Light scattering, straylight, and optical quality in hydrophobic acrylic intraocular lenses with subsurface nanoglistenings

Abstract

Dr. Das is an employee of Alcon Laboratories, Inc. The Complete Angle Instrument scatterometer was developed by Dr. Stover at the Scatterworks, Inc. Neither of the other authors has a financial or proprietary interest in any method or material mentioned.

Effects of Intraocular Lens Opacification on Light Scatter, Stray Light, and Overall Optical Quality/Performance

“…Interestingly, in another study performed on cadaver-eye removed hydrophobic acrylic (AcrySof; Alcon Laboratories, Fort Worth, TX, USA) lenses with subsurface nanoglistenings (small water molecules present within the lens subsurface), none of the lenses exhibited stray light values greater than or equal to 1.47 Log (s). 28 Also laboratory aged AcrySof lenses demonstrated stray light values much lower than the stray light hindrance. 18 However, further studies are necessary to assess the effects of glistenings (microvacuoles filled with water present within the IOL substance) on stray light based on the measurements of forward light scattering.…”

“…This is the same method we have recently used to evaluate hydrophobic acrylic IOLs with subsurface nanoglistenings removed from cadaver eyes. 28 In summary, we provided a complete characterization of the effects of IOL opacification on the visual function, by measuring forward light scattering and subsequently obtaining stray light, as well as other optical quality/performance indicators in a large series of lenses explanted because of calcification and snowflake degeneration. The levels of stray light found with the explanted lenses would be expected to cause a serious negative impact on the visual function, even if visual acuity was not significantly reduced.…”

Glistening Formation and Light Scattering in Six Hydrophobic-Acrylic Intraocular Lenses

“…42 Although very small, nano-glistenings can scatter light, producing a white discoloration of the IOL. 41 Despite the presence of increased diffuse light scattering, the straylight of the Aktis IOLs remained low but this this could have been expected, as there are reports that nanoglistenings do not have a significant straylight effect. 41,43 Since IOL manufacturers acknowledged the problem of glistening formation, some materials have been improved and this is especially well described for the Alcon Acrysof.…”

“…The whitish appearance of these lenses ( Figure 3) may suggest the presence of subsurface nano-glistenings, 41,42 given that the gross examination did not reveal visible microvacuoles in the lens centre. Nano-glistenings are submicron water vacuoles of 33nm to 190nm size that accumulate just underneath the lens surface.…”

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

“…Submicron particles have also been found in IOLs (i.e. nanoglistenings), but their potential straylight effects have received little attention [7,8], partly because of the difficulty of detecting submicron particles, and also because clinicians have limited access to objective straylight measurements.…”