|Read our E-Magazine|
|Receive our E-Newsletters|
|Become our Fan|
Cataracts are a common age-related vision problem. About 20.5 million Americans age 40 and older have cataracts, and the older a person gets the greater the risk for developing cataracts. Women are more likely to develop cataracts than men, and African Americans and Hispanic Americans are at particularly high risk.
In addition to age, other factors may increase the risk of cataract development. These include:
During the early stages, cataracts may have little effect on vision. Symptoms vary due to the location of the cataract in the eye (nuclear, cortical, or posterior subcapsular). Depending on the type and extent of the cataract, patients may experience the following symptoms:
Cataracts never go away on their own, but some stop progressing after a certain point. But if cataracts continue to grow and progress, they can cause blindness if left untreated. Fortunately, cataracts can almost always be successfully treated with surgery. Millions of cataract operations are performed each year in the United States, and there is a very low risk for complications. However, before opting for surgery, patients need to consider on an individual basis how severely a cataract interferes with their quality of life. Cataract surgery is rarely an emergency, so patients have time to consult with their doctors and carefully consider the risks and benefits of surgery.
Cataract Removal Surgery
Surgery involves removing the cataract and replacing the abnormal lens with a permanent implant called an intraocular lens (IOL). The operation takes less than 1 hour and is performed on an outpatient basis. The procedure is generally painless and most patients remain awake, but sedated, during it. If you have cataracts in both eyes, doctors recommend waiting at least 1 month between surgeries.
A cataract is an opacity, or clouding, of the lens of the eye.
The likelihood of developing cataracts increases with age. Cataracts typically occur in the following way:
Cataracts can form in any of three parts of the lens and are named by their location.
Although older age is the primary risk factor for cataracts, researchers are still not certain about the exact biologic mechanisms that tie cataracts to aging.
Particles called oxygen-free radicals may be a major factor in the development of cataracts. They cause harm in the following way:
Sunlight and Ultraviolet Radiation. Sunlight consists of ultraviolet (referred to as UVA or UVB) radiation, which penetrates the layers of the skin. Both UVA and UVB have destructive properties that can promote cataracts. The eyes are protected from the sun by eyelids and the structure of the face (overhanging brows, prominent cheekbones, and the nose). Long-term exposure to sunlight, however, can overcome these defenses.
Radiation Treatments. Cataracts are common side effects of total body radiation treatments, which are administered for certain cancers.
Electromagnetic Waves. Questions have been raised about the hazards of low-level radiation from computer screens. To date, no study has demonstrated an association between cataract development and video display terminals. It is a good idea, in any case, to sit at least a foot away from the front of a screen.
Corticosteroids. Long-term use of oral steroids is a well-known cause of cataracts. Studies have been conflicting, however, over whether inhaled and nasal-spray steroids increase the risk for cataracts. Information on cataract risk from inhaled steroids is important because they are commonly used for treatment of asthma and allergies.
Other Medications Associated with Cataracts.
Many others drugs have been weakly associated with cataracts, including allopurinol, tamoxifen, amiodarone, tricyclic antidepressants, potassium-sparing diuretics (but not other diuretics), thyroid hormone, tetracyclines, sulfamidase, and mepacrine. Statin drugs (used for managing cholesterol) may possibly reduce the risk for nuclear cataracts.
Rarely, about 1 in every 10,000 births, a baby is born with cataracts (called congenital cataracts).
Aging is the primary risk factor for cataracts, but other factors are also involved.
Nearly everyone who lives long enough will develop cataracts to some extent. Some people develop cataracts during their middle-aged years (40s and 50s), but these cataracts tend to be very small. It is after age 60 that cataracts are most likely to affect vision. Nearly half of people age 75 and older have cataracts.
Women face a higher risk than men.
Cataracts tend to run in families.
African-Americans appear to have nearly twice the risk of developing cataracts as Caucasians. This difference may be due to other medical illnesses, particularly diabetes. African-Americans are much more likely to become blind from cataracts and glaucoma than Caucasians, mostly due to lack of treatment.
Hispanic Americans are also at increased risk for cataracts. In fact, cataracts are the leading cause of visual impairment among Hispanics.
Glaucoma. Glaucoma and its treatments, including certain drugs (notably miotics) and filtering surgery, pose a high risk for cataracts. The glaucoma drugs that can increase risk for cataracts include demecarium (Humorsol), isoflurophate (Floropryl), and echothiophate (Phospholine).
Myopia. People who are nearsighted (myopia) are at increased risk of developing cataracts.
Uveitis. Uveitis is chronic inflammation in the eye, which is often caused by an autoimmune disease or response. Often the cause is unknown. It is a rare condition that carries a high risk for cataracts.
Other Eye Conditions. Physical injuries to the eye (such as a hard blow, cut, or puncture) or eye inflammation can also increase risk. Previous intraocular eye surgery increases cataract risk.
People with certain medical conditions, notably diabetes, are at high risk for cataracts, either because of a direct effect of the disease, its treatments, or both.
Diabetes. People with diabetes type 1 or 2 are at very high risk for cataracts and are much more likely to develop them at a younger age. They also have a higher risk for nuclear cataracts than nondiabetics. Cataract development is significantly related to high levels of blood sugar (hyperglycemia). Obesity, which is associated with diabetes type 2, may also be a risk factor for cataracts.
Autoimmune Diseases and Conditions Requiring Steroid Use. Medical conditions requiring long-term use of oral corticosteroids (commonly called steroids) pose a particularly high risk. Many of these medical conditions are autoimmune diseases, including rheumatoid arthritis, psoriasis, multiple sclerosis, systemic lupus erythematosus, Behcet's disease, and others.
Exposure to even low-level UVB radiation from sunlight increases the risk for cataracts, especially nuclear cataracts. The risk may be highest among those who have significant sun exposure at a young age. People whose jobs expose them to sunlight for prolonged periods are also at increased risk.
Smoking. Smoking a pack a day of cigarettes may double the risk of developing cataracts. Smokers are at particular risk for cataracts located in the nuclear portion of the lens, which limit vision more severely than cataracts in other sites.
Alcohol. Chronic heavy drinkers are at high risk for a number of eye disorders, including cataracts.
Long-term environmental lead exposure may increase the risk of developing cataracts. Gold and copper accumulation may also cause cataracts. Prolonged exposure to ionizing radiation (such as x-rays) can increase cataract risk.
Some cataracts stop progressing after a certain point. Cataracts are never reversible, however, even after eliminating factors (such as drugs or illnesses), which might have promoted their development. If extensive and progressive cataracts are left untreated they can cause blindness. In fact, cataracts are the leading cause of blindness among adults age 55 and older. More than 20 million Americans have at least one cataract. By 2020, that number is expected to jump to 30 million.
Fortunately, cataracts can nearly always be successfully removed with surgery. However, surgery is unavailable in certain parts of the world, leaving millions at risk for vision loss. Even in the U.S., where surgery has greatly reduced the risk of blindness, tens of thousands still lose their sight and millions more have poor vision because of cataracts.
Reduced vision ranks third only behind arthritis and heart disease as a cause of impaired function in older people. Some people who have small cataracts can see well enough around the clouded areas to live normally. Extensive cataracts, however, can compromise the ability to earn a living, read, drive, or live independently and can interfere greatly with daily activities.
Although cataracts are not completely preventable, their occurrence can be delayed. Quitting smoking, avoiding overexposure to sunlight, avoiding excess amounts of alcohol are important protective measures, and eating plenty of fresh fruits and vegetables may delay the formation of cataracts. No existing evidence suggests that using eye drops or ointments or performing eye exercises will stem the onset of cataracts.
The simplest and most effective way to protect against ultraviolet (UV) radiation is to stay out of the sun. Wear a hat and cover-up outside, particularly when the sun is most intense (10 a.m. - 3 p.m.). A wide-brimmed hat can significantly reduce eye exposure to UVB radiation. Because the sun's rays are highly reflective, sitting in the shade or under an umbrella by itself does not guarantee protection.
Note: Moderate sun exposure provides an important source of vitamin D, which is essential for healthy bones and other health factors. Fortunately, people who protect themselves from the ultraviolet radiation in sunlight can get the vitamins they need from supplements.
Sunglasses. Protective sunglasses do not have to be expensive. But it is important to select sunglasses whose product labels state they block at least 99 percent of UVB rays and 95 percent of UVA rays.
Polarized and mirror-coated lenses do not offer any protection against UV radiation. It is not clear if blue light-blocking lenses, which are usually amber in color, provide UV protection.
Scientists are not certain if nutrition plays a significant role in cataract development. Dark colored (green, red, purple, and yellow) fruits and vegetables usually have high levels of important plant chemicals (phytochemicals) and may be associated with a lower risk for cataracts.
In analyzing nutrients, researchers have focused on antioxidants and carotenids. Studies have not demonstrated that antioxidant vitamin supplements (such as vitamins C and E) help prevent cataracts. Still, fruits and vegetables containing these vitamins are important for overall good health.
Lutein and zeaxanthin are the two carotenids that have been most studied for cataract prevention. They are xanthophylis compounds, which are a particular type of carotenid. Lutein and zeaxanthin are found in the lenses of the eyes. Some evidence indicates that xanthophyll-rich foods (such as dark green leafy vegetables) may help retard the aging process in the eye and protect against cataracts. However, there is not enough evidence to suggest that taking supplements that contain these carotenoids lowers the risk for cataract formation.
During the early stages, cataracts have little effect on vision. As the cataract progresses, symptoms may include:
Symptoms may vary depending on the part of the lens that is affected.
Nuclear Cataracts. Cataracts of the lens nucleus are most commonly associated with aging. Symptoms include:
Cortical Cataracts. Cortical cataracts usually start on the outside of the cortex (the outer area of the lens).
Posterior Subcapsular Cataracts. Posterior subcapsular cataracts typically start near the center of the back part of the capsule surrounding the lens. These cataracts often advance rapidly. For many patients, major impairment of eyesight, including near-vision problems and glare, develops within several months.
Either an ophthalmologist or an optometrist can examine patients for cataracts, but only ophthalmologists are qualified to treat cataracts.
The eye professional can observe cloudy areas on the lenses with a physical examination, even before the cataracts begin to interfere with vision. Cameras can measure the cataract density. Various vision tests are also performed.
Snellen Eye Chart. To determine how clearly a person can actually see, the Snellen eye chart is used, with rows of letters decreasing in size:
Other Tests. A number of other tests are used to diagnose cataracts or to determine if surgery is needed.
Although eye tests help confirm a diagnosis of cataracts, results do not always reflect the quality of life and how effectively people function at home:
Although surgery is the only remedy for cataracts, it is almost never an emergency. Most cataracts cause no problem other than reducing a person's ability to see, so there is no harm in delaying surgery.
The following measures may manage early cataracts:
Progression of Cataracts. Patients and their families usually have plenty of time to carefully consider options and discuss them with an ophthalmologist. There is no constant rate at which cataracts progress:
Cataract removal is the one of the most common type of eye surgeries performed in the United States, especially for people over age 65. In the past, cataract surgery was not performed until the cataract had become well developed. Newer techniques, however, have made it safer and even more efficient to operate in earlier stages. Cataract surgery improves vision in up to 95% of patients and prevents millions of Americans from going blind.
Nevertheless, cataract surgery may be performed more often than needed. In general, even if cataracts are diagnosed, the decision to remove them should be based on the patient's own perception of vision difficulties and the effect of vision loss on normal activity. The patient should also be aware of all the risks and costs of surgery.
In general, surgery is indicated for people with cataracts under the following circumstances:
These guidelines are general, however. Whether surgery is appropriate or not further depends on the cataract patient's specific condition and needs. Some examples include:
Because of the risks, albeit small ones, of poorer vision or blindness, no one should be forced to have cataract surgery if they don't want it or are not strong enough to have the procedure. If there are any doubts about whether or not to have cataract surgery, consider a second opinion.
The patient should ask the ophthalmologist the following questions before agreeing to cataract surgery:
Cataracts in the Second Eye. If a person has a cataract in a second eye, the issues for decision making are the same as for the first eye. The timing of the procedure in the case of two cataracts is unclear. Doctors have long recommended postponing surgery on the second eye until the first eye has healed and the results are known. However, many patients have trouble reading and performing ordinary tasks while waiting for a second surgery. Patients with cataracts in both eyes should discuss all options with their eye surgeon.
Cataracts and Glaucoma. For patients with both glaucoma and cataracts, doctors recommend:
Cataracts and Corneal Disease. Patients with both cataracts and corneal disease may have one of the following procedures:
Infants. Treatment of infants first depends on whether one or both eyes are affected:
Toddlers and Older Children. Intraocular lens replacement is now standard treatment for children age 2 years and older.
Cataract surgery is usually done as an outpatient procedure under local anesthesia and takes less than an hour. Preoperative preparations may include:
All cataract procedures involve removal of the cataract-affected lens and replacing it with an artificial lens.
Phacoemulsification. Phacoemulsification (phaco means lens; emulsification means to liquefy) is the most common cataract procedure performed in the United States.
The procedure generally involves:
Phacoemulsification requires only local anesthesia. Newer methods for administering local anesthesia produce few complications. Most phacoemulsification procedures now take about 15 minutes, and the patient is usually out of the operating room in about an hour. There is little discomfort afterward, and visual rehabilitation takes about 1 - 3 weeks.
Phacoemulsification is sometimes combined with glaucoma surgical procedures, for patients who have both glaucoma and cataracts.
Extracapsular or Intracapsular Cataract Extraction. Extracapsular cataract extraction, the original standard procedure, is now generally used only in patients who have an extremely hard lens. It typically involves the following steps:
It takes about 2 - 4 weeks for vision to be completely restored.
With the clouded lens removed, the eye cannot focus a sharp image on the retina. A replacement lens or eyeglasses are therefore needed:
Intraocular Lenses (IOLs). In about 90% of cataract operations, an artificial lens, known as an intraocular lens (IOLs), is inserted. Most IOLs are made out of acrylic, although other materials, such as silicon, are also used.
IOLs are designed to improve specific aspects of vision. The choices include:
The patients and the doctor must make these decisions based on specific visual needs. Many patients also need eyeglasses after cataract surgery for reading or to correct astigmatism.
Modern cataract surgery is one of the safest of all surgical procedures. Most complications, even if they occur, are not serious. They can include:
Preventing Infection and Reducing Swelling. The ophthalmologist may prescribe the following medications after surgery:
Factors that Increase Risk for Complications. The risks of complications are greater for the following people:
Returning Home and Follow-up Visits.
Protecting the Eye. Postoperative protection of the eye typically involves:
Avoiding Glaucoma. Cataract surgery can cause glaucoma, a condition in which the pressure of fluids inside the eye rises dangerously. It is very important to minimize any activity that increases internal eye pressure. Postoperative cataract patients take the following precautions:
About 15% of patients who have cataract surgery develop a secondary "after-cataract" called posterior capsular opacification. Posterior capsular opacification, also called secondary “after-cataract,” is a clouding of the lens capsule that was left behind when the original cataract was removed. It generally occurs because after surgery there are still some natural lens cells left behind that proliferate on the back of the capsule.
The standard treatment for posterior capsular opacification is a type of laser surgery known as a YAG capsulotomy. (Capsulotomy means cutting into the capsule, and YAG is an abbreviation of yttrium aluminum garnet, the laser most often used for this procedure.) This procedure can help improve vision and reduce glare.
Complications. YAG laser capsulotomy is generally a safe procedure. Serious complications are rare, but can include retinal detachment.
Allen D. Cataract. Clin Evid (Online). 2008 Aug 14;2008. pii: 0708..
American Academy of Ophthalmology. Cataract in the Adult Eye, Preferred Practice Pattern. San Francisco: American Academy of Ophthalmology, 2006. Accessed July 1, 2008.
Awasthi N, Guo S, Wagner BJ. Posterior capsular opacification: a problem reduced but not yet eradicated. Arch Ophthalmol. 2009 Apr;127(4):555-62.
Bell CM, Hatch WV, Fischer HD, Cernat G, Paterson JM, Gruneir A, et al. Association between tamsulosin and serious ophthalmic adverse events in older men following cataract surgery. JAMA. 2009 May 20;301(19):1991-6.
Christen WG, Glynn RJ, Sesso HD, Kurth T, MacFadyen J, Bubes V, et al. Age-related cataract in a randomized trial of vitamins E and C in men. Arch Ophthalmol. 2010 Nov;128(11):1397-405.
Clinical Trial of Nutritional Supplements and Age-Related Cataract Study Group, Maraini G, Sperduto RD, Ferris F, Clemons TE, Rosmini F, et al. A randomized, double-masked, placebo-controlled clinical trial of multivitamin supplementation for age-related lens opacities. Clinical trial of nutritional supplements and age-related cataract report no. 3. Ophthalmology. 2008 Apr;115(4):599-607.e1.
Fernandez MM, Afshari NA. Nutrition and the prevention of cataracts. Curr Opin Ophthalmol. 2008 Jan;19(1):66-70.
Findl O, Buehl W, Bauer P, Sycha T. Interventions for preventing posterior capsule opacification. Cochrane Database Syst Rev. 2010 Feb 17;2:CD003738.
Friedman AH. Tamsulosin and the intraoperative floppy iris syndrome. JAMA. 2009 May 20;301(19):2044-5.
Guercio JR, Martyn LJ. Congenital malformations of the eye and orbit. Otolaryngol Clin North Am. 2007 Feb;40(1):113-40, vii.
Moeller SM, Voland R, Tinker L, Blodi BA, Klein ML, Gehrs KM, et al. Associations between age-related nuclear cataract and lutein and zeaxanthin inthe diet and serum in the Carotenoids in the Age-Related Eye Disease Study, an Ancillary Study of the Women's Health Initiative. Arch Ophthalmol. 2008 Mar;126(3):354-64.
Olitsky SE, Hug D, and Smith LP. Abnormalities of the lens. In: Kliegman RM, Behrman RE, Jenson HB, Stanton BF, eds. Nelson Textbook of Pediatrics. 18th ed. St. Louis, MO: WB Saunders; 2007; chap 627.
Vizzeri G, Weinreb RN. Cataract surgery and glaucoma. Curr Opin Ophthalmol. 2010 Jan;21(1):20-4.