Corneal nerve metrics do not recover to baseline levels at 1 year after SMILE
Corneal nerve metrics start to recover 3 months after SMILE but do not reach baseline levels at 12 months postoperatively, according to a study.
“We investigated the changes in tear neuromediators and corneal subbasal nerve plexus following small incision lenticule extraction,” Yu-Chi Liu, MD, MCI, told Healio/OSN. “We also studied its association with different refractive power of corrections.”
Forty eyes of 20 patients were included in a tear neuromediator analysis, while 20 eyes of 10 patients underwent corneal nerve analysis using in vivo confocal microscopy.
Tear samples were collected before the procedure and at 1 week and 1, 3, 6 and 12 months after SMILE and analyzed for substance P, calcitonin gene-related peptide (CGRP) and nerve growth factor (NGF) concentrations.
Corneal nerve fiber density, corneal nerve fiber length and corneal nerve branch density all decreased after the procedure, but they gradually increased starting at 3 months. However, they did not recover to baseline levels at 12 months.
Substance P and CGRP levels were stable over 12 months, while NGF levels were significantly decreased compared with baseline at 6 months (P = .03) and 12 months (P = .007).
The high myopia group had a significantly greater decrease in corneal nerve fiber density at 1 month, significantly higher substance P concentrations at 1 week, 1 month and 6 months, and significantly higher CGRP concentrations at 1 month and 6 months compared with the low to moderate myopia group
“High myopic treatment was associated with greater corneal denervation and neuroinflammation,” Liu said. “Future work will focus on the development of potential strategies to mitigate neuroinflammatory response and to stimulate nerve recovery in high myopia patients.”