In general, published results for Epi-Lasik and femto-Lasik procedures are comparable, meaning that they are both equally effective at correcting patients with myopia / hyperopia and astigmatism.
If you are referring to anecdotal examples of your friends who may report more frequent concerns of residual refractive error, you should consider that selection bias may have played a role in your observation, as patients who undergo epi-Lasik are usually not suitable for femto-Lasik (due to the combination of high refractive error, and thin corneas).
It is likely that these factors are the true cause of what you are observing. Namely that high pre-surgery refractive error increases the likelihood that a patient may need an enhancement, and a thin cornea / low residual cornea thickness means that the risk of regression is higher.
E-Shawn Goh
