An increase in intraocular pressure after intravitreal steroid injection facilitates reduction of macular edema

Sir,

Intravitreal triamcinolone acetonide (IVTA) injection is a relatively safe and effective treatment for macular edema in patients with branch retinal vein occlusion (BRVO).^{1, 2} However, IVTA sometimes causes increased intraocular pressure (IIOP) within 3 months of injection. In our clinical experience, IVTA treatment accompanied by IIOP facilitates reduction of macular edema.^{3, 4} Therefore, we reviewed the medical records of 43 BRVO patients who had received IVTA. Intraocular pressure (IOP) was assessed, best-corrected visual acuity (BCVA) was recorded, and total macular volume (TMV) and central retinal thickness (CRT) were measured using Stratus optical coherence tomography (OCT; Carl Zeiss Meditec Inc., Dublin, CA, USA). Data were collected before injection, and 1 month and 3 months after injection. Pre-injection mean IOP was 13±3 mm Hg and the 1-month mean IOP was 21±7 mm Hg. Using the 1-month IOP figures, we defined a ‘steroid responder’ as an eye that had an IOP >22 mm Hg. All other eyes were considered to be non-responders. We compared changes between steroid responders and non-responders in BCVA, CRT, and TMV (with reference to pre-injection values) at 1 month and 3 months following injection.

After injection, BCVA, CRT, and TMV improved in both responders and non-responders at the 1-month and 3-month follow-ups (Table 1). Although both responders and non-responders thus exhibited treatment effects, responders showed a greater extent of reduction in macular edema than did non-responders at 1-month follow-up (Figure 1). Responders also showed a greater improvement in visual acuity, with clinical significance, than did non-responders (Mann–Whitney U-test; P=0.027). On OCT, steroid responders exhibited a greater extent of TMV change than did non-responders (P=0.025). TMV changes (from pre-injection to 1-month follow-up) were 2.59±2.70 mm³ (responders) and 1.02±1.26 mm³ (non-responders). Responders showed a greater extent of CRT reduction than did non-responders (P=0.046). CRT changes (from pre-injection to 1-month follow-up) were 268±183 μm (responders) and 178±150 μm (non-responders).

Table 1 Characteristics of 43 eyes (43 patients)

Figure 1

Comparison of changes in BCVA, TMV, and CRT (in comparison to pre-injection figures) between steroid responders (red) and non-responders (blue). At both the follow-ups, responders exhibited more improvement in BCVA than did non-responders (a). At the 1-month follow-up, responders showed a more significant reduction in TMV than did non-responders (b). At the 1-month follow-up, responders exhibited a more significant reduction in CRT than did non-responders (c). The symbols * and ** denote statistical significance.

In conclusion, following injection of IVTA to treat BRVO, steroid responders experienced a greater reduction in macular edema than did non-responders. We suggest that some unknown feature(s) of responders with high IOP enables steroids to reduce retinal edema.