Weather impacts on the outcome of LASIK

Recently, we analysed the impact of seasonality¹ and distinct meteorological parameters on refractive and visual outcome of laser in situ keratomileusis (LASIK) in myopic eyes. Here, we present the highlights of this research.

Many factors to consider

In this study, we applied the meteorological definition of seasons. Accordingly, winter was defined to be the three coldest calendar months (December, January and February in the Northern Hemisphere), and summer as the months June, July, and August (Northern Hemisphere). This meteorological definition of summer also aligns with the commonly viewed notion of summer with the longest and warmest days of the year. The definition of distinct meteorological parameters was published elsewhere.^8,9

The LASIK procedure included mechanical flap preparation using an automated microkeratome (SKB, Moria, Antony, France) and a single-use 90.0-µm head. For all eyes, excimer ablation was performed with an Allegretto excimer laser platform (Eye-Q 200 or 400 Hz, WaveLight, Erlangen, Germany) under constant eye tracking (250 Hz) using an aspherical 'wavefront-optimized' profile aimed at reducing the induced spherical high-order aberration with an optical zone of 6.0, 6.5 or 7.0 mm, depending on the mesopic pupil diameter and expected residual stromal bed.¹⁰

Statistical but not clinical relevance

Our results indicate that, although being statistically significant, there is no clinically relevant correlation between seasonality or any of the analysed meteorological parameters and the actual outcome of LASIK.

Impact of temperature and light

We analysed the outcome of LASIK in myopic eyes and the impact of temperature and sunlight duration on the refractive and visual outcome.⁸ Our data show that eyes being treated on days with lower temperature have a statistically significant better efficacy index and higher predictability of SE.

There is a significant difference for safety index in eyes being treated on days with low temperature thereby suggesting that low temperature has a positive influence on the safety index. However, the present results indicate that there is no clinically relevant correlation between temperature and sunlight duration and the actual outcome of LASIK.

Impact of air pressure and wind speed

We also assessed the impact of air pressure and wind speed on the refractive and visual outcome of LASIK in myopic eyes.⁹ Bivariate comparisons showed that statistically significant better efficacy index was related to days with low-to-moderate air-pressure. This was confirmed by robust regression analysis. Moderate-to-high wind speed was related to more appropriate postoperative SE.

Again, there is no clinically relevant difference in outcome of LASIK, which demonstrates its highly standardized quality.