Light makes vision possible. Visible light that we see is electromagnetic radiation of any wavelength that travels in a vacuum with a speed of 186,000 miles per second. The ability to see begins with light. The eye processes begin with light passing through the cornea. The cornea does 3/4ths of the focusing. The light then passes through the lens, which adjusts the focus. This is the clear structure inside the eye that focuses light rays onto the retina. Next, light passes through the vitreous humor. This is the clear, jelly-like substance that fills the center of the eye. It helps to keep the eye round in shape. Finally, the light reaches the retina. This is the light-sensitive nerve layer that lines the back of the eye. Here the image is inverted. The optic nerve is then responsible for carrying the signals to the visual cortex of the brain. The visual cortex turns the signals into images.
Light has three layers:
- Ambient
- Accent
- Task
Ambient or general lighting is needed in every room. It provides comfortable overall lighting. Sources are typically overhead fixtures.
Accent lighting allows you to illuminate interesting features in a room. Sources used for accent lighting would be recessed lighting and wall sconces.
Task lighting, this is the type we will be focusing on, allows you to see while you perform a task. It supplies the intense, direct light for detailed work. Sources of this type are desk lamps, track lighting and work lamps.
So here is the big question, can bad lighting negatively affect vision?
Although reading in dim or poor lighting will not adversely affect your vision in the long-term, it will tire your eyes more quickly and can result in eye strain and the discomfort that goes with it.
Good lighting is even more important for those that already exhibit low vision. Research has shown a 60 year old requires twice as much lighting as a 30 year old does. As people get older, less light reaches the eye. Older adults are also more sensitive to glare.
Having the right lighting, that is sufficient to see without being harsh can improve reading ability, create a noticeable difference in color and prevent eyestrain.
Warm light is best for the eyes. It is also recommended to work, read or do tasks that require detail by direct lighting.
There are also some types of lighting to limit exposure to:
- UV (Ultra violet) is one of the most harmful to our eyes, such as that given off by the sun or fluorescent tube lighting.
- Blue light is another potentially harmful to the eyes. Blue light is emitted by computers, tablets, TVs and smartphones. Exposure to blue light can disrupt sleep, cause dry eye, headaches, digital eye strain, neck and back tension.
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