Inside every normal eye there is a lens which puts what we look at into clear focus. The picture of everything that we see must enter our eye through this lens on its way to the back of the eye. This situation is very similar to the working of a camera, where light must travel through the lens on its way to the film. As in a camera, the lens of the eye is normally crystal clear and is capable of producing sharp pictures. Under some circumstances, however, this lens becomes cloudy and light does not pass through it easily.

It is this clouding of the otherwise clear natural lens which is termed a cataract. A cataract is not a growth, a tumor, or a film. Nor is it on the outside of the eye, as some people believe. Rather, a cataract is a clouding, or haziness, of the lens inside the eye. If everyone lives long enough, everyone will get cataracts. The point in time when a cataract affects real world useful vision (not Snellen visual acuity) is variable from person to person.

The first change that occurs in the aging process of the eye is a loss of normal lens elasticity. This change, called presbyopia, causes poor near vision, requiring the use of bifocals, reading glasses, or for myopic individuals, removal of glasses for reading vision. Loss of lens elasticity begins at about age 45 and progresses with time, eventually developing into a cataract.

If a microscope is used to look at the lens at age 45, the lens begins to take on an amber color and small pockets of water are seen within the lens itself. These pockets act as light scattering sources. They reduce night vision, cause problems with glare from on-coming headlights, and create spokes of light emanating from light sources such as streetlights and car headlights.

As the cataract advances, colors become washed out. All of these changes can occur before the snelling visual acuity test (wall chart letter test) is abnormal. In other words, your visual acuity can be a perfect 20/20 but your quality of vision is not good.

This process is so gradual that half of the people don’t realize they have a problem with their vision.

To the person who has an advanced cataract it is like trying to see through frosted glass or into a steamy bathroom mirror.Depending on its density, a cataract can cause vision loss ranging from barely noticeable to complete blindness. The rapidity with which it will get worse is very unpredictable. Some cataracts appear and become very cloudy in just a few months, while others may change very little over many years.

With advancing cataracts, many people may notice they do not have to use their bifocals or reading glasses any more. Some people find that using sunglasses makes their vision better and others use a cap with a large visor to shield their eyes from direct sunlight to eliminate unwanted glare while driving.

Others find they have to change their prescription for glasses frequently and end up “chasing” their cataracts with glasses. This can become quite expensive without providing good overall vision. Fluctuating vision is very common because of varying lighting conditions and pupil sizes.

In many cases, the cataract comes on so slowly that many people don’t realize they have a vision problem.

Usually the first changes in vision occur at ages 43 to 47 and progress until complete clouding of the lens occurs. The point at which this condition is called a cataract varies from ophthalmologist to ophthalmologist.

Some use the old method of determining a cataract: when the cataract affects visual acuity as measured by the 150 year old Snellen letter wall charts. However, we now know that a special kind of cataract (a posterior subcapsular cataract) can give a very good reading on the Snellen chart (20/20) but horrible real world vision. This has caused some ophthalmologists to question the Snellen test as a criteria for cataracts and cataract surgery.

Newer methods of testing visual function for cataracts are beginning to be used along with the established slit lamp examination that gives a microscopic picture of the lens. Newer testing methods include contrast sensitivity and glare disability .

A patient questionnaire about the quality of vision and your own unique visual problems is also very informative and assists you and the surgeon in deciding if cataract surgery will be beneficial for you. You will also be asked to fill out patient satisfaction questionnaires after surgery. These help us assess how we are doing in serving you.

WHAT CAUSES A CATARACT? WHO IS LIKELY TO GET THEM?

Occasionally babies may be born with cataracts and sometimes young people may develop them as a result of injury or following exposure to excessive radiation or toxic substances. Sometimes cataracts are caused by taking certain medications for a given disease. All of these specific causes account for only a small percentage of cataracts. The vast majority are simply found in older people with no apparent cause except as a part of the aging process. Just as some people develop gray hair at an earlier age, some people develop cataracts earlier than others. If everyone lives long enough, everyone will develop cataracts. Cataracts may also develop at an earlier age if you are diabetic. There is a higher incidence of cataracts in glass blowers and people that are on the water a lot (commercial fisherman).