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Michelle Langeslag, Marrie Van der Mooren, Patricia Piers, Luuk Franssen; In vitro straylight levels for IOLs across forward scatter positions up to 30 degrees. Invest. Ophthalmol. Vis. Sci. 2013;54(15):855.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of the study is to combine the straylight levels of IOLs measured with a method for small and a method for large forward scatter position angles. The straylight levels were determined for intraocular lenses (IOLs) with different designs and materials.
IOLs were measured on two different lab-based set-ups: 1) for forward scatter positions between 0.6 and 2 degrees 2) for forward scatter positions up to 30 degrees. In both cases the IOL was placed in a saline filled cuvette on an optical bench set-up. A CCD camera was used to measure the line spread functions from which the angular dependent straylight parameters were then calculated. The straylight measured using the two methods were then combined in order to determine the magnitude over the entire angular range. Using this method IOLs made from 4 different materials (2 hydrophobic and 2 hydrophilic acrylics) and 3 different designs (spherical monofocal, aspheric monofocal and diffractive multifocal) were measured and compared. Additionally, the measured straylight levels were compared to the levels published for a 20 and 70 year old human crystalline lens.
All monofocal IOLs with the same type of optical design show comparable straylight parameters, both for small and large forward scatter angles. At a forward scatter angle of 2° the average value for the straylight parameter of diffractive multifocal lenses is 4.5. For an angle of 7.5° the average value for the same type of lenses is 1.2. Irrespective of material or design, the amount of straylight is reduced for larger forward scatter angles. All IOLs have a straylight parameter of approximately 1.0 for angles of 10° and larger. For an angle larger than 7.5° all IOLs have a straylight level below that of a 20-year old human crystalline lens.
Straylight parameter results from both set-ups can be combined to determine the straylight profile of an IOL over an angular range from 0.6 to 30 degrees. IOL design has more influence on the height of the straylight parameter than the IOL material does. IOL straylight parameters get smaller as the measurement angles increase. The straylight parameter of all IOLs measured is independent of design parameters for angles larger than 10°.
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