New system to measure chromatic contrast sensitivity defocus curves with multifocal intraocular lenses
First Author: J.Fernandez SPAIN
Co Author(s): M. Rodríguez-Vallejo J. Martínez N. Burguera D. Piñero
To evaluate the defocus shift, the effective addition, and the area under the contrast sensitivity defocus curve (CSDC) measured for red (R), green (G) and blue (B) isolated channels of an iPad (4th generation) for bandwidths centered on 610 nm, 543 nm and 462 nm and uniform luminance of 34 cd/m2 for all channels.
Qvision, Ophthalmology Department Vithas Virgen del Mar Hospital, Almería, Spain
17 subjects implanted with the Liberty IOL (Medicontur) were monocularly measured at the 3-month follow-up visit with the best spectacle refraction obtained with white light at infinity. The Multifocal Lens Analyzer (Beta version, defocuscurve.com) was used to measure Chromatic Contrast Sensitivity Defocus Curves at 2 m with a +0.50 D lens and manifest refraction. A previous calibration of the iPad was conducted with the SpydeXElite colorimeter (Datacolor). The test consisted of Sloan letters of 0.3 logMAR changing its contrast in 0.1 logCS steps for isolated RGB channels. Refractive Analysis Toolbox for Matlab (v1.0.3, test-eye.com) was used for processing defocus curves.
The median location of the far distance focus was at +0.25 D for R, at 0 D for G and at -0.25 D for B (p<0.05 for R vs B). The addition obtained from the curve decreased with the wavelength from a median of 3 D for R and 2.5 D for G and B (p<0.05 for R vs B). For all channels and additions, the interquartile range was 0.50 D. The area under the defocus curve was lower for B (0.82) than for R (1.58) and for G (1.54)(p<0.05). No differences were obtained between R and G (p>0.05).
This beta version of Multifocal Lens Analyzer resulted in promising results for detecting the defocus shift, computing effective addition and measuring contrast sensitivity for several bandwidths centered on a particular wavelength. The system could be used in clinical practice to provide new clinical evidence of multifocal intraocular lenses that correct chromatic aberration and enhance contrast sensitivity.
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