The importance of an impaired nutritional state in relation to night blindness and other visual disturbances was recognized by the ancient Egyptians1 as well as by Hippocrates.2 Until 1934, when Jeans, Blanchard and Zentmire3 reported the results of their studies among Iowa school children, night blindness was considered to occur rarely except during periods of religious fasting, famine or war.
If one is to accept the increasing number of reports in the literature, poor dark adaptation due to subclinical vitamin A deficiency occurs in approximately 40 to 50 per cent of the population.
Several excellent reviews4 have appeared which discuss the theoretic as well as the practical aspects involved in the study of night blindness and dark adaptation. The clinical literature has been summarized by Jeghers5 and by Sloan.6
The work of Tansley7 and of Fridericia and Holm8 stimulated further efforts to verify
ISAACS BL, JUNG FT, IVY AC. CLINICAL STUDIES OF VITAMIN A DEFICIENCY: BIOPHOTOMETER AND ADAPTOMETER (HECHT) STUDIES ON NORMAL ADULTS AND ON PERSONS IN WHOM AN ATTEMPT WAS MADE TO PRODUCE VITAMIN A DEFICIENCY. Arch Ophthalmol. 1940;24(4):698–721. doi:10.1001/archopht.1940.00870040084007
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