What Could Spot In The Back Of Eye Showed In MRI Suggest?

I have a friend (54 years old) who was dx'ed with breast cancer about 4 years ago. S.0he had a bilateral mastectomy, along with the standard chemo and radiation. The past 2 years her titers were ok, approx 8 months ago the titers started up. She is now in the four hundreds. She has gone had repeated PET scans, CT scans, xrays , etc. Nothing could be found but the titers kept rising.
A week ago she said to me "my eye is receding into the socket". I asked her if she had vision problems and she said no. I strongly suggested she call her onocologist or pd and ask them to get her into an opthomologist post haste. Thank God she did. Her onocologist ordered an immediate MRI which showed some kind of spot in the back of her eye. My internet research is driving me nuts. My friend was so upset she could not remember what was said. Could you help me understand what might be going on.