The Zohar says that every מכה that afflicted the Egyptians was a healing for the Jews [נגף ורפא]. The pasuk intends to give us a bracha. They couldn't see their brothers, the bracha is that we SHOULD see our brothers. When a fellow Jew is experiencing darkness we must see and feel his pain and be there for him. ולא ראו איש את אחיו but for us ראו איש את אחיו we DO see our brothers!
פלאי פלאות!
This Shabbos "Bo" let's make the tikkun:-)!
Love and blessings