That is a great article, great breakdown and research of the infamous droop-eye.
1.)I raised my arow from about 4"(no yoke sac). He is now just under a year old and over 14" and has droop-eye in the right side. My arow developed mild DE after about 6 months when he was 6-7". It has remained mild since, not progressively getting worse or improving. 2.)I keep the lights on a timer for only 8 hours a day, 3.)feed him floating sticks, pellets, and frozen and/or freeze dried krill. 4.)His tankmates are quite active, maybe drawing his eye to look down. I kept him with 2 black-banded leporinus, a pim pictus cat and a gold nugget pleco. 5.)His original tank was rather small, 36x12x24, and I've heard a lot of theories of narrow tanks causing DE. Since then is in a larger tank. 6.)I do 25% water changes 2-3 times a month. 7.) I perfer not to feed my arow live fish, I had one before that got sick and died after the very first time I fed it live prey.