The photoactivated agent produces activated oxygen species, such as hydroxyl radicals and {HEAD ~ other radicals}, that damage {TAIL ~ the new vessels}, and may occlude the vessels 
The photoactivated agent produces activated oxygen species , such as hydroxyl radicals and { HEAD ~ other radicals } , that damage { TAIL ~ the new vessels } , and may occlude the vessels
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH