The viewing angle provided by virtual reality glasses is the angular size of the space that falls into the user's field of view. Usually, the characteristics indicate the size of this space horizontally; however, if you need the most accurate information, this point needs to be specified separately.
The wider the viewing angle — the more the game space the user can see without turning his head, the more powerful the immersion effect and the less likely that the image will be subject to the "tunnel vision" effect. On the other hand, making the field of view too wide also does not make sense, given the characteristics of the human eye. In general, a
large viewing angle is considered to be an angle of 100° or more. On the other hand, there are models where this indicator is 30° or even less — these are, usually, specific devices (for example, drone piloting glasses and augmented reality glasses), where such characteristics are quite justified given the overall functionality.
The ability
to move the lenses of the glasses back and forth, thus changing their location relative to the screen and the user's eyes. The specific meaning of this function can be different: it can adjust the angle of view (so that the screen fits completely in the field of view and at the same time is not too small), play the role of diopter correction (which is important for users who wear glasses) or focus, change the setting interpupillary distance (see below), etc. These nuances should be clarified separately. However, anyway, this function will not be superfluous — it makes it easier to adjust the glasses to the personal characteristics of the user.