TNFSF15 and proliferative diabetic retinopathy: In view of the critical role of TNFSF15 in modulating vascular function and the interaction of TNFSF15 with VEGF, we examined the changes in TNFSF15 level and the TNFSF15/VEGF ratio in the vitreous of proliferative diabetic retinopathy (PDR) patients as well as the retinas of streptozotocin (STZ)-induced diabetic rats, to evaluate the effect of intravitreal TNFSF15 therapy.