Cataracts Overview
A cataract is a clouding of the normally clear lens of the eye. For patients who have cataracts, seeing through cloudy lenses is a bit like looking through a frosty or fogged-up window.
Cataracts form when protein builds up in the lens of the eye and makes it cloudy. This keeps light from passing through clearly. It can cause you to lose some of your eyesight. There are many types of cataracts.
Clouded vision caused by cataracts can make it more difficult to read, drive a car (especially at night) or see the expression on a friend’s face.
Most cataracts develop slowly and don’t disturb your eyesight early on. But with time, cataracts will eventually interfere with your vision.
At first, stronger lighting and eyeglasses can help you deal with cataracts. But if impaired vision interferes with your usual activities, you might need cataract surgery. Fortunately, cataract surgery is generally a safe, effective procedure.
Types of Cataracts
Cataract types include the following:
- Cataracts affecting the center of the lens (nuclear cataracts). A nuclear cataract may at first cause more nearsightedness or even a temporary improvement in your reading vision. But with time, the lens gradually turns more densely yellow and further clouds your vision.As the cataract slowly progresses, the lens may even turn brown. Advanced yellowing or browning of the lens can lead to difficulty distinguishing between shades of color.
- Cataracts that affect the edges of the lens (cortical cataracts). A cortical cataract begins as whitish, wedge-shaped opacities or streaks on the outer edge of the lens cortex. As it slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens.
- Cataracts that affect the back of the lens (posterior subcapsular cataracts). A posterior subcapsular cataract starts as a small, opaque area that usually forms near the back of the lens, right in the path of light. A posterior subcapsular cataract often interferes with your reading vision, reduces your vision in bright light, and causes glare or halos around lights at night. These types of cataracts tend to progress faster than other types do.
- Cataracts you’re born with (congenital cataracts). Some people are born with cataracts or develop them during childhood. These cataracts may be genetic or associated with an intrauterine infection or trauma. These types of cataracts may also be due to certain conditions, such as myotonic dystrophy, galactosemia, neurofibromatosis type 2 or rubella. Congenital cataracts don’t always affect vision, but if they do, they’re usually removed soon after detection.
Signs and Symptoms of Cataracts
Signs and symptoms of cataracts include the following:
- Clouded, blurred or dim vision
- Double vision in a single eye
- Fading or yellowing of colors
- Frequent changes in eyeglass or contact lens prescription
- Increasing difficulty with vision at night
- Need for brighter light for reading and other activities
- Seeing “halos” around lights
- Sensitivity to light and glare
Initially, the cloudiness in your vision caused by a cataract may affect only a small part of the eye’s lens and you may be unaware of any vision loss. As the cataract grows larger, it clouds more of your lens and distorts the light passing through the lens. This may lead to more-noticeable symptoms.
Causes of Cataracts
Most cataracts develop when aging or injury changes the tissue that makes up the eye’s lens. Proteins and fibers in the lens begin to break down, causing vision to become hazy or cloudy.
Some inherited genetic disorders that cause other health problems can increase your risk of cataracts. Cataracts can also be caused by other eye conditions, past eye surgery or medical conditions such as diabetes. Long-term use of steroid medications, too, can cause cataracts to develop.
How Cataracts Forms
A cataract is a cloudy lens. The lens is positioned behind the colored part of your eye (iris). The lens focuses light that passes into your eye, producing clear, sharp images on the retina — the light-sensitive membrane in the eye that functions like the film in a camera.
As you age, the lenses in your eyes become less flexible, less transparent and thicker. Age-related and other medical conditions cause proteins and fibers within the lenses to break down and clump together, clouding the lenses.
As the cataract continues to develop, the clouding becomes denser. A cataract scatters and blocks the light as it passes through the lens, preventing a sharply defined image from reaching your retina. As a result, your vision becomes blurred.
Cataracts generally develop in both eyes, but not always at the same rate. The cataract in one eye may be more advanced than the other, causing a difference in vision between eyes.
Diagnosis of Cataracts
- Visual Acuity Test: This is basically an eye chart exam. Your doctor will ask you to read letters from a distance to find out how sharp your vision is. First, you’ll try it with one eye and then the other. They may also then do a glare test, where they shine a bright light in your eye and then ask you to read the letters.
- Slit lamp Exam: This uses a special microscope with a bright light that lets your doctor check different parts of your eye. They’ll look at your cornea, the clear outer layer. They’ll also examine the iris, which is the colored part of your eye, and the lens that sits behind it. The lens bends light as it enters your eye so you can see things clearly.
- Retinal Exam: Your doctor puts medicine drops in your eyes to widen your pupils, the dark spots in the middle that control how much light gets in. This lets them get a good look at the retina. The tissue around the back of your eyes, and a better view of the cataract.
Treatment of Cataracts
Keep close tabs on how your cataracts affect the way you see. When your vision troubles start to get in the way of your daily routine, especially if they make driving dangerous, it’s time to talk to your doctor about surgery.
Cataract Surgery
There are several kinds of operations for cataracts, but they all have one thing in common. A surgeon takes out the cloudy lens and replaces it with an artificial one.
A patient may feel a uncomfortable with the idea of an operation on a sensitive spot like their eye. But it’s a very common procedure. You’ll get medicine called local anesthesia to numb your eye. You’ll be awake but sedated, and you won’t feel anything.
It usually takes about 15 to 20 minutes, and you don’t need to stay overnight in a hospital. If you have cataracts in both eyes, your doctor will wait until your first eye heals before they perform surgery on the second. More than 95% of people who have this done say they can see better afterward.
- Small-incision surgery: You may also hear your doctor call this phacoemulsification. Your surgeon makes a tiny cut on your cornea. They put a small device in your eye that gives off ultrasound waves that break up your cloudy lens. Then, they take out the pieces and put in the artificial lens.
- Large-incision surgery: This isn’t done as often, but doctors sometimes suggest it for larger cataracts that cause more vision trouble than usual. It’s sometimes called extracapsular cataract extraction. Your surgeon takes out your clouded lens in one piece and swaps it out for an artificial one. You’ll probably need a little more time to heal from this surgery than from the small-incision type.
- Femtosecond laser surgery: In this operation, your surgeon uses a laser to break up the lens. As with the other types, they’ll then put in the new lens. Your doctor may suggest this if you also have an astigmatism, a curve of your cornea that makes your vision blurry. Your surgeon can treat that problem during the cataract surgery by using the laser to reshape your cornea.
Post Cataract surgery
For most patients, recovery goes smoothly. How long it takes for an individual to recover depends on the type of surgery you get. Usually, you’ll notice that your vision gets much better a few days afterward. After about a week or two, you can go back to doing all the things you enjoy.
As with any surgery, there are risks. It’s rare, but you could have an infection or bleeding. There’s also a chance your retina could pull away from the tissues at the back of your eye. This is known as a detached retina.
Retinal detachment is a serious eye condition that happens when your retina, a layer of tissue at the back of your eye that processes light, pulls away from the tissue around it. Since the retina can’t work properly when this happens, you could have permanent vision loss if you don’t get it treated right away.
Some patients have an issue after cataract surgery called posterior capsule opacification (PCO). Your vision may get cloudy again because the capsule in your eye that holds the artificial lens in place gets thicker. Laser surgery called YAG can fix the problem. Sometimes, this happens 1 year after cataract surgery, but other times, it doesn’t happen until 10 years later.
The posterior chamber is located behind the iris and in front of the lens. In addition to supporting the shape of this area, aqueous supplies nutrients and nourishment to parts of the eye that lack blood supply. It also removes waste.
Improper drainage of the aqueous humor can cause an increase in intraocular pressure (pressure inside the eye). This increase can result in loss of vision or contribute to the development of glaucoma. Issues with aqueous humor drainage can be treated surgically.
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