Hess has studied experimentally the subjective light sensations occurring with sneezing, hard pressing, and the like. The sensations are readily produced by bending the head forward and making an expiratory effort with mouth and nose closed. Moderate pressure upon the eyes with the hands sufficed to prevent the appearance of the sensations.
Reference: von Hess C. On the excitation of the retina from increased venous tension. Arch Ophthalmol. 1902;31:40.
A look at the past . . .. Arch Ophthalmol. 2003;121(2):244. doi: