Nerve growth factor expression and nerve regeneration in monkey corneas after LASIK.
OBJECTIVE
To determine whether changes in cornea nerve growth factor (NGF) protein and gene expression correlate with corneal nerve regeneration after LASIK in rhesus monkeys.


METHODS
Ten rhesus monkeys underwent randomly assigned LASIK procedures to correct -8.0 diopters of myopia in both eyes and two additional monkeys (with no surgery) served as controls. The central corneas of the experimental animals were excised 3 and 7 days and 1, 3, and 6 months after the surgery. Nerve regeneration, NGF mRNA, and protein expression were analyzed by gold chloride staining, real-time polymerase chain reaction, and enzyme-linked immune sorbent assay analysis, respectively.


RESULTS
Compared to controls, the LASIK-treated animals had a significantly diminished nerve plexus in the sub-basal region of the cornea at all times after the surgery (P < .001). NGF protein levels decreased significantly on days 3 and 7 after LASIK (P < .001), but returned to control levels 1 month later. NGF mRNA levels increased 5.4-fold on day 3 after the surgery (P < .001), then reduced to two-fold (P < .05) above control levels on day 7 and were back to normal at 3 months and beyond. After LASIK, the changes of early NGF protein and NGF mRNA levels correlated with the density of the corneal nerve plexuses.


CONCLUSIONS
The results showed that the LASIK procedure in non-human primates was associated with changes in NGF protein and mRNA levels in the cornea. Such changes may be related to the initiation of nerve regeneration and the final recovery of nerve plexuses in the cornea.
Luxia
L
Chen
Rui Hua
RH
Wei
Donald T H
DT
Tan
Roger W
RW
Beuerman
Wenbo
W
Li
Shaozhen
S
Zhao
D000818:Animals; D003315:Cornea / Q000294:innervation* / Q000601:surgery; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D017612:Gold Compounds; D020731:Keratomileusis, Laser In Situ; D008253:Macaca mulatta; D020932:Nerve Growth Factor / Q000235:genetics* / Q000378:metabolism*; D009416:Nerve Regeneration / Q000502:physiology*; D009882:Ophthalmic Nerve / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D013194:Staining and Labeling
D017612:Gold Compounds; D012333:RNA, Messenger; C038016:gold chloride; D020932:Nerve Growth Factor