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June 27, 1986

Impaired Vision in Dim Light

Author Affiliations

Raleigh, NC

JAMA. 1986;255(24):3361. doi:10.1001/jama.1986.03370240031013

To the Editor.—  In the Jan 24/31 issue of The Journal,1 a physician requested information on impaired vision in dim light. In the reply, Dr Appen indicated that the cause might be a shift in the spectral sensitivity of the retina as it converts from cone vision, which predominates in bright light, to rod vision, which predominates in dim light, combined with the inherent chromatic aberration of the lens. Certainly these factors exist, but he may have overlooked spherical aberration, which should be a much more significant cause of decreased acuity in dim light.Even the poorest photographic lens will produce a relatively good image when it is stopped down to a very small iris opening, such as f1:16 or f 1:22, because only a small region centered on the axis of the lens is actually delivering light rays to the film plane. However, as you open the