18/01/2016

Author: Eleni Papadatou, MSc, University of Valencia, Spain

Bifocal and trifocal diffractive IOLs are designed to concentrate the light in two or three foci. However, not all the energy can be accurate focalized and therefore the presence of visual artifacts due to diffractive effects is possible to occur. In vitro evaluation of IOLs is essential to assure that they meet a minimum quality standard.

In a new study, the optical quality of fresh commercially available IOLs (aspeheric monofocal and diffractive multifocal IOLs) was evaluated by means of the modulation transfer function (MTF) and straylight. The MTF was obtained with the PMTF instrument (Lambda-X) for different pupil sizes and the straylight was recorded using the C-Quant device (Oculus) with a modification that allows for in vitro IOLs straylight assessment.

The results demonstrated thatalthough monofocal IOLs yielded a better optical quality in terms of MTF, multifocal IOLs were less affected by pupil size (Figure 1). In terms of straylight, all the IOLs values were too low when comparing to the normal eye (Figure 2). Moreover, multifocal IOLs had values similar to the monofocal IOLs, thus diffractive effects per se of these IOLs are not expected to elevate postoperative straylight of the eye.

Figure 1: Through Focus MTF at 50 cy/mm

Figure 2: Straylight values of IOLs (expressed in straylight parameter)

Preliminary data of this study have been submitted in an abstract form for ARVO 2016 congress (Seattle, USA).

References:

1. Montés-Micó, R., Madrid-Costa, D., Ruiz-Alcocer, J., Ferrer-Blasco, T., & Pons, Á. M. (2013). In vitro optical quality differences between multifocal apodized diffractive intraocular lenses. Journal of Cataract & Refractive Surgery, 39(6), 928-936.
2. Łabuz, G., Reus, N. J., & Van Den Berg, T. J. (2015). Ocular straylight in the normal pseudophakic eye. Journal of Cataract & Refractive Surgery, 41(7), 1406-1415.
3. Łabuz, G., Vargas-Martín, F., van den Berg, T. J., & López-Gil, N. (2015). Method for in vitro assessment of straylight from intraocular lenses. Biomedical optics express, 6(11), 4457-4464.