Intraretinal microvascular alterations in indirect traumatic optic neuropathy

Abstract PURPOSE To quantitatively evaluate macular and peripapillary microvascular alterations in patients with indirect traumatic optic neuropathy (TON) compared to normal controls using optical coherence tomography angiography (OCT-A [Topcon DRI OCT; Triton]) and determine their associations with other ocular parameters. METHODS We enrolled 33 eyes of 33 patients with TON and 34 eyes of 34 healthy controls. OCT-A was used to generate microvascular structure images of the superficial retinal capillary plexus (SRCP), deep retinal capillary plexus (DRCP), and radial peripapillary capillary (RPC) segment in the macula and peripapillary area. Age, gender, and spherical equivalent refractive errors were statistically adjusted for the analysis. RESULTS OCT-A revealed a significant reduction of the average vessel density in the RPC segment in TON patients compared to controls (48.5% ± 6.28 vs. 57.88% ± 3.06%, P < 0.0001, corrected P < 0.0001). The vessel density of the RPC segment in TON patients was also significantly lower than that in healthy controls in all four quadrants when compared by sectors. The inferior sector vessel density of the RPC segment was significantly associated with visual field defects (P = 0.0253) and visual acuity (P = 0.0369). The temporal sector vessel density of DRCP was also associated with visual field defects (P = 0.0377). The RPC segment in the temporal, superior, and inferior sector vessel density had a significant association with the average pRNFL thickness (P = 0.0092, 0.0171, and < 0.0001, respectively). CONCLUSIONS Patients with indirect TON show significant microvascular alterations compared to controls. This study confirms that TON can induce intraretinal microvascular changes and suggests that OCTA can be a useful biomarker for visual functional and structural changes.