LASIK Laser Eye Surgery Articles from
Mountain View Vision Specialist Dr. Shobha Tandon

Cataract: A Leading Cause of Preventable Blindness
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NeoVision Eye Center

Definition of Cataract

A cataract is a clouding of the normally clear lens of the eye. A cataract decreases the amount of light that is focused on the retina, resulting in an overall blurriness of images. Having a cataract disturbs vision much like looking through a fogged windshield.

The lens is the part of the eye that helps focus light on the retina. The retina is the eye's light-sensitive layer that sends visual signals to the brain. In a normal eye, light passes through the lens and gets focused on the retina. To help produce a sharp image, the lens must remain clear. The lens is made

up of mostly water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together. This can start to cloud small areas of the lens, blocking some light from reaching the retina and interfering with vision.

A cataract can occur in any part of the lens: In the front, center, or the back part. The front cataract causes problem in vision as well as causes glare from the light. Central cataract causes problem in far vision and may not affect reading. Posterior cataract causes problem in reading. A combination of all the 3 forms may also occur.

Myths & Facts about Cataract
There are many misconceptions about cataract.

• Cataract is not a curtain or film that grows over the eye.
• It is not caused by over using your eyes.
• It does not spread from one eye to other eye.
• It does not cause irreversible blindness.
• Cataract does not develop by use of computer.
• There are no medications, no eye drops, no exercises, or no glasses that will cause a cataract to disappear.
• Cataracts do not need to be "ripe" before they can be removed.
• Surgery is the only remedy to remove a cataract.
• At present, laser is not used to remove a cataract.
• In some people who have had a cataract surgery, the natural capsule that supports the intraocular lens becomes cloudy. Laser surgery is then used to open this cloudy capsule, restoring the clear vision.

Symptoms of Cataract

The most common symptoms of a cataract are:

• A painless blurring of vision, as if your glasses are dirty or scratched. This blurring of vision is gradually progressive.
• Needing brighter light to see and read clearly.
• Problems with light. These can include headlights that seem too bright at night; glare from lamps or very bright sunlight; or a halo around lights.
• Gradual loss of color vision, or yellowing of colors. As the cataract develops, its center becomes more and more yellow, giving everything a yellowish tinge.
• Appearance of dark spots or shadows that seem to move when the eye moves.
• Poor night vision. Double or multiple visions. The cloudiness in the lens may occur in more than one place, so that the light rays that reach the retina are split, causing double or multiple images. This symptom often goes away as the cataract grows.
• A stage where it may be easier to read without glasses. It is known as "second sight." This is a result of change in shape of lens due to cataract.
• Frequent prescription changes in your eyeglasses or contact lenses.

Detection of Cataract

A comprehensive eye exam by your ophthalmologist can detect the presence and extent of a cataract, as well as any other conditions that may be causing blurred vision or other symptoms. After diagnosis, regular follow-up care is needed to assure the best possible correction for the level of impairment. Cataracts can be successfully treated. Working together, you and your doctor can develop a plan that will help you maintain the best possible vision in spite of the gradual development of cataracts.

There may be other reasons for visual loss in addition to the cataract, particularly problems involving the retina or optic nerve. If these problems are present, removal of the cataract may improve vision, but perfect sight may not be possible.

Possible Causes of Cataract

• Age-related cataract: Most cataracts are related to aging. More than half of all Americans age 65 and older have a cataract.
• Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.
• Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to medications such as steroid use or previous eye surgery.
• Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.

Prevention of Cataract

Cataracts cannot be prevented because lens changes occur as the eye ages, however precautions may slow their development. Dark glasses should always be worn to protect from ultraviolet light rays. Recently, some researchers believe that antioxidants (vitamin E, Lutein etc.) may delay the development of cataract. Avoiding cigarette smoke, heavy alcohol consumption, and air pollution may also help.

Progression of Cataract

How quickly the cataract develops varies among individuals, and may vary even between the two eyes. Most age-related cataracts progress gradually over a period of years. Other cataracts, especially in younger people and people with diabetes, may progress rapidly over a few months. It is not possible to predict exactly how fast cataracts will develop in any given person.

Treatment of Cataract

When a cataract is small (i.e. cloudiness affecting only a small part of the lens), you may not notice any changes in your vision and it may not cause a problem. Stronger lighting, magnifying lenses, and eye glasses may alleviate vision problems caused by early-stage cataracts. However, over time, the cataract may grow larger and cloud more of the lens, making it harder to see. There are no medications, no eye drops, no exercises, or no glasses that will cause a cataract to disappear once it is formed. Surgery is the only remedy to remove a cataract. At a certain point surgery is performed to improve vision. Today, cataract surgery is very safe and very effective. At present lasers cannot be used to remove a cataract. In some people who have had a cataract surgery, the natural capsule that supports the intraocular lens becomes cloudy. Laser surgery is then used to open this cloudy capsule, restoring the clear vision.


Right Time for Cataract Surgery

If your vision cannot be improved by changing the prescription of eye glasses and you are limited in doing your daily routine activities such as driving, playing golf, watching television, or reading due to cataract formation, you can consider cataract surgery. It is not true that a cataract needs to be "ripe" before it can be removed. If you have cataracts in both eyes, your ophthalmologist will not remove them both at the same time. Each will be removed separately with an interval of at least two weeks. Sometimes, a cataract should be removed even if it doesn't cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration or diabetic retinopathy.

Cataract Surgery

At NeoVision, we first determine the presence of a cataract and evaluate its effect on your vision. Dr. Tandon performs a comprehensive eye exam including a series of sophisticated tests. A visual acuity test is performed to assess your central vision. Refraction determines how beneficial are your current eye glasses and whether a change in your glasses will be helpful. Additional tests include:

• Tonometry: It measures the pressure of the aqueous humor within the eye. This test is helpful in detecting glaucoma and monitoring its treatment.
• Keratometry: It measures the radius of curvature of the cornea.
• A-Scan Test: It measures the length of your eye. It helps in determining the refractive power of the intraocular lens implant that is used to replace your eye's cloudy lens in cataract surgery.

Additional examination may involve Brightness Acuity Tester (BAT) which evaluates glare disability due to cataract and a Potential Acuity Meter (PAM) which helps in determining improvement in vision that can be expected after removing the cataract. Visual-field testing may also be needed.

Dr. Tandon also examines for any other condition that may affect the outcome of cataract surgery. This thorough evaluation includes examination of your eyelids and lid margins, cornea, intraocular lens, retina, and optic nerve.

Cataract surgery is a highly successful procedure. Over 95% of patients experience improved vision, unless there is a problem with the cornea, retina, optic nerve or other structures. Cataract surgery is an outpatient procedure performed under local or topical anesthesia. First, a small (only 2.8mm) cut is made on the side of your cornea and a small instrument, phacoemulsification probe is inserted through this cut to emulsify and remove the cataract. The focusing power of the natural lens is restored by replacing it with a permanent intraocular lens implant. The initial wound is self-sealing and no stitches are required to close the wound. In some people who have had a cataract surgery, the natural capsule that supports the intraocular lens becomes cloudy. Laser surgery is then used to open this cloudy capsule, restoring the clear vision. After cataract surgery, you will be asked to avoid heavy lifting, bending or exercise for 2 weeks. You will be asked to use some eye drops in the operated eye. Your eye will be examined very frequently during the post-surgery period. When your eye is healed, second eye can be operated or a new prescription for eyeglasses is given.

After Cataract / YAG Laser / Posterior Capsulotomy

Today, nearly everyone having modern cataract surgery will have a lens implant placed inside their eye at the time of surgery. These plastic implants, or artificial lenses, permit rapid return of vision and avoid the frustrations associated with contact lenses and thick aphakic glasses with strong magnifications.

For removing an eye lens, surgeon makes a small incision in the front wall or capsule of the lens and emulsifies the internal contents of the lens. However, the back wall or capsule of the lens is left

intact, and the plastic artificial lens is placed inside the capsule, sometimes termed by the operating surgeon "in-the-bag." Over the next few months or year or two, a cloudy film or membrane may form, much like a sheet of wax paper, across the capsule behind the artificial lens implant. This cloudy film is termed a "secondary membrane" or an "after cataract."

In past years, such membranes needed to be cut with a very tiny surgical knife. To ensure safety and sterility, the procedure usually required another visit to the operating room. This opening is necessary only for those cataract surgery patients whose secondary membrane becomes sufficiently cloudy to impair a clear vision.

In recent years, however, a laser technique has been developed to cut open this secondary membrane in doctor's office. The laser is commonly called "Nd:YAG laser" or simply "YAG laser". Its real name is "Neodymium-YttriumAluminum-Garnet laser". The YAG laser can cut the opaque membranes by creating a series of tiny explosions in a line or cross pattern. This procedure is called posterior capsulotomy. Thus, if you experience impaired vision after cataract surgery, the YAG laser may promptly restore your vision without a risk of bleeding or infection inside the eye.

Some people believe that the cataract surgery is done by laser. It is not true. In USA, cataracts are currently removed surgically by phacoemulsification method, which is an ultrasound technology. The YAG laser is used only to treat "after cataracts" but not to remove the cataracts.

Secondary Lens Implants

A few years ago, cataract surgery did not routinely involve replacing the eye's cloudy lens with a plastic one. After the lens was removed, people had to use contact lenses or glasses with thick lenses. Now, a synthetic lens can be implanted into the eye, even years after a lens was removed.

Secondary intraocular lenses are used to improve vision for people who have had cataract surgery and now rely on thick glasses or contact lenses. Intraocular secondary lens implants are small eye lenses (made of plastic-like material, silicon, or acrylic) that an eye surgeon can put in your eye. They are usually 5-6.5mm in diameter, small enough to be inserted through a self-sealing, no-stitch incision. After the lens is implanted, you will have a much clearer vision. Before the operation, your surgeon will determine the type and power of lens that is best for you. You probably won't be able to feel your new lens, and it never needs to be handled, adjusted, or cleaned. If cost is an issue, remember that Medicare and many insurance plans often cover the costs of cataract surgery as well as secondary lens implants.

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