Anterior Migration of Triamcinolone Acetonide after Posterior Subtenon Injection for Macular Edema Predisposes to Intraocular Pressure Elevation

Purpose: To evaluate the effect of anterior migration of triamcinolone acetonide on intraocular pressure (IOP) elevation after posterior subtenon injection of triamcinolone acetonide (PSTA) for macular edema. Methods: One hundred and ten eyes from 89 patients who received PSTA for macular edema were prospectively enrolled. The extent of anterior migration of triamcinolone acetonide was recorded immediately after the injection. If TA particles were visible in the subtenon space (or subconjunctival space), it was recorded as “anterior subtenon migration” (or “anterior subconjunctival migration”). The correlation between anterior migration of triamcinolone acetonide and severe IOP elevation, which was defined as an increase of 8 mm Hg or more in IOP, was evaluated. Results: A total of 159 PSTAs were given to 110 eyes. After PSTA, anterior subtenon migration occurred in 70.4% and anterior subconjunctival migration occurred in 12.0% of injection. Severe IOP elevation occurred in 7.1% of those without anterior migration, in 25.9% of those with anterior subtenon migration, and in 31.6% of those with anterior subconjunctival migration after PSTA (P = .052). Compared to those without anterior migration of triamcinolone acetonide, the hazard ratio for severe IOP elevation was 3.307 in those with anterior subtenon migration (P = .12) and 5.289 in those with anterior subconjunctival migration (P = .042). Conclusions: Anterior migration of triamcinolone acetonide after PSTA predisposes eyes to severe IOP elevation. Careful injection to restrict the triamcinolone particle within the subtenon space and behind the equator may lower the rate of IOP elevation after PSTA.