Eye (overview)

The eye is a paired sensory organ that responds to light, collecting it from the external environment and converting it into nerve impulses that travel to the brain via the optic nerve (CN II) (Read more!). The brain interprets this information to create a visual image, making the eye responsible for the sense of sight.

Each object absorbs and reflects different wavelengths of light. The human eye can typically detect wavelengths from approximately 380 to 750 nanometers (nm). This is called the visual light spectrum. The human eye cannot see light outside this range (e.g., ultraviolet and infrared) because its photoreceptors (rods and cones) are not sensitive to those wavelengths. An object appears white if it reflects most or all wavelengths of visible light, and it appears black if it absorbs most or all wavelengths.

Humans have two eyes, each housed within the bony orbit (Read more!) of the skull and connected to the brain via the second cranial nerve (the optic nerve (Read more!)). Anatomically, each eye consists of a spheroid-shaped eyeball (Read more!) and accessory visual structures that protect and support it.

Note: This article reviews only the eyeball, excluding the accessory visual structures.