Title : Different spatial orientation of human eyes under hypoxia and color difference: An example of dynamic vision
Abstract:
Purpose: The purpose of this study was to investigate the human eye’s recognition of moving objects of various colors in different spaces (altitude, dark background and oxygen concentration). Through detailed analysis of the three major factors, namely, altitude, angular velocity (AV) and color, we will clarify the human eye’s colorful and dynamic visual localization in high-altitude environments and explore its possible related mechanisms.
Methods: The study group comprised 16 healthy participants, 20–26 years of age. Dynamic vision was measured with self-developed software Meidixin (Tianjin) Co., Ltd. Measurements were taken at 5 altitudes (d1: ground; d2: 3500m; d3: 4000m; d4: 4500m; d5: end of experiment) and at 6 colors (red, orange, yellow, green, blue and purple). Data analysis was performed using the Kolmogorov-Smirnov (K-S) test, paired sample T-test, one-way ANOVA, two-way ANOVA, Spearman rank correlation coefficient and Wilcoxon test.
Results: Altitude factor: Red LogMar dynamic visual acuities (DVAs) at d1 (at 40, 60 and 80dps), d2 (at 60 and 80 dps) and d3 (at 60 and 80dps) were significantly better than those at the corresponding AVs at d4. Orange LogMar DVA at d1 was significantly higher than that at d4 at 80 dps. Blue LogMar DVAs at d1 (at 60 dps), d2 (at 40, 60 and 80 dps) were significantly higher than those at d4 at the corresponding AVs. Purple LogMar DVAs at d2 (at 60 and 80 dps) were significantly higher than those at d4 at the corresponding AVs. Color factor: At d0 (at all AVs), the blue LogMar DVAs were remarkably better than other colors’ LogMar DVAs, with yellow and green LogMar DVAs being significantly lower than purple LogMar DVA at 40dps, and orange LogMar DVA was lower than the green LogMar DVA at 60 dps. Moreover, the orange, yellow, green and red LogMar DVAs were significantly lower than purple LogMar DVA at 60 and 80 dps. At d1 and d2, red, orange, yellow and green LogMar DVAs were significantly lower than blue LogMar DVA (at all AVs) and purple LogMar DVA (at 20, 60 and 80 dps). At 40 dps, red, yellow and green (at d1 and d2) LogMar DVAs were significantly lower than purple LogMar DVA. At d3 and d4, red, orange, yellow and green LogMar DVAs were statistically lower than blue (at all AVs) and purple LogMar DVAs (at 40, 60 and 80 dps). At d4 under 20 dps, orange, yellow and green LogMar DVAs were lower than purple LogMar DVA.
Conclusions: High altitude environment (acute hypobaric hypoxia) affects the human eye's ability to spatially localize objects of different colors, especially the 3 colored DVAs of blue, purple and green, which decrease progressively with increasing altitude (aggravated hypoxia). This will affect the pilot's ability to acquire visual information resulting in biased acquisition and judgment of instrument panel and surrounding information during flight.
