ConferencesDreiländertagung Medizinische Physik, Bern 2006; ARVO Annual Meeting, Ft. Lauderdale 2009; ARVO Annual Meeting, Ft. Lauderdale 2010; EFCLIN 2010;
Current research / employment

Short Abstract of IMPRS PhD Project

Aspheric intraocular lenses (IOL) are commonly used for correction of spherical aberration (SA) during cataract surgery. Available lens designs cover aberration free and aberration correcting types. Aberration free IOL do not induce spherical aberration and therefore do not change the corneal spherical aberration. In contrast, aberration correcting IOL are mostly designed to correct for a generic spherical aberration derived from eye models and therefore cannot individually correct for aberrations of an eye. Aberration free types are very robust to dislocation of the IOL after surgery as the optical design does not depend on superposition of wavefronts for correction of aberrations. Aberration correcting types are less robust against dislocation as the amount of correction is extremely dependent on the lens design and aperture. To investigate the effect of asphericity on the image quality, a standardized measurement principle was evaluated upon it’s useability for testing aspheric intraocular lenses. The device, based on measurement of the point spread function, was tested with several types of spherical and aspherical diffractive IOL. The lenses were tested with the standardized, aberration free model cornea (ISO) and a customized aspherical model cornea. It was shown that new aspherized designs cannot be characterized properly with the ISO model cornea.

In a second step a simulation of different lens designs (spherical, aberration free and aberration correcting) was implemented to evaluate the effect of decentration and tilt on the image quality with aspheric intraocular lenses. Therefore the natural lens in the Liou-Brennan Model Eye was replaced by different IOL designs to simulate successful cataract surgery. The lenses were then decentered and tilted and the modulation transfer function (MTF) was calculated for each position. The spherical and aberration free designs showed minor effect of decentration on the MTF whereas the aberration correcting designs showed different extent of MTF degradation depending on the amount of correction of spherical aberration.

Conclusions: Characterization of aspherical intraocular lenses requires a customized aspherical model eye which induces spherical aberration. In addition, the image achievable quality of aspherical IOL is extremely depending on the amount of intended correction of spherical aberration and exact alignment of the implant in the eye. In cases where exact alignment cannot be guaranteed, aberration free IOL may be a better choice to achieve good post surgical visual acuity.

Further research will show the effect of aberration correcting lenses with customized/personalized corneal aberrations.

Current research:

Now working at the department of Experimental Ophthalmology at the University of Saarland.

Publications T. Eppig, K. Zoric, A. Speck, B. Zelzer, J. Götzelmann, D. Nagengast, A. Langenbucher, Wave-front analysis of personal eye protection., Optics Express, 20, 17806-17815, (2012)

T. Eppig, A. Speck, M. Gillner, D. Nagengast, A. Langenbucher, Photochromic dynamics of ophthalmic lenses., Applied Optics, 51, 133-138, (2012)

J. Schrecker, K. Zoric, A. Meßner, T. Eppig, Effect of interface reflection in pseudophakic eyes with an additional refractive intraocular lens., Journal of Cataract and Refractive Surgery, 38, 1650-1656, (2012)

Z. Zhu, E. Janunts, T. Eppig, T. Sauer, A. Langenbucher, Iteratively re-weighted bi-cubic spline representation of corneal topography and its comparison to the standard methods, Z.Med.Phys, doi: 10.1016/j.zemedi., 2010.07.002, article in press, (2010)

T. Eppig, K. Scholz, A. Löffler, A. Messner, A. Langenbucher, Effect of tilt and decentration on the optical performance of aspheric intraocular lenses in a model eye, Journal of Cataract and Refractive Surgery, 35(6), 1091-1100, (2009)

K. Scholz, T. Eppig, A. Messner, H. Brünner, A. Langenbucher, Topography-based assessment of anterior corneal curvature and asphericity as a function of age, gender and refractive status, Journal of Cataract and Refractive Surgery, 35(6), 1054-1062, (2009)

M. Schürer, A. Walter, T. Eppig, H. Brünner, A. Langenbucher, Messsystem zur Bestimmung von Farbunterscheidungsschwellen bei Farbsinnstörungen und unter Einfluss von farbigen Filtern, Klinische Monatsblätter für Augenheilkunde, 226(7), 546-554, (2009)

A. Walter, M. Schürer, T. Eppig, A. Langenbucher, H. Brünner, Objective approach for measuring changes in color discrimination caused by transparent colored filter media, J. Opt. Soc. Am. A: Optics, Image Science & Vision, 26(10), 2219-2225, (2009)

T. Eppig, K. Scholz, A. Langenbucher, Assessing the optical performance of multifocal (diffractive) intraocular lenses, Ophthalmic and Physiological Optics, 28(5), 467-474, (2008)