It is really such an interesting question. When you sneeze, you need to use a lot of force ejected from the gas. At this time, the lungs in oral cavity and the nasal cavity have a lot of pressure, not only in the diaphragmatic muscle but also in the intercostal muscle. And respiratory muscle has sudden severe contraction. The neck facial frontal muscle will be nervous. Then dominated orbicularis oculi close their eyes which will shrink because facial muscle is dominated by facial nerve. You will spontaneously close your eyes on the other hand. At this time, the sneeze nervous system will be highly concentrated. In order to complete a series of sneeze reflection, you will close your eyes which can reduce outside interference. Its behavior can't be controlled. If you open your eyes on purpose to wait for the sneeze, you may not sneeze.
Nothing will happen if your eyes are open when you sneeze. Sneezing is involuntary and is a common action of our body. Usually, people will sneeze when they are exposed in cold air. In fact, sneezing is a good way to expel dust, pollen, pet hair and other allergens etc. There is no much affect on your eyes.
Why you always close your eyes when you sneeze? That is really one interesting question. In one hand, you must need a large power to expel the air from your body. There has huge pressure in your lungs, mouth as well as nasal cavity, all the aspiration muscle will be suddenly contract in your neck, face, forehead. At this time, orbicularis oculi which would control the eyes close will contract for the sake off it managed together with face muscle by facial nerves. You have no choice but close your eyes spontaneously. So the situation that you mentioned will never happen. In the other hand, close your eyes will reduce the disturbing of the outside for your concentration of your mind for the whole movement of the sneeze. It is a born habit to sneeze with your eyes close.
When WE sneeze, we close our eyes to protect our eyes. We may be protecting them from microorganisms and particles from our sneezes. But it could also be simply because a sneeze is a kind of body wide reflex in which a lot of muscles contract, not just in the nose and throat but also those in the diaphragm, the abdomen, thighs, back, even sphincters. At the same time, it is dangerous to open eyes because of the power of sneeze is too strong, which would cause damage to eyes if you are opening them.