title: Reply.
authors.affiliation: Office of the Clinical Director, National Eye Institute, National Institutes of Health, Bethesda, Maryland. Electronic address: Datilesm@nei.nih.gov.
authors.forename: Manuel B
authors.initials: MB
authors.lastname: Datiles
authors.affiliation: Office of the Clinical Director, National Eye Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Frederick
authors.initials: F
authors.lastname: Ferris
authors.affiliation: National Aeronautics and Space Administration (NASA), Glenn Research Center, Cleveland, Ohio.
authors.forename: Rafat R
authors.initials: RR
authors.lastname: Ansari
authors.affiliation: Wilmer Eye Institute, Johns Hopkins Hospital, Baltimore, Maryland.
authors.forename: J Samuel
authors.initials: JS
authors.lastname: Zigler