A simple histochemical technique permitted the development of a method of preservation of corneal tissue, and a large scale clinical trial was done in El Salvador, comparing fresh with living preserved tissue. Analysis of records of patients seen shortly after surgery, as well as those seen six months later, revealed that there were no significant differences between the results obtained with fresh tissue compared with those from frozen tissue, at either the short or the long time interval.
KAUFMAN HE, ESCAPINI H, CAPELLA JA, ROBBINS JE, KAPLAN M. Living Preserved Corneal Tissue for Penetrating KeratoplastyClinical Trial. Arch Ophthalmol. 1966;76(4):471-476. doi:10.1001/archopht.1966.03850010473002