need help with comma and semi colon.

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

Certainly! I'd be happy to help you with commas and semicolons. Commas and semicolons are punctuation marks that are used to separate and organize elements in a sentence. Here's a breakdown of when and how to use them:

Commas (,) are used in the following situations:

1. To separate items in a list: "I need to buy apples, oranges, and bananas."

2. To separate two independent clauses in a compound sentence: "John went to the store, and Mary stayed home."

3. To set off nonessential information (also known as an appositive or parenthetical phrase): "My dog, a golden retriever, loves to play fetch."

4. To separate adjectives that modify the same noun: "She had beautiful, bright red hair."

Semicolons (;) are used in the following situations:

1. To separate independent clauses when they are not connected by a coordinating conjunction (e.g., and, but, or): "He wanted to go to the party; however, he had other plans."

2. To separate items in a list when those items themselves contain commas: "The guests included Jack, the author; Emily, the musician; and Sarah, the artist."

3. To separate long and complex items in a series: "The company had locations in London, England; Paris, France; and Tokyo, Japan."

Remember, the proper use of commas and semicolons can enhance the clarity and flow of your writing. If you're ever unsure, it's always a good idea to consult a grammar guide or style manual for more specific rules and examples.