need help with comma and semi colon.

2 answers

https://owl.english.purdue.edu/owl/resource/607/04/

http://writing.wisc.edu/Handbook/Semicolons.html
where do I put a semicolon in this sentence. these changes doctors feel, take away oxygen that retina needs.(The retina is the back layer of the eye and it is where sharp images are formed) when this happens some small blood vessels may become weak and break vision problems occur when the blood leaks into the areas around the retina