Purpose: To document a new clinical manifestation in familial exudative vitreoretinopathy (FEVR) eyes, especially in mild asymptomatic eyes with normal vision.
Methods: Twenty individuals with mild Stage I or II FEVR with a conventional "normal-appearing" posterior pole and 20 healthy control eyes were recruited. The crossing numbers of retinal vessels with peripapillary inner reference circle, peripapillary outer reference circle, peripapillary temporal inner arc, peripapillary temporal outer arc, and branching points between the peripapillary outer reference circle and peripapillary inner reference circle were counted. Vessel bifurcation was evaluated by B/CI (defined as the branching number divided by the crossing number on peripapillary inner reference circle) and CO/B (crossing number on peripapillary outer reference circle divided by the branching number) ratios. The inter- and intraobservers' agreements were analyzed. All these parameters were compared between FEVR and control groups.
Results: The coefficient of repeatability for the parameters ranged from 2.597 to 5.096, and the intraclass correlation coefficients were all above 0.85. All the parameters showed good interobserver agreement with a narrow range of 95% limit of agreement (from -3.16 to 3.37) and high Pearson correlation (P < 0.001). The mean crossing numbers on peripapillary inner reference circle, peripapillary outer reference circle, peripapillary temporal inner arc, peripapillary temporal outer arc, and the branching numbers were larger in the FEVR group. No significant differences were found in CO/B and B/CI ratios.
Conclusion: Patients with FEVR have more vessels radiated from the optic disk in the posterior pole. Unlike the increased vessels in the peripheral retina, the increasing pattern of peripapillary vascularity in patients with FEVR does not appear to have a component of overbifurcation. This is a new documented clinical manifestation in patients with FEVR. Attention to an increased or arrangement pattern of retinal vessels may aid in the screening of FEVR.