[Comparison of sterile donor tomography in the eye bank and graft tomography after penetrating keratoplasty].

BACKGROUND

Since 2018 we routinely use sterile donor tomography in the eye bank to avoid refractive surprises after keratoplasty. The purpose of this study was to compare donor tomography parameters measured with anterior segment optical coherence tomography (AS-OCT) with tomography parameters of the graft after penetrating keratoplasty (PKP).

METHODS

This study enrolled 193 eye bank donor corneal tissues used for PKP (graft diameter 8.2 ± 0.7 mm). Preoperative measurements were taken using the AS-OCT Casia 2 (Tomey, Nagoya, Japan). The measurements were repeated postoperatively after 5 ± 4 months with all sutures in place and after 22 ± 4 months after removal of all sutures. Preoperative and postoperative values were compared using a Wilcoxon signed-rank test.

RESULTS

Postoperatively, with all sutures in place (or without sutures), the dioptric power (P) at the anterior surface (a) of the cornea remained unchanged (-0.2 D, p = 0.78) (2.7 D bigger, p < 0.01) in the steep meridian (S) (PaS) and 4.5 D (2.8 D, p < 0.01) smaller in the flat meridian (F) (PaF) in comparison with the donor tomography values. The astigmatism (a) was 4.3 D (5.4 D, p < 0.01) bigger. At the posterior surface (p) the PpS was 0.9 D (0.9 D, p < 0.01) and PpF 0.3 D (p < 0.01) (0.1 D, p = 0.42) smaller, while the astigmatism (p) was 0.7 D (0.9 D) bigger (p < 0.01). The central corneal thickness was 55.7 μm (p < 0.01) (27.5 µm, p = 0.01) smaller. The total power of the transplant after removal of all sutures did not change significantly in comparison with the eye bank measurements.

CONCLUSION

Central corneal thickness, dioptric power (P) and astigmatism all changed postoperatively compared to donor tomography values, except P at the steep meridian of the anterior corneal surface with all sutures in place and P at the flat meridian of the posterior corneal surface after removal of all sutures; however, the total power of the transplant after removal of all sutures did not change significantly. This information may be of value for IOL power calculation in the classical triple procedure.