Abstract
Purpose:
To compare clinical outcomes and subbasal corneal nerves in patients 8 to 10 years after laser in situ keratomileusis (LASIK) with flap creation by microkeratome (MK) or femtosecond laser (FL)
Methods:
Prospective, comparative, IRB approved study of 90 eyes of 47 patients who underwent myopic LASIK, with either MK or FL flap. Corneal fluorescein staining, tear break up time (TBUT), tear osmolarity, central corneal thickness (ultrasound pachymetry), corneal sensation (Cochet-Bonnet esthesiometry), tear production (Schirmer test), Ocular Surface Disease Index (OSDI) and sub-basal corneal nerves by in vivo confocal microscopy (IVCM) were assessed in all subjects. Two-tailed t-tests and Fishers’s exact test were performed to compare subjects with MK and FL. P-value less than 0.05 was considered statistically significant.
Results:
Flap creation was performed with MK in 47 eyes and with FL in 43 eyes. Mean age was 52.5 years in the MK group and 51.7 years in the FL group (p=0.75). Assessment at 8-10 years after surgery indicates a trend towards fewer corneal nerves (6.3 vs 7.8 nerves per image, p=0.053) and lower nerve density (9.3 mm/mm2 vs 12 mm/mm2, p=0.065) in the FL group. There were no significant differences in OSDI scores (p=0.866), tear osmolarity (p=0.285), schirmer (p=0.415), TBUT (p=0.927), corneal thickness (p=0.117), corneal sensation (p=0.118) and fluorescein staining (p=0.175) between the two groups.
Conclusions:
Our preliminary results indicate that there is a trend towards differences in the number of corneal nerves and nerve density. There may not be long-term differences in standard measures of ocular surface health (tear osmolarity, Schirmer, fluorescein stain, OSDI) between patients who had the two techniques of LASIK flap creation.