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 degrees C, and evaluated every 24 hours at 37 degrees 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 degrees C. The glistenings were smallest in the 1-piece AcrySof IOLs (P <.001): 6.3 microm versus 11.5 microm in the Sensar and 13.4 microm 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 microm. The 3-piece AcrySof IOLs showed a significant decrease in slitlamp-countable glistenings but acquired a dense haze seen as minute glistenings (4.0 microm) at x80 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 microm (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.