Glossary - Eye Care[return to top] Accommodation - the ability of the eye to focus. Amblyopia - sometimes called "lazy eye," is the reduction or dimming of vision in an eye that appears to be normal. Amsler grid - a chart featuring horizontal and vertical lines used to test vision. Anterior chamber - the front section of the eye's interior where aqueous humor flows in and out of providing nourishment to the eye and surrounding tissues. Astigmatism - a vision problem that results in blurred images. [return to top] Binocular vision - the ability to use both eyes at once. [return to top] Cataract - a change in the structure of the crystalline lens that causes blurred vision. Choroid - the thin, blood-rich membrane that covers the white of the eyeball; responsible for supplying blood to the retina. Ciliary body - the part of the eye that produces aqueous humor. conjunctiva - the membrane that lines the exposed eyeball and the inside of the eyelid. Conjunctivitis - inflammation of the conjunctiva of the eye. Cornea - the clear, dome-shaped surface that covers the front of the eye. Corneal curvature - the shape of the front surface of the eye. [return to top] Depth perception - the ability to distinguish objects in a visual field. Diplopia - double vision. [return to top] [return to top] [return to top] Glaucoma - increased intraocular pressure that can result in optic nerve damage and loss of sight. [return to top] Hyaloid canal - narrow passageway that allows blood to flow through the eye. Hyperopia - farsightedness. [return to top] Iris - the colored part of the eye. The iris is partly responsible for regulating the amount of light permitted to enter the eye. [return to top] [return to top] Keratitis - inflammation of the cornea. [return to top] Lens (also called crystalline lens) - the transparent structure inside the eye that focuses light rays onto the retina. [return to top] Macula - the portion of the eye that allows us to see fine details clearly. Macular degeneration - degeneration in the macular region of the retina that results in decreased central vision and sometimes, in blindness. Miosis - constriction of the pupil. Mydriasis - dilation of the pupil. Myopia - nearsightedness. [return to top] Near point of accommodation - the closest point in front of the eyes that an object may be clearly focused. Near point of convergence - the maximum extent the two eyes can be turned inward. [return to top] Ocular hypertension - high (greater than 21 mm Hg) intraocular pressure. Ophthalmoscopy - examination of the internal structure of the eye. Orthokeratology - the use of contact lenses to change the shape of the cornea in order to correct refractive error. Optic nerve - a bundle of more than one million nerve fibers that connects the retina with the brain. The optic nerve is responsible for interpreting the impulses it receives into images. [return to top] Photophobia - sensitivity to light. Photorefractive keratectomy (PRK) - surgical procedure using an excimer laser to change the shape of the cornea. Pinguecula - irritation caused by the degeneration of the conjunctiva. Posterior chamber - the back section of the eye's interior. Posterior optical segment - portion of the eye located behind the crystalline lens, and including the vitreous, choroid, retina, and optic nerve. Posterior vitreous detachment (PVD) - the separation of the vitreous from the retina. Presbyopia - a form of farsightedness in which it is difficult to focus on close objects or to read. Pupil - the dark center in the middle of the iris through which light passes to the back of the eye. Pupillary response - the constriction or dilation of the pupil as stimulated by light. [return to top] [return to top] Radial keratotomy - a surgical procedure in which incisions are made into the epithelium of the cornea to correct refractive error. Refractive error - the degree to which light reaches the back of the eye - myopia, hyperopia, astigmatism. Retina - the light-sensitive nerve layer that lines the back of the eye. The retina senses light and creates impulses that are sent through the optic nerve to the brain. Retinal detachment - separation of the retina from the epithelium layer and from its blood supply. [return to top] Sclera - the white visible portion of the eyeball. The muscles that move the eyeball are attached to the sclera. Scotoma - an area of partial or complete loss of vision surrounded by an area of normal vision. Stereopsis - ability to perceive three-dimensional depth. Suspensory ligament of lens - a series of fibers that connect the ciliary body of the eye with the lens, holding it in place. [return to top] Tonometry - test to measure intraocular pressure for glaucoma. [return to top] [return to top] Visual acuity - the space visible to an eye in a given position of gaze. vitreous body - a clear, jelly-like substance that fills the center of the eye. [return to top] [return to top] [return to top] [return to top] |