Eye

The eye is a biological optical organ that focuses light onto a photosensitive retina, where neural signals begin the process of vision.

Cornea: The transparent front surface of the eye that provides most of its optical focusing power. Its curved surface bends incoming light before it reaches the lens.
Iris: The colored contractile tissue surrounding the pupil that regulates its size. It changes pupil diameter in response to light and other signals.
Refractive error: A focusing mismatch in which the eye does not bring light to a sharp retinal image. It describes the optical problem corrected by lenses or surgery.
Compound eye: An eye made of many optical units, each sampling part of the visual field. Its many facets form images differently from the single-lens vertebrate eye.
Visual acuity: The ability to distinguish fine detail in a visual scene. Retinal sampling and optical focus set limits on image sharpness.
Crystalline lens: The transparent, flexible structure behind the iris that changes shape to focus images at different distances. It fine-tunes focus through accommodation.
Ciliary body: A ring of tissue that produces aqueous humor and helps control lens shape. Its muscle and suspensory fibers enable accommodation.
Myopia: A refractive error in which distant objects focus in front of the retina. It is a common consequence of excessive optical power or an elongated eye.
Camera eye: An image-forming eye with a single aperture and an interior light-sensitive surface. The human eye is one example of this broad optical design.
Color vision: The capacity to discriminate light by wavelength rather than brightness alone. Different cone photoreceptors allow the eye to encode spectral differences.

Linked from 4 pages