Generally speaking it's because it's relatively easy to scratch your eye as a contact wearing, in general non contact wearers don't put a piece of plastic on their eye every day nor jam their fingers in their eyes trying to get a contact out. scratch + swimming pool bacteria = bad combination. Eye infections can be nasty and really just in general contact lense wearers will be more susceptible to picking them up. I think the other issue is bacteria getting caught between eye/contact lense becomes a good breeding ground for bacteria again increasing the chance of an infection.
If you do ever scratch your eye, if you get any redness, don't hesitate and get straight to your optician or doctors and get antibiotic eye drops, do not **** around with your eyes.
In terms of eye vision, my contacts always give me significantly BETTER vision than glasses I've had. But as someone said it's a bit of a crap shoot as theoretically glasses can be made to ultra accurate prescriptions while contact lenses tend to be a bit more like off the rack prescriptions. For whatever reason daily focus toric "fit" my prescription great, even as the power has changed they have always given me better near, medium and far distance clarity compared to glasses.
There are other possibilities like, have contact lenses but if they don't suit near distance/computer distance perfectly, you could get a pair of very low prescription glasses just to bring the nearer range into better clarity. Hopefully you can find contacts that match you well though. I would though absolutely ask your optician if you could try the next power up or down to see if they better match your needs. You might lose a little far distance but gain at close up distances which may or may not work better for you.
I think things like, the blurry effect outside the edge of my glasses, the general comfort of not wearing glasses all make contact lenses hugely better.
In 15 years of wearing them I've had one eye scratch, one infection and while it was particularly painful and nasty for a few days... it doesn't put me off contacts in general... though it does make me lean towards finally getting laser surgery as it makes you realise both contacts and glasses aren't risk free. I've had the classic ball to face with glasses, eye infection from contacts, both have risks and so does laser surgery, upside is so huge though.
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