Do I need medial epicanthoplasty along with my double eyelid surgery? (photos)

The answer depends on the desired goals.  If it is just to have upper eyelid creases, then double eyelid surgery will suffice. If you also want the eyes appear more open, especially medially (close to nose), then epicanthoplasty would be needed too.

You concern should be will the scars from the epicanthoplasty be worthwhile.  Upper blepharoplasty scars associated with double fold surgery are hidden under the fold.  Epicanthoplasty scars have no place to hide.  The scars may be very acceptable.  However, it they are not and this is a real risk, they will not hide under a fold.  You potential surgeon should show you how the double fold will look like if you leave the eyelid with an inside fold and do not have epicanthoplasty.  Simulating the epicanthoplasty is also possible but it is impossible to show you what things will look like if you do not heal ideally.  Generally due to this risk, I do not recommend trying to take and inside fold to an outside which is what epicanthoplasty attempts to do.

A cosmetic medial epicanthoplasty isn't truly needed unless you actually want it.  You are correct, it is used to reduce the "Mongolian fold" (I dislike that term since I have seen this anatomic feature in caucasians as well) at the inner corners of the eyes.  It will give the illusion that the inner corners of the eyes are closer to the nose, but in actuality that is not the case- the tendon that attaches to the bone really is left alone unless the eyelids are being reconstructed after trauma or cancer surgery.  As far as distance between the eyes, the most widely accepted guideline is that the distance between the inner corners of the eye should be roughly that same as the width of the eye itself.  So based on your photos, that distance is already slightly wider than the eye, and an epicanthoplasty should not make your eyes appear too close to the nose.  But again it is an individual personal preference- if you like that feature on your face, don't change it.  You can still get a blepharoplasty without the epicanthoplasty, and if you change your mind in the future, you can have that done.  Going backward though is very difficult if not impossible.

Having an epicanthoplasty done with the blepharoplasty is a personal decision; however, based on the shape of your eyes, I'm not certain you need it.  Please consult with a board certified specialist in Asian eyelids who can guide you to achieve the results you seek.  

The purpose of the medial epicanthoplasty is to improve the appearance of the inner eye by fold reduction. But if you have concerns that it will make the eyes look too close together, then that concern along with the standard scar concerns of a medial epicanthoplasty, indicates that you should not do it with your double eyelid surgery. It can always be done later when you have a better perspective after healing of your upper eyelids.

There are several aspects to your question. Although the epicanthal folds can be corrected there will be scars left. Although the distance between the eyes will not change it will appear that they are closer together. You should decide if it is important enough to you to correct these folds in order to justify scars and the change in appearance. Additionally you should only go to someone is experienced in doing this procedure.