Friday, 27 February 2015


Which Vitamin is soluble in water ?
B & C

The back surface of eye is called ?

How we can see colours ?
Rode and Cones in our eyes (The retina contains two types of photoreceptors, rods and cones. The rods are more numerous, some 120 million, and are more sensitive than the cones. However, they are not sensitive to color. The 6 to 7 million cones provide the eye's color sensitivity and they are much more concentrated in the central yellow spot known as the macula.)

What is persistence of vision ?
The impression of image is remains on retina for about 1/16th of second is called persistence of vision. 

What is far point and near point of the human eye with normal vision?
It is infinite from the normal eye and 25 cm from the eye 

What are the three defect of eye ?
(1).Myopia or nearsightedness,(2)Hypermetropia or farsightedness,(3)Presbyopia (eyestrain, difficulty seeing in dim light, problems focusing on small objects or fine print.)

What are the different reason of Vision problems ?
Myopia- it occurs when the eyeball is too long,relative to the focusing power of the cornea and lens of the eye.This causes light rays to focus at a point in front of the retina, rather than directly on the surface.
It also can be caused by the cornea and/or lens being too curved for the length of the eyeball.In some cases, myopia is due to a combination of these factors.

                                                 Myopia and Hypermetropia
Hypermetropia -It occurs when light is focused behind the retina. In reality, light cannot actually be focused behind the retina. So, the lens changes its thickness(becomes fatter or more rounded)which aims to bring the light into focus on the retina.

Myopia and Hypermetropia
Presbyopia- It is caused by an age-related process. This differs from astigmatism(it is an optical defect in which vision is blurred due to the inability of the optics of the eye to focus a point object into a sharp focused image on the retina. This may be due to an irregular or toric curvature of the cornea or lens,nearsightedness and farsightedness,which are related to the shape of the eyeball and are cause by genetic and environmental factors,it generally is believed to stem from a gradual thickening and loss of flexibility of the natural lens inside your eye. 

Who developed Braille system ?
Charles Barbier. 

In eye which is responsible for colours ?
cones .

Which part of eye provides most of refraction of the light entering the eye?
Cornea and aqueous humor.

Why birds wake up with sunrise and sleep in the resting place by sun set ?
Their retina has cones in excess,which are sensitive to bright light only.

Which is the most insensitive part of the eye retina ?
Blind spot is the spot on retina,which is insensitive to light.  

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