Radiation Alternatives to Brain Mets?

Hello Ladies and Gentlemen,

I've been lurking on this forum and many others on this website and you all have been an inspiration to me and have provided a wealth of knowledge. For background, my mother was diagnosed with stage 2B breast cancer last year around January/February. She went through of the chemotherapy, had her surgery, radiation, and additional infusions just to find out it had spread to regions in her brain. She is ER -/PR- and is HER2+. Her oncologist and radiologist have created a plan that will allow her to get SRS targeted radiation to her brain since she has 6-7 legions and afterwards she will start on Enhertu (hopefully I spelt that correctly) every 3 weeks thereafter.

My mother has three larger tumors located on her cerebellum and optical lope. The ranges of these tumors are from 1.6 cm to 2 cm. She is off balance due to the tumors growing and pushing on her brain on her cerebellum which is understandable. My main concern however is in regards to the radiation of the optical tumor. I understand that radiation can be used to break down the tumor and hopefully kill all of the cancer cells. However with a focus beam of radiation hitting her optical lobe that can potentially cause her to have a reduction if not a lost in vision. My mother's biggest fear is going blind due to the radiation treatment and I'm unable to provide much comfort with this like I can with some of her other treatment options. Has anyone heard of only treating brain mets with chemotherapy that crosses the blood brain barrier? We have two follow up appointments with her oncologist and radiologist before her treatment starts so I'll be sure to ask these questions.

I'm just trying to explore all possible options that will allow my mother to stay in good spirits and remain relatively mobile and independent in preparation what is to come. Any information you can provide whether it's for or against radiation will be extremely helpful. Additionally, moderators if you find that there is a better place for this topic please feel free to move it.

Thank you all again and keep up the good fight, I'm rooting for you all!