Introduction
The functionality of eye components is very similar to that of a camera. Each component of the eye plays a crucial role to provide a clear vision. This section will discuss how the human eye works analogously to a camera. As a camera, the cornea part behaves like the lens cover. This part can be described as the main focusing element of the eye which has the capability of taking light divergent rays and bends these rays through the pupil (Pasadenaeye, 2011). The pupil is found in the center of the iris, these two parts play a similar role to that of the aperture of a camera.
The lens part of the eye is similar to the lens in a camera. It helps in focusing light on the back section of the eye. This is similar to the camera lens which focuses the light to the film which is normally at the back of the camera. The back section of the eye is known as the retina which functions similar to the film section of the camera. The function of the retina is to change the rays of light into electrical signals. After this conversion, it sends these signals to the brain through the optical nerve. The brain does the work of image processing that helps human beings to see the images in an upright manner (Pasadenaeye, 2011).
Vision defects
There are normally four types of vision defects namely astigmatism, nearsightedness, presbyopia, and farsightedness. This section will only deal with three types of vision defects. These defects cannot be considered as diseases but as minor defects which can be rectified easily. These defects usually disappear when individuals are in their twenties because this is the time when the human eyes get their normal shape and size.
Nearsightedness
The scientific name of nearsightedness vision defect is myopia. People suffering from myopia defects are unable to see distant objects. However, nearby objects are very clear to them. This does not mean that people with this defect have excellent or perfect near vision and imperfect distance vision. In extreme cases, nearsightedness individuals are unable to see things. In nearsighted eyes, the rays of the right are focused before they reach the retina and the focal point created by these rays of right will start to diverge thus creating a blurred image (Palsson, 2008). In a normal eye, the rays of light focus on a point/spot on the retina. The focal point of nearsightedness eye lies in front of the retina due to their elongated size.
Farsightedness
The scientific name of farsightedness vision defect is hyperopia. This defect is contrary to myopia. Individuals suffering from this defect can see things that are at a distance more clearly compared to things that are close to them. In the farsighted eye, the rays of light reach the retina before coming to focus thus creating a blurred image. That is, the focus occurs behind the retina (Palsson, 2008). In this context, the eyeballs of individuals experiencing this defect are normally too short, therefore, cannot handle the refractive power of its optical arrangement. People suffering from this defect usually do not realize it until they are middle-aged. At this age, they start having problems seeing at close distances. This is why many middle-aged people are using reading glasses yet they were not using them at younger ages.
Astigmatism
Individuals suffering from this defect see everything distorted irrespective of the distance. The cause of this defect is the irregular shape of the cornea. The astigmatic eye cornea is normally curved in an irregular form resulting in different refractory powers (Palsson, 2008). The numerous refractory powers distort the sight because some rays of light focus behind the retina while others focus in front of the retina. As a result of this, the retina will never receive a sharp image.
Lens needed to correct vision defects
Vision defects can be corrected by the use of lenses and the individual suffering from them will be in a position to see like a normal person. Due to the advancement of technology, other methods can be used to solve problems associated with vision defects. For instance, LASIK surgery can offer a permanent solution to these defects (Palsson, 2008). Nearsightedness can be solved by the use of a negative lens. Here, the negative lens is used to lessen the refractive power. The negative value of the lens depends on the level of nearsightedness. The more extreme it is, the higher the negative value is supposed to be.
To correct the farsightedness a positive lens is required to add refractive power to the optical system. Compensation of the insufficient refractive power of farsightedness can be solved by the use of a neutral lens. Astigmatism can be corrected by the use of asymmetric or cylindrical lenses which will assist in compensating for the asymmetry of the eye’s lens.
Reference List
Palsson, J., 2008. Eyes Vision Defects.
Pasadenaeye, 2011. How does the human eye work?