Eyes
LOOK INTO THE BEAUTIFUL EYES
Conceal anything but your eyes would tell the truth. Don’t utter a word but your eyes would explain everything. Beautiful eyes are holding an amazing 3 D camera with convex lens. Let us know more about this astonishing creation.
With one eye only, the world looks flat, i.e two dimensional only. With two eyes , the view is three dimensional making horizontal field view of 180 degrees. The unit of power of lens is Dioptre.
The eye ball is approximately of diameter 2.3 cm. Eyes has the following parts :-
Cornea: it is the transparent spherical membrane covering the front of the eye.
Iris: is the coloured black part. It could of variable colour like blue or grey. The white part is sclera.
Pupil: the small hole in the iris, this controls the amount of light entering into the eyes. It changes its size according to the intensity of light.
Eye lens: it is a transparent lens made of jelly like material.
Ciliary muscle: these muscles hold the lens in position.
Retina: it is the screen on which the image is formed. The image of an object persist on retina for 1/16th of a second.
Blind spot: the point at which the optic nerve leaves the eye. An image formed at the point is not sent to the brain. Optic nerve sends the signal to the brain and spinal cord.
Aqueous humour: a clear liquid region between the cornea and the lens.
Vitreous humour: the space between eye lens and retina is filled with another liquid called vitreous humour.
The smallest distance at which the eye can see objects clearly without strain is called near point i.e 25 cm. So make sure you are keeping this much of distance while reading.
Two important cells of the retina
Rod cells- photoreceptor cells in retina of the eye that function in dim light and detect only shades of grey with no colours.
Cone cells- are responsible for colour vision with fine details but only works in bright light. (Learn it like C for colour , C for cone cells)
The whole part of the eye is covered by a thin transparent membrane, the conjunctiva, which sense any dust or particles on the eye.
DEFECTS
ASTIGMATISM – A person suffering from this defect can not see in all directions equally. He can not see vertical and horizonatal lines simultaneously. This happens due to imperfection in spherical shape of eye lens. This can be corrected with cylindrical lens.
CATARACT- happens due to the haziness in eye lens. This can be corrected surgical removal of lens and replaced with lens of suitable focal length.
MYOPIA- Near sightedness , in which a person can see near objects but not the far away objects. This can be corrected with Concave lens.
HYPERMETROPIA- Far sightedness, in which a person can see distant objects but can not read or see nearby things. This can be corrected with Convex lens.
PRESBIOPIA- is an old age sight problem and could be corrected using lens of suitable power.
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Conceal anything but your eyes would tell the truth. Don’t utter a word but your eyes would explain everything. Beautiful eyes are holding an amazing 3 D camera with convex lens. Let us know more about this astonishing creation.
With one eye only, the world looks flat, i.e two dimensional only. With two eyes , the view is three dimensional making horizontal field view of 180 degrees. The unit of power of lens is Dioptre.
The eye ball is approximately of diameter 2.3 cm. Eyes has the following parts :-
Cornea: it is the transparent spherical membrane covering the front of the eye.
Iris: is the coloured black part. It could of variable colour like blue or grey. The white part is sclera.
Pupil: the small hole in the iris, this controls the amount of light entering into the eyes. It changes its size according to the intensity of light.
Eye lens: it is a transparent lens made of jelly like material.
Ciliary muscle: these muscles hold the lens in position.
Retina: it is the screen on which the image is formed. The image of an object persist on retina for 1/16th of a second.
Blind spot: the point at which the optic nerve leaves the eye. An image formed at the point is not sent to the brain. Optic nerve sends the signal to the brain and spinal cord.
Aqueous humour: a clear liquid region between the cornea and the lens.
Vitreous humour: the space between eye lens and retina is filled with another liquid called vitreous humour.
The smallest distance at which the eye can see objects clearly without strain is called near point i.e 25 cm. So make sure you are keeping this much of distance while reading.
Two important cells of the retina
Rod cells- photoreceptor cells in retina of the eye that function in dim light and detect only shades of grey with no colours.
Cone cells- are responsible for colour vision with fine details but only works in bright light. (Learn it like C for colour , C for cone cells)
The whole part of the eye is covered by a thin transparent membrane, the conjunctiva, which sense any dust or particles on the eye.
DEFECTS
ASTIGMATISM – A person suffering from this defect can not see in all directions equally. He can not see vertical and horizonatal lines simultaneously. This happens due to imperfection in spherical shape of eye lens. This can be corrected with cylindrical lens.
CATARACT- happens due to the haziness in eye lens. This can be corrected surgical removal of lens and replaced with lens of suitable focal length.
MYOPIA- Near sightedness , in which a person can see near objects but not the far away objects. This can be corrected with Concave lens.
HYPERMETROPIA- Far sightedness, in which a person can see distant objects but can not read or see nearby things. This can be corrected with Convex lens.
PRESBIOPIA- is an old age sight problem and could be corrected using lens of suitable power.
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