Diabetic macular edema refers to swelling (fluid accumulation) in the center of the retina. The retina is like the film of a camera and is located in the back of the eye. This condition can develop in diabetics where swelling results from leaking of fluid from the blood vessels of the eye, into the center of the retina, the macula. If left untreated, this can affect central vision. The current standard treatment for diabetic macular edema includes medications injected directly into the eye (intravitreal injections) and laser eye treatment. The drugs that are injected directly into the eye are known as anti-Vascular Endothelial Growth Factor (anti-VEGF) agents which help to reduce the leaking. This includes bevacizumab (Avastin®) and ranibizumab (Lucentis®).

However, some patients do not respond well to these anti-VEGF treatments will be given the option of switching to an another class of medications, called steroids. Triamcinolone acetonide is one of these steroids and is also injected directly into the eye. These steroids will help reduce inflammation and possibly as a consequence, reduce swelling in the eye.

The purpose of this study is to determine what cellular factors affect a patient's treatment response (amount of swelling reduction) following triamcinolone acetonide intravitreal injections for diabetic macular edema.

Inclusion Criteria:

• Presence of Non Proliferative Diabetic Retinopathy (NDPR) or Proliferative Diabetic Retinopathy as confirmed by IntraVenous Fluorescein Angiography (IVFA)
• Prior treatment with ≥ 6 intravitreal anti-VEGF injections but no treatment in last 4 weeks
• Less than 10% improvement in Central Macular Thickness on OCT scan and less than 1 line improvement in vision from baseline
• Less than 10% reduction in macular volume
• Age 18 years or older
• Subjects with Type I or II diabetes mellitus
• snellen Acuity 20/40 to 20/400 and its ETDRS equivalent
• Ability to provide signed informed consent
• Capable of complying with study protocol.

Exclusion Criteria:

• Previous intraocular injection of steroid medication.
• Concurrent ocular disease (wet Age-Related Macular Degeneration, significant Epiretinal Membrane, vitreomacular traction etc) that would limit visual acuity in the opinion of the treating physician
• Proliferative diabetic retinopathy in the study eye or PanRetinal Photocoagulation within the last 12 months
• Poor glycemic control HbA1c >9%
• Prior vitrectomy surgery.
• Prior intraocular surgery within 3 months in study eye
• Laser treatment within 3 months of study eye
• Use of systemic steroids (eg, oral, intravenous, intramuscular, epidural, rectal, or extensive dermal) within 1 month prior to study enrollment.
• Known history of Intraocular Pressure (IOP) elevation in response to steroid treatment in either eye that resulted in any of the following: a) = 10 mm Hg increase in IOP in response to steroid injection, or b) IOP = 25 mm Hg and required 2 or more anti-glaucoma medications to keep IOP below 21 mm Hg.
• Known allergies to study drug or fluorescein
• History of stroke or acute Myocardial Infarction within 6 months of enrolment
• Patients receiving dialysis for renal failure
• Patients currently on systemic immunosuppression
• Patients with glaucoma
• Patients who are pregnant.
• Unwilling or unable to follow or comply with all study related procedures