Clinically significant macular edema (CSME) is one of the leading causes of vision loss in diabetic retinopathy. The current standard of care for CSME is focal/grid laser photocoagulation. However, many patients experience further vision loss and/or require multiple laser treatments. In recent studies, intraocular (intravitreal) injection of triamcinolone acetonide has been shown to be beneficial for CSME, however, risks of this procedure include endophthalmitis and increased risk of steroid-induced intraocular pressure (IOP) elevation. Posterior sub-Tenon injection (PST) of triamcinolone acetonide is commonly used for inflammatory conditions of the eye and recently, has been increasingly used for diabetic macular edema. The objective of this study is to determine whether combined treatment with PST triamcinolone acetonide and laser photocoagulation for CSME has decreased rates of moderate vision loss, increased visual gain, and decrease in central macular thickness compared to laser photocoagulation alone. Both primary (no previous history of focal/grid laser) and refractory (previous history of focal/grid laser) CMSE will be studied. Thirty (30) eyes with primary CSME and thirty (30) eyes with refractory CSME will be randomized into one of two groups: 1) PST/Laser group and 2) Laser alone group. All patients will have an Optical Coherence Tomography (OCT) at the initial and final visits. Patients assigned to PST/Laser group will use topical steroid (1% prednisolone acetate) four times a day for two weeks. Patients who have elevated IOP with topical steroids will not receive PST steroid injection. Following treatments, patients will be evaluated at 1 and 2 months for a dilated eye exam, visual acuity, and assessment of IOP. Moderate vision loss (loss of 15 ETDRS letters), vision gain (in ETDRS letters), and central macular thickness (measured by OCT) will be compared between groups. Multivariate analysis will also be used to compare outcomes from the two arms of the study.