Validation of a spectral light scattering method to differentiate large from small particles in intraocular lenses

Abstract

Abstract:A psychophysical approach has been designed to measure straylight from intraocular lenses (IOLs) in vitro. This approach uses a clinical straylight meter (C-Quant) and an observer's eye as optical detector. Based on this, we introduced a method for study of straylight-wavelength dependency for IOLs. This dependency can be used to distinguish between 2 types of scattering particles (small and large) as defined by Mie theory. Validation was performed using a turbidity standard and scattering filters. Several IOLs were analyzed to identify potential scattering sources. Large particles were found to predominate in scattering from the studied lenses. This was confirmed by straylight-angular dependency found in these IOLs.

Assessment of straylight and the modulation transfer function of intraocular lenses with centrally localized opacification associated with the intraocular injection of gas

“…Hence, only straylight of the lens under test was measured. 21,22 In this manner, the straylight measured in vitro directly corresponds to the straylight (increase) experienced by the patient.…”

“…2, 5, 9-12, 17, 18 Although numerous studies on histological examination have been performed, 2, 5, 7, 9-12, 17, 18 little can be found on the optical quality of the affected IOLs. 7,11 The optical performance of opacified lenses has been studied by means of light scattering (straylight) measurements, [21][22][23] and quality metrics derived from the point spread function, such as the modulation transfer function (MTF) and the Strehl ration (SR). [24][25][26][27] Studies on straylight from different types of IOL opacification such as calcification, snow-flake degeneration, and glistenings, have shown that straylight is a very sensitive measure to detect the presence of IOL pathology.…”

“…20,30 MTF levels of a calcified IOL after the DMEK/DS(A)EK procedure were presented in two studies, however, straylight was not included in those reports. 12,22 The aim of this laboratory study was to assess the effect of centrally localized IOL calcification, associated with the intraocular injection of gas, on the lens optical quality by measuring the MTF and straylight measurements. The relationship was established between the straylight parameter and morphological parameters, which were derived from the laboratory analysis and image processing.…”

“…Light scattering was assessed using a commercial device (C-Quant; Oculus GmbH, Germany) adapted for in vitro straylight measurements of IOLs. 21,22 In short, the straylight meter consists of a central test field surrounded by an annular straylight source with effective 7° radius. [31][32][33] It uses the two-alternative forced choice psychophysical compensation comparison method, which has been described extensively elsewhere.…”

Intraocular light scatter, reflections, fluorescence and absorption: what we see in the slit lamp

“…[102][103][104][105][106][107][108] Often the problem shows up clearly in the slit lamp image, but not always. 109…”