title: Response to Dr Sandhu and Dr Clarke.
authors.affiliation: Department of Ophthalmology and Visual Science, University of Iowa, Iowa City, IA, USA.
authors.forename: P S
authors.initials: PS
authors.lastname: Kemp
authors.affiliation: Department of Ophthalmology and Visual Science, University of Iowa, Iowa City, IA, USA.
authors.forename: T A
authors.initials: TA
authors.lastname: Oetting