The redeye effect occurs when light enters pupils which are mostly dilated (open), and the light is mostly parallel to the line-of-sight between the camera and the subject. The redness is caused by blood in the back of the eyes.
Redeye occurs more often in cameras where the flash is very close to the lens, because then the angle between the flash and the subject, and the lens and the subject, is very small, allowing almost all of the light to reflect back as redeye.
If the light shining on the eyes comes from a different angle than the camera's line-of-sight, such as from a remote flash, then the redeye effect is reduced.
If the pupils are closed by a bright flash prior to the picture being taken, then the redeye effect is reduced. Some cameras can do this redeye reduction pre-flash.
Redeye effects can be reduced or nearly eliminated in digital cameras with post-processing software, either on the camera or off of the camera.
Often, people who take pictures will notice that their photos come out with people having bright red eyes. This is caused by the flash of a camera actually seeing the light reflecting off a person's retina.
Visual disturbances include night blindness and increased sensitivity to light and glare.
Causes: eye injury, lack of vitamin A, infection, congenital Prevention: personal hygiene, eye care, supplement of Vit A, screeing of eye disease
visual
The eye's visual receptors reside within the retina. The eye's visual receptors consist of four different types of receptors including rods, blue cones, red cones and green cones.
The optic nerve is responsible for transmitting visual information from the eye to the visual cortex in the brain. It carries signals in the form of electrical impulses that are generated by the retina in response to light stimulation.
opthamology
An eye examination is a series of tests that measure a person's ocular health and visual status, to detect abnormalities in the components of the visual system
Eye of the Tiger
There are 4 visual pigments held in cone cells of the eye.
Visual snow is a rare condition that causes people to see static or flashes of light in their field of vision. It typically does not cause blindness, and most people with visual snow retain normal vision. However, in some cases, visual snow may interfere with visual tasks and quality of life, requiring management by an eye care professional.
visual receptor for the brain