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A B C D E F G H I J K LM N O P Q R S T U V W X Y Z 0-9
(A-Z listing includes diseases, conditions, tests and procedures)

Glossary - Eye Care

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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.


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Binocular vision - the ability to use both eyes at once.


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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.


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Depth perception - the ability to distinguish objects in a visual field.

Diplopia - double vision.


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Glaucoma - increased intraocular pressure that can result in optic nerve damage and loss of sight.


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Hyaloid canal - narrow passageway that allows blood to flow through the eye.

Hyperopia - farsightedness.


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Iris - the colored part of the eye. The iris is partly responsible for regulating the amount of light permitted to enter the eye.


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Keratitis - inflammation of the cornea.


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Lens (also called crystalline lens) - the transparent structure inside the eye that focuses light rays onto the retina.


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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.


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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.


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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.


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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.


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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.


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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.


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Tonometry - test to measure intraocular pressure for glaucoma.


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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.


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