Eyes are organs which detect light and send signals to the brain, where the signals can than be interpreted. The parts of the human eye include: the lens, the retina, the cornea, the pupil, the iris, the macula, the sclera, the conjunctiva, and the vitreous humor. These parts play an important function in the human eye and thus in our vision.
The most obvious part of the eye is probably the iris. The iris is the colored part of the eye which surrounds the dark pupil, which is at its center. The iris allows for the changing of the pupils size, to regulate how much light enters the eye. The cornea and sclera (the white portion of your eye) together are what makes the eye appear spherical. Because the cornea is transparent, the iris is clearly visible. The lens is responsible for focusing light on the retina. The cornea refracts the light to the lens. Because the lens can change shape, it is capable of helping the retina focus on distances near and far.
The retina, the extremely light sensitive part of the human eye, is made up of rods and cones. These rods and cones are photoreceptor cells. Rods function in dim light and are responsible for black and white vision, while cones support daytime and color vision.
The pupil, the center portion of the iris, is the part of the eye which controls how much light goes into the eye. The pupil appears black because all of the light which enters it is absorbed by the tissues behind the eye.
The macula is a pigment layer located near the center of the retina. This part of the eye acts as a pair of sunglasses would, helping to absorb excess light that enters the eye. The macula also helps us see what is right in front of us and gives us the ability to see details needed to read and write.
The vitreous humor is a clear jelly-like substance that acts as filler because it fills the inside of the eye between the lens and the retina. The vitreous is composed mostly of water and makes up two-thirds of the eye's volume.
The conjunctiva is a mucus membrane which covers the sclera and also lines the inside part of the eyelids. The conjunctiva lubricates the eye and helps to produce tears needed to clean the eye. By doing this, the conjunctiva helps to free the eye of invading bacteria.