Is the ocular cavity completely closed? Flakes of lead paint in eye?

Even though the cavity is surrounded and protected by bony structures, the optic nerve does has to pass through that structure to the brain. I really don't think you need to worry about this, but if you are at all concerned check with your doctor. If you think you still have a fleck of paint in your eye, rinse it well for several minutes with cool water. From what I have read you need to be exposed to lead over time and to a relatively high level for it to have an effect, through either breathing in dust or through ingestion. Again, check with your doctor if you are concerned.