Exploring the characteristics of retrograde trans-synaptic de- generation from retinal ganglion cells loss in patients with homonymous hemianopia caused by acquired cerebral lesions.

The existence of retrograde trans-synaptic degeneration (RTD) had been a controversial due to no structural continuity of two neurons in human. The study aimed to detect the macular retinal ganglion cell layer (mRGCL) loss in homonymous hemianopia (HH) patients caused by acquired cerebral lesions using optical coherence tomography (OCT) to explore RTD characteristics. 40 HH patients (80 eyes) were enrolled this study. All the patients underwent OCT examination to evaluate the peripapillary retinal nerve fiber layer (pRFNL) and mRGCL loss. Their VF defects (mean deviations, MD) were assessed by Humphrey Perimeter. pRNFL and mRGCL thicknesses in HH patients reduced markedly compared to that in healthy eyes. Temporal mRGCL thicknesses in ipsilateral eyes reduced 4.77 ± 7.98μm (p = 0.002) in contrast to their contralateral eyes. Nasal mRGCL thickness in contralateral eyes reduced 5.75 ± 10.44μm (p = 0.004), compared to their ipsilateral eyes. Additionally, trauma (p= 0.08) and tumor(p = 0.030) cerebral lesions caused more pRNFL loss than that of cerebrovascular diseases. VF defects (MD) had linear correlations to mRGCL thicknesses in nasal hemisphere in contralateral eyes(r = 0.397, p = 0.0404). The mRGCL and pRNFL loss occurred as early as 2-3 months after cerebral lesions occurred and progressed over time. RTD caused by acquired cerebral lesions were objectively detected by OCT and its characteristics were consistent to anatomic features of visual pathway. The mRGCL loss due to RTD correlated to VF defects and trauma and tumors caused greater injuries in pRNFL. Visual pathway could be an ideal model and OCT is a useful tool for RTD.