Today I just thought to do a post to help us along this line so we can appreciate what we have and know how to value and cater for it. You have sight. That is amazing. Now learn something about it.
Our eyes are responsible for four-fifths of all the information our brain receives. Let’s find out how the eyes work.
How do eyes work?
The images we see are made up of light reflected from the objects we look at. This light enters the eye through the cornea, which acts like a window at the front of the eye. The amount of light entering the eye is controlled by the pupil, which is surrounded by the iris – the coloured part of the eye.
Because the front part of the eye is curved, it bends the light, creating an upside down image on the retina. The brain eventually turns the image the right way up.
The retina is a complex part of the eye, and its job is to turn light into signals about images that the brain can understand. Only the very back of it is light sensitive: this part of the retina is roughly the area of a 10p coin, and is packed with photosensitive cells called rods and cones.
Cones are the cells responsible for daylight vision. There are three kinds, each responding to a different wavelength of light: red, green and blue.
The cones enable us to see images in colour and detail. Rods are responsible for night vision. They are sensitive to light but not to colour. In darkness, the cones do not function at all.
How do we see an image?
The lens is a clear disc-like structure that helps to focus light on the retina. It can do this because it is adjustable, and uses a muscle called the ciliary muscle to change shape and help us focus on objects at different distances. The automatic focusing of the lens is a reflex response and is not controlled by the brain.
Once the image is clearly focused on the sensitive part of the retina, energy in the light that makes up that image creates an electrical signal. Nerve impulses can then carry information about that image to the brain through the optic nerve.
Other parts of the eye include the aqueous humour, a liquid which sits in a chamber behind the cornea, and the vitreous humour, the clear gel that fills the space between the lens and the retina. The sclera is the white part of the eye, forming an outer layer that protects everything inside, while the choroid is the layer of the eye that lies between the retina and the sclera. It is made up of layers of blood vessels that nourish the back of the eye.
Common eye problems
Refractive errors are eye disorders caused by irregularity in the shape of the eye. This makes it difficult for the eyes to focus images clearly, and vision can become blurred and impaired.
Short sight (myopia) and long sight (hypermetropia) are common conditions, both caused by the cornea and lens not focusing properly on the retina. Short sight is where the eyeball is elongated or the lens is too thick, causing the image to focus in front of the retina. Long sight is where the eyeball is too short or the lens too thin, causing the image to focus behind the retina. Prescription glasses can help with both long and short sightedness.
There are other sight-threatening eye conditions and eye diseases that are not so easily corrected, including cataracts, and neglected tropical diseases such as trachoma and river blindness, all of which can cause blindness if left untreated.
You can find out more about what you can do to improve care for and improve your eye sight: helping you gain control of your health and well being is our major focus..we provide the information; you experience the transformation.
Refractive errors are eye disorders caused by irregularity in the shape of the eye. This makes it difficult for the eyes to focus images clearly, and vision can become blurred and impaired.
Short sight (myopia) and long sight (hypermetropia) are common conditions, both caused by the cornea and lens not focusing properly on the retina. Short sight is where the eyeball is elongated or the lens is too thick, causing the image to focus in front of the retina. Long sight is where the eyeball is too short or the lens too thin, causing the image to focus behind the retina. Prescription glasses can help with both long and short sightedness.
There are other sight-threatening eye conditions and eye diseases that are not so easily corrected, including cataracts, and neglected tropical diseases such as trachoma and river blindness, all of which can cause blindness if left untreated.
You can find out more about what you can do to improve care for and improve your eye sight: helping you gain control of your health and well being is our major focus..we provide the information; you experience the transformation.
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