http://www.5tjt.com/lace-front-sheitels-an-exploding-controversy/
Rabbi Yitzchok Berkowitz rules that since there is no ma’aris ayin in sheitels according to the responsum of Rav Moshe Feinstein, zt’l (Igros Moshe Even HaEzer Vol. II #12), there would be no problem in lace-front sheitels. Rav Moshe’s letter was written in the summer of 1962 to Rabbi Dovid Lappa, z’l (who lived in Bayswater at the end of his life), and contained a number of rationales as to why there is no ma’aris ayin regarding sheitels. (1) Ma’aris ayin is only for a lav and not an issur aseih; (2) Most of the time it is recognizable that it is a wig; (3) Even if men do not recognize that it is a wig, women do recognize it, and that is enough to prevent a ma’aris ayin, as we can see in regard to shaving with an electric razor; (4) Since she is known as an ishah kesheirah, no one would dare suspect her of not following halachah.