Differences in biometric features of LASIK flaps may confer no benefit for dry eye

J Cataract Refract Surg. 2009;35(12):2092-2098.

Specific architectural features of flap design in LASIK surgery appear to have little impact on postoperative dry eye, according to a study.

In 190 consecutive eyes of 95 patients who had their LASIK flaps cut with a 30-KHz or 60-KHz femtosecond laser (IntraLase), corneal sensation began to improve at the 3-month follow-up visit but did not reach preoperative levels by 12 months. Additionally, there was no difference in corneal sensation as measured by Cochet-Bonnet esthesiometry or according to hinge position (superior vs. temporal), angle (45° vs. 90°) or flap thickness (100 µm vs. 130 µm).

However, "there was statistically significant greater loss of central corneal sensation at 3 months with the 45° hinge angle than with the 90° hinge angle," the study authors wrote.

Clinical diagnostic testing reinforced the results of corneal sensation evaluation. Scores on the Ocular Surface Disease Index increased postoperatively but normalized by 6 months, with no difference seen with regard to flap architecture. Likewise, tear film breakup time (TBUT) increased after surgery, but differences were noted in subgroup analysis: At 1 month, 13 eyes in the superior-hinge flap group vs. seven eyes in the temporal-hinge flap group had decreased TBUT, and seven eyes in the 130-µm flap group vs. three eyes in the 100-µm flap group had decreased TBUT.