Collie et al. (1978) described a 'disorder' characterized by nearly uncontrollable paroxysms of sneezing provoked in a reflex fashion by the sudden exposure of a dark-adapted subject to intensely bright light, usually sunlight. The number of successive sneezes ... Collie et al. (1978) described a 'disorder' characterized by nearly uncontrollable paroxysms of sneezing provoked in a reflex fashion by the sudden exposure of a dark-adapted subject to intensely bright light, usually sunlight. The number of successive sneezes was usually 2 or 3, but could be as many as 43. The 4 authors were the probands of the 4 families they reported. Several instances of male-to-male transmission were noted. 'Photic sneeze reflex' was suggested as the appropriate designation by Everett (1964), who found it in 23% of Johns Hopkins medical students. Lewkonia (1969) described sneezing as a complication of slit lamp examination. Sneezing in response to bright light was said by Peroutka and Peroutka (1984) to be a common yet poorly understood phenomenon. In a poll of 25 neurologists at Johns Hopkins, Peroutka and Peroutka (1984) found the phenomenon in 9, but only 2 of the respondents knew that such a specific reflex existed. The Peroutkas (father and daughter) reported the reflex in 3 generations of their family: grandfather, the father (the proband), his brother and his daughter. The index subject (S.J.P.) invariably sneezed twice when he moved from indoors into bright sunlight. Katz et al. (1990) found light-induced sneezing in 5 of 19 patients with nephropathic cystinosis (219800). This was presumably related to the crystal deposition in the cornea. Lerner (1991) took Hunter (1990) to task for referring to the photic sneeze reflex as a 'comic syndrome.' He cited reports by Beckman and Nordenson (1983), Forrester (1985), Morris (1987), and Lang and Howland (1987), in addition to those already cited here. Benbow (1991) reported that he had suffered from photic sneezing for over 20 years and having just learned of its existence found that the 'symptoms are more easily tolerated if you can put a name to them, even if that produces only an illusory understanding of their significance.' He commented on the potential hazards of photic sneezing if it occurs while one is driving a car on a sunny day. He said that he found that 'sudden exposure to sunlight when emerging from a road tunnel of sufficient length is sure to induce a sneeze.' Furthermore, 'driving through sunlit gaps in otherwise dense forest or past blocks of buildings can bring on a sneeze.'