Impact of Fixation Direction on Dynamic Accommodative Response

Purpose : The purpose of this study was to measure accommodative response when looking at different direction such as downgaze and sidegaze either right or left. Methods : This study was performed with 13 adult males and females(22.40±0.41 years old) no subject had ophthalmic surgery or disease and placed the targets at the primary, 10° and 20° sidegaze, 10° and 20° downgaze, The accommodative responses was measured by a open-field autorefractometer under the distances of 3 m, 1 m and 40 cm that enable consecutive measurement. Results : In all gaze directions as distance became shorter the accommodative response increased. At each viewing distance 1m and 40 cm, the accommodative responses showed the peaks 1.09± 0.10 D in 10° and 2.04±0.11 D in 20° downgaze. respectively, while the lowest accommodative responses were 0.44±0.05 D and 1.54±0.06 D in 20° and 10° sidegaze, which showed statistical differences(p＜0.050). There were significant differences in each viewing direction except for in 10° and 20° sidegaze(p＜0.050). The gaze direction and the accommodative responses were significantly different(p＜0.050). Conclusion : This study demonstrates that the accommodative responses vary with the gaze direction and gaze angle for the same modulating stimulus. Therefore, it is assumed that 20° downgaze makes the object sharper and minimizes the eye fatigue.