Morphological results after eccentric penetrating keratoplasty

Objective. Due to unfavourable optical and immunological conditions,an ecce ntric position of the corneal transplant is limited to curative or tectonic indications. The purpose of this study was to assess the morphological res ults of eccentric homologous penetrating keratoplasty (PK) with respect to diagnosis as well as position and size of the corneal graft. Patients and methods. In our retrospective study, 122 cases of eccentric ho mologous PK in 96 eyes between 01/1989 and 10/1997 were included,which in 1 04 patients was necessary because of a corneal ulcer(36 previous PK,21 area ctive/rheumatic, 20 herpetic, 15 bacterial, 12 other). Elective PK was perf ormed on 6 eyes with corneal scars, 7 eyes with ectatic corneal diseases (E CT) and 5 others. Using postoperative slides the following pa ra meters wer e quantified: the graft diameter (GD) and transparency,the distance of the geometric centre of the Cornea from the central trephination margin (ABS) a s well as from the geometric centre of the graft (decentration, DEZ). Of th ese, 17 grafts were classified as eccentric peripheral keratoplasty(EPK) wi th the optical axis through the host cornea and 67 as eccentric central ker atoplasty (ECK) with the optical axis through the graft. Results. The average follow-up period was 25 months. In EPK (ulcers only, 5 .0 +/-1.7 mm) the mean GD was significantly lower than in ECK (78% ulcers,7 .0 +/-1.3 mm) (p <0.001). The decentration of EPK(3.5 +/-1.1 mm) was signif icantly higher than far ECK (1.4 +/-0.8 mm, p <0.001). ABS of EPK was +1.3 +/-0.9 mm and for ECK was -2.0 +/-1.0 mm. Of the grafts in EPK and ECK 46%/ 57% respectively were crystal clear; 18%/15% respectively showed minor deco mpensation and 36%/28% were completely cloudy. In cases of ulcers/scars/ECT /others, 45%/75%/100%/75% were crystal clear, respectively, 18%/25%/0%/0% s howed minor decompensation and 37%/0%/0%/25% were completely cloudy. With i ncreasing stages of cloudiness, the mean graft decentration increased from 1.4 +/-1.1 mm (crystal clear) to 1.7 +/-1.2 mm (minor decompensation) and 2 .2 +/-1.4 mm (completely cloudy). Transplants with greater GD (p=0,04) and ABS (p=0,01) were significantly more often clear. Ulcers were significantly more cloudy than scars/ECT (p <0,01). The position of the graft and its cl oudiness was not significantly correlated. Conclusion. The diagnosis leading to eccentric PK seems to have the greates t impact on long-term graft transparency. Our results indicate that an incr easing decentration of the graft is not inevitably associated with an incre asing probability of clouding. A central penetrating repeat keratoplasty ma y be considered in the non-inflamed interval after eccentric tectonic mini- keratoplasty.