Dry Eye After LASIK.
Post-LASIK dry eye is the most common postoperative dry eye after ophthalmic surgeries. The clinical signs of post-LASIK dry eye include positive vital staining of the ocular surface, decreased tear breakup time and Schirmer test values, reduced corneal sensitivity, and decreased functional visual acuity. The symptoms and signs usually last for about 1 month after LASIK. A small number of patients continue to experience symptoms more than 1 year postoperatively. It has been suggested that the loss of corneal innervation caused by flap-making is the major cause, affecting the corneal-lacrimal gland, corneal-blinking, and blinking-meibomian gland reflexes, resulting in decreased aqueous and lipid tear secretion and mucin expression. A new type of corneal refractive surgery, SMILE, which has less impact on corneal nerves, induces less postoperative dry eye, supporting the association between corneal denervation and postoperative dry eye. As LASIK enhancement by flap-lifting induces fewer dry eye symptoms and signs than initial surgery, factors other than neurotrophic effects may be involved in the mechanisms of post-LASIK dry eye. Post-LASIK ocular surface pain is a type of postoperative chronic pain and discomfort, and is thought to be a different clinical entity from dry eye, possibly induced by abnormal reinnervation or neural sensitization of peripheral nerves and the central nervous system after LASIK. Treatments include tear supplements, anti-inflammatory agents, meibomian gland dysfunction management, ointment and eye patches, punctal plugs, and autologous serum eye drops. For patients with preoperative dry eye, careful patient selection, and preoperative ocular surface management are mandatory.