When one leaves Earth’s magnetic field – natural protection – he becomes exposed to x-radiation – the flow of heavy charged particles. The eye traces the impact of such particle as a flash of light. Participants of Moon expeditions and orbital flights and airplane pilots on high altitudes have noticed such light flashes. The researchers from several Moscow institutes under the supervision of academician M.A. Ostrovsky have come to a conclusion that x-radiation can cause irreversible damage of visual pigment, photosensitive and nerve retinal cells, which leads to eyesight loss.

The scientists have extracted visual pigment – rhodopsin – from brown frog’s eye retina. This pigment bleaches after being treated with common light, but then recovers and is ready to work again. The situation is different if one irradiates rhodopsin with deuterons – deuterium (hydrogen heavy isotope) nuclei. Deuteron flow in the particle accelerator is equivalent to carbon nuclei flow in the galactic radiation. Under deuteron influence rhodopsin bleaching similar to being exposed to common light is detected, but the pigment is unable to recover, thus x-radiation destroys the pigment irreversibly.

In order to study deuteron effect on eye retina, the scientists have put it on a wet filter paper in a special lightless chamber. Electrodes, registering cell response to light flashes and deuteron beam, were attached to the retina. The response of the isolated retina to the heavy charged particle irradiation was similar to that of common light. The difference was only in lifetime of retina cells after irradiation: frog retina in a nutrient medium usually works for several hours, but after deuteron beam irradiation it died in 10-15 minutes. X-radiation has killed photosensitive and nerve retinal cells.

Moscow scientists were the first to show that heavy charged particles bleach visual pigment and damage retina. Unfortunately, deuterons cause light flashes that are prophetical of eyesight degradation or loss. It happens not only in space because people come across x-radiation in their ordinary life.