An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
Rosenfield M, Gilmartin B.Rosenfield M, et al. Among authors: gilmartin b.Optom Vis Sci. 1990 Feb;67(2):74-9. doi: 10.1097/00006324-199002000-00002.Optom Vis Sci. 1990.PMID: 2336258