1. Drance S, Berry V, Hughes A. Studies on the effects of age on the central and peripheral isopters of the visual field in normal subjects. Am J Ophthalmol. 1967; 63: 1667–1672.
2. Sekuler R, Hutman L. Spatial vision and aging. I: Contrast sensitivity./Gerontol. 1980; 35: 692–699.
3. Millodot M. The influence of age on the sensitivity of the cornea. Invest Ophthalmol Visual Sci. 1977; 16: 240–242.
4. Duane A. An attempt to determine the normal range of accommodation at various ages—being a revision of Donders’ experiments. Trans Am Ophthalmol Soc. 1908; 11: 634–639.
5. Vision Problems in the US. Schaumburg, IL: Prevent Blindness America; 1994.