Abstract
Abstract: :
Purpose: The lack of sleep results in not only physical fatigue but also in asthenopia. We evaluated accommodative function using accommodative microfluctuation of high frequency component (HFC), which reflects fluctuations of the refractive power of the lens. We compared accommodative responses of day shift with enough sleep (day) and late night shift (night) conditions. Methods: We used 25 healthy volunteers aged 27.4±3.2 years (mean±SD), using there dominant eyes, except for there refractive error. We tested accommodative response and HFC by using an accommodation analyzer (AA –1TM, NIDEK) at the day shift's time and the night shift’s time. We added accommodative demands to the value of objective refraction from +0.5 to –3.0D by 0.5D steps. All measurements were performed between 8:00 a.m. and 10:00 a.m.; moreover, we defined the lack of sleep (fatigued condition) as less than 50% of enough sleeping hours. We analyzed the data using Wilcoxon signed–ranks test. Results: Mean sleeping hours were 6.56hr (day) and 2.02hr (night). Mean spherical equivalent (SE) of object refraction were –4.12±3.17D (day) and –4.00±3.16D (night). There was no significant difference between both conditions (p> 0.1). The mean accommodative responses were 2.11±0.37D (day) and 1.82±0.48D (night). There was a significant decrease between both conditions (p<0.01). In fatigued night shift group, there was a significant decrease of HFC in 2.0D, 2.5D, and 3.0D of accommodative demand (p< 0.05). Conclusions: In the night shift group, we could find no change in the refraction in spite of the lack of sleep. However, we found significant deterioration in the accommodative response and in the HFC of the night shift group, especially in the accommodative demands of more than 2D, as compared with day shift group. This study suggests that the lack of sleep due to night duty decreases accommodative functions.