Our eyes allow us to express ourselves, understand the world, and judge others' character. Biologically, the eye is an organ that detects light and sends signals to the brain along the optic nerve. Structurally, the human eye resembles a camera, with a spherical shape about 2.5 cm in diameter covered by sclera. The front features the cornea, with the iris and pupil located further back, and tears are produced by lacrimal glands to keep the eye moist.