Change in the size of the pupil, why this happens
Change in the size of the pupil, why this happens
Sometimes you may notice that your crustaceans are narrowing or widening. For alarm there is not the slightest reason. This is normal.
Instructions
1
The size of the pupil is unstable. The diameter of this always black, as if going into the depth of the hole located in the center of the rainbow rim of the eye, can vary from 1.5 to 8 millimeters. The pupil's size is reflexive, depending on the illumination: the more light, the pupil already, and, conversely, the smaller , the wider it is. By adjusting the amount of light entering the eye, the pupil provides conditions for ideal illumination of the mesh shell.
2
No less important is its other function: the pupil helps the eye systems not to allow optical image distortions, focused on the mesh shell. Here, the analogy with the camera is appropriate: it is known that the narrower the aperture, the sharper the image. The optimal diameter of the pupil is 2-4 millimeters: in this case, rays of light enter the retina, passing only through the central part of the cornea, and a clear image of the objects is projected onto the retina.
3
The pupil reacts not only to light. It is a sensitive indicator of the physical and emotional state: the pupil expands from physical pain, from fear ("eyes expanded from horror"), from excitement, joy and tapers when a person is depressed and depressed.
4
The constant play of the pupils is a physiological phenomenon. But the violation of their reactions to light, pain, uneven enlargement or narrowing of the pupils indicate a disease of the eye or of a dysfunction in the central nervous system.
