To the Editor.
—In 1970, the Archives published a clinical test for evaluating donor corneas designed by us' using practical individual units of trypan blue fashioned by Smith, Miller, and Patch (SMP unit). Because of difficulties in obtaining these units commercially, we devised a simple method by which the dye can be easily prepared in any hospital laboratory.2Nonsterile trypan blue solution is aspirated into a syringe. Disposable bacterial filter (F) and a sterile hypodermic needle are attached to syringe.We would appreciate your printing this change in technique which is as follows:
Twelve and one-half milligrams of trypan blue powder is placed in a small (15 ml) bottle and sealed. It is practical to have several such units prepared and kept on the shelf, in order to have one at hand whenever it is needed.
To prepare the 0.25% dye solution, 5 ml of normal saline
Stocker FW, Moore LW, Stinson I. Clinically Evaluating Donor Corneas. Arch Ophthalmol. 1973;90(1):84-85. doi:10.1001/archopht.1973.01000050086019