Ranibizumab in Residual Diabetic Macular Edema Following Previous Anti-VEGF Therapy

Inclusion Criteria: * Subjects will be eligible if the following criteria are met: 1. Age \> 18 years 2. Diagnosis of diabetes mellitus (type 1 or 2) 3. Residual edema as determined by mean foveal thickness on Cirrus OCT \> 300 microns and leakage seen on FA at baseline 4. Clinical evidence of retinal thickening due to macular edema involving the center of the macula, associated with diabetic retinopathy. 5. Previous history of at least 4 or more consecutive anti-VEGF intravitreal injections of Pegaptanib sodium or Bevacizumab (consecutive injections administered no more than 6 weeks apart in the last year) for the treatment of diabetic macular edema. 6. Previous history of focal laser and/or intravitreal steroid injection for the treatment of diabetic macular edema. 7. BCVA of 20/32-20/400 (ETDRS) 8. Media clarity, pupillary dilation and patient cooperation sufficient to allow OCT testing and retinal photography Exclusion Criteria: 1. Pregnancy (positive pregnancy test) or known to be pregnant; also pre-menopausal women not using adequate contraception. . The following are considered effective means of contraception: surgical sterilization or use of oral contraceptives, barrier contraception with either a condom or diaphragm in conjunction with spermicidal gel, an IUD, or contraceptive hormone implant or patch. 2. Participation in another ocular investigation or trial simultaneously. 3. Systemic use of anti-VEGF within 3 months prior to day 0. 4. Previous intravitreal ranibizumab within 3 months prior to day 0 5. Blood pressure \> 180/110 (systolic above 180 OR diastolic above 110) 6. Any condition that, in the opinion of the investigator, would preclude participation in the study (e.g. chronic alcoholism, drug abuse). 7. Evidence of vitreoretinal interface abnormality after ocular exam or OCT that may be contributing to the macular edema. 8. An eye that, in the investigator's opinion, has no chance of improving in visual acuity following resolution of macular edema (e.g. presence of subretinal fibrosis, ischemic maculopathy or geographic atrophy). 9. Presence of another ocular condition that may affect the visual acuity or macular edema during the course of the study (e.g. AMD, uveitis, Irvine-Gass). 10. Evidence of active neovascularization of the iris or retina. 11. Evidence of central atrophy or fibrosis in the study eye. 12. Presence of substantial cataract, one that might decrease the vision by 3 or more lines of vision at sometime during the study. 13. History of vitreous surgery in the study eye. 14. History of cataract surgery within 6 months of enrollment. 15. History of YAG capsulotomy within 2 months of enrollment.