The Genei Ryodan still has a couple of scarlet eyes. Kortopi had made a copy during the last auction Yorkshin.
I think Kurapika, to retrieve the last pairs, face once again Kuroro.
In the comic it shows 10 eyes .. but it could have collected 10x7 = 70 (if we consider the depth of the altar) ... it is possible that missing just a pair of eyes.
36 pairs of eyes = 72 eyes
I hope that you have understood what I wrote: P