Help dating sunglasses please?

[zannew]

I have acquired a few pair of vintage sun glasses. I am not very familiar with them and wondered if you could help me in dating? Here's one of my favorites.

Thanks in advance!

 

[joules]

I love this maker, May - so innovative. How nice that you also have the cute coordinating Chinoise case. I "think" your bamboo look pair is early to mid 60s, though perhaps a bit earlier?

Here is a selection of various vintage styles by May Optical:
http://www.eyeglasseswarehouse.com/pages/may-optical.html

And here is a pair of 80s May clear eyeglasses, with hand-painted flower detail:

Vintage 80's eyeglass frames

 

[zannew]

Thank you for that info. Could I ask one more question? Is this a certain kind of plastic that needs to be mentioned?

 

[joules]

It would be great if you could identify it,
but that may be easier said than done.

I think we can rule out optyl and Zyl.
http://www.allaboutvision.com/eyeglasses/eyeglass_frame_materials.htm