Can droopy eyelids cause blurred vision and is it bad for long term vision?

Generally not permanent.  I encourage you to be assessed by an ophthalmologist or an oculofacial plastic surgeon to be assessed for your concerns.

When droopy eyes become significant enough, they end up blocking the peripheral vision. A functional blepharoplasty can improve this.

Drooping of the eyelids can be a factor in causing blurred vision, but the blurring usually resolves with correction of the eyelid problem (and glasses if needed). Ptosis can induce astigmatism. Likewise floppy eyelid syndrome can be associated with refractive error or induce refractive error. If your are symptomatic, then it is very reasonable to proceed with evaluation by an oculoplastic surgeon. Best wishes.