People's irises are about the same diameter. Of course, the size will vary from person to person, but the error is very small, so it should be difficult to observe with the naked eye ... According to statistics, the average iris diameter of human beings is 12mm, and that of China people is slightly smaller, about11.4mm.

Compared with the iris, the size of the pupil changes almost at any time, ranging from 1.2mm to 9.6mm. When people observe the iris, the size of the pupil will also affect the iris (black eyeball) of the same person. Pupils look bigger when dilated than when constricted. According to this principle, it explains why people look bigger and more emotional in the dark (watery eyes). ......

In addition, it is said that myopic eyes (eyeballs) are bigger than hyperopia (generally speaking, myopic eyeballs are bigger, the front and rear axes are longer, and hyperopia is shorter). So in theory, the iris of myopia will be larger than that of hyperopia. This theory is very interesting, and I can't prove it. It needs the result of crazy research! ! !

There are two other special situations that can cause the iris to become larger:

1. Dark iris is bigger than light iris (illusion)

2. The iris with dilated pupils is larger than that with constricted pupils (also an illusion).

3. The iris of myopia is bigger than that of hyperopia (this is a theory and needs statistics).