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In a retrospective study we evaluated 49 consecutive penetrating keratoplasties for herpes simplex keratitis. Mean follow-up was 44.2 months. Survival analysis with Kaplan-Meier curve showed an overall survival rate (clear graft) of 88% at one year, 76% at two years and 72% at four years postoperatively. Survival analysis showed a recurrence-free survival rate of 72% at one year, 59% at two years and 51% at four years postoperatively. Of the 13 non-primary graft failures, 9 happened in eyes with an HSV recurrence. Recurrence of HSV infection occurred in 18 (39%) eyes at an average of 12.6 months after surgery (range 0.3-46). Five (28%) of the recurrences occurred within two months after the start of steroid treatment for rejection. Nine (50%) of the recurrences cases resulted in a clouded graft at the end of follow-up. 73% of the eyes with a clear graft had a VA of 0.25 or better. We conclude from these data that a recurrence of a herpetic infection following corneal transplantation is the main reason for graft failure in this group.

The composition of oxidic groups at a glassy‐carbon surface has been studied using phase‐sensitive ac‐voltammetry. Two types of quinones have been identified, i.e. the 1, 2‐naphtoquinone‐ and the 9, 10‐phenanthrenequinone‐like structures. The 1, 4‐naphtoquinone‐ and 9, 10‐anthraquinone‐like structures are, most probably, also present at the glassy‐carbon surface, although in lower surface concentrations. The o‐quinones can be converted into the corresponding benzophenazines (by reaction with o‐phenylenediamine), which are also electroactive. The differences in redox potentials between the quinones and phenazines make detection of intermediate reaction stages possible. The effect of oxygen and argon rf‐plasma treatment upon the composition of the quinone‐surface groups has also been studied. Pretreatment of the glassy‐carbon surface by an oxygen rf‐plasma is a very powerful and clean oxidation technique. Argon rf‐plasma increases the 9, 10‐phenanthrenequinone‐like structures, while oxygen rf‐plasma, with successive cooling in an argon atmosphere, diminishes the surface concentration of quinone structures and increases that of the acidic surface groups, as can be concluded from modification experiments. From phase‐sensitive ac‐voltammetry measurements, a lower limit of 103 s−1 was determined for both the quinone and the phenazine surface reaction rate constants (ks).

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