MICROVASCULAR FLOW ABNORMALITIES ASSOCIATED WITH RETINAL VASCULITIS: A Potential of Mechanism of Retinal Injury.

PURPOSE: To investigate the structural optical coherence tomography and related microvascular flow characteristics in eyes with retinal vasculitis.

METHODS: Regions involved with perivascular infiltration in eyes with retinal vasculitis, but no evidence of large vessel occlusion were evaluated with optical coherence tomography (OCT), OCT angiography, and fluorescein angiography.

RESULTS: Ten eyes of 5 patients with a variety of etiologies of retinal vasculitis were evaluated. These patients did not have either cotton wool spots or deeper placoid areas of retinal ischemia. Around large vessels there was perivascular infiltration with leakage and staining seen during fluorescein angiography. Structural OCT showed slight thickening with loss of visualization of normal retinal laminations. OCT angiography showed a lack of flow signal in capillary sized vessels in the same areas. Treatment resulted in a rapid thinning of the affected areas, with the inner and middle layers of the retina becoming thinner than surrounding uninvolved areas. OCT angiography did not show a return of capillary perfusion in these regions. The thickness change in the structural OCT as shown by a heat map had a pattern mimicking the original perivascular infiltration around large retinal vessels.

CONCLUSION: Capillary level perfusion abnormalities can develop in regions adjacent to large vessel inflammatory infiltrate that result in retinal thinning without the development of usual stigmata of acute microvascular flow obstruction such as cotton wool spots. This suggests that retinal damage may occur in retinal vasculitis that would not be recognized without using OCT-based imaging modalities.