Sight is probably the most developed sense in humans, followed closely by hearing. The human eye is the organ of vision. It has a complex structure consisting of a transparent lens that focuses light on the retina. The retina is covered with two basic types of light-sensitive cells-rods and cones. The cone cells are sensitive to colour and are located in the part of the retina called the fovea, where the light is focused by the lens.
The rod cells are not sensitive to colour, but have greater sensitivity to light than the cone cells. These cells are located around the fovea and are responsible for peripheral vision and night vision. The eye is connected to the brain through the optic nerve. The point of this connection is called the “blind spot” because it is insensitive to light. Experiments have shown that the back of the brain maps the visual input from the eyes.
The brain combines the input of our two eyes into a single three-dimensional image. In addition, even though the image on the retina is upside-down because of the focusing action of the lens, the brain compensates and provides the right-side-up perception. Experiments have been done with subjects fitted with prisms that invert the images. The subjects go through an initial period of great confusion, but subsequently they perceive the images as right side up.
Table of Contents
In a number of ways, the human eye works much like a digital camera:
Eye function renders you the sense of sight. They convert light into electrical signals. Afterwards, the brain deciphers these electrical signals into images. Properly working healthy eyes are able to perform the following functions.
Colour blindness or “Daltonism” is a common abnormality in human vision that makes it impossible to differentiate colours accurately. One type of colour blindness results in the inability to distinguish red from green. This can be a real handicap for certain types of occupations. To a colour-blind person, a person with normal colour vision would appear to have extrasensory perception. However, we want to reserve the term “extrasensory perception” for perception that is beyond the range of the normal.
These extremely delicate organs can fall prey to different eye problems due to allergic factors, unhygienic conditions and the old age. Below are some of the most common diseases of eyes.
Conjunctivitis has got a common name – the pink eye disease. It is an inflammation of conjunctiva, the transparent membrane which covers the sclera. Inflammation of tiny blood vessels found in conjunctiva makes our eyes appear red.
Cataracts affect the eye lenses. They may occur due to old age or exist as a defect by birth. Parts of lenses become opaque, blocking the passage of light to the retina, thereby obstructing our vision.
Glaucoma is a disease which leads to blindness due to a damage to the optic nerve. When the optic nerve fails to transmit electric signals to the brain, an individual is unable to see at all.
This post aims to demonstrate and explain the properties and effects of static electricity, shedding…
Many of the everyday effects of electrostatics involve a charged object losing its charge and…
Area expansion of solids refers to the increase in the surface area of a solid…
The increase in the length of a body resulting from being heated is known as…
Different disciplines have developed theories of aging due to the complex nature of aging process.…
The 2023 Zambia Education Curriculum Framework (ZECF) has been developed not only to provide guidance…
Leave a Comment