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It’s natural to worry about losing your vision someday. After all, three of the leading causes of blindness in the United States — cataracts, glaucoma and age-related macular degeneration — all become more common as we age. But some makers of drugs, supplements and lenses — and even some doctors — take advantage of that fear, recommending treatments that are expensive, unnecessary and even risky. Here’s what you need to know:

Cataracts

The only way to cure cataracts — a clouding of the lens of the eye that impairs vision — is with surgery to replace the bad lens with an artificial one. Although the procedure is very safe and effective, some doctors recommend needless tests or push newer types of lenses that pose risks.

Skip unneeded pre-surgery tests. Cataract surgery, usually performed as an outpatient procedure, requires only a local anesthetic to numb your eye. Research shows that for most people the only pre-op requirements are that you be free of infection and have normal blood pressure and heart rate. Yet many doctors routinely order other tests, including blood counts and electrocardiograms, as would be necessary before a major procedure.

Be wary of premium lenses. In standard cataract surgery, doctors remove the clouded lens and replace it with an artificial, monofocal lens, which provides clear images at either near or far vision. Multifocal lenses do both, so you don’t also have to wear glasses. But these lenses cost up to $4,000 — and usually aren’t covered by insurance. More worrisome, a 2012 review found that while the lenses provided better near vision, they also produced more complaints of halos and glare. However, you might consider a premium intraocular lens if you have an astigmatism, an irregularly shaped cornea.

Glaucoma

More than 2.2 million Americans have glaucoma, but only half know it. That makes screening important. Treatment is key, too, because glaucoma can lead to permanent vision loss. But treatment, which often requires several different daily eyedrops, can be expensive and complicated.

Get the right tests. Glaucoma often goes undiagnosed because it causes no symptoms until vision declines, at which point treatment no longer helps. So people ages 40 to 60 should consider being examined by an ophthalmologist or optometrist every three to five years; those older than 60 need an eye exam every one to two years. Though many eye doctors screen for the disease with tonometry — a test that measures eye pressure — that’s not enough. The exam should also include an ophthalmoscopy, which involves examining your optic nerve.

If you have elevated eye pressure but no other signs of glaucoma, you may not need to start treatment, which can be expensive. Instead, your doctor might screen you more often.

Go for generics.The most common treatment for glaucoma is eyedrops known as prostaglandin analogs (PGAs), which lower eye pressure. Generic versions of most of those drugs are much cheaper than the brand-name versions. And perhaps because of the lower cost, people taking them tend to do a better job of using the drops on schedule, which is important, according to a recent study in the journal Ophthalmology.

Many people need several drugs to control glaucoma, which usually means adding a beta-blocker drop. In that case, ask your doctor about drugs that combine medications, minimizing the number of drops.

Macular degeneration

Age-related macular degeneration, the leading cause of vision loss for Americans 50 and older, damages the macula, the small area near the center of your retina, causing vision loss in the center of your visual field. The advanced disease comes in two main forms: dry AMD, the more common variety, which is treated mainly with dietary supplements; and wet AMD, the more serious form, which requires monthly injections from an ophthalmologist with one of three drugs. There are controversies about both the supplements and the drugs.

Get the right supplement. Research funded by the National Institutes of Health has shown that a specific blend of vitamins and minerals — vitamins C and E, plus copper, lutein, zeaxanthin and zinc — cuts the risk by about 25 percent that dry AMD will progress. But not all eye supplements contain the proper formulation, and some research suggests that those with high doses of zinc — 80 milligrams — may increase the risk of urinary problems. So ask your doctor before choosing a supplement.

Consider drugs that are inexpensive. Each of the three drugs used to treat wet AMD — aflibercept (Eylea), bevacizumab (Avastin) and ranibizumab (Lucentis) — works equally well in slowing vision loss. But Avastin costs just $50 per month, compared with $2,000 for the others. So experts recommend Avastin as the first choice for most people with wet AMD.

But be aware that Avastin is officially approved only as a cancer drug, and it doesn’t come in appropriate doses for AMD. So doctors need to get the medicine from a compounding pharmacy, which combines, alters or — in this case — repackages its ingredients. That poses some risk of contamination, and there have been reports of people being harmed by bacteria that got into Avastin.

Copyright 2015. Consumers Union of United States Inc.

For further guidance, go to www.ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.