The optical characteristics of the major progressive addition lenses were measured using an automated lensometer with a specially designed lens holder to simulate eye rotation. Measurements were made every 3° (about 1.5 mm) and graphs of isospherical equivalent lines and isocylinder lines were developed. Generally the near zone of these lenses is narrower and lower than in bifocal or trifocal lenses. Distinct differences exist between the various progressive lenses. The width of the near zone, rate of power progression, amount of unwanted cylinder (level with the distance center), and clarity of the distance zone are compared for the various lenses. The optical measurements demonstrate an apparent trade-off between the size of the cylinder-free area of the lens and the amount of the cylinder.
Received March 20, 1986; revision received July 21, 1986.
* Optometrist, Ph.D., Member of Faculty, F.A.A.O.
‡ Optometrist, M.S., Member of Faculty, F.A.A.O.
§ Optometrist, L.L.D., D.Sc., Member of Faculty, F.A.A.O.
James E. Sheedy
School of Optometry
University of California, Berkeley
Berkeley, California 94720
© 1987 American Academy of Optometry