Minimal impact from glistenings

Ten years after cataract surgery, even severe glistenings had no deleterious visual impact on patients, according to a new report. “Most patients in this case series operated 10 years previously had severe glistenings and a high level of light scattering from their intraocular lenses,” reported lead study author Eva Mönestam, M.D., Ph.D., department of clinical sciences and ophthalmology, Umeå University, Umeå, Sweden. “No detectable impact on BCVA [best corrected visual acuity], LCVA [low contrast visual acuity] 10% and 2.5% was found.”
The study was published online in January in Acta Ophthalmologica. Glistenings, Dr. Mönestam noted, are refractile microvacuoles found within all IOL materials but most notably in hydrophobic acrylic IOLs and “have been proposed to consist of excess of water or aqueous inflow into the plastic material of the IOL.”
Dr. Mönestam believes this study has the longest follow-up period studying glistenings but suggested that further follow-up over the coming decades will be important since patients are now having refractive lens exchange at an early age, meaning many will retain IOLs for 40 years or longer.
“Because of the progressive nature of the glistenings, the future will show whether there is a point when the glistenings start to have clinical consequences,” Dr. Mönestam wrote. “There is no known remedy other than IOL exchange if the glistenings are believed to be bothersome to the patient.”
A critical look
Dr. Mönestam analyzed 103 patients who underwent implantation with the AcrySof MA60BM IOL (Alcon, Fort Worth, Texas) 10 years earlier. The mean BCVA was –0.02, the mean LCVA 10% was 0.26, and the mean LCVA 2.5% was 0.66. “Mean BCVA was significantly better in the group with a low number of glistening,” Dr. Mönestam reported. “After adjustment for age, this difference was no longer significant.”
Glistenings also did not appear to impact light scattering. “There was no difference in measured light scattering between eyes graded as having moderate and pronounced/ intense amounts of glistening,” Dr. Mönestam reported.
Patients were further divided into subsets depending on the grade of their glistenings and degree of light scattering. “In two subsets of patients, paired data from the patients’ eyes were analysed,” Dr. Mönestam reported. “It was not possible to detect any significant impact on visual function, BCVA and LCVA 10% and 2.5%, not even in patients with pronounced light scatter or a higher degree (3+ and 4+) of glistenings as graded at the slit-lamp.”
This was a surprise to the researchers. “It is well known that light scatter together with aberration and diffraction in the visual system is among several possible limitations of visual performance,” Dr. Mönestam noted. “We focused on BCVA and LCVA and the relative difference between these parameters because glistenings cause increased light scattering of the IOL, which primarily affect contrast sensitivity. One reason it is difficult to find any clinical impact on visual function despite severe glistenings might be that the AcrySof IOL in itself is believed to have a favourable optical performance compared with other IOLs.”
Still, the results were a continuation of some shorter-term previous results suggesting glistenings are relatively harmless, Dr. Mönestam noted. “In vitro studies on the optical quality of IOLs have also shown no significant effect of glistening within the clinical range, regarding the optical quality as measured by spectral transmittance, intensity of forward scattering, modulation transfer function and resolving power at various contrasts,” Dr. Mönestam reported. “Only in IOLs with the most severe glistenings, believed to be beyond the clinical range, it was possible to detect mild to moderate deterioration of the optical quality.”
William B. Trattler, M.D., cornea specialist, Center for Excellence in Eye Care, Miami, nonetheless said he remains concerned about glistenings. “I have been concerned for awhile,” he said. “They’re not problematic for most patients but some can get significant glistenings.”

Editors’ note: Dr. Mönestam reported no financial interests related to this study. Dr. Trattler has financial interests with Abbott Medical Optics (Santa Ana, Calif.).

Contact information

Mönestam: eva.monestam@vll.se
Trattler: 305-598-2020, wtrattler@earthlink.net