In some Shuls the women’s section is in a gallery above the men’s section. Being on two separate floors this is a best mechitza possible. In this case would there be a need to have a curtain or a mechitza so that there will be no eye contact between the men and women?
The Sridei Aish (1:OC:14) says that the Rambam says in Peirush HaMishnayos Succah 5:2 that the reason for having a women’s gallery in the Bais HaMikdash is that the men should not look at the women. This implies that even a gallery would need a Mechitza. However the Rambam in Yad HaChazaka (Hilchos Lulav 8:12) writes that the reason is, so that the men and women should not mix, implying that a gallery without a Mechitza is sufficient. This is also the language used by the Tosefta (Succah 4:1).
In summation he says that in Poland and Lithuania they were not Makpid to have a Mechitza for the second floor gallery because the men looked in their siddur and did not look up. In Germany they did have a Mechitza. One should go by the place and times that they live. If it is easy to institute this Chumra it is worthwhile. However no machlokes and destruction of a Kehilla is warranted over this Hiddur Mitzva.
Important Note: We try to convey the Tshuva to the best of our
ability. We admit that our understanding may not be accurate. Please
also understand that this Tshuva may not be the final word on this
topic. One should consult a Rav before drawing any conclusions.