Christ, flanked by figures that I could hardly see. There was no explanation, it may well be Mary on the left and John the Baptist on the right, as in the Deësis in the more famous Hagia Sophia in Istanbul.
It was almost impossible to take a decent picture: the floor reflected in the glass, reflections of people would get in the picture or block the light, and the metal rim projected a shadow on the picture. May I suggest one constructs a larger piece of glass, , so the frame does not project on the image? And maybe some good artificial light?

I took some pictures of details, but again: they're almost impossible to see. Partly due to presentation, partly just age.