The present review will provide a detailed critique of the current knowledge of Corneal confocal microscopy (CCM),the instruments employed to capture images and the basis on which images are interpreted and analysed. Imaging and quantifying corneal nerves using CCM is now increasingly recognised as a powerful, non-invasive and reiterative test to enable diagnosis and assess progression and the benefits of therapeutic intervention in a range of peripheral neuropathies and other systemic diseases.