Prentice position

The Prentice position is an orientation of a prism, used in optics, optometry and ophthalmology.^[1] In this position, named after the optician Charles F. Prentice, the prism is oriented such that light enters it at an angle of 90° to the first surface, so that the beam does not refract at that surface. All the deviation caused by the prism takes place at the exit surface. ^{[citation needed]}

The Prentice position

In ophthalmology, glass prisms were classically calibrated for use in the Prentice position, while plastic prisms were calibrated for use in the frontal position.^[2]

See also

• Prism correction
• Prentice's rule