vision alone at this age does not give an idea of how far the object is away in the judge distance in part by interpreting the stresses and strains  degree of convergence of the eyes held in determining the distance of nearby objects familiarity with the size of an object helps in estimating distance when it is beyond reach we learn to suppress vision when the eyes are in motion otherwise we would have a blurry like this which would cause severe nerve strength we learn to ignore motionless objects at the edge of the as we contemplate partial blindness and the blind we realize more  are globes shaped and rotate in a socket these two muscles control the up and down motion of the eyeball altogether six muscles control the motion and the position of the these fibers merge into what cable called the optic nerve which leaves the eye at the back through that same opening blood vessels arteries and veins enter the i find nourishment and  the front layer of the retina contains millions of perceptor cells rub cells shown here in black and clone the cells shown in why it is these cells which transform light energy into another form of energy which is transmitted by the optic nerves to the brain one has its own nerve fiber leading to the brain these cones cells have to do with sharp vision and color vision toward the periphery of the retina the raw dominate these perceived to light then light from the side without color elimination or when we turn out these bright lights we can see almost nothing but within a short time we are able to make out objects in the room our eyes have become adapted to the dim li vitamin a is necessary for good vision in dim li the place in the retina where the nerves gather and leave the retina is called the optic nerve this area is blind because it has no rods or cones we are not conscious of this blind spot because the blind spots of the two eyes do not correspond and are located in areas of less acute vision arctic fibers arrive at the primary site center in the back part of the brain in babies the eyes turn in until they learn to regard an object with both eyes working together the image should always fall on the sensitive part of the retina for distant vision the eyes look straight ahead but for near vision the eyes turn in eventually the dim image is suppressed and finally that i may lose its ability to see clearly proposing of the image on the retina here the players are out of focus or the foreground spectators are in focus this is near sightedness which results when the eyeball is too long from front to back the focus is in front of the retina this defect vision may be corrected by wearing concave lenses when the eye is too short the images form the back of the r this is farsightedness by accommodating the lens proper focus may be attained but this stress may lead to discover that carrying glasses bacterial infection of the i often come from using public swimming pools from rubbing the eyes with the fingers and from using st particle becomes lives on the eyeball and especially on the cornea it should be removed by a competent person after applying a local anaesthetic this doctor carefully works the particle loose and radiation from the red end of the spectrum such as heat from the sun may penetrate the eye and injure the lens retina or nerves and lead to permanent blindness ultraviolet light does not penetrate as far but may cause injury to the cornea in this situation of contracting light the eye is unable to adjust properly either for the bright page or the dark room eyes by proper lighting proper food preventing disease and injury to this delicate mechanism