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Meredith E. Jansen, BoKaye Dietmeier, Pete S. Kollbaum; Ghosting With Presbyopic Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6546.
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© ARVO (1962-2015); The Authors (2016-present)
Presbyopic lens designs create a focused image surrounded by a defocused image, which is often clinically described as ghosting. The purpose of the current study is to validate and implement a questionnaire designed to quantify the multiple dimensions of ghosted images.
Ten best-corrected subjects viewed several series of computationally-generated simulated ghosted images on a high-resolution monitor. Images were of a 20/160 letter "R" each containing a focused and a defocused component. Each series contained 40-50 images spanning a range of a single dimension of ghosting: direction of ghost, magnitude of offset of ghost from focused image, relative intensity of focused and blurred images, and blur. This was repeated with letters of different sizes and orientations containing a single ghosting dimension, and also all randomly varied amounts of all dimensions. Using a test card containing a numbered sequence of focus/ghost pairs matching those displayed on the monitor, subjects had to identify the ghost blur level, relative intensity, lateral off-set and direction of off-set of each simulated bifocal image presented on the monitor. Additionally, 20 subjects wearing presbyopic corrections in one eye viewed a stimulus and used this card to quantify their visual experience in this eye by viewing the questionnaire with their other eye wearing best-correction.
Regardless of ghost letter size and orientation subject responses were within 1 rating unit of expected on >95% of all trials for all dimensions when asked to directly match a single dimension of ghosting. When asked to rate targets with randomly varied amounts of all dimensions, the percentage of trials within 1 rating unit of expected remained high when describing the direction (92%), and position (84%), but dropped slightly for blur (77%) and blur (53%). Wearers of increasing add power designs reported more severe ghosting.
Subjects can quantify ghosting into 4 dimensions using a newly developed ghosting questionnaire with a very high degree of accuracy. Improved quantification of the multiple dimensions of ghosting observed in presbyopic designs can drive changes in lens design and fitting.
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