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  • Glistening and Straylight in Hydrophobic-Acrylic IOLs

    By Lynda Seminara
    Selected By: Richard K. Parrish II, MD
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    Journal Highlights

    American Journal of Ophthalmology, December 2018

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    Glistenings, or fluid-filled microvac­uoles (MVs), have been reported for implanted intraocular lenses (IOLs). However, relationships between glistenings and glare symptoms (i.e., straylight) and their effects on visual acuity are subjects of debate. In a study of 6 IOL models, Łabuz et al. found that although glistening formation var­ied, higher quantities correlated with elevated levels of straylight, regardless of the type of IOL. In 20% of IOLs, the amount of light scatter was high enough to hinder vision.

    The authors looked at 5 samples of all 6 hydrophobic-acrylic IOL models. (Each model has a unique composition of polymers.) All lenses were manufac­tured recently and had an expiration date of ≥3 years. To mimic accelerated aging, IOLs were incubated for 24 hours at 45 degrees C (113 degrees F) before placement into a water bath (37 C; 98.6 F) for 2.5 hours. Light micros­copy and digital processing of images revealed the number of MVs per square millimeter and their size. A modified clinical meter depicted in vitro stray­light originating from the IOL before and after the aging process. Results were compared with data from 20-, 70-, and 80-year-old crystalline lenses.

    Glistenings were observed in all but a single IOL model. The number of glistenings ranged from 0-3,532 MV/mm2, and their mean size varied from 5.2 μm to 10.2 µm. In 4 models, peak density occurred in the center of the lens; in another model, glisten­ing appeared only in the periphery. Aging increased the mean straylight in IOLs from 0.6-5.0 degrees squared per steradian, and a strong correlation was observed between straylight parameters and the number of glistenings.

    Although the importance of stray­light remains debatable, such light has been associated with impaired visual function, especially during driving. In this study, light scattering was sufficient to compromise visual function in one-fifth of the IOLs. The relationship be­tween MVs and straylight was maintained despite differences in glistening size and IOL material. Glistening varia­tions were observed between, as well as within, the IOL models.

    The original article can be found here.