tokens: At the end of the procedure , Group A ( n = 20 ) had 20 mg / 0 . 5 mL of methylprednisolone and 10 mg / 0 . 5 mL of gentamicin injected into the posterior sub - Tenon ' s space and Group B ( n = 20 ) had the same combination injected into the anterior sub - Tenon ' s space .