Area behind the cornea and in front of the lens and iris. It contains aqueous humor.
Consisting of two surfaces that are rounded, elevated, and curved evenly, like part of a sphere. The lens of the eye is a biconvex body.
Structure surrounding the lens that connects the choroid and iris. It contains ciliary muscles, which control the shape of the lens, and it secretes aqueous humor.
Photoreceptor cell in the retina that transforms light energy into a nerve impulse. Cones are responsible for color and central vision.
Delicate membrane lining the undersurface of the eyelids and covering the anterior eyeball.
Fibrous transparent layer of clear tissue that extends over the anterior portion of the eyeball.
Pigmented layer that opens and closes to allow more or less light into the eye. The central opening of the iris is the pupil.
Transparent, biconvex body behind the pupil of the eye. It bends (refracts) light rays to bring them into focus on the retina.
Yellowish region on the retina lateral to and slightly below the optic disc; contains the fovea centralis, which is the area of clearest vision.
Region at the back of the eye where the optic nerve meets the retina. It is the blind spot of the eye because it contains only nerve fibers, no rods or cones, and is thus insensitive to light.
Central opening of the eye, surrounded by the iris, through which light rays pass. It appears dark.
Bending of light rays by the cornea, lens, and fluids of the eye to bring the rays into focus on the retina.
Relay center of the brain. Optic nerve fibers pass through the thalamus on their way to the cerebral cortex.
Soft, jelly-like material behind the lens in the vitreous chamber; helps maintain the shape of the eyeball.
Retinal effects of diabetes mellitus include microaneurysms, hemorrhages, dilation of retinal veins, and neovascularization (new blood vessels form in the retina).
Increased intraocular pressure results in damage to the retina and optic nerve with loss of vision.
hordeolum (stye or sty)
Localized, purulent, inflammatory staphylococcal infection of a sebaceous gland in the eyelid.
Blockage, inflammation, and infection of a nasolacrimal duct and lacrimal sac, causing redness and swelling in the region between the nose and the lower lid.
Outward sagging and eversion of the eyelid, leading to improper lacrimation and corneal drying and ulceration.
Inversion of the eyelid, causing the lashes to rub against the eye; corneal abrasion may result.
Intravenous injection of fluorescein (a dye) followed by serial photographs of the retina through dilated pupils.
visual field test
Measurement of the area (peripheral and central) within which objects are seen when the eyes are fixed, looking straight ahead without movement of the head.
Intense, precisely focused light beam (argon laser) creates an inflammatory reaction that seals retinal tears and leaky retinal blood vessels.
Use of an excimer laser to correct errors of refraction (myopia, hyperopia, and astigmatism). LASIK is an acronym for LASer In situ Keratomileusis.
Ultrasonic vibrations break up the lens, which then is aspirated through the ultrasonic probe.
auditory nerve fibers
Carry impulses from the inner ear to the brain (cerebral cortex). These fibers compose the vestibulocochlear nerve (cranial nerve VIII).
Snail-shaped, spirally wound tube in the inner ear; contains hearing-sensitive receptor cells.
Maze-like series of canals of the inner ear. This includes the cochlea, vestibule, and semicircular canals.
Central cavity of the labyrinth, connecting the semicircular canals and the cochlea. The vestibule contains two structures, the saccule and utricle, that help to maintain equilibrium.
Benign tumor arising from the acoustic vestibulocochlear nerve (eighth cranial nerve) in the brain.
Disorder of the labyrinth of the inner ear; elevated endolymph pressure within the cochlea and semicircular canals.
cochlear implant procedure
Surgical insertion of a device that allows sensorineural hearing-impaired persons to understand speech
Measurement of the temperature of the tympanic membrane by detection of infrared radiation from the eardrum.