Abstract
Purpose::
Asthenopia is not only caused by sustained tasks at a near distance but also by physical fatigue. We evaluated accommodation function using accommodative microflcutuation of high frequency component (HFC), which reflects fluctuations of the refractive power of the lens, during accommodation both after having enough sleep (control) and after night shift (night).
Methods::
21 nurses right eyes (26.0±3.9 years) except for their refractive error were used. We tested HFC by using an accommodation analyzer (AA-1 TM, NIDEK) in both conditions. We added accommodative demands to the value of objective refraction from +0.5D to -3.0D by 0.5D step, and averaged HFC from -1.0D to -3.0D of accommodative demands; moreover we asked 25 subjective symptom questions (20 for asthenopia and 5 for physical fatigue), and each question was scored from 1 to 5 points.
Results::
Mean sleeping hours were 8.5hrs(control) and 1.5hr(night). Mean HFC after the night shift divided into increase group (A; n=11) and decrease group (B; n=10). The amount of the changes were A=+3.64(+0.08~+13.61) and B=-5.31(-0.44~-13.8). The results of the questionnaire were (A= asthenopia +24.0 point, physical fatigue +11.8 point) and (B= asthenopia +13.6 point, physical fatigue +7.4 point)(p<0.05).
Conclusions::
These results suggest that the change in an autonomic balance is one of the factors that influence visual function after night shift, and the dominant parasympathetic nerve causes asthenopia and physical fatigue.