Experimental and analytical quantification of light scattering from vacuoles in intraocular lenses

Abstract

Purpose: To develop an advanced test methodology for quantification of scattered light from intraocular lenses (IOLs) and to evaluate the correlation between IOL vacuole characteristics and measured scattered light. Setting: U.S. Food and Drug Administration, Optical Therapeutics and Medical Nanophotonics Laboratory, Silver Spring, Maryland, USA. Design: Experimental and analytical study. Methods: Twenty-four IOLs containing vacuoles were evaluated using a digital microscopy approach for identifying and characterizing the vacuoles present. A scanning light scattering profiler (SLSP) was used to evaluate and quantify the amount of scattered light from each IOL and from a 25th control IOL without any vacuoles. A variety of IOLs and vacuoles were also modeled in a Zemax simulation of the SLSP, and the simulated scattered light was modeled. Results: The scattered light as measured with SLSP was well correlated with vacuole characteristics, specifically density and size, as measured under the digital microscope for the 24 vacuole-containing IOLs. Additional correlations were found between vacuole sizes, orientations, and the angle at which light was scattered most severely. These correlations were also present in the Zemax model. Conclusions: Vacuole optical characteristics can be well correlated with measured scatter, demonstrating an ability to predict scattered light based solely on microscope evaluation. Furthermore, the quantitative amount of scatter predicted with Zemax simulations trended closely with the experimentally measured trends.

Visualization of Forward Light Scatter in Opacified Intraocular Lenses and Straylight Assessment

“…While its measured straylight parameter was markedly less than those of the calcified IOLs, it was still approximately 2-fold higher straylight than a 70-year-old lens, implying the clinical relevance of the glistenings in vivo. As size, density, and affected area of the glistenings have been shown to influence the magnitude of light scattering effects [34,35], future studies comparing the forward light scatter pattern of various IOLs with different glistenings' morphology may be insightful in determining a correlation.…”