Millions of older people are getting tests they don’t need to prove they are healthy enough to have cataracts removed, a new study finds. The excess testing before this quick, ultra-safe eye procedure is costing them and Medicare a bundle, and many patients don’t know they can question it, doctors say.

“They should ask, ‘Is it really necessary?’ ” and how much it will cost them in co-insurance – usually 20 percent under Medicare, said one study leader, Dr. R. Adams Dudley of the University of California, San Francisco.

Removing cataracts that cloud vision is the most common elective operation for older adults, done 1.7 million times each year in the United States. It’s an outpatient procedure that takes about 18 minutes and requires only numbing eye drops.

“This is one of the lowest-risk surgery procedures you can have,” with less than a 1 percent risk of major heart problems or death, said Dr. Catherine Lee Chen, a UCSF anesthesiologist who led the study.

Yet many doctors order preoperative tests such as blood work and chest X-rays.