Retinal arterial occlusive vasculitis after multiple intravitreal brolucizumab injections for diabetic macular edema

To describe a case of unilateral retinal arterial occlusive vasculitis after multiple intravitreal brolucizumab (IVBr) treatments for diabetic macular edema (DME).

A 68-year-old Japanese woman who had a 3-year history of insulin-dependent diabetes mellitus presented with decreased vision in the right eye (oculus dexter, OD). After two consecutive IVBr (3 mg) treatments for DME, spaced 6 weeks apart, her best corrected visual acuity improved from 20/32 to 20/28 OD, as central macular thickness (CMT) decreased from 368 μm to 253 μm on optical coherence tomography (OCT). Immediately after the 3rd IVBr, the right intraocular pressure (IOP) increased. One week later, iritis (aqueous flares: 65.0 photon count [PC]/ms) was observed, followed by localized vasculitis 2 weeks later. One month after the 3rd IVBr, extensive vasculitis and vasculitis occluding retinal arterioles were identified. Based on the history of IVBr use and clinical findings, intraocular inflammation (IOI) and subsequent retinal arterial occlusive vasculitis due to IVBr was diagnosed. Topical steroid administration (i.e., eye drops and subtenon injection) resulted in improvement of IOI after 3 months. She subsequently underwent two intravitreal aflibercept injections for DME and panretinal photocoagulation (PRP) to prevent the development of proliferative changes due to diabetic retinopathy. One year after the diagnosis of retinal arterial occlusive vasculitis, the patient had slight loss of vision (20/50) compared to baseline, due to the progression of cataracts, and OCT angiography (OCTA) showed extensive non-perfusion area on the temporal side. However, other examination findings (IOP: 16 mmHg, aqueous flares: 30.5 PC/ms, CMT: 283 μm) were stable.

Diagnosis and treatment at a relatively early stage after the onset of IOI prevented severe visual impairment in this case. Topical betamethasone eye drops reduced anterior chamber inflammation associated with IVBr; however, vascular sheathing worsened when topical drops alone was used. Occlusive retinal vasculitis, diagnosed with fluorescein angiography (FA) and OCTA, appeared to stabilize when subtenon triamcinolone injection was added to topical steroid administration. Because the central macula was not involved, severe vision loss was prevented. It is unknown if topical steroid administration would be adequate to prevent worsening of occlusive vasculitis in other cases. Although not used in this case, oral prednisone is one treatment option that may prevent severe vision loss. However, it requires monitoring of side effects, such as elevated blood glucose levels. PRP is also an option in cases where progression of proliferative changes is a concern, as was done in this case. With these considerations in mind, it is important to diagnose brolucizumab-associated IOI and subsequent retinal arterial occlusive vasculitis in DME patients early and initiate treatment to prevent severe visual impairment. Diagnosing new IOI and subsequent retinal arterial occlusive vasculitis is more difficult in DME than in neovascular age-related macular degeneration because of the inflammatory component often associated vascular occlusions. Therefore, early IOI diagnosis and follow-up using various instruments such as laser flare cell meter, wide-field color imaging, OCT/OCTA, and FA, in addition to usual comprehensive ophthalmologic examinations, is crucial.