Can hyaluronidase decifer between filler(Restyln) and natural hyaluronic acid found in soft tissue and skin?

You're right, it would not be able to differentiate. It will take a few months for you to go back to your "normal". However, fillers, lasers, and microneedling/PRP can improve the under-eye area. See an expert. Best, Dr. Emer

Hyaluronidase is the enzyme responsible for the metabolic breakdown of hyaluronic acid, whether naturally occurring or injected in the form of a filler. This means that the crepeyness, crinkles, lines and sagging that you are now complaining of may very well be from both the loss of the injected Restylane as well as the natural hyaluronic acid in this region. Happily in a few months, the area will return to normal as your normal synthesis replenishes much of what you naturally had present prior to your treatment. 

However, your question raises some important issues. For one thing, straight Restylane is not used much by experienced injectors for treating the area under the eyes because of its propensity for leaving bumps, nodules and, if injected too superficially, even resulting in the unwanted, grayish-bluish Tyndally Effect. Instead, diluted Restylane was used and more recently Restylane Silk. In my Upper East Side Manhattan practice, I personally prefer Belotero Balance, and in my Israel satellite facility, where a far greater number of regulatory agency approved fillers are available, my choice is Teosyal Redensity II. The second point is that the under eye region is not a region to be left to novice injectors trained only to inject plain Restylane into ordinary smile lines. Injection the delicate region under the eyes is an advanced injection technique that should be left to experienced injectors only. So, going forward, be sure to seek out care by a board certified, aesthetic core physician and make certain to ask to see his/her before and after photos. Good luck to you.

Hyaluronidase cannot differentiate between your own hyaluronic acid and those found in fillers. However, your body constantly produces this material, so, over time, anything lost from the dissolving injection, should be replaced. I would wait a few months and see if the situation resolves itself before seeking treatment.