Operational military personnel are increasingly using virtual or augmented reality headsets in the field or in training. However, these devices cause a conflict between accommodation (focus to see clearly) and vergence (alignment of both eyes on the object being viewed) that can be a source of visual fatigue and altered visual and perceptual abilities. Although techniques exist to limit this conflict for screen-based stimuli, the use of helmet visuals (or immersive headsets) adds technological complexity. Indeed, since accommodation on the screen of the helmet visual is impossible (i.e., distance too small) for the human visual system, lenses are used to virtually shift the image (referred to as a collimated image) so that accommodation can occur much further away. However, this material configuration also modifies the vergence, thus causing a conflict between accommodation and additional vergence that persists regardless of the attenuation technique used.

In this study, the investigator proposed to modify the image display to take into account the technical features of the helmet to correct this techno-dependent conflict. This study is aimed at determining whether the setting recommended by the algorithm developed by the investigator limits visual fatigue better than the conventional setting recommended by manufacturers or a subjective setting controlled by the user.

Inclusion Criteria:

• Age over 18
• Non-presbyopic
• Stereoscopic acuity ≤ 60 min of arc

Exclusion Criteria:

• Accommodative insufficiency (APP ≤ 13-"age"/4, in diopters)
• Accommodative inertia (+ and - block in binocular)
• Compensation by orthokeratology
• Present or past binocular pathology: strabismus or amblyopia

The study population is composed of healthy subjectfs with no history of visual disorders.