The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth. The human eye can distinguish about 10 million colors. In common with the eyes of other mammals, the human eye's non-image-forming photosensitive ganglion cells in the retina receive the light signals which affect adjustment of the size of the pupil, regulation and suppression of the hormone melatonin and entrainment of the body clock.
The eye is not properly a sphere, rather it is a fused two-piece unit. The smaller frontal unit, more curved, called the cornea is linked to the larger unit called the sclera. The corneal segment is typically about 8 mm (0.3 in) in radius. The sclera constitutes the remaining five-sixths; its radius is typically about 12 mm. The cornea and sclera are connected by a ring called the limbus. The iris – the color of the eye – and its black center, the pupil, are seen instead of the cornea due to the cornea's transparency. To see inside the eye, an ophthalmoscope is needed, since light is not reflected out. The fundus (area opposite the pupil) shows the characteristic pale optic disk (papilla), where vessels entering the eye pass across and optic nerve fibers depart the globe.
How to take care of our eyes?
* Make it a habit to clean your eyes daily.
* In order to avoid eye fatigue, only read under sufficient and uniform illumination. * Rest your eyes for a while if they feel tired.
* Keep away from the targets of darts and arrows.
* Walk, don't run, when holding sharp object, keep the point turned down. * Watch out for pointy things, such as tree branches.
* Wear eye safety equipment when playing eye hazardous sports * Wear safety goggles when engaged in eye hazardous chores. * Wear prescription glasses, if needed, with polycarbonate...
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