You will find that natural lashes do not sit neatly in a row. If you look closely at someone's natural lashes you will see that there are levels. These can be quite distinct with some people and barely noticeable on others. For those clients that have quite an obvious jump in their lash layers, eyelash extensions can emphasise this change in level.
However, we can combat this by changing up the curls and lengths that we use. For those lashes that are sitting on a higher level, we can use weaker curls to help disguise the fact that they are raised. For those on the bottom layer, we can use stronger curls. This will help the lash tips to meet to create the illusion of a single layer. Be aware that when using stronger curls we must increase the length by 1 or 2mm as the increase curvature makes them appear shorter.