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Human rather than ape-like orbital morphology allows much greater lateral visual field expansion with eye abduction.

Denion E, Hitier M, Levieil E, Mouriaux F - Sci Rep (2015)

Bottom Line: This rearward position does not obstruct the additional visual field gained through eye motion.In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°).This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°).

View Article: PubMed Central - PubMed

Affiliation: 1] Inserm, U 1075 COMETE, Avenue de la côte de nacre, Caen, 5 Avenue de la côte de nacre, 14033 Caen cedex 9, France [2] Department of Ophthalmology, CHU de Caen, Avenue de la côte de nacre, 14033 Caen cedex 9, France [3] Medical School, Unicaen, pôle des formations des recherches en santé, 2 rue des Rochambelles, CS 14032, 14032 Caen cedex, France.

ABSTRACT
While convergent, the human orbit differs from that of non-human apes in that its lateral orbital margin is significantly more rearward. This rearward position does not obstruct the additional visual field gained through eye motion. This additional visual field is therefore considered to be wider in humans than in non-human apes. A mathematical model was designed to quantify this difference. The mathematical model is based on published computed tomography data in the human neuro-ocular plane (NOP) and on additional anatomical data from 100 human skulls and 120 non-human ape skulls (30 gibbons; 30 chimpanzees / bonobos; 30 orangutans; 30 gorillas). It is used to calculate temporal visual field eccentricity values in the NOP first in the primary position of gaze then for any eyeball rotation value in abduction up to 45° and any lateral orbital margin position between 85° and 115° relative to the sagittal plane. By varying the lateral orbital margin position, the human orbit can be made "non-human ape-like". In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°). This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°).

No MeSH data available.


Related in: MedlinePlus

Schematic cross-section of the human orbit in the neuro-ocular plane.φ = opening angle ( = 107.1° in Human; 98.7° in Pan; 94.3° in Gorilla; 94.4° in Pongo; 101.6° in Hylobatidae), T = temporal orbital margin, N = nasal orbital margin, S = skin projection of T in a direction orthogonal to NT, A = cornea apex, P = pupil centre, C = cornea centre, E = eyeball centre, B = posterior pole of the eyeball, D = any point on the temporal part of cornea, ray = ray refracted at point D and passing through the pupil centre (P), ω = angle between “ray” and sagittal plane, χ = angle between SD and sagittal plane, θ = eyeball abduction angle (from 0° for primary position of gaze to 45° for maximum eye abduction). Any variation of angle φ modifies the position of points N and S. NS = 1 mm, NT = 40.17 mm.
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f5: Schematic cross-section of the human orbit in the neuro-ocular plane.φ = opening angle ( = 107.1° in Human; 98.7° in Pan; 94.3° in Gorilla; 94.4° in Pongo; 101.6° in Hylobatidae), T = temporal orbital margin, N = nasal orbital margin, S = skin projection of T in a direction orthogonal to NT, A = cornea apex, P = pupil centre, C = cornea centre, E = eyeball centre, B = posterior pole of the eyeball, D = any point on the temporal part of cornea, ray = ray refracted at point D and passing through the pupil centre (P), ω = angle between “ray” and sagittal plane, χ = angle between SD and sagittal plane, θ = eyeball abduction angle (from 0° for primary position of gaze to 45° for maximum eye abduction). Any variation of angle φ modifies the position of points N and S. NS = 1 mm, NT = 40.17 mm.

Mentions: The opening angle (OA) denotes the more or less rearward lateral orbital margin position. The higher this angle, the more rearward the lateral orbital margin position. Details about the OA measurement method used on 100 human skulls and 120 non-human ape skulls have already been published4. The average OA (+/−standard error of the mean) was 107.1° (+/−0.245°) in humans, 98.7° (+/−0.408°) in Pan, 94.3° (+/−0.401°) in Gorilla, 94.4° (+/−0.489°) in Pongo and 101.6° (+/−0.486°) in Hylobatidae4. The lowest OA value recorded was 85°, in the right orbit of a male Gorilla beringei and in the left orbit of a male Pongo pygmaeus4. The highest OA value was 115° in the left orbit of a male human from Romania4. In this study, the OA was denoted by φ (Fig. 5).


Human rather than ape-like orbital morphology allows much greater lateral visual field expansion with eye abduction.

Denion E, Hitier M, Levieil E, Mouriaux F - Sci Rep (2015)

Schematic cross-section of the human orbit in the neuro-ocular plane.φ = opening angle ( = 107.1° in Human; 98.7° in Pan; 94.3° in Gorilla; 94.4° in Pongo; 101.6° in Hylobatidae), T = temporal orbital margin, N = nasal orbital margin, S = skin projection of T in a direction orthogonal to NT, A = cornea apex, P = pupil centre, C = cornea centre, E = eyeball centre, B = posterior pole of the eyeball, D = any point on the temporal part of cornea, ray = ray refracted at point D and passing through the pupil centre (P), ω = angle between “ray” and sagittal plane, χ = angle between SD and sagittal plane, θ = eyeball abduction angle (from 0° for primary position of gaze to 45° for maximum eye abduction). Any variation of angle φ modifies the position of points N and S. NS = 1 mm, NT = 40.17 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507258&req=5

f5: Schematic cross-section of the human orbit in the neuro-ocular plane.φ = opening angle ( = 107.1° in Human; 98.7° in Pan; 94.3° in Gorilla; 94.4° in Pongo; 101.6° in Hylobatidae), T = temporal orbital margin, N = nasal orbital margin, S = skin projection of T in a direction orthogonal to NT, A = cornea apex, P = pupil centre, C = cornea centre, E = eyeball centre, B = posterior pole of the eyeball, D = any point on the temporal part of cornea, ray = ray refracted at point D and passing through the pupil centre (P), ω = angle between “ray” and sagittal plane, χ = angle between SD and sagittal plane, θ = eyeball abduction angle (from 0° for primary position of gaze to 45° for maximum eye abduction). Any variation of angle φ modifies the position of points N and S. NS = 1 mm, NT = 40.17 mm.
Mentions: The opening angle (OA) denotes the more or less rearward lateral orbital margin position. The higher this angle, the more rearward the lateral orbital margin position. Details about the OA measurement method used on 100 human skulls and 120 non-human ape skulls have already been published4. The average OA (+/−standard error of the mean) was 107.1° (+/−0.245°) in humans, 98.7° (+/−0.408°) in Pan, 94.3° (+/−0.401°) in Gorilla, 94.4° (+/−0.489°) in Pongo and 101.6° (+/−0.486°) in Hylobatidae4. The lowest OA value recorded was 85°, in the right orbit of a male Gorilla beringei and in the left orbit of a male Pongo pygmaeus4. The highest OA value was 115° in the left orbit of a male human from Romania4. In this study, the OA was denoted by φ (Fig. 5).

Bottom Line: This rearward position does not obstruct the additional visual field gained through eye motion.In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°).This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°).

View Article: PubMed Central - PubMed

Affiliation: 1] Inserm, U 1075 COMETE, Avenue de la côte de nacre, Caen, 5 Avenue de la côte de nacre, 14033 Caen cedex 9, France [2] Department of Ophthalmology, CHU de Caen, Avenue de la côte de nacre, 14033 Caen cedex 9, France [3] Medical School, Unicaen, pôle des formations des recherches en santé, 2 rue des Rochambelles, CS 14032, 14032 Caen cedex, France.

ABSTRACT
While convergent, the human orbit differs from that of non-human apes in that its lateral orbital margin is significantly more rearward. This rearward position does not obstruct the additional visual field gained through eye motion. This additional visual field is therefore considered to be wider in humans than in non-human apes. A mathematical model was designed to quantify this difference. The mathematical model is based on published computed tomography data in the human neuro-ocular plane (NOP) and on additional anatomical data from 100 human skulls and 120 non-human ape skulls (30 gibbons; 30 chimpanzees / bonobos; 30 orangutans; 30 gorillas). It is used to calculate temporal visual field eccentricity values in the NOP first in the primary position of gaze then for any eyeball rotation value in abduction up to 45° and any lateral orbital margin position between 85° and 115° relative to the sagittal plane. By varying the lateral orbital margin position, the human orbit can be made "non-human ape-like". In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°). This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°).

No MeSH data available.


Related in: MedlinePlus