You are most probably suffering from scarring on the cornea after the healing of the ulcer. If that is the case and the scar is superficial, it can be treated with Excimer Laser by a procedure known as Phototherapeutic Keratectomy (PTK). If, however, it is a deep scar you will have to undergo corneal grafting. Get a detailed eye examination by the cornea specialist at a reputed centre for the above said treatments.