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20 Cards in this Set
- Front
- Back
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Meniscus |
A lens having a convex surface on the front and a concave on the back |
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Axis |
The axis oreintates the sphere power of a compound lens |
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Base curve |
Beginning front curve of a lens which the net power is based |
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Power cross |
A schematic representation of the 2 major meridians of the lens power |
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Nominal power |
The total or estimated power of the lens determined by the power cross |
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Regular astigmatism |
A non spherical cornea which has its 2 major curves 90 degrees apart |
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Irregular astigmatism |
Non spherical cornea where the 2 meridians are not 90 degrees apart |
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Compound myopic astigmatism |
When light entering the eye is broken into 2 different focal points, and both of them come to a point focus after the retina |
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Compound hyperopic astigmatism |
When light entering the eye is broken into 2 different focal points, and both of them come to a point focus after the retina |
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Mixed astigmatism |
When light entering the eye is broken into 2 different focal points, and the other ray after the retina |
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Isometropia |
The same refractive error in both eyes |
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Amitropia |
The refractive power is a plus in one eye and a minus in the other |
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CR 39 |
Common plastic lens material with an index of 1.490 |
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Crown glass |
Common glass lens material with an index of 1.523 |
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Trivex |
Strong lightweight lens material with an index of 1.530 |
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Polycarbonate |
Bullet proof, light weight lens recommended for children with an index of 1.589 |
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High index |
A material with an index number that is higher than the average of 1.530 |
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Abbe value |
An index to measure the chromatic aberration or clarity of a lens material |
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Ametropia |
Generic refractive error |
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Plano |
No lens power needed |
