I can tell you this, so fast I haven't had any of the side effects with regards to vision yet. Funny thing you ask about LGD 4033 in which I'm stacking then together. These two together are amazing, I've put on about 3lbs in the week I've started them. The pumps are crazy good, almost to whereas I have to stop my workouts because my muscles almost cramp up (especially in my biceps ). I can say I don't know if it's coming from the LGD or S4 but in tandem they're great.