Calcification and Membrane Formation on the Surface of Intraocular Lenses in a Rabbit Model

Abstract

Purpose: The aim of this study is to evaluate the calcification and membrane formation in different intraocular lenses (IOLs) models by implanting the IOLs in the subcutaneous plane of a Rabbit model. Design: Experimental study. Methods: IOLs were implanted subcutaneously in 13 Japanese albino rabbits for 1 month (n = 6), 3 months (n = 4) and 6 months (n = 3). Five kinds of IOLs were used, including three hydrophobic acrylic IOLs, the MA60AC (Alcon), ZA9003 (AMO) and X-60 (Santen), and two hydrophilic acrylic IOLs, the HP60M and MI60 (Bausch & Lomb). Scanning electron microscopy was used to observe the IOL optics. Energy dispersive x-ray spectroscopy and infrared spectroscopy were used to analyse any surface depositions on the optics, and the modulation transfer function was applied to evaluate the optical performance. Results: Membrane formation was noted to have occurred on the surfaces of the two hydrophobic acrylic IOLs (MA60AC and ZA9003) during the investigation period. The membrane components originated from a serum protein that most likely would be serum albumin. Calcification was noted to have occurred on the surfaces of the two hydrophilic IOLs. However, no calcification was observed on the hydrophobic IOLs, nor was there any membrane formation on the hydrophilic IOLs. The values for the MI60 were not measurable at all at 3 or 6 months. The values of the three hydrophobic IOLs were significantly better than the value for the HP60M at three and six months (p < 0.01). Conclusion: Calcification to the hydrophilic IOLs severely affected optical performance, whereas, membrane formation on the hydrophobic IOLs did not affect optical performance. The X-60 had the optics that best maintained long-term transparency.