Corneal Sensitivity to Hyperosmolar Eye Drops: A Novel Behavioral Assay to Assess Diabetic Peripheral Neuropathy

Diagnosis of peripheral neuropathy (PN), which affects approximately 50% of the diabetic population, is subjective, with many patients seeking a diagnosis only after presenting with symptoms. Recently, in vivo confocal microscopy of subepithelial corneal nerve density has been promoted as a surrogate marker for early detection of PN, but imaging of corneal nerves requires sophisticated instrumentation, expertise in confocal imaging, cooperative patients, and automated analysis tools to derive corneal nerve density. As an alternative, we developed a simple screening method that is based on the sensitivity of corneal nerves to cause reflex eyelid squinting in response to hyperosmolar eye drops.