MPO and snowflake vitreoretinal degeneration: However, there was a highly significant (p < 0.001) decrease in plasma MPO levels found in the TRF 60, TRF 120, and DON group of rats compared to the AlCl3 group rats; thus, indicating that TRF and DON may have reduced AlCl3-induced vascular inflammation and SVD development in rats (Figure 3).