Is a decreased nitric oxide concentration after triamcinolone acetonide intravitreal injection one of the reasons for intraocular pressure rise?

Diabetic macular edema is the most common cause of vision loss in patients affected by diabetes mellitus. For eyes with persistent retinal thickening despite anti-VEGF therapy, treatment with intravitreal triamcinolone may be considered, especially in pseudophakic eyes. The aim of this study was to examine aqueous humor nitric oxide concentration changes in pseudophakic eyes with persistent diffuse diabetic macular edema after intravitreal injection of triamcinolone acetonide, as well as the potential im-pact of these changes on the intraocular pressure values. In 10 pseudophakic eyes with persistent diffuse di-abetic macular edema, paracentesis of anterior chamber with aspiration of aqueous humor and nitric oxide concentration measurements were done on the day of the intravitreal application of 20 mg triamcinolone acetonide, and after 1, 3, 6 and 9 months. Also, we were recording intraocular pressure values before the intravitreal triamcinolone acetonide injection and during the next 9 months. One month after the intra-vitreal triamcinolone acetonide injection, we noticed a decrease of nitric oxide concentration (45.37 +/- 5.55 mu mol/L) by 31.79% compared to the initial values (66.52 +/- 7.66 mu mol/L). After that, nitric oxide concen-trations began to rise slightly, and at the end of the ninth month the mean nitric oxide concentration was similar to that recorded at the beginning of the study. Intraocular pressure values had increasing trend one month after the intravitreal triamcinolone acetonide injection (23.70 +/- 4.08 mm Hg) compared to the ini-tial values (16.21 +/- 1.55 mm Hg), but after nine months these values returned to normal levels. Decreased concentration of nitric oxide could be one of the reasons for increased intraocular pressure after intravitreal application of triamcinolone acetonide in the treatment of diffuse diabetic macular edema.