Corneal confocal microscope(CCM)is a non-invasive instrument for the study of living cornea and is increasingly being used to evaluate corneal nerve plexus and Langerhans cell lesions. This paper reviews the recent advances in corneal nerve plexus and Langerhans cell lesions from the perspective of the use of CCM in the study of systemic diseases such as diabetes mellitus, Sjogren's syndrome, multiple sclerosis, thyroid-associated ophthalmopathy, fibromyalgia, chronic migraine and Parkinson's disease.