Abstract
Purpose :
To measure and characterize the size and density of particles inside an intraocular lens(IOL) using a Human Model Eye.
Methods :
A time domain partial coherence interferometry system (TD-PCI) based on two light sources at 820 nm ,673 nm and a piezoelectric motor (PI-type M-663 Compact LinearTranslation) with a spatial accuracy of up to 0.1 μm.
A SLD (type EXS8310, λ = 820 nm, Exalos, Switzerland) und a SLD (type SLD-261-MP1, λ = 673 nm, Superlum , Ireland) were used as light sources. With a fiber coupler both light sources coming into the measurement system, so that an equal profile for both light sources was achieved.
As a model for cataract inside the IOL, microparticles of 1 and 3 microns, are randomly distributed with different densities (0-800.000 beads/IOL) were by Human Optics AG prepared.
For detecting the transmitted scattered light of the IOL a CCD camera is used. the point-spread functions (PSF’s) are analyzed.
Influence of density of particles site on Refractive indices inside the IOL is evaluated by the signal processing of the TD-PCI-system.
Results :
The Analysis of the obtained PSF’s shows that the PSF is influenced by the size and density of the particles. For 3 microns particles both radial profiles of PSF’s have in our setup a crossing point between radial profiles at 1.5 mm from the center. the crossing point of the clear intraocular lens was at 5,5mm from the center.
The density of the particles is linearly correlated with the amplitude of the TD-PCI-signal.
High densities of particles inside the IOL had to a change further focus length.
For the highest density of the 3 microns particles an increase of the focal length of 30µm was found.
Conclusions :
The combined setup of the two wavelengths TD-PCI-system shows a significant improvement for detecting size and density of particles inside an IOL of Human Eye. This may be used for an objective classification of cataract.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.