Comparative Surface Imaging Study of Multifocal Diffractive Intraocular Lenses

Purpose: To analyse and compare the surface topography and roughness of three different types of diffractive multifocal IOLs.

Methods: Using scanning electron microscope (SEM, Inspect F, 5.0 KV, maximum magnification up to 20,000) and atomic force microscope (AFM, Park Systems, XE-100, non-contact, area profile comparison, 10 × 10 µm, 40 × 40 µm), the surface quality of the following diffractive IOLs was studied: the AcrySof IQ PanOptix (Alcon, USA), the AT LARA 829MP (Carl Zeiss Meditec, Germany), and Tecnis Symfony (Johnson&Johnson Vision, USA). The measurements were made over three representative areas (central non-diffractive optic, central diffractive optic, and diffractive step) of each IOL. Roughness profile in terms of mean arithmetic roughness (R) and root-mean-squared roughness (R) values were obtained and compared statistically.

Results: In SEM examination, all IOLs showed a smooth optical surface without any irregularities at low magnification. At higher magnification, Tecnis Symfony showed unique highly regular, concentric, and lineate structures in the diffractive optic area which could not be seen in the other studied diffractive IOLs. The differences in the measured R and R values of the Tecnis Symfony were statistically significant compared to the other models (p < 0.05).

Conclusion: Various different topographical traits were observed in three diffractive multifocal IOLs. The R values of all studied IOLs were within an acceptable range. Tecnis Symfony showed statistically significant higher surface R values at both central diffractive optic and diffractive step areas. Furthermore, compared to its counterparts, Tecnis Symfony demonstrated highly ordered, concentric pattern in its diffractive surfaces.