Phoropter

Phoropter is an instrument commonly used by optometrists and ophthalmologists during an eye examination to measure an individual's refractive error and determine their eyeglass prescriptions. Also known as a refractor, it is an essential tool in optometry.

History[edit | edit source]

The phoropter was first introduced in the early 20th century, following the development of the monocular refractor by Henry DeZeng in 1909. The modern design of the phoropter was later refined by Frederick W. Heine in 1921.

Function[edit | edit source]

The phoropter works by changing lens power in each eye to correct vision. It contains multiple lenses of different strengths which can be moved into the patient's view. These lenses are used to measure the patient's refraction to determine the level of hyperopia (farsightedness), myopia (nearsightedness), astigmatism, and presbyopia.

Components[edit | edit source]

A phoropter consists of several components including a series of rotating wheels that contain lenses of different powers, a viewing device, and an adjustable chin rest. The main components are:

Sphere wheel: This contains lenses that correct for myopia or hyperopia.
Cylinder wheel: This contains lenses that correct for astigmatism.
Axis wheel: This is used to adjust the orientation of the cylinder lens.
Prism wheel: This contains prisms to measure and correct for any misalignment of the eyes.

Usage[edit | edit source]

During an eye examination, the patient sits behind the phoropter and looks through it at an eye chart. The optometrist or ophthalmologist changes lenses and other settings, while asking the patient for feedback on which settings give the clearest vision.