Cataract
Cataract is the clouding of the eye’s natural lens causing visual deterioration. Cataract is the most common cause of vision loss in aging people and is also the principal cause of blindness in the world.
There are several types of cataracts:
A posterior subcapsular cataract. It occurs at the back portion of the lens. People with diabetes or those taking high doses of steroid medications have a greater risk of developing a posterior subcapsular cataract.
A nuclear cataract. This form of cataract forms deep in the central zone (nucleus) of the lens. Nuclear cataracts usually are associated with aging and it called senile cataract.
A cortical cataract. This spoke like cataract characterized by white, wedge-like opacities that start in the periphery of the lens and work their way to the center in a spoke-like fashion. This type of cataract occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
Symptoms and signs of the cataract:
At first, a cataract has little effect on your vision. At the beginning you notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting.
A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did.
The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called “second sight.”
Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens.
What causes cataracts?
The lens inside the eye works much like a camera lens, focusing light onto the retina for clear vision. It also adjusts the eye’s focus, letting us see things clearly both up close and far away.
The lens is mostly made of water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.
But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract, and over time, it may grow larger and cloud more of the lens, making it harder to see. One theory of cataract formation is that many cataracts are caused by oxidative changes in the human lens. This is supported by nutrition studies that show fruits and vegetables high in antioxidants.
Besides advancing age, cataract risk factors include:
Ultraviolet radiation
Diabetes
Hypertension
Obesity
Smoking
Prolonged use of corticosteroid medications
Previous eye injury or inflammation
Previous eye surgery
High myopia
Family history
Prevention of cataract
Though there is significant controversy about whether cataracts can be prevented, a number of studies suggest certain nutrients and nutritional supplements may reduce your risk of cataracts.
Another step you can take to reduce your risk of cataracts is to wear sunglasses that block the sun’s UV rays when you are outdoors.
Cataract treatment
The only way to know for sure if you have cataracts is to see an eye doctor for a comprehensive eye exam. The only way to treat cataract is to have cataract surgery.
Many people consider poor vision an inevitable fact of aging, but cataract surgery is a simple, relatively painless procedure to regain vision. During surgery, the surgeon will remove your clouded lens and in most cases replace it with a clear, plastic intraocular lens (IOL).
New IOLs are being developed to make the surgery less complicated for surgeons and the lenses more helpful to patients. Presbyopia-correcting ( Multifocal ) IOLs potentially help you see at all distances, not just one. Another new type of IOL blocks both ultraviolet radiation and high-energy visible blue light, which research indicates may damage the retina.
Eye glasses after cataract surgery
In most cases, unless you choose presbyopia-correcting IOLs, you will still need reading glasses after cataract surgery. You may also need progressive lenses to correct mild residual refractive errors as well as presbyopia.
לפרטים נוספים
