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In the mammalian eye, light enters the pupil and is focused on the retina by the lens. Light-sensitive nerve cells called rods (for brightness), cones (for color) and non-imaging ipRGC (intrinsically photosensitive retinal ganglion cells) react to the light. They interact with each other and send messages to the brain.
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
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The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. [3]
The main purpose of the bulbus oculi is to refract photons passing through the cornea, pupil, and lens to focus onto the retina, where the photons in the refracted light rays trigger electric and chemical reactions within the layers of the retina, specifically the fovea centralis. These reactions are then passed as electrical signals through ...
Scleral lenses may be used to improve vision and reduce pain and light sensitivity for people with a growing number of disorders or injuries to the eye, such as severe dry eye syndrome, microphthalmia, keratoconus, [1] corneal ectasia, Stevens–Johnson syndrome, Sjögren's syndrome, [2] aniridia, neurotrophic keratitis (anesthetic corneas), complications post-LASIK, higher-order aberrations ...
This also allows a larger aperture for a given sharpness of image, allowing more light to enter the lens; and a flatter lens, reducing spherical aberration. Such a non-homogeneous lens is necessary for the focal length to drop from about 4 times the lens radius, to 2.5 radii. [1]
The ciliary nerves run under the endothelium and exit the eye through holes in the sclera apart from the optic nerve (which transmits only optic signals). [10] The nerves enter the cornea via three levels; scleral, episcleral and conjunctival. Most of the bundles give rise by subdivision to a network in the stroma, from which fibres supply the ...