Misalignment limited the repeatability of TMS-5 and Pentacam HR, but had little influence on the repeatability of CASIA SS-1000.

The number of presbyopia correcting intraocular lenses (IOLs) is increasing and new technologies are constantly emerging with the aim of correcting the loss of accommodation after cataract surgery. Various optical designs have been proposed to implement multifocality or an extended depth of focus (EDOF). Depending on the optical principle of an implanted lens, the visual performance often is deteriorated by superposition of individual image planes and halos of varying intensity. This experimental study presents a concept to visualize the light fields and especially the halos of mono- and multifocal IOLs using the well known alcoholic beverage “ouzo” in order to obtain qualitative data on the imaging characteristics. We conclude that ouzo is a useful, cost effective, and nonpolluting medium for beam visualization and an alternative to fluorescein or milk, which could find an application for educational purposes.

Purpose To implement a setup which allows simultaneous visualization of the far and near distance light field of multifocal intraocular lenses (MIOL) with two different wavelengths. Methods We used two different laser systems (532 nm and 405 nm) in junction with Powell lenses to create vertical laser lines. One laser line was collimated to simulate far distance imaging while the second laser line was diverging simulating near distance imaging at approximately 0.3 m distance. The MIOL was placed in a glass cuvette filled with balanced saline solution which was doped with two different fluorophores. The fluorophores were chosen to have a large Stokes shift and good separation between their excitation and emission bands. Image acquisition was performed with a slit lamp bio microscope and a digital single reflex camera. We investigated three different IOL types: a bifocal MIOL, a trifocal MIOL and an extended depth of focus IOL. Results We found that Propidium iodide and Fluorescein were appropriate fluorophores. Propidium iodide was excited at 532 nm and showed a red fluorescence while Fluorescein was excited at 405 nm showing the green fluorescence. Both lasers required a high power of approximately 30 mW in order to create a visible fluorescent reaction in the cuvette. All three MIOL types provided a good separation between far and near distance light. The regions of overlapping light fields were visible as yellow fluorescence. Conclusions In contrast to the previously published setups using a single wavelength with collimated excitation light and axially separated far and near distance foci the current setup allows superposition of the far and near distance foci which is more realistic compared to the situation in the eye. The dual wavelength approach enables an easy optical separation of far and near distance light.