This is fixable, but for anything larger than a 4x6" print, not easy.
Your Best Bet is to reshoot it or find another image from the shoot that works. Scroll down for shooting advice.
If you have another image without this problem in that eye, copy and paste that eye from that picture into the image you posted here, then distort and adjust curves for a perfect match.
If this is the only image available, (and there's no time to reshoot: see below) I'd carefully select the properly lit eye with the lasso tool. (Make your selection slightly larger than necessary. You can erase with a softened eraser later.) Copy and past into a new layer. Flip the layer horozontally and move it in place of the offending eye. Distort it (Edit>Transform>Distort), if necessary, until it fits closely within the frame of the glasses. I then add a curves adjustment layer and link it to the overlaying new eye layer using the option key. Drag the lower third of the RGB master curve up slightly until the eye appears to be highlighted like the right side (his right side) of his face. Your'e on your own after this. Burn, dodge, liquify, paint. Still doesn't look natural. I've gotta get some sleep.
If you're planning on a larger reproduction, I've used a great technique for this a couple of times, but would not go through it again. (pgs. 247-259 of "The PhotoShop World Dream Team Book: Volume 1" <www.peachpit.com/dreamteam.html>) I'm sorry that I don't have the time to write out the steps. Besides, the idea comes from Eddie Tapp (one of the authors) not me. His results are truly remarkable.
You'll need a Wacom tablet, Photoshop CS and no small amount of artistic talent to pull it off nicely. It took me about 45 minutes or an hour last time. The first attempt took at least a couple of hours. It involves rebuilding the major tonal & color components (i.e. drawing) and then blending in noise and textures to bring it to life. it is more realistic, since the right eye is not actually a mirror image of the left one. With carefull attention to detail, an artist can reconstruct the missing parts from scratch.
Can you re-shoot it? (This is also Eddie Tapp's suggestion) It may take less time than fixing this properly. Your main light is too low. It appears to be level with their eyes. Are you bouncing an on-camera strobe here? I noticed that you tried to minimize the effect by riding their glasses up the side of their heads. Good try.
Either raise the light source, lower the subjects, or raise the camera angle. If you have the power/light intensity, use a polarizing filter. There are probably a few other solutions.
It's much, much easier to shoot this than it is to fix it.
I've attempted to attach my quick fix. Not familiar with your site, so it might not work.
Sorry in advance if this makes no sense. Friday night Christmas party.
Good luck,
Ron