People of different races have different iris colors. Scleral is a compact collagen fiber structure, opaque, milky and tough. The middle layer, also called uvea and pigmented membrane, is rich in pigments and blood vessels, including iris, ciliary body and choroid.

Iris: ring-shaped, located at the forefront of the uvea and in front of the lens, with radial wrinkles on the surface called texture and uneven depressions. The ciliary body is located in front of the iris root, behind the choroid, on the side of the sclera, and inside the equatorial part of the lens through the suspensory ligament. The choroid lies between the sclera and retina. The blood circulation of choroid nourishes the outer layer of retina, which is rich in pigment to cover the darkroom.

Corneal nerve is rich and sensitive. Therefore, the cornea is not only the main structure of light entering the eye and refracting imaging, but also plays a protective role and is an important part of measuring people's perception.

Extended data

Eyes are the visual organs of people and animals. It consists of eyeball and its accessory organs, the main part of which is eyeball.

The eyes are the most important organs in human senses, and about 80% of the knowledge in the brain is obtained through the eyes. Reading books, looking at pictures and appreciating paintings, appreciating people and enjoying beautiful scenery all need eyes. The eyes can distinguish light with different colors and brightness, and convert this information into nerve signals and transmit them to the brain.

The human eye is the benchmark of telescope magnification, that is to say, the magnification is 1, and the aperture is the size of the pupil of the human eye, which varies with the change of illumination intensity and generally fluctuates between 2-7 mm.

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