Corneal sensitivity to touch can be assessed by an aesthesiometer, which measures the corneal touch threshold. Decreased corneal sensation is associated with a decreased corneal reflex (HP:0008000); however, impairment of the corneal reflex can have other causes such as trigeminal nerve compression or a cerebellopontine angle lesion. Well known causes of decreased corneal sensation include Herpes simplex keratitis, neuroparalytic keratitis, leprosy, acoustic neuroma, and absolute glaucoma.