“…Whereas some authors have reported that iPD patients have a significant and marked thinning of the macula 10,12-14 and its inner retinal layers, 8,9,11,[21][22][23][24][25][26] others have evidenced outer retinal layer thinning, 27 or even thickening, 11,24 and some have failed to find any differences. [28][29][30][31][32][33][34] The variability in scanning protocols, acquisition parameters and built-in segmentation algorithms across different OCT systems is a well-established limitation for comparing the results of different studies 35 and could account for the discrepancies found in the literature regarding retinal alterations in iPD. Specifically, the differences in acquisition speed and axial resolution between time-domain and spectral-domain OCTs might explain why studies using older time-domain OCT devices (eg, Stratus) only detected significant differences between iPD patients and controls when absolute differences in thickness were greater than 10 μm, 20,36 whereas studies using spectraldomain OCTs have yielded significant results with differences from 2 to 7 μm in thickness regardless of the area analyzed, 7,9,12,24,25,27,34,[37][38][39][40] which is consistent with the magnitude of inner retinal thinning observed in our E46K-SNCA cohort.…”