Ophthalmic Cross Cylinder Lenses
Definition : Ophthalmic devices designed to assess the refractive error (cylinder power and axis) that require an examinee's responses by using two cylinder lenses with equal powers and opposite signs in the proper axis positions (two principal meridians). These lenses are available with different optical powers (e.g., +0.25D, +0.50D, +0.75D, +1.0D); they are used to determine astigmatism and refine cylinder power and axis for eyeglass fitting.
Entry Terms : "Lenses, Cross Cylinder" , "Phorometers" , "Ophthalmic Refraction Measuring Instruments"
UMDC code : 24547