The effects of age and ametropia (nearsightedness or farsightedness) on the dark focus of visual accommodation have not been extensively investigated. Participant pools of students are generally screened and their vision "standardized" by testing them while they wear their corrective lenses. In this study, nearsighted and farsighted subjects were measured for their near points, far points, and dark focuses. It was found that the more nearsighted the eye the larger the dark focus shift. Age was also found to have a relationship to the dark focus. Older individuals tended to have a smaller dark focus shift, and the dark focus was found to recede with age at roughly the same rate as the far point.
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References
1.
Davson, H.The physiology of the eye.New York: Academic Press, 1972.
2.
Gawron, V. J.Eye accommodation, personality, and autonomic balance. Las Cruces, NM: New Mexico State University, Department of Psychology. Technical Report BEL-79-2/AFOSR79–6, 1979.
3.
Johnson, C.Effects of luminance and stimulus distance on accommodation and visual resolution. Journal of the Optical Society of America, 1976, 66, 138–142.
4.
Leibowitz, H. W., and Owens, D. A.Anomalous myopias and the intermediate dark focus of accommodation. Science, 1975, 189, 646–648. (a)
5.
Leibowitz, H. W., and Owens, D. A.Night myopia and the intermediate dark focus of accommodation. Journal of the Optical Society of America, 1975, 65, 1121–1128. (b)
6.
Leibowitz, H. W., and Owens, D. A.New evidence for the intermediate position of relaxed accommodation. Documenta Ophthalmologica, 1978, 46, 133–147.
7.
Miller, R. J.Mood changes and the dark focus of accommodation. Perception and psychophysics, 1978, 24, 437–443. (a)
8.
Miller, R. J.Temporal stability of the dark focus of accommodation. American Journal of Optometry and Physiological Optics, 1978, 55, 447–450. (b)
9.
Roscoe, S. N., Olzak, L., and Randle, R.Ground-referenced visual orientation with imaging displays. Monocular versus binocular accommodation and judgments of relative size. In Proceedings of the AGARD Aerospace Medical Panel Specialists Meeting, Athens, Greece. Neuilly-sur-Seine, France: NATO, 1976.
10.
Simonelli, N. M.Apparent size and visual accommodation under day and night conditions. In Proceedings of the Human Factors Society, 23rd Annual Meeting. Santa Monica, CA: Human Factors Society, 1979, 374–378. (a)
11.
Simonelli, N. M.The dark focus of visual accommodation: Its existence, its measurement, its effects.Las Cruces, NM: New Mexico State University, Department of Psychology, Behaviorial Engineering Laboratory, Technical Report BEL-79-3/AFOSR-79-9, 1979. (b)
12.
Simonelli, N. M.Polarized vernier optometer. Behavior Research Methods and Instrumentation, 1980, 12, 293–296.
