While working with text in XR there are some essential things to keep in mind when it comes to how we perceive the text. The factors mentioned below play a crucial role in how we select and do typesetting of text in XR experiences.
Visual Acuity: commonly describes the clearness of vision. Visual acuity is dependent on optical and neural factors:
The sharpness of the retinal focus within the eye,
The health and functioning of the retina, and
The sensitivity of the interpretative professors of the brain.
Spatial Frequency: refers to the level of details present in an image (stimulus) per degree of visual angle. A letter with small details and sharp edges contains higher spatial frequency as compared to a simplified letter with round edges.
Crowding: is the effect of separation which hinders the reading, it is a perceptual phenomenon in which recognition of letters presented away from the fovea (centre of gaze) is impaired by the presence of neighbouring letters
Foveal and parafoveal reading: Human eyes do not move continuously along a line of text while reading; instead, they jump across the line in rapid movements (known as saccades), between these saccades the eyes stop for a fraction of seconds (fixations). During this process, the Foveal area is where the fixation happens and the user focuses on that area however the parafoveal region helps in continuous reading
All these factors above are discussed in detail in the following section. In case you want to read it in an article format then visit this link on my website.