[Clearing of the host cornea after penetrating keratoplasty for pseudophakic bullous keratopathy]

Abstract

Background: In this study, we have focussed on the clearing of the host cornea after successful penetrating keratoplasty (PK) for pseudophakic bullous keratopathy and the clinical factors that may influence this phenomenon.

Patients and methods: We recruited the study group out of all keratoplasties performed in our department between 1984 and 1996 using the following criteria: (1) pseudophakic bullous keratopathy that involved the whole host cornea preoperatively, (2) no additional ocular diseases, (3) all operations performed before January 1st 1996, (4) sufficient photodocumentation, (5) complete clinical records, (6) clear graft at the end of the follow-up period. Using these criteria, 48 patients (28 females and 20 males; mean age at the time of surgery 72.7 +/- 8.8 years) were included in the study group. Donor age ranged from 34 to 86 years (mean age 65.8 +/- 12.0 years). The opacity of the host cornea was graded from 0 to 3 (0 = clear cornea; 3 = total opacity) within a circular zone of 1 mm diameter adjacent to the graft in four quadrants (I-IV). Finally, an index for the mean opacity index was calculated [TG = (I + II + III + IV)/4] and correlated with clinical parameters.

Results: The index for the mean opacity was 2.8 preoperatively. After a mean follow-up of 9.6 +/- 12.3 months, the index decreased significantly to 1.8 (p = 0.01). Mean visual acuity before PK was 20/400, at the end of the follow-up it was 20/50. The index of opacification was significantly correlated with patients age (p = 0.03; r = 0.2) and inversely with the follow-up period (p = 0.001; r = -0.6) and with the visual acuity at the end of the follow-up period (p = 0.05; r = -0.2). Using the 193-nm excimer laser for donor and host trephination led to a higher clearing of the host circular zone (mean opacification index 1.7) than mechanical trephination (mean 2.1) (p = 0.01).

Conclusion: Our results indicate that expansion of donor endothelial cells onto host's Descemet's membrane is possible and successful with respect to clearing of the host cornea in pseudophakic bullous keratopathy. Nonmechanical excimer laser trephination of donor and host from the epithelial side seems to promote this phenomenon due to a better apposition of the cut surfaces.