Just as you hear your past self asking what happened to your eye, you jab Sawbuck with your BUTTERFLY EFFECT KNIFE. You remember a little while ago asking yourself about your eye, and not giving yourself an answer just before disappearing. Maybe if you stopped and thought about it for a second, you could have warned yourself and avoided the whole mess, albeit in the process of creating a paradox. But your strict policy of stabbing first and answering questions later prevented it. You're sure your past self understands/understood. You are sure of this because you very clearly remember understanding/understooding.