QUES: If your principal customers are other companies you can start with the question of whether it is the customers or you yourselves that determine the products design and function

correct the punctuation.

CORRECTED: If your principal customers are other companies, you can start with the question of whether it is the customers or you yourselves that determine the product's design and function.

QUES: Earlier studies have shown that it is possible to reduce the risk of macular degeneration with certain antioxidants Recent studies are interesting because thy have shown that natural measures can be used to in increase the retinas contents of important chemicals thereby decreasing the risk of macular degeneration

correct the punctuation.

CORRECTED: Earlier studies have shown that it is possible to reduce the risk of macular degeneration with certain antioxidants. Recent studies are interesting because thy have shown that natural measures can be used to in increase the retina's contents of important chemicals, thereby decreasing the risk of macular degeneration.

QUES: clicking on the website

correct the punctuation.

CORRECTED:
clicking on the website.