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.
Haworth KM, Nichols JJ, Thangavelu M, Sinnott LT, Nichols KK.Haworth KM, et al. Among authors: nichols jj, nichols kk.Optom Vis Sci. 2011 Apr;88(4):525-33. doi: 10.1097/OPX.0b013e318214ac0f.Optom Vis Sci. 2011.PMID: 21378589Free PMC article.
Nichols KK, Mitchell GL, Simon KM, Chivers DA, Edrington TB.Nichols KK, et al.Optom Vis Sci. 2002 Jan;79(1):20-30. doi: 10.1097/00006324-200201000-00009.Optom Vis Sci. 2002.PMID: 11828895