You can extract both your eyes by selecting them with one of the selection tools, and then hit (Apple + J for mac) to set just your eyes on another layer. From here it's not that difficult to make your first layer without the extracted eyes black and white. You can do this with the levels function or in modes. Lastly you can move the extracted (colored) eyes portion to the top layer so that it layers over the first image and is the only colored portion over the black and white.