Abstract

Trifluorothymidine (TFT) and adenine arabinoside (ara-A) are effective antiviral drugs with a very low toxicity for the cornea. In our study no difference between these 2 drugs in antiviral activity was noted. The average healing time for TFT was 11-14 days and for ara-A 10-54 days. These data differ markedly from those of other studies. This was the result of the use of additional criteria for healing of the lesion. Not only absence of fluorescein staining of the cornea but also the absence of oedema and cystic changes in the epithelium over the previous ulcer were considered criteria for healing. In addition to clearly defined healing criteria and the healing time we found the interval between the first symptoms and the commencement of the therapy of greatest importance in the clinical evaluation of antiviral drug efficacy. An effort was made to approximate this relationship for TFT and ara-A mathematically.