In vitro glistening formation in IOLs: automated method for assessing the volumetric density and depth distribution of microvacuoles

Glistening on intraocular lenses: A review

The glistening in intraocular lenses (IOLs) is a phenomenon in which tiny water-filled microvacuoles (MVs) form within the IOL material, causing light to scatter and create a sparkling or shimmering effect. The presence of glistening is common in many types of IOL materials and models and has been extensively studied in recent years to determine its incidence, risk factors, evolution, and possible clinical relevance. Classically, it has been studied in vitro in the laboratory or by means of photography obtained with a slit lamp, but these were techniques that required either specific technology or an expert explorer, complex image processing, and required a lot of time. In recent years, proposals based on the Scheimpflug camera and optical coherence tomography have emerged to try to simplify the analysis of glistening in IOLs. It has been described that the manufacturing process, the hydrophobic acrylic material, or the time since surgery are risk factors for the appearance of glistening. In addition, many issues related to this phenomenon are still unknown, such as not knowing from what number of points or their size they may have relevance to visual function since different optical phenomena related to glistening have been described on the IOLs.

Quantification of the In Vitro Predisposition to Glistening Formation in One Manufacturer's Acrylic Intraocular Lenses Made in Different Decades

Introduction

Foldable hydrophobic acrylic intraocular lenses (IOLs) are prone to develop a long-term postoperative material change called glistenings. The aim of this study was to investigate the changes in the predisposition for glistening formation in one type of hydrophobic acrylic IOL material from its introduction to the present day.

Methods

In a laboratory setup, an in vitro model was used to induce glistenings in hydrophobic acrylic IOLs manufactured by one company (Alcon, Fort Worth, TX, USA) in different years: 23 1990s-manufacture hydrophobic acrylic three-piece IOLs (MA30BA/MA60AC) that were explanted in 1996 and 1997, and five of each of the newer AcrySof IOL models (MA60AC, SA60AT, TFNT00 and SN60WF) from 2014 to 2017. Furthermore, five Clareon (SY60WF) IOLs were put through the same accelerated aging procedure. The number of microvacuoles per square millimeter (MV/mm²) was determined in the central part of each IOL optic and compared between the groups.

Results

The mean number of MV was highest in the 1990s-manufacture Alcon acrylic IOLs, with 1289 (± 738) MV/mm². The number decreased to 650 (± 101), 192 (± 105), 175 (± 112) and 47 (± 26) for MA60AC, SA60AT, TFNT00 and SN60WF, respectively. The lowest count was obtained in the Clareon group, with 1 (± 1) MV/mm².

Conclusions

A high number of glistenings was induced in the explanted IOLs from the 1990s. The propensity for glistening formation decreased considerably after that decade and now in current use. Even though in vitro glistening formation in today’s AcrySof material was low, the Clareon material was essentially glistenings-free.