Analysis of light energy distribution by multifocal intraocular lenses through an experimental optical model

Abstract

Purpose: To analyze and compare the light energy distribution generated by multifocal intraocular lenses (IOLs). Setting: Laser Laboratory of the Department of Electronics, Electrotechnics and Informatics, University of Trieste, Italy. Methods: An optic system to examine the division of a laser beam in the various focal spots of multifocal IOLs was developed. The model consists of a helium-neon laser and an optical system: a triangular optical bench with a precision collimator, a micropositionable immersion stage supporting the IOL to be measured, and a digital image-processing system. Four bifocal and three multifocal IOLs were studied. This system is able to expand the distance between foci, leading to a sharper separation of the focal spots. The resolution of the images makes it possible to analyze the distribution of total light energy among the foci. Results: Results showed the variation in light intensity of the focal spots of multifocal and bifocal IOLs, as well as their disposition in the dioptric range. Conclusion: Light distribution among various focal distances corresponded to the foci provided by monofocal, bifocal, and multifocal IOLs. The percentage of light energy distribution was related to the importance of each focus.