Changes in Thresholds of Electrically Evoked Phosphene and Electrical Lability of the Optic Nerve in the Ground Station Crew in the International Experiment SIRIUS 20/21

Abstract

In the ground sealed station crew, during the 8 months international experiment SIRIUS 20/21 simulating an interplanetary flight, electrically induced phosphene (EIP) thresholds, which reflected the electrical sensitivity (ES) of the retina, and the optic nerve. ES&L was assessed using the “ESOM” device (“Neuron”, Ufa, Russia) once a month, twice a day (morning/evening), under mesopic conditions. An increase in ES and other patterns of changes in ES&L parameters during period of isolation were established, reflecting the adaptation of the crew to the conditions of the experiment and the reaction of the visual system to physical and psycho-emotional stress. Further study of the thresholds of the EIP and L of the optic nerve in experiments of increasing duration will make it possible to determine the biomarkers that differentiate the individual adaptive reaction of astronauts from dysfunction of the retina and optic nerve under real space flight conditions. The L of the optic nerve showed greater resistance to experimental conditions than the ES of the retina. The results suggest that the determination of the L in the ES&L test can become an express test on board the ISS to assess the functional state of the papillomacular bundle of optic nerve fibers, the risk of developing or diagnosing SANS (flight-associated neuro-ocular syndrome) in long-term space missions.