There is also experience using Kenalog doses of 1mg and 2mg. These doses anecdotally have been reported to reduce the macular edema. There is a rationale for using a dose lower than 4mg. Glucocorticoids bind to glucocorticoid receptors in the cell cytoplasm, and the steroid-receptor complex moves to the nucleus where it regulates gene expression. The steroid-receptor binding occurs with high affinity (low dissociation constant (Kd) which is on the order of 5 to 9 nanomolar). Complete saturation of all the receptors occurs about 20-fold higher levels, i.e., about 100-200 nanomolar. A 4mg dose of triamcinolone yields a final concentration of 7.5 millimolar, or nearly 10,000-fold more than the saturation dose. Thus, the effect of a 1mg dose may be equivalent to that of a 4mg dose, because compared to the 10,000-fold saturation, a 4-fold difference in dose is inconsequential. It is also possible that higher doses of corticosteroid could be less effective than lower doses due to down-regulation of the receptor. The steroid implant studies provide additional justification for evaluating a lower dose, a 0.5mg device which delivers only 0.5 micrograms per day has been observed to have a rapid effect in reducing macular edema.