[Postkeratoplasty astigmatism: comparison of three suturing techniques]

The aim of this study was a retrospective analysis of postkeratoplasty astigmatism and best corrected visual acuity (BCVA) in patients following penetrating keratoplasty (PK) and a comparison of three suturing techniques.

In this retrospective analysis penetrating keratoplasty (PK) was carried out on 150 eyes with 3 suturing techniques: single running (SR), double running (DR counterclockwise) and interrupted (IR) sutures. Of the eyes 37 (24.7%) underwent PK with SR sutures, 81 eyes (54%) with DR sutures and 32 eyes (21.3%) had IR. PK for Fuchs' dystrophy was used on 46 eyes (30.7%), on 33 eyes (22%) for keratoconus, on 12 eyes (8%) for herpetic keratitis and on 7 eyes (4.6%) for pseudophakic bullous keratopathy. For trephination a guided trephine system (GTS) was used in 44%, rotortrepan in 46.6% and best trepan in 5.3%. Postkeratoplasty astigmatism and best corrected visual acuity (BCVA) were evaluated 1, 4, 12 and 24 months after surgery (all sutures removed). Subjective and objective refractions and corneal topography were performed to assess astigmatism. The Kolmogorov-Smirnov test (95% significance) was used to evaluate statistical significance.

Mean topographic astigmatism 4 months (12 months/2 years) after keratoplasty was 4.9 dpt (5.3/4.1, n=4) for SR, 4.2 dpt (4.0/5.3) for DR and 9.7 dpt (n=7) (4.9, n=8/6.8, n=2) for IR suturing techniques. Mean objective astigmatism 4 months (12 months/2 years) after PK was 5.9 dpt (4.1, n=7/5.0, n=3) for SR, 3.4 dpt (4.5/4.98) for DR and 8.0 dpt (n=3) (6.9, n=4/7.4, n=2) for IR sutures. Mean refractive cylinder 4 months (12 months/2 years) after keratoplasty was 4.5 dpt (3.9/4.9) for SR, 3.2 dpt (3.3/3.6) for DR and 6.2 dpt (3.7/4.7) for IR suturing. Mean BCVA 4 months (12 months/2 years) was 0.3 (0.3/0.4) for SR, 0.3 (0.4/0.5) for DR and 0.3 (0.4/0.4) for IR sutures. BCVA 4 months (12 months/2 years) after PK (GTS only) reached 0.3 (0.3/0.5) for SR and 0.3 (0.4/0.6) for DR suturing.

Topographic and objective astigmatisms were highest for the IR suturing technique. Topographic astigmatism and refractive cylinder were less in the DR (compared to SR) group 4 and 12 months after surgery (statistically significant). After suture removal (2 years after PK) refractive cylinder was still lower for DR compared to SR but there was no statistical difference between DR and SR regarding topographic and objective cylinders. For the interpretation of these data it should be emphasized that due to the retrospective character of this analysis the number of patients in the subgroups is decreasing with time and as a consequence single (strongly deviating) measurements can have a more powerful impact on the outcome in the individual subgroups.