Clinical studies conducted at the Van Andel Research Institute in Michigan, USA have identified nineteen (19) cytokines significantly elevated in the vitreous of proliferative diabetic retinopathy (PDR) patients, including five (5) novel cytokines not previously associated with PDR. The novel cytokines may represent new therapeutic targets for the treatment of PDR, in addition to contributing to a further elucidation of the molecular pathology under-lying PDR and several other retinal disorders. The five novel cytokines not previously associated with PDR include sCD40L, GM-CSF, IFNa2, IL-12p40, and MCP-3. Of the nineteen elevated cytokines, sixteen were found to be statistically independent of VEGF.