The FDA requires online contact stores to abide by strict guidelines. You must have a current valid prescription. This requires a regular eye exam by your eye doctor. You should get a regular eye exam every year to make sure you are not doing any damage to your eyes. Wearing contact lenses can be safe as long as you follow good hygiene. Your eyes are going to change and very often you will notice you can’t see as well with your old prescription. This change is normal.
People definitely can have serious complications when they do not take care of their eyes properly. Many patients try to wear contacts a lot longer then they are supposed to. The result can be irritation and infection. Repeated infections can permanently affect your vision. If you are comfortable sleeping in your contact lenses and they are approved for extended wear that is fine. Even if your contacts are approved for extended wear you should take them out when you have irritation. The safest course to follow is to listen to your body. If your eyes are hurting then something is wrong. If you do not take care of the irritation you may get in big trouble. if your shoes started hurting your feet, you would take them off and try to correct the problem because hurting is not normal. I suggest you use the same common sense with your eyes.
If you follow these guidelines and get your eyes examined on a regular basis then shopping online for contacts can be safe and economical.