The modelling of the visual system needs to provide realistic retinal responses (spike trains) to visual stimuli. Our team [1] developed a retina simulator that allows a large scale simulation (about 100.000 cells) and provides spikes train output as a response to visual stimuli. This model contains several blocks representing the retina layers. It is able to reproduce realistic individual responses of retinal ganglion cell (RGC). However, as emphasized in the present work, we checked that the collective responses of RGC don't match to real data. Comparing our simulator outputs to real acquisitions data made by B. Kolomiets and S. Picaud (Institut de la Vision) we have shown, using statistical methods developed by our team (EnaS) [3], that real data show a significant synchronization and correlations between RGC outputs, that is absent from our simulator outputs. It is commonly believed that those correlations come from the overlap of RGC receptive fields. However, since, our simulator carefully reproduces this overlap this suggests that synchronization must be explained by other mechanisms such as long range connections from Amacrine to RGC or electrical connections (gap junctions) between RGC which have not been implemented yet in our simulator.