The cataract specialists at New York Eye and Ear Infirmary of Mount Sinai (NYEE) are at the forefront of studying the causes and treatments of cataracts. Understanding what cataracts are and how they affect your vision is vital to making the right decisions about your treatment.

What is a Cataract?

A cataract is a clouding of the clear lens in the eye, often compared to looking through a fogged-up window. The lens focuses light on the retina at the back of the eye, changing it to nerve signals that are relayed to the brain. The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image reaching the retina will, in turn, be blurry. Cataracts usually develop slowly and may not affect your vision early in life. Over time, however, the cataract—which can occur in one or both eyes—may grow larger, covering more of the lens and affecting everyday tasks like reading, working, and driving. At this stage, removal of the cataract is generally a safe and effective solution.

What Causes a Cataract?

Most cataracts are caused by the aging process. As we get older, a cloudy lens can reduce the light that reaches the retina resulting in blurry vision. Common causes of cataracts also include:

• Eye injury
• Other eye conditions
• Previous eye surgery
• Chronic medical problems such as diabetes
• Hereditary disorders

How Do I Know if I Have a Cataract?

For most people, the onset of cataracts is a slow process. Cataract symptoms develop over time and may include:

• Gradual blurring or dimming of vision.
• Decreased color perception.
• Some people see a halo or haze around lights, especially at night, or experience double or multiple vision. At first, the symptoms may only occur in dim light or when you face bright oncoming car headlights, making night driving especially difficult.
• Frequent changes in eyeglass or contact lens prescription, which can be another early warning sign of cataracts.

Is It Possible to Have a Cataract and Not Notice It?

Yes. If the cataract is small, it may not disturb your vision. Even a dense cataract may go unnoticed if the other eye is providing clear vision. Cataracts usually progress slowly over a period of months or years.

When Should a Cataract be Removed?

When cataracts start to interfere with your vision enough to make a noticeable difference in your life  they should be removed. This decision will vary from person to person. It’s not necessary, however, to wait until the cataract is “ripe” (totally opaque) before having it removed.  This can make surgery more complex. It is important that you get regular eye exams and monitor your condition. Your ophthalmologist will advise you if you are a candidate for cataract surgery.