Sickled erythrocytes, hyphema, and secondary glaucoma: IV. The rate and percentage of sickling of erythrocytes in rabbit aqueous humor, in vitro and in vivo.

The number of erythrocytes adopting the sickled configuration in rabbit aqueous was determined with a masked counting technique in vitro and in vivo. The percentage of cells that became sickled in aqueous humor was greater than that observed in a control salt solution and in the donor blood itself. Aqueous humor, therefore, can be considered a particularly deleterious medium for erythrocytes having a propensity for sickling. Blood samples from six donors with systemically severe hemoglobinopathies (SC, Sthal, and SS) had relatively high levels of hemoglobin S and, in general, showed faster and more frequent sickling than did blood samples from donors with low levels of hemoglobin S (one SS patient, whose chronic blood transfusion regimen had replaced most of his hemoglobin S with normal hemoglobin, and two AS patients). Even erythrocytes from sickle cell trait cases, however, were capable of sickling when immersed in acqueous humor.