PURPOSE: To evaluate the effect of hinge positions on corneal sensation and dry eye parameters after femtosecond laser assisted-LASIK (Laser in situ Keratomileusis).
DESIGN AND METHODS: Eighty-six consecutive eyes of 43 patients who underwent bilateral myopic LASIK surgery with Femtosecond laser (IntraLase, Abbott Medical Optics, Inc., USA) were evaluated in a prospective non-randomized contralateral-eye study to compare the difference between nasal-hinged and superior-hinged locations. Central Cochet-Bonnet esthesiometry, Schirmer basic tear secretion test, tear breakup time (TBUT), ocular surface staining with fluorescein and Rose bengal strips, the Ocular Surface Disease Index (OSDI) questionnaire were evaluated preoperatively as well as 1 week and 1, 3, and 6 months postoperatively.
RESULTS: Corneal sensation decreased significantly in both nasal-hinge and superior-hinge flaps at 1 week post-operatively (nasal: P<0.05; superior: P<0.01) and gradually recovered respectively by 1 month and 3 months postoperatively. The Schirmer basic secretion test values increased significantly at 1 month to 6 months postoperatively in both the nasal-hinged and superior-hinged eyes (P<0.05). Although decreased postoperatively, there was no significant change in TBUT after surgery in both hinge groups at all time points. Corneal fluorescein staining increased significantly in both hinge groups at 1 week and slowly recovered in nasal-hinged group postoperatively (P<0.05 at 3 months). Gradual but insignificant increase of conjunctival Rose Bengal staining was noted after 1 week postoperatively in both hinge groups, and then decreased significantly at 6 months postoperatively in the superior hinge group when compared with baseline(P<0.05) . The OSDI significantly increased 1 week after surgery(P<0.01) and gradually but not completely returned to baseline at 6 months postoperatively in both hinge groups (P<0.05). There were no significant differences in all the parameters tested between nasal-hinged and superior-hinged flaps at any time point.
CONCLUSION: Femtosecond laser-assisted LASIK procedures reduced corneal sensitivity and increased corneal staining postoperatively, but recovered to baseline value within 6 months. The OSDI increased after surgery and did not improve by 6 months postoperatively. Hinge position had no significant effect on central corneal sensation and dry-eye parameters in Femtosecond laser-assisted LASIK.