Comparison of combination posterior sub-tenon triamcinolone and modified grid laser treatment with intravitreal triamcinolone treatment in patients with diffuse diabetic macular edema

Abstract

Purpose: To compare the efficacy of posterior sub-Tenon's capsule triamcinolone acetonide injection combined with modified grid macular photocoagulation (PSTI + MP) with intravitreal triamcinolone acetonide (IVTA) injection in the treatment of diffuse diabetic macular edema (DME).

Materials and methods: Forty eyes of 33 patients with diffuse DME were randomly allocated into either PSTI + MP (20 eyes) or IVTA (20 eyes). Best corrected visual acuity (VA) and foveal thickness were measured.

Results: The ETDRS scores at baseline were 25.2 +/- 13.6 (mean +/- SD) letters in the PSTI + MP group, whereas 21.7 +/- 16.3 letters in the IVTA group. The ETDRS scores improved by 33.2 +/- 15.9, 34.7 +/- 16.6 and 30.9 +/- 19.0 letters in the PSTI + MP group whereas by 30.9 +/- 15.4, 30.1 +/- 17.9 and 31.5 +/- 15.0 letters in the IVTA group at 1, 3, and 6 months after the treatments, respectively. The VA improved significantly at 1 month and 3 months after both treatments (all p < 0.02, paired t-test). The VA improvements were no longer significant at 6 months in either group. There were no statistically significant differences at any time points between the 2 groups (all p > 0.05, Student's t-test). The foveal thicknesses at baseline and 1, 3, and 6 months after the treatments were 382.8 +/- 148.3, 309.1 +/- 131.3, 319.3 +/- 93.3, 340.4 +/- 123.5 microm (mean +/- SD) in the PSTI + MP group vs. 369.1 +/- 123.1, 241.4 +/- 52.3, 277.5 +/- 137.4, 290.2 +/- 127.9microm in the IVTA group, respectively. Pairwise comparisons revealed significant decrease in foveal thickness at 1 month (p = 0.01, paired t-test) for the PSTI + MP group, and at both 1 month (p < 0.001) and 3 months (p = 0.016) for the IVTA group. There were no statistically significant differences at any time points between the 2 groups (all p > 0.05, Student's t-test). In contrast to the PSTI + MP group, where no complications were noted, the elevation of intra-ocular pressure in 3 of 20 eyes (15%) and a significant increase in average cataract grading were observed in the IVTA group.

Conclusion: PSTI + MP treatment provides significant improvement of vision in patients with diffuse DME over 3 months, and achieves outcomes comparable to those after IVTA treatment, however, with fewer complications.

Fig. 1

Changes in mean ETDRS scores after treatments. ETDRS, Early Treatment Diabetic Retinopathy Study. PSTI, posterior subtenon triamcinolone injection; IVTA, intravitreal triamcinolone acetonide injection; ETDRS, Early Treatment of Diabetic Retinopathy Study

Fig. 2

Changes in mean foveal thicknesses after treatments. PSTI, posterior subtenon triamcinolone injection; IVTA, intravitreal triamcinolone acetonide injection.

Fig. 3

Changes in mean intraocular pressures after treatments. IOP, intraocular pressure; PSTI, posterior subtenon triamcinolone injection; IVTA, intravitreal triamcinolone acetonide injection. ^*IOP was significantly higher in the IVTA group (p = 0.006 at 1 month, p = 0.026 at 3 months; Student's t-test).