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KMID : 1159320150170040461
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Korean Journal of Vision Science
2015 Volume.17 No. 4 p.461 ~ p.470
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Analysis of the Optical Characteristics Using RMSPE in Progressive Additional Lens
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Lee Seung-Shin
Mah Ki-Choong
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Abstract
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Purpose: To analyze the optical characteristics of the progressive additional lens(PAL) using the value of RMSPE(Root Mean Square Power Error) calculated from refractive power error of distance, intermediate and near portions of PAL.
Methods: 17 different progressive additional lens, being prescribed in the clinic, were selected (distance portion refractive power was 0.00D, additional power were 1.50D, 2.00D and 2.50D, respectively). The front surface refractive power was measured by the Free Form Verifier(FFV, Rotlex, Israel) at 6953 points (0.5 mm measurement grid) of PAL. Each data was converted from sphere and cylinder error into RMSPE that represent deviations (or errors) from the power of the desired distance, intermediate and near portions, and visualized by color topographic maps in 0.25D steps at physical position of distance, intermediate and near portions. Clear zone defined by 0.25D of RMSPE at distance portion, and 0.50D at intermediate and near portions.
Results: There were no significant differences according to 3 different additions in the clear zone width at distance portion which 9.53±5.25 mm in 1.50D, 9.56±3.86 mm and 9.65±4.73 mm in 2.00D and 2.50D each. The clear zone width at intermediate portion were reduced as the addition is increased which 15.66±10.35 mm in 1.50D, 7.79±4.15 mm and 6.56±3.89 mm in 2.00D and 2.50D each. The clear zone width at near portion were reduced more as the addition is increased which 20.63±4.86 mm in 1.50D, 16.00±2.30 mm and 10.58±6.35 mm in 2.00D and 2.50D, respectively. In addition, it could be compared easily changes in the width of the clear defined area and peripheral astigmatism according to change of the addition in the same design from color topographic maps applying the RMSPE value.
Conclusions: This study proposed a method to analyze the changes in the optical properties according to the change of the addition in same design and various optical properties of the progressive addition lens. And it was considered that this method provided the basic data which may be prescribed the appropriate design fits specific needs and working conditions of wearer by a variety of applications with relatively simple design and easy analysis for the clinician.
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KEYWORD
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Progressive Additional Lens, Color topographic map, RMSPE, Free Form Verifier(FFV)
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