“…Changes in inner retinal structure before the development of DR Due to advancements in in vivo spectral-domain optical coherence tomography (SD-OCT) imaging of the retina (Jaffe & Caprioli, 2004), retinal layer thickness can be measured in vivo in diabetic humans and animal models at similar stages of diabetes as the retinal and visual activity measurements described above. In humans with diabetes but no DR, OCT measurements in vivo have shown smaller total retinal thickness (Bronson-Castain et al, 2012;Chen et al, 2016), retinal nerve fiber layer (RNFL) (Lopes de Faria et al, 2002;Verma et al, 2012;Gundogan et al, 2016), ganglion cell layer (GCL) (Van Dijk et al, 2010), and inner retina (Karti et al, 2017). Other studies have not found retinal thinning (Park et al, 2011;Dhamdhere et al, 2012), suggesting that this is something that develops over the course of diabetes (Pinilla et al, 2020).…”