Fractal Changes of the Retinal Microvasculature in Birdshot Chorioretinopathy

BACKGROUND AND OBJECTIVE: Retinal vascular disorders are associated with lower fractal dimension (FD). We analyzed FD in birdshot chorioretinopathy (BSCR). PATIENTS AND METHODS: This was a retrospective cohort study. We performed optical coherence tomography angiography (OCTA) and analyzed FD of the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris (CC) using ImageJ. For each vascular layer, we analyzed the presence of BSCR, subjects' age, sex, and presence of diabetes mellitus to determine which may predict lower FD. RESULTS: We compared 28 eyes (14 patients) with BSCR to 34 control eyes (17 patients). Mean FD of BSCR was lower in SCP (1.584 [+/- 0.126] vs 1.706 [+/- 0.118], P < 0.001), DCP (1.637 [+/- 0.134] vs 1.780 [+/- 0.096], P < 0.001), and CC (1.884 [+/- 0.063] vs 1.917 [+/- 0.047], P = 0.036). FD of SCP was lower per increasing year (0.005 [ P = 0.014]). Male patients had lower FD-DCP (0.101 [ P = 0.043]). CONCLUSION: In BSCR, fractal analysis showed significant involvement of the SCP, DCP, and to a lesser extent the CC.