What organ system does an eye belong to?

It doesn't belong to any organ system.

An organ system is a group of organs that work together to perform a certain function in an organism’s body. The human body has 11 different organ systems.

The human organ systems are:

Integumentary: including the skin, fingernails, and hair.

Skeletal: all the bones in the human body

Muscular: includes the different types of muscles in the body: cardiac, smooth, and skeletal muscles.

Circulatory: consists of the heart, veins, arteries, and capillaries.

Respiratory: including the lungs, diaphragm, trachea, bronchi, and bronchioles.

Digestive: includes the esophagus, stomach, liver, and intestines, tongue, liver, pancreas, and gallbladder.

Urinary: kidneys, ureters, bladder, and urethra.

Immune: leukocytes (white blood cells), bone marrow, and the thymus.

Nervous: The central nervous system includes the brain and spinal cord, while the peripheral nervous system is made up of nerves.

Endocrine: all the glands in the body that produce hormones. (the pituitary gland, the adrenal glands, etc. )

Reproductive: the vagina, uterus, and ovaries, pen*is, testes, prostrate, and vas deferens.