Glistening formation in an AcrySof lens initiated by spinodal decompositionof the polymer network bytemperature change

Abstract

Purpose: To examine the effect of temperature change on the structural alteration and glistening formation in an AcrySof® intraocular lens (IOL). Setting: Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Kobe, Japan. Methods: The equilibrium water content of a Wagon-Wheel-packaged AcrySof IOL was determined at various temperatures by the gravimetrical method. Alterations in the microscopic structure of the lens were analyzed in situ with a reflecting microscope without staining, while the temperature of the lens was changed at different rates. Results: Microvacuoles of 1.0 to 20.0 μm formed in the bulk of a swollen AcrySof IOL as the temperature decreased. The morphology of the vacuoles was similar to that of glistening particles observed in vivo. The size and density of the glistening-like vacuoles varied depending on the magnitude and rate of the temperature decrease. The glistening-like vacuoles were imprinted in the bulk of the IOL during the preceding cooling process in aqueous humor. Conclusions: Glistenings formed in the bulk of an AcrySof IOL as the medium temperature decreased. The mechanism may involve spinodal decomposition of the swollen polymer network, which initiates the formation of microvacuoles consisting of water and loosely packed network chains.