支持 [s:61] [s:61] [s:60] [s:60] LZ专门发眼科的帖子？支持
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