From your description, you have a challenging unilateral congenital ptosis on the right - apparently with poor levator function. The challenge is this: you will need BILATERAL fascia lata frontalis slings with release of the left upper lid levator. Most likely, you have had sling procedures on the right side only (is that correct?). Unilateral surgery will not produce successful lift or symmetry. Surgery on "the good lid" as well as the ptotic lid is the only approach to provide good lid levels and symmetry. Banked fascia lata is available and very effective - which allows surgery under local anesthesia with minimal sedation. With a modified Crawford technique, the fascia may be directly sutured to tarsus and frontalis, so that it is unlikely to slip (synthetic materials will slip). An Oculoplastic surgeon experienced with this type of surgery could help you. Best wishes for success!