Topical delivery of the neurotrophic factor CNTF and the GLP-1 analog exendin-4 to the eye of diabetic mice was used to explore use of corneal confocal microscopy as a bridge between in vitro studies that assess the capacity of agents to promote neurite outgrowth in sensory neuron cultures and studies that use systemic treatment to prevent or reverse indices of peripheral neuropathy in diabetic rodents. This evidence concerns the gene CNTF and peripheral neuropathy.