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ABO VOCABULARY
Term | Definition |
---|---|
Deviation from a single focus of light rays emanating from one source | Abberation |
The ability of the eye to adjust focus for varying distances | Accomadation |
Descriptive of a lens capable of refracting light without creating a rainbow effect | Achromatic |
Visual expression of sharpness of vision | Acuity |
Difference in plus power between the reading and distance portions of a multifocal lens | Addition |
Loss of vision without any apparent diseas of the eye | Amblyopia |
A refractive error in which the eye, when in a state of rest, does not focus the image of an object upon the retina; includes hyperopia, myopia, and astigmatism | Ametropia |
A condition in which the image of an object as seen by one eye differs so much in size or shape from that seen by the other eye that the two images cannot be fused into a single impression | Aniseikonia |
A condition in which the refractive error of one eye significantly differs from that of the other | Anisometropia |
Front cavity or compartment of the eye, located between the cornea and crystalline lens. Contains the Aqueous Humor | Anterior Chamber |
thinnest edge of a prism | Apex |
An absence of the crystalline lens of the eye | Aphakia |
not spherical; a lens having a number of curves with different radii | Aspheric |
A defect of the eye, of a lens or of an image formed by either. The curvature of the refracting surface or surfaces being different in different planes. This results in the focal lengths also being different in different planes | Astigmatism |
The meridian of cylinder power in a spherocylinder lens | Axis |
Thickest edge of a prism | Base |
The curve used as a base of a series of powers; the degree of curvature of the front surface of a lens | Base Curve |
A group of parallel rays of light | Beam |
Pertaining to vision with both eyes | Binocular |
Instrument used to measure thickness, calibrated in fifths and tenths of a millimeter | Caliper |
The angle at either end of the slit between the eyelids | Canthus |
A condition when the crystalline lens of the eye becomes opaque | Cataract |
One, which originates at birth | Congenital Cataract |
The lens has become either solid and shrunken or soft and liquid | Hyper-mature Cataract |
Any cataract in its early stages | incipient Cataract |
The lens is completely opaque | Mature Cataract |
A hard opacity of the lens occurring in the aged | Senile Cataract |
Cataract following an injury | Traumatic Cataract |
Vasculair layer of the eye; its function is to nourish the other parts of the eye, primarily the retina | Choroid |
Distortion of an optical image produced by the dispersion of light passing through a lens and generally characterized by blurred, multicolored edges | Chromatic Abberation |
The thick rim of the choroid to which the crystalline lens is attached | Cilary Body |
The refractive error which results in two points of focus falling behind the retina. +1.00 +2.00 x090 | Compound Hyperopic Astigmatism |
The refractive error which results in two points of focus falling in front of the retina -1.00-2.00x090 | Compound Myopic Astigmatism |
Light sensitive cells in the retina responsible for color vision, daytime vision, and the central portion of the visual field (6 million) | Cones |
The clear membrane that lines the eyelids and covers exposed surface of the eyeball | Conjunctiva |
Inflammation of conjunctiva; commonly reffered to as "pink eye" | Conjunctivitis |
The refractive, transparent, anterior wall of the eye, equal to 43 diopters in power. This is the fastest healing part of the body. Five. | Cornea |
Pure silicate glass of general excellence for the spectacle lens; index of refraction is 1.523 | Crown Glass |
A transparent, colorless body suspended in the front part of the eyeball, between the aqueous humor and vitreous humor. Its function is to bring light rays to focus on the retina. | Crystalline Lens |
Paralysis of the ciliary body | Cyclopegia |
Distance between the optical center placement of a lens and its geometric center; usually expressed in millimeters | Decentration |
The scattering of light | Diffusion |
Unit of measurement of the refractive power of a lens | Diopter |
The seeing of one object as two, due to uneven tracking of the eyes. Commonly know as double vision | Diplopia |
Defect in a lens which causes a straight line to appear curved | Distortion |
Two or more light rays proceeding outward from a point | Divergent |
The refractive condition of a normal eye. When the eye is at rest, the image of distant objects is brought to focus on the retina. | Emmetropia |
A tendency for one eye to deviate of the visual axis toward the other eye | Esophopia |
Actual deviation of one eye toward the visual axis of the other eye (cross eyed) | Esotropia |
A tendency for one eye to deviate off the visual axis away from the other eye | Exotropia |
Point in space which is sharply focused on the retina with the eye's accommodation relaxed | Far Point |
A glass of high refractive index 1.65 containing lead | Flint Glass |
The point to which the rays of a pencil of light converge or where they appear to diverge. In plus lenses, the focus is a real focus; in mius lenses, it is a virtual focus | Focus |
A small depression in the retina, at the back of the eye. It is part of the macula adapted for the clearest vision | Fovea |
The power of coordination by which the images received by the two eyes become a single image | Fusion |