I have 10/20 vision which is really good better than 20/20 in my right eye but SFA in my left. Plus I have a cataract which isn't ready to come off yet so my vision isn't really clear. I wear transition lenses and my optometrist said there are approx 1500 changes in the lens. I love them and wouldn't have anything else and they darken down when outside as well. Wouldn't have anything else. My wife was very short sighted and when she had her cataracts taken off she had a Toric Lens put in each eye. She really doesn't need glasses anymore except for close-ups now. They were 1000 bucks an eye but well worth it.