The variable efficacy of intravitreal bevacizumab and triamcinolone acetonide for cystoid macular edema due to radiation retinopathy

Abstract

Background: Both intravitreal bevacizumab and triamcinolone have been shown to be effective in treating macular edema secondary to VEGF-mediated disease. The purpose of this study is to describe the variable effects of intravitreal bevacizumab (IVB) and triamcinolone acetonide (IVTA) in the treatment of macular edema secondary to radiation retinopathy.

Methods: Retrospective, nonrandomized, interventional case series. Charts of five patients with macular edema due to radiation retinopathy who received IVB with subsequent IVTA were reviewed. Clinical examination, Snellen visual acuity (VA), and central macular thickness (CMT) on optical coherence tomography (OCT) were examined. Main outcome measures included VA and CMT.

Results: Of the five patients reviewed, patient 1 demonstrated complete resolution of macular edema both clinically and by OCT with IVB after the first two injections with a decrease in CMT to 243 and 284 µm from a baseline CMT of 340 µm. However, response diminished following successive injections and the patient was switched to IVTA with a complete response. Mean CMT was 249 µm following four injections of IVTA and vision improved 3 lines. Patients 2 and 3 demonstrated a partial response to IVB with a mean CMT of 362 and 451 µm from 436 and 596 µm, respectively. They similarly had a partial response to IVTA with a mean CMT of 363 and 433 µm from 460 and 429 µm. There was no improvement in vision. Patient 2 was then switched to a combination of IVB and IVTA with complete resolution of macular edema with a CMT of 299 and 289 µm following two treatments. Patients 4 and 5 failed to respond to IVB with a mean increase in CMT of 64.5 and 6 µm. Both responded well to IVTA with complete resolution of macular edema. Mean decrease in CMT was 146 and 183 µm with a mean CMT of 254 and 281 µm. Final vision was stable in patient 4 and improved 3 lines from 20/100 to 20/50 in patient 5.

Conclusion: IVB and IVTA have variable effects on the reduction of macular edema due to radiation retinopathy. IVB appears to have an initial effect in reducing macular edema in some patients but after multiple injections there can be resistance to its effects. IVTA was effective in three of five patients with complete resolution of macular edema. The combination of IVB and IVTA completely resolved macular edema in one patient resistant to IVB or IVTA alone. The reason for this may be due to their different therapeutic mechanisms of action and consideration should therefore be given to their use in combination.

Keywords: Avastin; VEGF; bevacizumab; eye; macular edema; radiation retinopathy; steroid; triamcinolone acetonide.