As we age, the eye’s lens may become cloudy and changes from crystal blue to dull yellow. The cloudy lens is called a cataract. As the cataract develop, vision becomes blurry and dim, as less light passes into the eye. Cataracts may eventually cause temporary vision loss. In the early stages, low-vision aids can compensate for these problems. Fortunately, the cloudy lens can be removed and replaced by clear plastic lenses or other devices that restore vision.
What is a cataract?
As we age, the normally clear lens within the eye may become cloudy. This cloudiness — a cataract — blocks the passage of light into the eye. Looking through a cataract is like trying to see clearly on a foggy day.
Cataracts develop without pain or discomfort. Over time, your sight worsens. Changes are most noticeable when driving, reading or watching television. The location and density of cataracts affect how soon and which symptoms appear. Common symptoms are:
- blurred vision
- halos around lights
- sensitivity to light or glare
- difficulty seeing at night
- distorted images or spots
Cataracts are a leading cause of temporary vision loss in people over 65. By 75, just about everyone has cataracts, and 50% of people have vision loss.
No one knows exactly what causes cataracts, but chemical changes occur as the eyes’ lenses grow cloudy and changes color from crystal blue to dull yellow. Everyone gets some cloudiness as they grow older, but eye injuries or diseases, such as iritis or diabetes, may cause cataracts to form. Cataracts tend to run in families. Occasionally, infants are born with cataracts or develop them shortly after birth. Some may also occur as a result of an accident or a blow to the eye.
People overexposed to ultraviolet radiation from sunlight over many years, who smoke cigarettes or who use certain medications (such as corticosteroids for arthritis, certain tranquilizers or diuretics), are more likely to get cataracts.
Three types of cataracts can disrupt your vision. Each is found at a different location in the eye’s lens.
A nuclear cataract clouds the central part (nucleus) of the eye’s lens. The most common type, it develops as we age. It affects the ability to see distant objects. This cataract may temporarily improve reading vision — a symptom often called "second sight".
A subcapsular cataract affects the back of your lens. Until it is fully developed, vision is often unaffected. This cataract causes blurriness and glare. People with diabetes, high myopia, retinitis pigmentosa or who take steroids are prone to this type of cataract.
A cortical cataract begins in the lens’s outer rim. Wedge-shaped spokes extend from the rim to the central core. The spokes block light, causing glare and loss of contrast. Near and distance vision are slowly disrupted. People with diabetes often develop this kind of cataract.
Stronger bifocals, adjusting lighting to avoid glare or using eye drops to widen the pupil may improve your vision for a while.
The gradual loss of sight caused by cataracts is alarming but treatable. In the United States, 1.3 million cataract operations are performed each year. Over 90% of people regain useful vision between 20/40 and 20/20.
When cataracts disrupt daily life and independent activity, an optometrist can refer you to an eye surgeon. Surgery is performed on an outpatient basis. Under local anesthesia, the eye’s natural lens is gently removed and replaced with an artificial lens. Vision often improves after the first day.
Cataract surgery
There are many different types of cataract surgery, but all fall into one of two groups:
1. Extracapsular: The eye’s lens is surrounded by a protective capsule. In extracapsular surgery, the eye surgeon carefully opens the front of this capsule. Ultrasonic waves are used to break the cloudy lens into tiny pieces, which are vacuumed from the capsule through a long, narrow tube. This process is known as phacoemulsification. The back of the capsule remains untouched. At this point, the eye surgeon may insert a clear, plastic intraocular lens.
2. Intracapsular: If the lens is too hard for phacoemulsification, the eye surgeon may decide to remove both the lens and capsule. Once standard, this operation has been largely replaced by extracapsular surgery.
World without lenses?
Without a lens, the eye loses its ability to focus images on the retina. People have three options for lens replacement: an intraocular lenses (IOL), cataract glasses or soft contact lenses.
About 90% of people achieve 20/40 vision or better with an IOL. This clear, plastic lens is implanted in the eye during cataract surgery. People cannot see or feel the lens, and it needs no special care.
People who are sensitive to IOL materials may choose to wear special contact lenses or cataract glasses. These eyeglasses magnify objects by 25% to 30%. Distances may be harder to judge, and peripheral (side) vision may be somewhat distorted.
People who live at high altitudes or who spend a lot of time outdoors develop cataracts sooner. Although there’s no firm link between exposure to the sun’s ultraviolet rays and cataracts, experts recommend that people wear sunglasses and wide-brimmed hats to avoid too much sun exposure — just in case.
Smoking may hasten the development of cataracts. The use of certain drugs, especially steroids, diuretics and major tranquilizers, may be linked to cataracts, but experts still don’t know the exact connection.
Cézanne described Monet, his friend and French impressionist painter, as "only an eye, but what an eye!"
Monet, as it happens, had cataracts. Over time, the focusing lenses of his eyes grew cloudy, making the world appear dim and colors look muted. Everything he painted looked blurry. In later life, Monet had cataract surgery to replace his clouded right lens.
In 1912, when Monet first learned about his cataracts, he was almost blind in his right eye. In the following years, his left eye gradually began to lose its clarity of sight. In the summer of 1922, Monet’s loss of vision forced him to stop painting.
In 1914, Monet began to paint large-scale paintings with a flat, two-dimensional perspective — probably due to his lack of binocular vision. His perceptions of color also changed.
"I no longer saw colors with the same intensity," he wrote. "The reds seemed muddy to me, the pinks insipid, and the intermediate colors or lower tones escaped me."
The muted colors in Monet’s paintings at this time may represent exactly what he saw through his cataracts. When cataracts develop, whites becomes yellowish, greens become yellow-green, red becomes orange.
Experts have studied over 100 paintings from Monet’s early and late (cataract-affected) periods. They found that the artist used more cold tones in earlier paintings, while later paintings had more warm hues. Was this a direct effect of his cataracts?
In 1922, his failing sight inspired Monet to have surgery to remove the cataract in his right eye. "My poor eyesight means that I see everything through a mist," he wrote. "It is beautiful, all the same, and it is this that I should like to be able to depict."
Monet resumed painting in 1923 and continued until a few months before his death in 1926.
For more information
http://www.aoanet.org
http://www.aao.org
Sources
Points de Vue, May 1993, v. 29: pp. 13-25
