Evaluation of long-term changes in physicochemical properties of hydrophobic intraocular lenses in a laboratory model

Background: In ophthalmology, the surface properties of implants such as intraocular lenses (IOLs) play a crucial role in the quality of vision because they may affect posterior capsule opacification (PCO), which is one of the most common long-term complications of cataract surgery, inevitably leading to revision surgery. The PCO effect increases when the epithelial cells of the lens remaining in the capsule’s bag after IOLs implantation adhere, proliferate, grow, migrate and differentiate. For this reason, in vitro performance of IOLs, including protein adsorption on the implant surface (the initial step of cells adhesion), allows predicting its stability in vivo. Material and methods: We evaluated the physicochemical properties of six different hydrophobic commercial intraocular lenses (IOLs) in a two-step model experiment. During the first step, IOLs were immersed in the BSS solution. This stage simulated a 5-year implantation of the IOL within the eye. During the second step, IOLs were incubated in the albumin solution. These processes simulated protein adsorption onto the IOLs’ surface. Results: On the surface of the examined IOLs glistening was observed in all the lenses after the in vitro condition. The model experiment showed that the transparency of the IOLs decreased by about 2–20% compared with the initial IOLs (p < 0.05). Surfaces of all IOLs became more hydrophilic after the glistening phenomena and after the time of protein (albumin) adsorption. Such surfaces are presumed to be more susceptible to adhesion of cells promoting the PCO effect. Conclusions: The in vitro results (57 days/85°C/PBS) showed that the synergistic effect of two factors — glistening and protein adsorption — did not deteriorate the quality of visual acuity; however, it may facilitate cell adhesion that precedes the PCO phenomenon