In this paper we formulated a paraxial eikonal equation with depth as evolution direction. Then we presented high order ENO difference schemes to solve the eikonal equation for traveltime and the advection equation for take-off angle. To deal with the singularity of point source, we proposed a new adaptive traveltime eikonal solver and detailed the implementation. Numerical experiments showed that the new method is not only accurate but also gives us efficiency gain of more than an order of magnitude in computational time. The extension to 3D isotropic media is straightforward.