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Ads say that Lasik can "reduce or eliminate dependency on glasses or contact lenses" and "vision improves almost immediately." The downsides are less widely advertised.

More than half of Americans who have Lasik or other laser vision-correction surgery still need to wear glasses at least sometimes. Side effects such as dry eyes, halos, glare and starbursts around lights are common. Those results are from a Consumer Reports National Research Center survey of 793 adults who have had vision-correction surgery since 2001.

Although 80% of respondents said they were highly satisfied with the surgery, our findings point out the need for realistic expectations.

Among the main reasons for having surgery (respondents could cite more than one): 61% said they were tired of wearing glasses; 52% said they wanted to see a bedside clock in the morning; 38% said contact lenses were uncomfortable and hard to care for. But afterward, 55% still needed to wear glasses or contacts at least sometimes. And of those who found it very hard to see that clock, just 36% had little or no trouble seeing it after surgery.

If you're considering laser eye surgery, find basic information at www.fda.gov (search "lasik"). Talk to others who have had the surgery. And ask yourself:

Am I a good candidate?

Your vision should have been stable for the past year. You should be at least 18 and not pregnant or breast-feeding. You shouldn't have a disease that impedes healing (diabetes, say) or take medications that do so. Skip surgery if you have dry eyes. People who were nearsighted before surgery tended to be slightly more satisfied with the results than those who started out farsighted or with astigmatism.