How much can our eyeballs rotate towards the nose, away from it, towards the top and bottom?
There shall be slight differences due to physiology. Nevertheless, the average vertical ascending angle is 25 degrees and descending angle, 30 degrees. Within the x-y plane of which we assume to be coplanar with the central line of vision, the maximal angle of rotation is 35 degrees in the left and right directions respectively.
I attempted to construct an image which depicts these angles - simply a Cartesian diagram. You can find further clarification of details from this link by Nelson & Associates
Finally, it is important to note that although the eye may be capable of these rotations, the eye may not be able focus on all objects in this field acutely, namely, focusing light on the fovea.
Happy muscular experiments.
$\begingroup$ "Finally, it is important to note that although the eye may be capable of these rotations, the eye may not be able focus on all objects in this field acutely, namely, focusing light on the fovea." Any ideas wht that happens? Also, how reliable are Nelson & Associates as a scientific source? $\endgroup$ Apr 17, 2018 at 16:34
$\begingroup$ @MarkLegault To answer your first question, I can consider two primary reasons: at the farthest rotation of one of the two eyes respectively, there is no binocular vision. Therefore, the depth-perception is limited in these areas. Moreover, for an object to be acutely focused on by the eye, the reflected light waves must hit a certain area of the retina: the fovea. Full eyeball rotation may allow for increased peripheral vision - around 95 degrees total vision. Regrettably, perhaps due to the difficulty in measuring rotation as opposed to field of vision, data are limited. $\endgroup$ Apr 17, 2018 at 17:45
$\begingroup$ These angles roughly correspond to the angle which would achieve the maximum peripheral vision, available from: www.vision-and-eye-health.com/visual-field.html $\endgroup$ Apr 17, 2018 at 17:51