Human Eye Structure, Vision, and Eye Movements

Human eye as sensory organ of vision

The human eye is a sensory organ of the visual system that enables sight by reacting to visible light. It functions like a living optical device: light enters through the cornea, passes through the pupil (whose size is controlled by the iris), is further focused by the crystalline lens, and finally forms images on the retina. The retina converts light into electrical signals using photoreceptors (rods and cones) and other specialized light-sensitive cells, and these signals are transmitted to the brain via the optic nerve for interpretation as vision. Structurally, the eye is housed in the orbits and consists of multiple layers (fibrous tunic, vascular/uveal tunic, and retina) with fluid-filled chambers and a vitreous body. The eye’s shape and protection are maintained by its components, while extraocular muscles move the eyes to place images on the fovea, the region of highest visual acuity. Vision also depends on dynamic processes such as pupil adjustment for changing light levels (dynamic range), and coordinated eye movements (including saccades, smooth pursuit, and reflexes) that stabilize images on the retina. Beyond vision, the eye supports other functions such as maintaining circadian rhythm. Eye health can be affected by aging and disease; for example, presbyopia results from reduced focusing ability and macular degeneration can damage central vision. Eye care professionals diagnose and manage vision disorders, often using corrective lenses (e.g., for myopia, hyperopia, astigmatism, and presbyopia).

0/2 modes complete

Development from ectoderm, neural ectoderm, neural crest

0/2 modes complete