Posters

Features of the optical surface of an extended-depth-of-focus intraocular lens

Poster Details

First Author: F.Vega SPAIN

Co Author(s):    M. Millan   N. Garzón   M. Arnal   F. Rigato           

Abstract Details

Purpose:

To present the main characteristics of the optical surface, radii and boundary step height of the diffractive zones, of an extended depth of focus intraocular lens -EDOF IOL- (AT LARA® 829MP, Zeiss Meditec) and show that these features agree well with a kinoform-type, low-addition, hybrid refractive-diffractive intraocular lens design that uses 1st and 2nd diffraction orders for the far and intermediate foci respectively.

Setting:

Universitat Politècnica de Catalunya, Barcelona tech. Barcelona, Spain.

Methods:

An optical confocal microscope was used to measure the radii and step heights of thirteen diffractive zones (rk and hk respectively, where k is the zone number) of the EDOF IOL. The experimental values of the radii rk, were compared to the theoretical ones that would correspond to either a kinoform or a binary diffractive structure. Additionally, the expected addition of the IOL was derived from the rk values. The values of hk were converted to phase delay to obtain the diffraction orders that contributed to the foci of the IOL and the energy split between the lens’s foci.

Results:

The measured radii rk led to a calculated lens addition of +2.0 D (IOL plane). The sequence of rk values were in excellent agreement with the one expected in the case of a kinoform diffractive structure that split light in two diffraction orders. From the experimental values of hk, it was deduced that the lens worked with the 1st and 2nd diffraction orders to form the distance and intermediate foci respectively, which would permit chromatic aberration reduction in both foci. Furthermore, the theoretical energy split between the diffraction orders tended to favor the 1st one, and thus the distance focus.

Conclusions:

The radii and boundary step heights of thirteen diffractive zones of the EDOF IOL AT LARA® 829MP have been experimentally measured with a confocal optical microscope. The values of the radii and their progression from center to periphery, in addition to the measured heights, agree very well with a kinoform diffractive design that splits light into the 1st and 2nd diffraction orders to form the distance and intermediate foci of the IOL respectively. We hypothesize that this result jointly with the relatively low calculated addition (+2.0D), may provide focus extension from distance to intermediate vision with chromatic compensation.

Financial Disclosure:

None