As of now, no H1 for nurses after OPT. Let alone H1, there are very few jobs open for fresh graduates from nursing. (I hope I am wrong). So nurses will have to go for masters. One more thing to keep in mind is for most of the masters degree in nursing, its too hard to get into the program and most of them require 1-2 years of work experience as an RN. So you will need lots of planning and plenty of time set aside before your OPT ends to decide about school.