Even though it is a normal reaction, sneezing still remains an enigma when it is caused by exposure to light. Sneezing caused by the exposure to a very powerful light source is a genetical disorder called Photic sneeze reflex, or the ACHOO syndrome (a backronym for Autosomal Dominant Compelling Helioophthalmic Outburst), or Peroutka Sneeze Reflex. It cannot be fully explained, as it is a poorly understood phenomenon; photic reflex is an autosomal dominant hereditary trait, that can affect a rate of 18-35% of the worldwide population, the procent of the Swedish population being estimated, in example, at 20%.
Because this condition isn`t associated with a disease, documentation made in the medical field is too little to be significant. Usually, a sneeze occures when the nasal mucosa is irritated; the nerve that is responsible for the sneeze is the trigeminal nerve, the cranian nerv guverning the facial sensations and the motric control of the face. The optical nerv, which takes informations to the retina when a powerful light appears, being located closely to the trigeminal nerve, it transmits a part the signals received from the outside environment to it. In theory, that small signal detected makes the brain think that an irritant substance is inside the nose and causes the sneeze.
The genetical reason behind this phenomenon still remains unidentified, but scientists try to find an explication. A base for their researches is given by the seizures caused by powerful flashes of light and the photophobia that follow the migrens. Despite the apparent harmless nature of this kind of sneeze, it can still be a health risk for people, sneezing being a way of spreading diseases. Bacterial infections can occure through the spread of microorganisms suspended in the droplets expelled by a sneeze. Bacterial meningitis and tuberculosis are one of the bacterial diseases transmitted by sneezes. Viral infections can also be spread by sneezing, including influentza, mumps, measles and rubella.
Of course, sneezing isn’t only a medical problem; it can also be considered as a social issue. In example, a person who suffers from the ACHOO symptome cannot drive a vehicle, because lose of control can occure. Even in social groups, someone who has the ACHOO symptoms may be the subject of embarassment, because of the fact that the others do not know the cause of his unusual outbursts. The greatest risk that can occure in ACHOO patients are in the medical field, when patients are sedated with a substance called propofol, so that they could undergo periocular or retrobulbar injection. The risk of eye damage exists, because the patient sneezes with a needle in the eye or around it and sneezing causes a violent and rapid movement of the head.