HUMAN · VISION
ACT 01 · THE EYE
a real scan, and the six muscles that aim it
This is a real right eye, from an anatomical scan: the white sclera, the clear cornea in front, and the six muscles that swing it. Four straight muscles pull it up, down, in and out; two oblique ones twist it. They move it several times a second, every waking minute, and you never notice.
where this comes from
- Geometry: BodyParts3D 4.0 (© The Database Center for Life Science, CC BY-SA 2.1 JP) — sclera, cornea, choroid, iris, lens, vitreous body, the six extraocular muscles, the levator palpebrae and the right optic nerve. The retina, fovea and optic disc are drawn.
- Optics: Le Grand's full theoretical eye (Le Grand & El Hage 1980; Atchison & Smith, Optics of the Human Eye, 2000). Rays are traced exactly through the four spherical surfaces with Snell's law; glasses are a thin lens 12 mm in front of the cornea.
- Blind spot: the optic disc sits about 15° temporal to fixation and about 1.5° below it, and spans roughly 5.5° wide by 7.5° tall (Armaly 1969; standard perimetry).
- Cones: peak sensitivities 420, 534 and 564 nm (Bowmaker & Dartnall 1980); curve shape from Govardovskii et al., Visual Neuroscience 2000. The S cones are absent from the central ≈0.35° of the fovea (Curcio et al. 1991).
- Afterimages: cone adaptation and colour-opponent processing (Hering; Hurvich & Jameson 1957).
Education only, not medical advice. If something about your sight worries you, see an optometrist or an eye doctor.