• A 3D task was performed in an AR-HMD with ocular measurements pre- and post-task. • Accommodation but not vergence responses were affected after performing the task. • Findings suggest a disrupted vergence-accommodation cross-coupling in AR-HMD-wear. • Implications for the use of AR-HMDs for extended periods in training and education. The recent increase in use of augmented reality (AR) head-mounted displays (HMDs) has been accompanied by concerns of their potential effects on the oculomotor system, due to the vergence-accommodation conflict. Studies have reported symptoms of visual discomfort from performing visually and cognitively demanding procedural tasks in AR, but the extent to which AR affects vergence and accommodation responses is not known. Here, the aim was to investigate the effect on vergence and accommodation responses from performing a visually and cognitively demanding 3D task in an AR-HMD. Thirty-five young adults manipulated virtual objects at around 40 cm (near) using their hands to match a configuration presented on a physical 2D display at 4 m (distance). Before and after performing the task, simultaneous vergence and accommodation responses were measured. Accommodation but not vergence responses were affected after performing the task in AR. These findings suggest that using AR-HMDs with a fixed focal plane for visually and cognitively demanding tasks might give rise to short-term visuo-oculomotor changes.