My Vision Suddenly blurred in my left eye what is wrong?

I just got off work from my lifeguard job and was teaching in the water, i got out and everything seemed fine, then as i started driving home my left eye was noticeably blurry but not too bad, i stopped at a store to get groceries and by the time i left i could not read anything at all because of how blurred my left eye became its been about an hour now and its still blurry and if i only use my left eye i cant read or see anything clearly but my right eye is perfectly normal, what could be the cause of this? And also it is not red, and does not hurt also I'm assuming its not dry because i used eye drops and it did not help.