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William Duncan, Jim Schwiegerling; Simulation of three-dimensional scenes through multifocal contact lenses. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1487.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of this study is to develop optically correct simulations of three dimensional scenes for use with multifocal and extended depth of focus lenses.
The effects of blur and aberrations on objects such as optotypes, eye charts and two dimensional scenes are often simulated by convolving the point spread function (PSF) of an optical system with the object. This technique captures the optical effects for a certain object distance, but fails to account for changes in the wavefront shape that result from the object being located at various distances. Consequently, scenes viewed through multifocal optics are typically analyzed serially where the object distance is changed and the object blurred for each distance independently. Here, we have developed a technique where a three dimensional scene is created. The scene consists of multiple objects (a cell phone, a computer screen, and the outdoors) each located at distinct distances. Each of the objects is convolved with a depth-adjusted PSF and the three objects are recombined to form a simulation of the whole scene. Occlusion of the background objects by the foreground objects is also taken into account.
Three dimension scene simulation is computationally expensive. In principal, each object point has a unique PSF that independently needs to be added to the final simulation. The processing can be greatly speeded by assuming several separate depth layers within the scene where the PSF is slowly varying. An additional complication is occlusion of background objects by subsequent layers in the foreground. Occlusion is handled by blurring the deepest layer first and then masking it by the near layers. The process is then repeated for the next deepest layer. The resultant image provides insight into effects such as multifocal and extended depth of focus lenses.
Three dimensional scene simulation provides a useful tool for analyzing the performance properties of various types of presbyopic correction. The scenes provide realistic comparison of common visual situations such as reading a cell phone or computer screen and viewing distant objects. Such simulations may be useful for patient education as well as for providing feedback to designers regarding the effects of presbyopic corrections.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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