Iris
the colored part
Cornea
a clear dome over the iris
Pupil
the black circular opening in the iris that lets light in
retina
Light sensitive nerve tissue in the eye that converts images
Sclera
the white of your eye
Conjunctiva
a thin layer of tissue that covers the entire front of your eye, except for the cornea
eyelids
covering the front of the eye, which protect it, limit the amount of light entering the pupil, and distribute tear film over the exposed corneal surface.
choroid
Vascular (major blood vessel) layer of the eye lying between the retina and the sclera. Provides nourishment to outer layers of the retina.
anterior chamber
Fluid-filled space inside the eye between the iris and the innermost corneal surface
lens
Transparent, biconvex intraocular tissue that helps bring rays of light to a focus on the retina.
optic nerve
Largest sensory nerve of the eye; carries impulses for sight from the retina to the brain.
vitreous humor
Transparent, colorless gelatinous mass that fills the rear two-thirds of the eyeball, between the lens and the retina.
aqueous humor
Clear, watery fluid that fills the space between the back surface of the cornea and the front surface of the vitreous, bathing the lens
peripheral vision
Side vision; vision elicited by stimuli falling on retinal areas distant from the macula.
suspensory ligament
ringlike fibrous membrane connecting the ciliary body and the lens of the eye and holding the lens in place
astigmatism
Optical defect in which refractive power is not uniform in all directions (meridians)
cone
Light-sensitive retinal receptor cell that provides sharp visual acuity and color discrimination.
floaters
Particles that float in the vitreous and cast shadows on the retina; seen as spots, cobwebs, spiders,
optician
Professional who makes and adjusts optical aids, e.g., eyeglass lenses, from refraction prescriptions supplied by an opthalmologist or optometrist
low vision
Term usually used to indicate vision of less than 20/200.
rod
Light-sensitive, specialized retinal receptor cell that works at low light levels (night vision)
20/20
Normal visual acuity
blind spot
small area of the retina where the optic nerve leaves the eye
any image falling there will not be seen
external accessories
conjunctiva , eyelids, eyebrows
night blindness
a lack of vitamin A for the opsin to function in dark areas