The retina is a membrane located within the eye which is responsible for receiving the images and, through the optic nerve, to send them to the brain. Composed of different cell layers, the retina is a kind of tissue that is light sensitive and that it generates diverse processes until arriving at the transmission of a nervous impulse towards the brain.
The photoreceptor cells (they get that name because they are sensitive to light ) are the Canes and the cones . It is estimated that, in humans, the retina harbors more than 126 million of these cells, mostly canes. The latter, precisely, come into operation when there is poor luminosity and provide a black and white vision. The cones, on the other hand, act in good light conditions and allow the development of color vision.
The outer layer of the retina is called pigmentary epithelium . Then others appear layers until you reach the so-called internal limiting layer , which divides the retina from vitreous humor (liquid that is between the retina and the lens).
The retina can be affected by various problems that reduce the ability of eyesight. The Hypertensive retinopathy causes retinal deformation due to high blood pressure, while the Diabetic retinopathy it involves damage caused by diabetes in the blood vessels that are responsible for irrigating the membrane.
The retinitis (an inflammation of the retina), the age-related macular degeneration (a deterioration in the central layer of the retina, called the macula) and the retinal detachment (the separation of the epithelial membrane to which it must adhere) are others disorders that the retina may suffer.
Retinal detachment usually occurs when it undergoes a perforation or tear, which leads to the filtration of fluid from the eye . What it usually looks like in this case, which is called posterior vitreous detachment, can be compared with that of an air bubble between a sheet of paper and a piece of adhesive tape. Other possible causes are very severe myopia or trauma, and the chances increase if there is a family history.
Regarding the symptoms of retinal detachment, we can point out the following: view poorly defined; spots on the image; flashes of light, mainly in peripheral vision; inability to capture a complete image (partial blindness).
Name Retina Display (or Retina display) refers to a trademark belonging to the North American company Manzana , used to identify a series of screens that are characterized by having a pixel density especially high.
According to Apple, thanks to this technology You get a larger amount of pixels than the human eye's retina is able to perceive, although many specialists have opposed this statement, considering it a mere marketing instrument.
Among the companies that are responsible for the development and manufacture of screens retina meet Sharp, Samsung, Japan Display and LG . The technology on which they are based is In-plan switching (with its acronym IPS), created by Hitachi in 1996 to improve viewing angles and color quality on monitors Twisted nematic (TN), which, on the other hand, offer an optimal response time.
The density of pixels of the retina display is of 326 per inch , and Apple relied on this number to maintain that it exceeded the capacity of our retina, noting that it does not exceed 320 ; In other words, on a monitor with these characteristics, we are not able to distinguish one pixel from another, so that the sharpness is theoretically insurmountable (or excessive).