The Human Eye

As vital organ of vision, the eye, allows us to learn more about the world around us more than any other organ or senses. Sight, the physical sensory experience and vision, the metaphysical concept of how our brain interprets images both work harmoniously and play a huge role in our everyday lives. However, almost a billion people are either blind or visually impaired simply due to not having a pair of glasses. Being able to lead people in the direction of good vision is what developed my interests.

After being shown a picture of an elephant they eye will take the light that is reflected from the object and it will enter the eye through the pupil. Then the light will be focused by the cornea and the lens to form a sharp image of the elephant in the retina. The retina is the network of neurons that cover the back of the eye and contains the visual receptors for a person vision. The visual receptors are made up of cones and rods that contain light sensitive chemicals called visual pigments. Visual pigments reacht to light and cause a triggered electrical signals to occur. These electrical signals will then flow through a network of neurons and this network of neurons is what makes up a persons retina. After the flow through the network of neurons occurs the electrical signals will emerge from the back of the eye in the area

Focusing an image clearly onto the retina is the initial step in the process of vision, but although a sharp image on the retina is essential for clear vision, a person does not see the picture on the retina. Vision occurs not in the retina, but in the brain. Before the brain can create vision, the light on the retina must activate the visual receptors in the retina by a two-element

When it comes to vision, we see things based on the light reflected from surfaces. The reflected light waves enter the eye through the cornea at the front of the eye, it's resized at the pupil, focused by the lens, and hits the retina at the back. The light is then detected by rods and cones, photoreceptors, which alters the light into electrical signals. The optic nerve transmits those vision signals to the lateral geniculate nucleus, where visual information is transmitted to the visual cortex of the brain then converts into the objects that we see.

The retina is what houses the eye’s rods and cones. The eye has about 6 million cones and 120 million rods. Both rods and cones get their names from their shape. Rods do not provide color vision, and are sensitive to dim light. Cones function well in the day and provide color vision.

The eye is the organ of sight. It is used in almost everything we do, from playing sport to reading. A normal and well functioning eye can focus objects and images, both near and far, perceive depth and adapt to changes in light.

Humans have a unique and wonderful device in how one sees. The eye and brain work together to turn the world into visual data one’s brain can understand and use. There are some eye conditions that inhibit the sight or the recognition of the shapes one sees. Research continues to overcome these conditions as well as to further understand the biochemical reaction that gives humans the sight and understanding one has of visual data. Included in the paper are some of the latest research methods.

The eyeball holds many parts to allow eyesight. The retina holds the key to allowing the human eye to see color. The pupil appears as the black part of the eye that people see, the pupil however does not have much to do with comprehending color. As Clarence Rainwater said in his book “The pupil is simply the hole in the iris through which light enters the eye.” (84) The light then has to pass through many parts of the eye before reaching the retina such as the transparent cornea, the aqueous humor, the lens, and the vitreous humor. Clarence Rainwater described the retina as “... the eye’s sensitive inner surface.” (86) The exciting part of the eye starts here. The retina holds the key as stated by Clarence Rainwater, “... a complex system

Phase 1: During the initial phase, optical system is activated. Optical system is placed in the frontal eye area. Parts of the optical system are lens and cornea, and their role can be compared with the role of lens on a camera. They gather and focus the light on the retina in order to create a picture.

responses. The optic nerve is a continuation of rods and cones which make up the retina.

Humans have three cone cells that are extremely sensitive to Red, (620-700nm), Green (490-570nm) and Blue (450-495nm) wavelengths of light. Although these three cones are most sensitive to these wavelengths, they are still sensitive to the remaining wavelengths of visible light between 400-700nm. When a light with a wavelength of 600nm is transmitted through the retina, the Red and Green cones capture, sense and signal the brain that orange light is observed. In this case the Red and Green cones absorb light but the Green cones are less sensitive. Also, the Blue cones don’t absorb much light and are not sensitive

The visual system of the cells within the brain contain an area known as the receptive field and is the point in which light enters hits the cell of a receptor (Kalat, 2013). This part of the visual system relies on sensory information, such as light, to either excite or inhibit the cells within the center portion of the receptive field. One of the most significant processes of transmitting information from the visual field is through primary cells of the visual receptors, which include the retinal ganglion cells. In the retina, ganglion cell send information from the eye to the brain. Both the rods and cones within the visual system have a rather small receptive field that connects to bipolar or amacrine cells, of which have their own receptive field consisting of ganglion cells, and then the ganglion cells ultimately make up a larger receptive field (Kalat, 2013).

The optic nerve reaches from behind the eyes to the occipital lobe where this visual information can finally be interpreted into what we know as ‘seeing something’. It is at this point that it is useful as this is when colours can be perceived (Breedlove, 2010).

Light, a concept that has been worked with for many years dating back to 500 B.C. Pythagoras hypothesized that humans perceive light due to the human eyes ability to emit rays upon the environment and the emittance gives a human his or her sight (Sekuler). Afterward, human intellectuals started making it more concise to present day knowledge of light. This development of light came from two intellectuals named Christian Huygens and Isaac Newton. Newton exclaimed during the 1700s that light was a stream of particles carrying energy but Huygens, Newton’s contemporary, thought that light needed this invisible “ether” in order for these streams to make light travel. Then, a couple hundred years later, modern scientists such as Albert Einstein, Thomas Young, and Augustin Fresnel proved Isaac’s and Huygens’ hypotheses of light (Rossing, 23-24). This is how the basis of light was created.