Comparison of Three Techniques in Measuring Progressive Addition Lenses

*PhD †OD, PhD, FAAO ‡MS §MCOptom, PhD, FAAO Shu Zen College of Medicine and Management, Department of Optometry, Taiwan (C-YH), College of Optometry (TWR), College of Engineering (AYY), The Ohio State University, Columbus, Ohio, Pacific University, College of Optometry, Forest Grove, Oregon (JES, BA), and University of Houston, College of Optometry, Houston, Texas (MAB).
Optometry and vision science: official publication of the American Academy of Optometry (Impact Factor: 1.6). 10/2012; 89(11). DOI: 10.1097/OPX.0b013e31826ca26b
Source: PubMed


To measure progressive addition lenses (PALs) by three techniques and to compare the differences across techniques.

Five contemporary PALs (Varilux Comfort Enhanced, Varilux Physio Enhanced, Hoya Lifestyle, Shamir Autograph, and Zeiss individual) with plano distance power and a +2.00 diopters (D) add were evaluated under the condition of lateral displacement of the lens (no rotation and no tilt) using three methods. A Hartmann-Shack wavefront sensor (HSWFS) on a custom-built optical bench was used to capture and measure wavefront aberrations. A Rotlex Class Plus lens analyzer operating as a moiré interferometer was used to measure spherical and cylindrical powers. A coordinate measuring machine (CMM) was used to measure front and back surfaces of PALs and converted to desired optical properties. The data were analyzed with MATLAB programs. Contour plots of spherical equivalent power, cylindrical power, and higher-order aberrations (HOAs) in all PALs were generated to compare their differences.

The differences in spherical equivalent and cylinder at distance, near, and progressive corridor areas among the HSWFS, Rotlex, and CMM methods were close to zero in all five PALs. The maximum differences are approximately 0.50 D and located below the near power zone and the edge areas of the lens when comparing the HSWFS and CMM with the Rotlex. HOAs measured both by the HSWFS and CMM were highest in the corridor area and the area surrounding the near zone in all PALs. The HOAs measured by the CMM were lower than those from the HSWFS by 0.02 to 0.04 μm.

The three measurement methods are comparable for measuring spherical and cylindrical power across PALs. The non-optical method, CMM, can be used to evaluate the optical properties of a PAL by measuring front and back surface height measurements, although its estimates of HOAs are lower than those from the HSWFS.

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    No preview · Article · Jan 2013 · Optometry and vision science: official publication of the American Academy of Optometry
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    Full-text · Article · May 2013 · Optometry and vision science: official publication of the American Academy of Optometry
  • [Show abstract] [Hide abstract] ABSTRACT: Injection molding is an important mass-production tool in the optical industry. In this research our aim is to develop a process of combining ultraprecision diamond turning and injection molding to create a unique low-cost manufacturing process for progressive addition lenses (PALs). In industry, it is a well-known fact that refractive index variation and geometric deformation of injection molded lenses due to the rheological properties of polymers will distort their optical performance. To address this problem, we developed a method for determining the optical aberrations of the injection molded PALs. This method involves reconstructing the wavefront pattern in the presence of uneven refractive index distribution and surface warpage using a finite element method. In addition to numerical modeling, a measurement system based on a Shack-Hartmann wavefront sensor was used to verify the modeling results. The measured spherocylindrical powers and aberrations of the PALs were in good agreement with the model. Consequently, the optical aberrations of injection molded PALs were successfully predicted by finite element modeling. In summary, it was demonstrated in this study that numerically based optimization for PAL manufacturing is feasible.
    No preview · Article · Aug 2013 · Applied Optics
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