could anyone give me the meaning of accommodation and dark adaptation?
dark adaptation is easy. To see in low light levels, you need to be in low light levels for a period (depending on your age) of about 20-30 minutes. If you are exposed to normal or bright light, even for a brief period, you have to start over. It was standard practice for me to stand a deck watch at night to adapt before I went on watch.
Accomodation: This is where the normal eye adjusts the thickness of the lens to focus on the object, whatever its range is. My digital camera does a good job of it also.
I searched Google under the key words "visual accommodation" and "dark adaptation"to get these possible sources:
http://www.ski.org/Vision/glossary.html#V
http://www.answers.com/topic/accommodation?cat=health
http://webvision.med.utah.edu/light_dark.html
http://www.yorku.ca/eye/darkada1.htm
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search.
To see the effect of dark adaptation, you can keep one eye closed for a period of time in a well-lighted room. Then go into a darkened room or closet, so the opened eye has trouble seeing. Now open the dark-adapted eye. The difference will be greater, if the time the one eye was closed is longer.
If you anticipate going into a darkened area, you can at least partially dark adapt by closing one eye for a period of time before entering that area. (Since most of your depth perception cues are monocular [one-eyed], you don't need to worry about bumping into things while you are still in the lighted area.) Try it!
I hope this helps a little more. Thanks for asking.
Sure! I can explain the meanings of both accommodation and dark adaptation.
1. Accommodation:
Accommodation refers to the ability of the eye to adjust its focus in order to see objects clearly at different distances. The process is primarily achieved by changing the shape of the lens inside the eye. When you shift your focus from a nearby object to a distant object or vice versa, your eye's muscles contract or relax to change the lens shape, allowing you to see the object clearly. Accommodation is an automatic and involuntary process that occurs constantly as you look at objects at different distances.
2. Dark Adaptation:
Dark adaptation is the process by which the eyes adjust to low levels of light after being exposed to brighter conditions. This adjustment allows us to gradually see better in dim or dark environments. When we are exposed to bright light, our eyes become more light-sensitive: the pupils constrict to reduce the amount of light entering the eye, and the photoreceptor cells in the retina become desensitized. In a darker environment, the pupils dilate to allow more light into the eye, and the sensitivity of the photoreceptor cells increases, allowing us to perceive shapes and objects.
To get a more detailed explanation or further information on these terms, you can refer to reliable sources such as textbooks on human physiology, vision science, or optometry. Additionally, medical websites, educational platforms, or reputable scientific articles can provide valuable insights and references to explore these concepts in depth.