Effects of different colors on accommodation in emmetropic children when viewing a visual display terminal

Objective To investigate the effects of different colors on accommodation in emmetropic children when viewing a visual display terminal (VDT).Methods Fourteen emmetropic children with normal color vision were enrolled in this cross-sectional study.They were required to read 7 automatically activated text displays on a VDT at 50 cm.The 7 texts were presented in 2series of patterns.The first series of patterns was set according to the background color, including black/white,white/red,white/green,white/blue.The second series of patterns was set according to the character color, including black/white, red/white, green/white, blue/white. Accommodative response was measured with an objective infrared autorefractor.The difference in accommodative response,accommodative lag and corrected accommodative lag among groups were then compared, using the randomized blocks analysis of variance.Results All the fourteen emmetropic children successfully completed the task.There were no statistically significant differences in the mean accommodative response (F=0.282,P=0.946) and accommodative lag (F=0.281,P=0.945) among the 7 texts.After correcting for longitudinal chromatic aberration, the mean accommodative lags were (0.77±0.21)D,(0.98±0.26)D,(0.34±0.23)D, (-0.26±0.25)D,(0.96±0.27)D, (0.30 ±0.28)D,and (-0.23±0.26)D,respectively. Multiple comparisons with the Bonferroni test showed that there were statistically significant differences between each pair of groups (P＜0.01) except that between black/white and red/white.Conclusion Greater accommodative lag is detected in emmetropic children when reading texts in long wavelength light.The lag tend to reduce the response to short wavelength light and even accommodative lead is found to some extent for blue light. Key words: Color;  Accommodation,ocular;  Longitudinal chromatic aberration;  Lag of accommodation