A cataract develops when the natural crystalline lens of the eye, the part of the eye that helps to focus light on the retina, changes from crystal clear to cloudy or yellow over time. This probably occurs because of changes in the composition of naturally occurring proteins in the lens. The changes in the protein composition of the lens alter its ability to focus light clearly on the retina, resulting in steadily worsening blurry vision, dimming of colors, problems seeing well at night, shifting refractive error, or all of the above.

The development of cataracts is considered a natural process of aging. Almost everyone over the age of 60 has at least the start of a cataract, and while many cataracts are not advanced enough to cause vision changes, more than half of all Americans will eventually develop cataracts severe enough to affect vision and require treatment.

Cataracts take a long time to develop to the point that they are a serious problem for your vision. There are many types of cataracts, but the three types linked to aging are seen most frequently. The most common form is called a nuclear cataract because it affects the central “nucleus” of the lens. In cortical cataracts, the outside of the lens becomes cloudy; this type of cataract is more likely to cause problems with glare and halos around bright lights. The third type of age-related cataract is a posterior cataract; it usually develops faster than the other two varieties and is also commonly seen in patients who have been on steroids or sustained ocular trauma.

In developed countries, cataracts are routinely removed by a simple operation. However, cataract continues to be the leading cause of reversible blindness worldwide.


Age is the greatest risk factor for developing cataracts. The older you get, the greater your chance of developing cataracts. Family history also seems to play a role; patients with parents who required cataract surgery are more likely to also require surgery.

There are a number of other factors that can cause cataracts to develop more rapidly or occur in younger patients. Certain medications, most notably steroids, can cause cataracts to develop at a younger age. Ocular trauma or prior ocular surgery (particularly retinal surgery) can hasten the development of cataracts.

Systemic illnesses such as diabetes can cause the rapid development of cataracts. Certain rare genetic conditions are associated with infantile or juvenile cataracts. (Wilson’s disease, Alport disease, Lowe disease are a few examples). Even in the absence of systemic diseases, otherwise healthy babies can be born with congenital cataracts.

Women live, on average, several years longer than men. For this reason, many more women than men live long enough to develop cataracts. Furthermore, for unknown reasons, women are intrinsically at a somewhat higher risk than men of getting the cortical form of cataract.


The main symptoms of a cataract are blurred, cloudy, or dulled vision in the affected eye that cannot be corrected by wearing stronger glasses or contact lenses. Colors may seem faded. In addition, a brighter light may be needed for reading. Increased sensitivity to glare can also be a sign of cataract; a halo may be seen around bright lights at night, and this can cause a problem in driving. If you notice any of these symptoms, you should visit an eye care professional.


Cataracts are considered part of the normal aging process and cannot be prevented, though there are things patients can do to try and delay or slow their development. There is very strong data showing smoking greatly increases the chance of getting nuclear cataracts, the most common type in the United States. Smoking is also linked to a higher risk of other potentially blinding eye conditions, including macular degeneration. Quitting smoking (or even better, never starting) is one of the best things a patient can do for overall health, eye health, and cataract prevention.

Evidence suggests patients with poorly controlled systemic diseases, including diabetes, high blood pressure, or heart disease, are more likely to develop visually significant cataracts earlier than those without these conditions. Diabetics, in particular, can rapidly develop cataracts in the setting of elevated blood sugar. There is also some evidence to suggest that UV exposure can hasten the development of cataracts. Antioxidants (especially vitamin C) and carotenoids in the diet may slow down the progression of some types of cataracts, but the evidence is conflicting.

The best advice is to stay healthy; if you are currently a smoker, stop smoking, eat a balanced diet rich in vegetables and fruit, exercise, and protect yourself from the sun with sunglasses and wide-brimmed hats. Even if these actions don’t prevent a cataract, it will help protect against heart disease, skin cancer, and probably macular degeneration. Unlike some other eye conditions associated with aging (glaucoma or macular degeneration), the vision changes associated with cataracts are not permanent, but it can be difficult for patients to differentiate between vision loss from cataracts and vision loss from other eye conditions. For this reason, it is recommended all patients over the age of 60 have an eye examination through dilated pupils at least every two years. This kind of exam allows your eye care professional (optometrist or ophthalmologist) to check for signs of cataracts, as well as screen for other age-related eye conditions.


Cataract is a curable eye disease. Mild cataracts are often symptomatic. As they progress, patients may be able to negate the vision changes with better lighting and stronger eyeglasses. At a certain point, however, the vision changes caused by cataracts will be significant enough that surgery is needed to improve vision. Cataract surgery is indicated only when it interferes with vision enough to prevent driving, reading, or other essential activities. Cataract surgery is the most common operation performed today in the United States. The procedure is outpatient, quick, painless, and very safe. If you have cataracts in both eyes (which is often the case), the surgeon will remove only one of them at first; you will have to return at a later date for the second eye to be operated on.

Cataracts are usually removed these days by a procedure called phacoemulsification, or phaco (phaco is Greek for lens, and emulsification means to liquify, just like the setting on a blender). Your doctor makes a small incision (about 2 mm) on the side of the cornea where the white and colored part of the eye meet. The doctor then inserts a tiny probe into the eye that uses ultrasound waves to break up the lens and suction out the pieces. A clear, artificial lens (called an intraocular lens or IOL) is placed in the eye during surgery to replace the removed lens. These artificial lenses can be tailored to the individual needs of each patient’s eye and can correct common refractive errors, such as near-sightedness, far-sightedness, and sometimes astigmatism as well. Because of this, patients are usually much less reliant on glasses after cataract surgery. The new lens requires no care and remains in the eye for the rest of the patient’s lifetime.

Patients often ask if cataracts can return after surgery. Just like with the removal of an appendix or gallbladder, a cataract cannot grow back after it is removed. However, up to 20 percent of people will develop something called a posterior capsular opacification (PCO) after cataract surgery. This is simply a proliferation of some residual lens cells left in the eye after surgery, and while these cells do not represent the growth of a new cataract, the can sometimes result in visual symptoms similar to that of cataracts. For this reason, this condition is sometimes referred to as a “second cataract.” Unlike with a true cataract, a PCO requires only a very quick, in-office laser procedure called a YAG capsulotomy to remedy. Development of a PCO can be detected in routine dilated eye exams after surgery.