How Soon Can I Tell if my Vision Will Be Affected by Botox?

It would be HIGHLY unlikely for you to suffer any visual disturbances from a cosmetic Botox injection - but always refer back to your provider for reassurances and visit their website for any and all potential side effects.

At this point, there is minimal risk of complications from your previous Botox injections.  Vascular occlusion would be a very rare complication from neurotoxin injections. Raffy Karamanoukian, Los Angeles

It sounds like you have been reading too much and are a bit confused.  Vascular occlusion does not happen with Botox, but only with fillers (extremely rare as well).  Changes in vision are mostly related to the Botox migrating to the extraocular muscles.  This leads to double vision, which is temporary.  How this happens is when the injection is too close to the eye and with alot of volume so there is diffusion.  I've also heard that people who have had strabismus in the past are more susceptible to this problem.  In any event, it is so rare it should not be a concern.  Also, getting a drop of Botox in the eye can lead to pupil issues, so closing you eyes during injection is also a good idea.