In Merles there are two colors of merles a blue merle which is a blue-gray color that is carried over through black and a red merle which is a dilute chocolate in the doodle breed, for some reason when produced in the doodle the red comes through as chocolate and really is a chocolate merle by color.
Chronic sinusitis, or sinus infections, cause a stuffy or runny nose, tooth pain, fever, sore throat and more. Migraines are a common type of headache that can cause severe pain, aura or flashes in vision, and tingling. Tension headaches, caused by muscle tension, are marked by pain, pressure and tightness around the head. Ocular migraine usually refers to a type of migraine that can cause temporary blindness in one eye.
So whether there is light entering the eye or not, any stimulation of the retina will be translated into a light show by the brain. If you see stars or flashes after sneezing, it could be from a pressure on the eye itself, or from stimulation of the nerves that have to do with sight.