Are contact lenses really safe for long term use?

Asked my optometrist if I could switch to contacts (power= -5.25).
After an extended (half an hour long) series of tests on my eyes using some (what looked like) high-tech machines, she okay'd me for contacts, and offered me various choices.

I picked a brown, yearly-disposable pair of lenses (B&L).
She advised monthly disposables are better, but the overall cost increased, hence i asked for the yearly ones.
I am now wearing them, and my sight seems to be great - better than it ever was with spectacles.

But i just did a couple of google searches, and looks like contact lenses can cause permanent (irreversible) changes in your eyes.

Is this true? I went to a qualified optometrist, and she must be aware of this. Then why did she allow me to purchase contacts? Just because I ask for something doesn't mean the doctor will give it to me. I can't go to a doctor and ask for a morphine shot!
Added (1). By long term, i mean longer than 5 years

Read more: Are contact lenses really safe for long term use?