Treatment of Diabetic Macular Edema With Aflibercept in Subjects Previously Treated With Ranibizumab or Bevacizumab

Inclusion Criteria: 1. Men and women ≥ 18 years of age. 2. Foveal-involving retinal edema secondary to DME based on investigator review of clinical exam and SDOCT with central subfield thickness value of 325 microns by Zeiss Cirrus SD-OCT. 3. E-ETDRS best-corrected visual acuity of: 20/25 to 20/400 in the study eye. 4. History of previous treatment with anti-VEGF with at least 4 injections over the last 6 months. 5. Willing, committed, and able to return for all clinic visits and complete all study related procedures. 6. Able to read, (or, if unable to read due to visual impairment, be read to verbatim by the person administering the informed consent or a family member.) understand and willing to sign the informed consent form. \- Exclusion Criteria: 1. Any prior or concomitant therapy with another investigational agent to treat DME in the study eye. 2. Prior panretinal photocoagulation in the study eye within the past 3 months. 3. Prior intravitreal anti-VEGF therapy in the study eye within 30 days of enrollment. 4. Prior systemic anti-VEGF therapy, investigational or FDA-approved, is only allowed up to 3 months prior to first dose, and will not be allowed during the study. 5. Previous treatment with intravitreal aflibercept injection 6. Significant vitreous hemorrhage obscuring view to the macula or the retinal periphery as determined by the investigator on clinical exam 7. Presence of other causes of macular edema, including pathologic myopia (spherical equivalent of -8 diopters or more negative, or axial length of 25 mm or more), ocular histoplasmosis syndrome, angioid streaks, choroidal rupture, choroidal neovascularization, age-related macular degeneration or multifocal choroiditis in the study eye. 8. Presence of macula-threatening traction retinal detachment. 9. Prior vitrectomy in the study eye. 10. History of retinal detachment or treatment or surgery for retinal detachment in the study eye. 11. Any history of macular hole of stage 2 and above in the study eye. 12. Any intraocular or periocular surgery within 3 months of Day 1 on the study eye, except lid surgery, which may not have taken place within 1 month of day 1, as long as it's unlikely to interfere with the injection. 13. Uncontrolled glaucoma at baseline evaluation 14. Active intraocular inflammation in either eye. 15. Active ocular or periocular infection in either eye. 16. Any ocular or periocular infection within the last 2 weeks prior to Screening in either eye. 17. Any history of uveitis in either eye. 18. History of corneal transplant or corneal dystrophy in the study eye. 19. Significant media opacities, including cataract, in the study eye which might interfere with visual acuity, assessment of safety, or fundus photography. 20. Any concurrent intraocular condition in the study eye (e.g. cataract) that, in the opinion of the investigator, could require either medical or surgical intervention during the 52 week study period. 21. Any concurrent ocular condition in the study eye which, in the opinion of the investigator, could either increase the risk to the subject beyond what is to be expected from standard procedures of intraocular injection, or which otherwise may interfere with the injection procedure or with evaluation of efficacy or safety. 22. Participation as a subject in any clinical study within the 12 weeks prior to Day 1. 23. Any systemic therapy with an investigational agent in the past 3 months prior to Day 1. 24. Any history of allergy to povidone iodine. 25. Pregnant or breast-feeding women 26. Women of childbearing potential who are unwilling to practice adequate contraception during the study -