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  2. Cornea - Wikipedia

    en.wikipedia.org/wiki/Cornea

    The cornea is the transparent front part of the eyeball which covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. [1] [2] In humans, the refractive power of the cornea is approximately 43 dioptres. [3]

  3. Eye - Wikipedia

    en.wikipedia.org/wiki/Eye

    In most vertebrates and some molluscs, the eye allows light to enter and project onto a light-sensitive layer of cells known as the retina. The cone cells (for colour) and the rod cells (for low-light contrasts) in the retina detect and convert light into neural signals which are transmitted to the brain via the optic nerve to produce

  4. Human eye - Wikipedia

    en.wikipedia.org/wiki/Human_eye

    Light energy enters the eye through the cornea, through the pupil and then through the lens. The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle. Between the two lenses (the cornea and the crystalline lens), there are four optical surfaces which each refract light as it travels along the optical path.

  5. Visual system - Wikipedia

    en.wikipedia.org/wiki/Visual_system

    Light entering the eye is refracted as it passes through the cornea. It then passes through the pupil (controlled by the iris) and is further refracted by the lens. The cornea and lens act together as a compound lens to project an inverted image onto the retina. S. Ramón y Cajal, Structure of the Mammalian Retina, 1900

  6. Purkinje images - Wikipedia

    en.wikipedia.org/wiki/Purkinje_images

    Light reflected away from the surfaces of the lens can in turn reflect back into the eye from the rear surface of the cornea. The first and fourth Purkinje images are used by some eye trackers, devices to measure the position of an eye. The cornea reflection (P1 image) used in this measurement is generally known as glint. [2]

  7. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    Above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nm and the internal lens below 400 nm. Furthermore, the rods and cones located in the retina of the human eye cannot detect the very short (below 360 nm) ultraviolet wavelengths and are in fact damaged by ...

  8. Mammalian eye - Wikipedia

    en.wikipedia.org/wiki/Mammalian_eye

    The light information from these cells is not involved in vision and it reaches the brain not directly via the optic nerve but via the retinohypothalamic tract, the RHT. By way of this light information, the body clock's inherent approximate 24-hour cycling is adjusted daily to nature's light/dark cycle. Signals from these photosensitive ...

  9. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    Before reaching the retina, light must first transmit through the cornea and lens. UVB light (< 315 nm) is filtered mostly by the cornea, and UVA light (315–400 nm) is filtered mostly by the lens. [20] The lens also yellows with age, attenuating transmission most strongly at the blue part of the spectrum. [20]