ABSTRACT The temporal stability of the dark focus of accommodation (the refractive power of the eye in total darkness) was examined using a laser optometer. It was found that dark focus does not vary greatly in most subjects over a period of 2–3 weeks. Intrasubject ranges varied from 0.08–2.92 D over that period, with a mean range of 1.07 D. Theoretical and practical implications of these findings are discussed.
R. J. Miller (Sat,) studied this question.