[17] Similarly, using rhodopsin knockout mice (Rho−/−) as an RP model, de Gooyer et al. proved that hypoxia and VEGF-A increased and vascular density attenuated in the retina of wild-type diabetic mice, but these changes did not occur in Rho−/− mice. [18] They concluded the loss of the outer retina might decrease oxygen consumption by the photoreceptors and thus prevent DR progression. This is the same reason retinal laser photocoagulation is helpful in controlling PDR, since it decreases photoreceptor bulk and hypoxia [19]. The gene discussed is RHO; the disease is retinitis pigmentosa 1.