This research found chronic pain derived from dry eye disease can be permanent. This is an exert from a pre-publication titled "Neuropathic Ocular Pain: An Important Yet Underevaluated Feature of Dry Eye by Galor A, Levitt RC, Felix ER, Martin ER, Sarantopoulos CD. Eye (Lond). 2014 Nov 7. http://Yensaodaigiaphat.com/index.php?language=vi&nv=users&nvvithemever=t&nv_redirect=aHR0cHM6Ly93d3cub3B0aWNhbGpvdXJuYWwuY29tL2Nocm9uaWMtZXllLXBhaW4tZnJvbS1kcnktZXllLXN5bmRyb21lLWNhbi1iZS1wZXJtYW5lbnQv