"Age-related cataracts start small, usually in the centre of the lens, and may develop in one or both eyes."
By the time a person turns 65, chances are about 50-50 that they will have begun to develop a cataract, a clouding of the clear lens that focuses light onto the retina (the light-sensitive tissue at the back of the eye that sends the image to the brain via the optic nerve). The lens is composed of water and proteins arranged to let light through with minimal distortion. With age, the proteins can clump together, letting less light through and blurring vision. People may also be at increased risk for cataract if they regularly take corticosteroids or the anti-cancer drug tamoxifen. (
For other risk factors, see below: ‘Can cataract be prevented?
Age-related cataracts start small, usually in the centre of the lens, and may develop in one or both eyes. At first they cause no symptoms, but as they grow over months or years, problems such as blurring, glare, double vision, dull colour vision, poor night vision, and worsening nearsightedness can make it frustrating to read and dangerous to drive.
Cataract surgery was once complicated and risky, so ophthalmologists usually waited until vision was severely limited before proceeding. Today, cataract surgery is one of the easiest, most common, and safest surgeries performed in the United States.
Americans spend $6.8 billion annually to treat cataracts, which account for over half the medical costs for vision problems in people ages 65 and over. Patients should consider it as soon as vision problems start to interfere with usual activities. (
See "Is it time for surgery?"
One treatment, many choices
Despite promises on the Internet and in other media, a cataract can't be cured with exercise, supplements, or eye drops. The only way to do it is surgical removal of the cloudy or discoloured lens and replacement with a clear artificial lens. The procedure is usually performed under local or topical anaesthesia on an outpatient basis.
The most common technique is phacoemulsification, also called small incision surgery. The surgeon makes a 1/8-inch incision in the side of the eye's clear domed surface (the cornea) and inserts a slender probe. The probe delivers ultrasound waves to break up the central part of the lens, then vacuums up the lens. The replacement lens, folded to fit inside the probe, is inserted through the incision and into the lens capsule, where it unfolds. The surgeon may close the incision or allow it to heal on its own.
Conventional extracapsular cataract extraction, also called large-incision surgery, is more invasive. Instead of breaking up the clouded lens, the clinician removes most of it in one piece through a larger incision (approximately 3/8 inch) under the upper eyelid. After the replacement lens is inserted, the incision is stitched. Recovery takes four to six weeks; during that time the patient must restrict exercises and activities, particularly bending that could put stress on the incision. This type of surgery can also worsen astigmatism by changing the shape of the cornea.
A third procedure, intracapsular surgery, carries a high risk of complications and is seldom used today.
Preparing for surgery
Before surgery, a clinician uses ultrasound to evaluate the shape of the eye and calculate the strength of the replacement lens. Other specialized eye exams may be used to help predict the outcome of surgery.
Patients should be asked about all medications they're taking. If they have glaucoma, they may need to stop or change their eye drops temporarily. If they take an alpha blocker or have ever taken one they should speak up. Alpha blockers - including Flomax (tamsulosin), Hytrin (terazosin), Cardura (doxazosin), and Uroxatral (alfuzosin) - can interfere with the medications used to keep the pupils dilated during cataract surgery, so the surgeon may need to make adjustments to compensate.
After the cataract is removed, the lens must be replaced. For most people, that means inserting an intraocular lens within the lens capsule at the time of surgery. Several types are available. The choice depends on the shape of the eye, other vision problems or eye diseases they may have, and their preferences and priorities. Before surgery, patients need to think about the type of lens best suited to their situation. They should also think about their usual daily activities and know which of they'd most like to perform without glasses. The options include the following:
These lenses restore clear vision at a set distance. If a patient wears glasses or contacts for distance vision, their vision without glasses may be much improved after surgery. But they will need separate glasses for reading and perhaps also for intermediate distances (such as working at the computer or playing piano).
To eliminate the need for reading glasses, the surgeon can implant a distance lens in one eye and a close-up lens in the other (just as some people wear a different contact lens prescription in each eye).
"With this option, some people don't need eyeglasses," says Claudia Richter, M.D., a clinical instructor in ophthalmology at Harvard Medical School's Massachusetts Eye and Ear Infirmary. "But not everyone adjusts well - they may feel lopsided, clumsy, or bothered by diminished depth perception. If depth perception is very important to you, this is not a good option."
These are shaped to correct astigmatism and reduce the need for glasses to correct distance vision. Patients should see better without glasses, but some astigmatism may still remain. Because of their shape, toric lenses (brand names Staar Surgical Intraocular Lens and AcrySof Toric IOL) occasionally slip out of alignment during the first few days after surgery and require a minor surgical correction.
Like bifocals and progressive eyeglasses, multifocal lenses are designed to help with presbyopia, the age-related difficulty in shifting focus from far to near. Multifocal lenses (ReZoom and AcrySof Restor) combine correction for near, intermediate, and distance vision. Your vision will improve over the first couple of months as your brain learns to see at various distances through the new lenses. Training may help this process.
In a 2006 Cochrane Library review of several controlled trials, multifocal and monofocal lenses provided similar distance vision without glasses. Multifocal lens users were more likely to be able to read without glasses (26%-47%) compared to those fitted with monofocal lenses (1%-11%). But users of multifocal lenses are more likely to be bothered by glare and see haloes around lights at night. They may also have more difficulty seeing in low light or distinguishing an object in front of a background of a similar colour. One brand (ReZoom) incorporates two extra focusing zones to make vision clearer in low light.
Multifocal lenses do not work well in people with much astigmatism and certain other eye conditions. The size of your pupil also matters. If a person's pupils are small, light won't get through the part of the lens that provides near vision; if they are very large, they'll notice more glare and haloes at night.
These hinged lenses (brand name Crystalens) move in response to the eyes' focusing muscles, providing distance, intermediate, and near vision.
A 263-person clinical trial submitted to the FDA found that accommodative lenses provided significantly better vision than standard monofocal lenses. At intermediate and near distances, about half of accommodative lens users (and fewer than 5% of monofocal lens users) had near vision of 20/25 or better. Distinguishing objects from backgrounds was equally easy with both kinds of lenses. Accommodative lenses haven't been directly compared with multifocal lenses in clinical trials. Patients with a high level of nearsightedness, farsightedness, or astigmatism, will not be offered accommodative lenses.
Unless a patient has a medical condition that warrants close observation in the hospital or makes it unsafe to recuperate at home, someone will need to drive them home after they leave the recovery room. After phacoemulsification, they will probably be able to use their eyes within hours and resume all but the most strenuous activities within days. They will take antibiotics and use cortisone drops or ointment and nonsteroidal anti-inflammatory drops to prevent infection and reduce inflammation while their eyes heal.
Depending on which kind of lens they have implanted, they may see better immediately, or their vision may improve over several weeks. More than 98% of people eventually have improved vision. Possible complications include bleeding within the eye, glaucoma, and infection; they'll also always be at a slightly increased risk of a detached retina.
After about 30% of cataract operations, the lens capsule supporting the implant eventually becomes cloudy. This is sometimes called an after-cataract or secondary cataract. To remedy the problem, the ophthalmologist can drill a tiny hole in the capsule with a laser to let the light through. This is usually a quick and painless office procedure.
The Aging Eye:
Preventing and Treating Eye Disease (Harvard Health Publications, 2006)
A Patient's Guide to Treatment, by David F. Chang, M.D., and Howard Gimbel, M.D. (Addicus Books, 2004)