Posterior subtenon and intravitreal triamcinolone acetonide for diabetic macular edema

AIM: To evaluate retroprospectively the clinical consequences of posterior subtenon (PSTT) and intravitreal (IVT) triamcinolone acetonide injections in diabetic macular edema (DME) refractory to conventional grid laser photocoagulation. MATERIAL AND METHODS: Eyes with clinically significant DME refractory to grid laser photocoagulation were assessed for the inclusion in the study. Complete ophthalmic examination with fluorescein angiography (FA) and optic coherence tomography (OCT) were performed before and in the 1st, 3rd, and 6th months of the treatment. The IVT group received 4 mg/0.1 ml and the PSTT group received 20 mg/0.5 ml triamcinolone injection. PSTT but not IVT injection was repeated in case of recurrent edema. IVT was also applied to the eyes with resistant macular edema after PSTT injection (secondary IVT group). RESULTS: There were 85 eyes of 60 patients in the PSTT group and 41 eyes of 35 patients in IVT group. There were 24 eyes in the primary IVT group and 17 eyes in the secondary IVT group. Mean follow-up time was 4.1+/-1.9 and 4.6+/-2.2 months after PSTT and IVT injections, respectively. In the PSTT group, the mean visual acuity increased from 0.19+/-0.18 to 0.22+/-0.19 and the mean central foveal thickness decreased from 413.1+/-117.5 to 312.1+/-103.1 microm (P=.001 and P=.0001, respectively) during the first 3 months. In the IVT group, the mean visual acuity and central foveal thickness were found to be 0.15+/-0.14 and 494.5+/-141.3 microm before the treatment and 0.20+/-0.16 and 288.4+/-88.5 microm 3 months after the treatment, respectively (P=.008 and P=.001, respectively). The effect in central foveal thickness was significantly greater in the primary IVT group than in the PSTT group (P=.002). There was no significant difference with respect to the decrease in the central foveal thickness and increase in visual acuity between the primary and secondary IVT injections (Mann-Whitney U test, P>.05). The steroid effect started to diminish after the 3rd month. The recurrence of macular edema was seen in 7.1% in the PSTT group starting after 3 months. Twenty percent of the eyes in the PSTT group did not respond to the treatment at all and had secondary IVT injections. Significant intraocular pressure increase was found in 8.2% of the PSTT group and in 24.3% of IVT injection. There was one case of pseudomonas endophthalmitis in the IVT group. CONCLUSION: This study is the first study comparing the clinical outcomes of PSTT and IVT injections for the treatment of DME. Both PSTT and IVT injections caused a significant increase in visual acuity and a decrease in central foveal thickness, especially in the short term. The effect was more pronounced in the IVT group; however, PSTT injection also seemed to be a safe and effective technique for the treatment of DME. Further prospective studies are warranted to assess the efficacy and side effects of IVT and PSTT injections for the treatment of DME.