In vitro comparison of glistening formation among hydrophobic acrylic intraocular lenses

Purpose: To compare glistening formation induced by temperature stressing in vitro among hydrophobic acrylic intraocular lenses (IOLs) available in the United States. Setting: John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Methods: Wagon Wheel (WW) packaged 1‐piece AcrySof® IOLs (Alcon), WW‐packaged 3‐piece AcrySof IOLs, and Sensar® IOLs (Allergan Medical Optics) were analyzed in vitro for 5 consecutive days. Ten IOLs of each type were inserted into viewing chambers filled with balanced salt solution, maintained at 37°C, and evaluated every 24 hours at 37°C and then, after a 2‐hour cooling, at room temperature. The IOLs were examined by slitlamp to quantify glistenings and by digital photography to determine glistening size. Results: The glistening quantity was minimal and did not differ among IOL types at 37°C. The glistenings were smallest in the 1‐piece AcrySof IOLs (P < .001): 6.3 &mgr;m versus 11.5 &mgr;m in the Sensar and 13.4 &mgr;m in the 3‐piece AcrySof. Upon cooling, the glistening quantity increased dramatically in the 1‐piece AcrySof IOLs (P < .008) and was the highest among the IOL types at room temperature (P < .001). The mean glistening size was 7.7 &mgr;m. The 3‐piece AcrySof IOLs showed a significant decrease in slitlamp‐countable glistenings but acquired a dense haze seen as minute glistenings (4.0 &mgr;m) at ×80 magnification. The glistening quantity in the Sensar IOLs was fairly stable upon cooling; a statistical increase was seen on the last day (P = .007). Cooling nearly doubled the size of the Sensar glistenings, which were the largest at room temperature, 21.7 &mgr;m (P < .001). Conclusions: Glistening quantity varied among hydrophobic acrylic IOLs and was temperature dependent. Sensar IOLs were more stable than the 2 other IOL types. The glistening phenomenon must be studied further to eliminate the problem.