The most possible factor is that your cold cause watery eyes. Cold is easy to cause eye infection because of bacteria and virtues. Eye infection included eye pain, eye redness, pink eye and some other eye problems. Cold is also commonly due to bacteria and germs enter our body and some organs occur problems, and then cause some eye problems, such as watery eyes, dry eyes, eye pain and so on.
Yeah, it is normal that when you are sneezing, your eyes will be filled with water. As far as I know, there are two kinds of reasons. On one hand, maybe you have a cold, so your eyes will be filled with water while sneezing. If so, you can just take some aspirin, and drink much water, it will go away the next day. On the other hand, if you do not have a cold, there will no pills that can help you. Because you know that when you sneeze, the certain muscles in your face will be tense, of course, this case includes the tear ducts. Meanwhile, all the sinuses are connected, including the eyes, nose, mouth and ears, so your will sense that your eyes are filled with water when you sneeze. If you are on of the second group, you just let it go, because nothing can help you with it.
You eyes are always secreting tears every second; the tears are running around the eyeball's surface. However, you are hard to find the tears' movements around the eyelid and eyeball. When you blink your eyes, these tears are absorbed the canalis nasolacrimalis. It is the channel which connects the eyes and the nose. All the tears is duct to the nasal cavity, so people do not tears in the normal. Your nose's air pressure will increase when you sneeze by the contract of facial muscle. This time the tear discharge from noso-lacrymal dust will be blocked for a while, it would only be accumulate into the eyes, and you will be tears. Actually, people will get water eyes when they laugh, sneeze and cough; they are the same principle and normal!