Method to quantify the decentration of the multifocal intraocular lenses in relation to the visual axis

Abstract

Since position and centration have shown to affect the effectiveness of multifocal intraocular lenses (MFIOLs), some authors have proposed using the "coaxially sighted IOL light reflex" as a landmark to allow consistent centration of MFIOLs. Postoperatively, assessing the location of the intraocular lens with respect to the visual axis is also important. Centration of the MFIOLs can be identified postoperatively by slit lamp biomicroscopy, but it is still a qualitative method. The Nidek OPD Scan III is used. The instrument obtains retro illumination images, which allows the observation of the diffractive rings of the multifocal intraocular lenses implanted following phacoemulsification. The retro illumination image describes the location of the visual axis (white cross with blue borders +), the center of the photopic (pink cross) and mesopic (turquoise cross) pupil, quantifies the distance between the center of the pupil and the visual axis, and places the visual axis in degrees. It is attempted to match the rings of the lens with that of the acetate grid. Once the best possible equidistance between the lens and grid rings has been achieved. This method can be useful to be able to have reference of a real value of decentration of the lenses and thus have a surgical plan and try to center the lenses. We are also creating a technique to properly center the lenses, in addition to performing an analysis of the results in terms of postoperative visual quality in relation to the lens's decentration and thus see how this really affects.