New answers tagged eyes
http://www.allaboutvision.com/conditions/spotsfloats.htm Floaters and spots typically appear when tiny pieces of the eye's gel-like vitreous break loose within the inner back portion of the eye.
According to Mayo Clinic: Eye floaters are spots in your vision. They may look to you like black or gray specks, strings or cobwebs that drift about when you move your eyes and appear to dart away when you try to look at them directly. (http://www.mayoclinic.org/diseases-conditions/eye-floaters/basics/definition/con-20033061)
Short answer The relative large surface area of the white sclera in humans has been linked to an enhanced ability to detect eye gaze. Background The white of the eye is caused by the sclera. Human eyes indeed have the highest relative amount of visibly exposed white sclera. The amount of visible sclera provides information about the orientation of the ...
The sinuses connect the ear, nose and throat as well as the tear ducts of the eye. The pressure created when holding your nose and blowing is transferred to any area it can get to; in this case, the eyes and ears.
Short answer In mammals dedicated UV cones have been found, as well as photoreceptors with secondary peak-sensitivity in the UV range. In fact, human blue cones are sensitive to near-UV. Background In humans, the visible spectrum is generally accepted to range from 390 to 700 nm. Figure 1 shows the spectral sensitivities of the various photoreceptors in ...
Yes, they have different photoreceptors as well as the circuitry to interpret the information from those photoreceptors. Humans have 3 types of cones which are tuned to respond best to red, green, or blue light, but it's not an on or off signal. A red or blue cone may still fire in greenish light, it just fires much less often. The brain takes that input and ...
I don't know WHY snakes have no eyelids, but the lack of eyelids doesn't mean they aren't as highly evolved as animals that do have eyelids. Rather, snakes simply followed their own evolutionary path. Whether or not snakes have eyelids may be a matter of perspective. According to this article, snakes' eyelids have evolved together into a single transparent ...
Snakes have no eyelids. Each eye is covered with a single, transparent scale. These eye scales protect the eyes from mechanical damage, and prevent the eyes from drying out, just as an eye lid would do. In effect, snakes developed another solution to protect their eyes. As a result, snakes cannot blink and they sleep with their eyes open. A snake’s eye ...
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