Reduced Peripapillary and Macular Vessel Density in Unilateral Postgeniculate Lesions With Retrograde Transsynaptic Degeneration

Background: Retrograde transsynaptic degeneration (RTSD) of the retinal ganglion cells and retinal nerve fiber layer after postgeniculate injury has been well documented, but to the best of our knowledge, associated retinal microvascular changes have not been examined. The purpose of our study was to assess vessel density (VD) at macular and peripapillary regions in patients with RTSD. Methods: Cross-sectional study including 16 patients with homonymous visual field defects secondary to unilateral postgeniculate visual pathway injury and 18 age-matched controls. All participants were examined with AngioVue optical coherence tomography angiography to measure the peripapillary vessel density and macular vessel density (pVD/mVD) as well as the peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell complex (GCC) thicknesses. The pRNFL and macular ganglion cell-inner plexiform layer (GCIPL) thicknesses also were evaluated using Cirrus OCT. A normalized asymmetry score (NAS) was calculated for GCIPL and GCC thickness, and mVD. Results: Average pRNFL and macular GCIPL/GCC thicknesses were significantly thinner in both eyes of patients compared with control eyes (all P ≤ 0.05). Eight patients (50%), who showed a RTSD of the GCIPL map, had a relative thinning of the GCIPL/GCC ipsilateral to the brain lesion in both eyes (represented by a positive GCIPL-NAS/GCC-NAS). The mean pVD and mVD also were significantly reduced in patients (all P ≤ 0.05). There was a strong correlation between GCIPL-NAS/GCC-NAS and mVD-NAS index in both eyes (all r > 0.7, P = 0.001). Furthermore, there was a similar spatial pattern of damage for the macular GCC thickness and VD values. Conclusions: We demonstrated a significant VD decrease in peripapillary and macular areas of patients with RTSD because of postgeniculate lesions. The structural and microvascular asymmetry indexes were significantly correlated. These findings provide new insights regarding transsynaptic degeneration of the visual system.