PRISM DIOPTER Meaning and
Definition
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A prism diopter is a unit of measurement used in optometry and ophthalmology to quantify the amount of deviation or displacement of light as it passes through a prism. It is commonly denoted by the sign "Δ" or "dpt". The term "prism" refers to a transparent, triangular medium that can bend light by refraction, causing it to change direction. The diopter, on the other hand, is a unit used to measure the refractive power of a lens or prism.
In optometric practice, a prism is often prescribed to correct binocular vision disorders, such as strabismus (misalignment of the eyes) or double vision. By introducing a prism into corrective lenses, the light entering the eyes is bent in such a way that it enables the brain to fuse the images seen by both eyes into a single, clear image.
The measurement of a prism diopter indicates the amount of angular displacement produced by a prism. One prism diopter is equal to the displacement of a ray of light perpendicularly by a distance of one centimeter at a one-meter distance from the prism. Hence, a prism diopter is a measure of deviation per unit distance.
Prism diopters can be specified as base-in (BI) or base-out (BO), base-up (BU) or base-down (BD), corresponding to the direction in which the apex of the prism is oriented, resulting in different effects on the incoming light. These measurement units play a vital role in optometric prescriptions, aiding in the precise adjustment of corrective lenses and prisms to enhance binocular vision and alleviate visual discomfort.
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• The unit of measurement of the deviation of light in passing through a prism, being a deflection of one centimeter at a distance of one meter.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
Common Misspellings for PRISM DIOPTER
Etymology of PRISM DIOPTER
The word "prism" comes from the Greek word "prisma", meaning "something shaped like a prism". In ancient Greek, "prisma" referred to a three-dimensional geometric shape with a polygonal base and triangular sides. The term later evolved to refer to transparent glass or crystal objects with triangular sides that were used to refract light.
The word "diopter" has its roots in the Greek word "dioptron", which means "something seen through". It comes from the combination of "dia" meaning "through" and "optos" meaning "seen". In the context of optics, "diopter" refers to a unit of measurement that quantifies the focusing power of a lens or optical system.
When combined, "prism diopter" refers to a lens that incorporates both the properties of a prism (refracting and deviating light) and diopter (correcting refractive errors of the eye).
