Considerable variation is seen in ophthalmic literature concerning sugar concentration ratios of aqueous humor to whole blood and aqueous humor to blood plasma. These variations may be caused, in part, either by differences in sugar levels of different species of animals studied, or because animals were given a general anesthetic before sugar samples were withdrawn, or because adequate samples were not taken to justify a conclusion. The greatest variable, however, appears to be in the blood sugar method that has been used to make the determinations.
The majority of investigators have found that the sugar levels in plasma were higher than in aqueous humor,1-7 but there was a rather marked variation in aqueous-blood ratios found by these investigators. Furthermore, Kirby and Wiener8 found a higher level of dextrose in whole blood of human beings than in the aqueous humor. Aqueous and plasma sugar levels, however, have been described
JANES RG, ALERT HA, JOHNSON NK. Dependence of Aqueous-Blood Sugar Ratios on Method of Determination. AMA Arch Ophthalmol. 1959;61(5):720-726. doi:10.1001/archopht.1959.00940090722008