Intraocular pressure responses to a virtual reality shooting simulation in active-duty members of the Spanish Army: The influence of task complexity.

• Intraocular pressure was higher after completing more demanding shooting task. • Reaction time was shorter during less compared to more cognitively demanding task. • Intraocular pressure might be used for assessing mental state in real-world contexts. Ocular physiology is sensitive to cognitively demanding tasks. However, it is unknown whether the intraocular pressure is also affected by the cognitive demands of military operations. The main objective was to determine the impact of a virtual reality shooting simulation with two levels of complexity on intraocular pressure levels in military personnel. Eighteen active-duty members of the Spanish Army and eighteen civilians performed two 4 min simulated shooting tasks with two levels of complexity using a virtual reality. In the "easy" task participants performed a simulated shoot when the stimulus (military with a rifle) appeared, while in the "difficult" task the stimulus randomly was a military with a rifle or with his hands on the air and participants were instructed to respond only when the military with a rifle appeared. Intraocular pressure was measured with a rebound tonometer before and immediately after each task. Complementarily, perceived levels of mental load and shooting performance (reaction time) were assessed. Intraocular pressure was greater after completing the more complex task in both military personnel (p-value < 0.01, Cohen´s d = 1.19) and civilians (p-value < 0.01, Cohen´s d = 1.16). Also, perceived levels of task load and reaction time were higher in the difficult compared to the easy shooting tasks (both p < 0.001). The rise in intraocular pressure is positively associated with the cognitive demands of simulated military operations. The potential application of this finding is the development of objective tools based on intraocular pressure for the evaluation of the mental state in real-world contexts, permitting to improve soldiers´ safety and performance. [ABSTRACT FROM AUTHOR]