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? Do s: * 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 lenses. *
If your eyes feel uncomfortable, consult an eye doctor. Don’t s: * Do not look at the sun or any strong light source directly. * Do not use other people’s towel, handkerchief or cosmetics. If any particles get into the eye, do not rub the eye with your hand. Close the eye for a while and let your natural tear wash the particles out. * Avoid throwing pointed or sharp objects, sand or dirt. * Avoid playing with firecrackers. Keeping Your Eyes Healthy There’s also the possibility that we may be developing an eye health problem, like glaucoma, with no early noticeable symptoms. Seek medical attention if you notice any of the following symptoms: * blurred vision, even if gradual over time * sudden loss of double vision * flashes floaters in vision * sudden marked distortion in vision * severe redness of the eye * severe pain in the eye, itching or dryness * scratchy feeling of eye * light sensitivity, especially if severe or painful * halos around lights * discharge with pain or redness of the eye * inability to see at night * protrusion of the eye * pain or loss of vision * fluctuating vision Any of there can indicate serious medical condition, because many aliments can be controlled if detected at an early stage. Seek medical advice promptly if there is anything wrong.
To maintain proper health, vitality and functioning of your eyes and ensure a lifetime of reliable use. It is important to have regular eye exams by a qualified eye doctor. Children’s eyes should be examined by an eye doctor immediately after birth. Thereafter children should have their eyes checked at around three years of age and every year after till seven. After the age of forty, an eve exam should be carried out every year or two, and then every year after 65. Keep your eyes healthy and lead a happy life.