Purpose:The aim of this study is to assess the macular ultrastructure measuring by optical coherence tomography angiography in adult patients with Familial Mediterranean fever.Methods:Participants were 62 Familial Mediterranean fever patients and 54 healthy individuals in control group with similar age and sex. The superficial and deep vascular plexus structures covering the central fovea in an area of 6 mm × 6 mm were measured using AngioVue images taken with optical coherence tomography angiography. Vasculature structure, foveal avascular zone, acircularity index of foveal avascular zone (the ratio of the perimeter of foveal avascular zone and the perimeter of a circle with the equal area), and superficial and deep retinal plexus densities were measured.Results:The inferior deep vascular density was measured: 49.17% ± 8.59% in Familial Mediterranean fever patients, 55.56% ± 5.92% in the control group. The deep inferior-hemi vascular density was measured: 48.59% ± 10.34% in Familial Mediterranean fever patients, 56.54% ± 8.05% in the control group. Deep inferior and deep inferior-hemi vascular density was significantly reduced in Familial Mediterranean fever patients compared with healthy controls (p = 0.04 and p = 0.03, respectively).Conclusion:The vascular abnormalities in optical coherence tomography angiography show subclinical signs of microangiopathy in Familial Mediterranean fever patients. This observation, which can be obtained only through optical coherence tomography angiography, may be an ocular hallmark for Familial Mediterranean fever disease.