2007 ICD-9-CM Procedure 15.21 Lengthening procedure on one extraocular muscle 15.21 is a specific code that can be used to specify a procedure 15.21 contains 3 index entries View the full Volume 3 15.* hierarchy Index entries containing 15.21: Lengthening extraocular muscle NEC 15.21 multiple (two or more muscles) 15.4 muscle 83.85 extraocular 15.21 multiple (two or more muscles) 15.4 Myotomy 83.02 eye (oblique) (rectus) 15.21 multiple (two or more muscles) 15.4