Abstract: Seven studies, involving 632 DME eyes were included. Four examined the effectiveness of intravitreal triamcinolone acetate injection (IVTA), three examined intravitreal steroids implantation (fluocinolone acetonide implant (FAI) or dexamethasone drug delivery system (DDS)). Two trials were at low risk of bias, one was at median risk of bias, two were at high risk of bias and the remaining two were at unclear risk of bias.  The preponderance of data suggest a beneficial effect from IVTA. Comparing IVTA with controls, the mean difference in visual acuity was -0.15 LogMAR (95% CI -0.21 to -0.09) at 3 months (based on three trials), -0.23 LogMAR (95% CI -0.33 to -0.13) at 6 months (two trials), -0.29 LogMAR (95% CI -0.47 to -0.11) at 9 months (one trial), and -0.11 LogMAR (95% CI -0.20 to -0.03) at 24 months (one trial), all in favor of IVTA. The relative risk (RR) for one or more lines improvement in visual acuity was 2.85 (95% CI 1.59 to 5.10) at 3 months (two trials), 1.25 (95% CI 0.66 to 2.38) at 6 months (one trial), and 2.17 (95% CI 1.15 to 4.11) at 24 months (one trial), all in favor of IVTA. We did not find evidence for three or more lines improvement in visual acuity. The mean difference in retinal thickness was -131.97 um (95% CI -169.08 to -94.86) at 3 months (two trials), -135.00 um (95% CI -194.50 to -75.50) at 6 months (one trial), -133.00 um (95% CI -199.86 to -66.14) at 9 months (one trial), and -59.00 um (95% CI -103.50 to -14.50) at 24 months (one trial), all in favor of IVTA. The RR for at least one grade macular edema resolution was 5.15 (95% CI 2.23 to 11.88) at 3 months in favor of IVTA (one trial).  Two trials reported improved clinical outcome when FAI was compared to standard of care. Beneficial effect was also observed in one dexamethasone DDS trial.  Increased intraocular pressure and cataract formation were side effects requiring monitoring and management. RCTs included in this review suggest that steroids placed inside the eye by either intravitreal injection or surgical implantation may improve visual outcomes in eyes with persistent or refractory DME. Since the studies in our report focused on chronic or refractory DME, the question arises whether intravitreal steroids therapy could be of value in other stages of DME, especially the earlier stages either as standalone therapy or in combination with other therapies, such as laser photocoagulation.

Plain-language summary: This systematic review included seven randomized clinical trials involving 632 eyes from five countries evaluating the effectiveness and safety of intravitreal steroids for treating DME. Two trials were at low risk of bias, one was at median risk of bias, two were at high risk of bias, and the remaining two had an unclear risk of bias. In this systematic review, the preponderance of data suggest a beneficial effect from IVTA. The average improvement in visual acuity was 7.5 letters more (-0.15 LogMAR; 95% CI -0.21 to -0.09) in the IVTA treated eyes than in those treated with other therapies at three months (based on three trials), 11.5 letters more (-0.23 LogMAR; 95% CI -0.33 to -0.13) at six months (two trials), 14.5 letters more (-0.29 LogMAR; 95% CI -0.47 to -0.11) at nine months (one trial), and 5.7 letters more (-0.11 LogMAR; 95% CI -0.20 to -0.03) at 24 months (one trial). Improved clinical outcomes were also reported in FAI and dexamethasone DDS trials. Elevation of intraocular pressure and cataract progression occur in both IVTA and implants treated eyes but appear manageable.