Figure 2. Cell death of human RPE cells from primary culture exposed to 75 μM HQ. LDH assays demonstrated the time-dependent cytotoxicity of 75 μM HQ on primary RPE culture (P5). The 3.6% and 9.5% cell death rates occurred at 12 h and 24 h after exposure to 75 µM HQ, respectively (mean±SD). RPE culture at the starting point of exposure served as control, which represented 0% cell death. The HQ-induced cell death reached a significance level of p<0.05 at 12 h or 24 h compared with control. p<0.05 (shown with asterisks).