PURPOSE: In this study, we hypothesized that thickening along the major arcade vessels is a noninvasive marker of inflammation in eyes with birdshot retinochoroiditis (BRC). METHODS: In this single-center retrospective study, patients with BRC were identified. Perivascular thickening was categorized as mild, moderate, or severe, based on a set of standard reference retinal thickness maps derived from representative spectral domain optical coherence tomography volume scans. The assigned perivascular severity thickness category was then compared with other inflammatory markers and optical coherence tomography measurements. These parameters were also examined in eyes with intermediate uveitis to assess the diagnostic specificity of perivascular thickening. RESULTS: In eyes with BRC, greater perivascular thickening was associated with increased vitreous haze (P = 0.009) and retinal vascular leakage on fluorescein angiography (P = 0.0001). Perivascular thickening was correlated with central subfield thickness and total macular volume on optical coherence tomography. Controlling for central subfield thickness and total macular volume, the odds of higher severity level of perivascular thickening were nine times greater in eyes with BRC than those with intermediate uveitis (P < 0.0001). Eyes with BRC and active inflammation were more likely to have moderate or severe perivascular thickening (P = 0.02). CONCLUSION: Perivascular thickening, determined by optical coherence tomography, may be a useful noninvasive biomarker of inflammation in eyes with BRC.