Hallo steemians, how are you today? In the previous post, I discussed the working principle of the eyes and the camera. On this occasion, I want to explain about the types of eye defects. Before that, it's better if I discuss about the eye process in seeing an object.
How can the eyes see ? Do you know how the eyes can see ? The eye process of seeing objects is as follows:
- The light reflected by the object is captured by the eye, penetrating the cornea and transmitted through the pupil.
- The intensity of the light that has been set by the pupil is passed through the lens of the eye.
- The power of accommodation on the eyepiece set the light to fall right in the yellow spots.
- In yellow spots, light is received by cone cells and stem cells, then delivered to the brain.
- Light delivered to the brain will be translated by the brain so that we can know what we see.
The refraction of light from an object will form the shadow of an object if it falls on the yellow spot on the retina, because the light falling on this part will affect the stem cells and cones that pass it on to the optic nerve and the optic nerve passes it to the brain resulting in an impression of seeing . Conversely, the shadow of an object will be invisible, if the refraction of light from a body falls on the blind spot on the retina. Therefore, based on the above discussion it can be concluded that the eye can see an object if the shadow objects (light) right fall in yellow spots / retina.
Today, we see many adults and even children who wear glasses. Eyeglasses are a tool used to help one's eyesight. Naturally if we see adults who wear glasses because of the age factor that affects the work of organs, the eyes. But what about the little boy? After the research turned out "eye defect" is not only experienced by adults only but also can be experienced by children. The types of eye defects can be explained as follows.
1. Hipermetropi
A person who can not see an object at close range can then be said that the person is suffering from "Hipermetropi". The hypermethropi sufferer has a close point (punctum proximum = PP) farther from the point near the normal eye that is more than 25 cm and the distant point is infinite. the shadows formed falling behind the retina. Suffixy sufferers are assisted by using convex lens (plus / positive). Convex lenses can help the shadow that originally fell behind the retina to fall right in the retina.
2. Miopi
The myopia patient has a distant point (punctum remotum = PR) closer to the point of the normal eye (the distance of the infinitely normal eye), and the closer point is approximately 25 cm. Shadows that form will fall in front of the retina. Suffixes are assisted by using concave lens glasses (minus / negatives). Concave lenses can help the right shadow fall on the retina. Generally, people with Miopies are children and adolescents.
3. Presbyter
Presbyteris is a common eye defect experienced by an adult whose accommodation power of eyes has diminished. The presbyter patient has a closer point closer than the normal eye which is less than 25 cm and the point away is less than infinite so that it can not see near or far objects. Elderly sufferers are assisted using double lens glasses (bifocals) consisting of concave lenses and convex lenses.
4. Astigmatism
Astigmatism is an eye defect when the light entering the eye is not centered perfectly because the light can not curve in the area of the transparent membrane. Astigmatism sufferers can not distinguish vertical or horizontal lines and are assisted by cylindrical lens sunglasses.
