Does outside environmental humidity influence the outcome of laser refractive surgery? Results from the Hamburg Weather Study

Abstract

Purpose: This study was initiated to assess the impact of outside environmental humidity on the refractive and visual outcome of laser-assisted in situ keratomileusis (LASIK) in myopic eyes. Materials and Methods: One thousand and fifty-two eyes of 1,052 consecutive myopic patients (419 males and 633 females; mean age at surgery 35.0 ± 9.0 years) with mean preoperative refractive spherical equivalent (SE) of −3.88 ± 1.85 diopters (D) were studied. Two subgroups were defined, which had undergone surgery either during meteorological winter or summer. Result: By 1-month (33.0 ± 5.0 days) follow-up, a mean postoperative SE of −0.18 ± 0.44 D was obtained. Bivariate comparison showed that statistically significant better safety index (SI) was obtained for high outside environmental humidity. Robust regression methods indicated high humidity to be associated with significant better SI and postoperative SE. No change of more than one line on logMar scale was obtained. Conclusion: Although being statistically significant, there is no clinically relevant difference in outcome of LASIK, which demonstrates its highly standardized quality. However, we observed a tendency that high outside environmental humidity at the day of LASIK and during early perioperative time, tends to produce better refractive outcome. Prospective, longitudinal studies are warranted to address meteorotropic reactions through evaluating individual risk profiles.

Keywords

• Ambient humidity
• laser refractive surgery
• outside environmental humidity
• weather