Eye problem - help

[Martin Ho]

Dear all,
I have a friend who found his left eye had a problem during his recent eye
check. After consulting with several eye experts, they concluded the blood
vessel in his retina was being blocked and warned that he can't use his left
eye anymore if it was not cure. But they don't know how to cure it but give
him some medicine.
Is there any expert could help? Pls. give me a reply.
Thanks in advance.
Martin