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Purpose To study the impact of eye motion on visual field extent. Methods Visual fields were tested in 15 healthy volunteers with the Goldmann perimeter using a V4 test‐object, from seen to unseen, first in primary position of gaze, then allowing eye motion. Temporal points falling out of the cupola were tested again after a controlled nasal head rotation using a headband prototype fitted with a line‐laser level having two orthogonal vial levels. Visual field surface areas (cm2) were calculated as projections on a 30 cm virtual Goldmann cupola whose extent would have been large enough to include all points. Reproducibility error of the method assessed by calculation of the relative difference between surface areas of 12 visual field tests and 12 visual field retests was estimated at 14%. Hertel exophthalmometry was recorded to study the influence of globe position on visual field extent. Results Binocular visual field surface area increased by 37% with eye motion (p‐value = 1.20.10‐9). This increase was highest (46%; p‐value = 1.2.10‐24) in the temporal quadrant. Median maximal visual field temporal excentration with eye motion was 128.3° (minimum: 109.5°; maximum: 137.7°) and more than 135° in 4 eyes of three subjects. Hertel exophthalmometry was positively linked to visual field temporal surface area with eye motion (p‐value = 0.013). Conclusion Eye motion greatly expands the temporal visual field. This peculiarity is likely an adaptation to terrestrial life with upright bipedal locomotion, and may save head movements through horizontal eyeball scanning.

Purpose Like many mammal predators, Humans have frontal (forward‐facing) orbits. This design allows a large overlap of monocular visual fields with good stereoscopic vision but is considered to harm lateral space perception. In Humans, on average, temporal visual field extends 95° in primary position of gaze but 128° with eye abduction. Which anatomical peculiarity may allow such a visual field expansion? Methods Comparative orbit osteology study in 100 human skulls and 120 Apes’ skulls (30 gibbons; 30 orang‐utans; 30 gorillas; 30 chimpanzees and bonobos). Orbit width and height were recorded. Using a protractor and laser levels two orbit angles were recorded: “convergence angle” (the lower this angle, the more frontal the inner orbital rim orientation) and “opening angle” (the higher this angle, the more backward the temporal orbital rim position). Results The largest orbit width/height orbit ratio is 1.19, in Humans (p < 0.001). Humans have a higher “convergence angle” (98.1°) than all Apes except gibbons (99.2°; p > 0.05). Humans have by far the largest “opening angle” (107.1°; p < 0.001) and the largest difference between “opening angle” and “convergence angle” (9°; p < 0.001). Conclusion The largest orbit width/height ratio found in Humans suggests a design that favours lateral vision. More specifically, human orbital rim is unique in that, while frontal, it has by far the most backward temporal orbital rim. This peculiarity ‐ likely and adaptation to terrestrial life with upright bipedal locomotion ‐ allows both good stereoscopic vision and large temporal visual field extent through eye motion.

Purpose To compare the impact of two types of sunglasses on visual field and glare: one (“thick sunglasses”) with a thick plastic frame and wide temples, and one (“thin sunglasses”) with a thin metal frame and thin temples. Methods Using the Goldmann perimeter, visual field surfaces (cm2) were calculated as projections on a 30 cm virtual cupola. A V4 test object was used, from seen to unseen, in 15 healthy volunteers in the primary position of gaze (“base visual field”), then allowing eye motion (“eye motion visual field”) without glasses, then with “thin sunglasses”, followed by “thick sunglasses”. Visual field surface area differences superior to the 14% reproducibility error of the method and having a p‐value inferior to 5% were considered significant. A glare test was done using a surgical lighting system pointed at the eye(s) at different incidence angles. Results No significant “base visual field” nor “eye motion visual field” surface area variation were noted comparing tests done without glasses and with the “thin sunglasses”. In contrast, a 22% “eye motion visual field” surface area decrease (p‐value = 2.7.10‐13) was noted comparing tests done without glasses and with “thick sunglasses”. This decrease was most severe in the temporal quadrant (‐33%; p‐value = 6.3.10‐20). All subjects reported less lateral glare with the “thick sunglasses” than with the “thin sunglasses” (p‐value = 6.10‐5). Conclusion The better protection from lateral glare offered by “thick sunglasses” is offset by a severe temporal “eye motion visual field” surface area constriction.