We have previously investigated the effects of repetitive acute (6 hours every 3 days for 4 weeks) and transient (6 hours followed by a recovery phase, every 5 days for 6 weeks) exposure of ARPE-19 cells to HQ on matrix metalloproteinase-2 activity and extracellular matrix turnover relevant to the pathogenesis of dry AMD [26]. This evidence concerns the gene MMP2 and dry age related macular degeneration.