What are the common reasons for condom failure?

I live in Prague, Czech Republic — Europe. Before asking any question, I should tell you that I really appreciate your service. As for my question, I would like to ask you about the most common reasons for condom failure as a contraceptive method. I suppose that the most frequent one is condom breakage. But what are the others? I am especially concerned about pregnancy risk implied by the accidental transfer of sperm in pre-cum to condom by fingers while putting it on.


Which type of contact lenses are better?

I read that disposable contact lenses are actually worse for your eyes than the normal one-year ones because they allow less oxygen to go to your eyes, and the only advantage is that there are less cleansing problems. Also, it is claimed that inadequate oxygen to your eyes (possibly caused by prolonged wearing of contact lenses) leads to a condition when extra blood vessels sprout around the iris, which leads to sight problems at old age. Is that true?

I am very concerned because I normally wear (one-year) contact lenses from 8am to 8pm, and maybe to 12am during reading periods. I don't feel very comfortable with glasses because they give distorted visions and fatigue. I thought switching to disposable contact lenses would do my eyes good. My current lenses contain 38 percent water. Is this good enough?