OCT 03, 2012
Nick Mamalis, MD, discusses the relatively common phenomenon of glistenings in this "From the editor" item in the July Journal of Cataract & Refractive Surgery. He concludes that while time has been shown to be the most significant factor in the formation of glistenings, which are addressed in two studies in the issue, it remains unclear whether they have a significant effect on visual acuity or visual functioning. He recommends future long-term studies on glistenings and visual function, but notes that promising new generations of hydrophobic acrylic IOL materials may provide a glistening-free IOL.
Glistenings, fluid-filled microvacuoles that form within an IOL optic when the IOL is in an aqueous environment, have been reported most commonly in patients with hydrophobic acrylic IOLs. Dr. Mamalis says that most studies that have looked at the CDVA have not found a statistically significant difference in eyes with glistenings.
The results for contrast sensitivity have been mixed, with some studies finding no effect of glistenings but others finding a difference in high contrast sensitivity when looking at high spatial frequencies. He says that the question of light scattering in IOLs with glistenings and its effect on quality of vision and contrast sensitivity is still unclear. However, even significant glistenings and high-level light scattering from the IOLs have not been shown to have a detectable impact on CDVA or low contrast visual acuity.
A retrospective study in the issue addressed glistenings in eyes implanted with a monofocal hydrophobic acrylic posterior chamber IOL with an aspheric optic and a blue light-filtering chromophore that renders the IOL yellow. The study's authors conclude that while glistenings were common in these eyes and increased in severity over time, the phenomenon did not have a clear effect on visual acuity.
A second study in the issue examined a new generation of "glistening free" hydrophobic acrylic material used in the manufacture of IOLs and found that it combined the advantages of hydrophobic and hydrophilic acrylic materials but was not susceptible to postsurgical changes that promote glistenings. It performed much like a conventional hydrophobic acrylic material in terms of hydrophobicity and bioadhesiveness, allowing for the potential advantages of a normal hydrophobic acrylic material with a glistening-free optic.