[C-Quant scattered light measurement and corneal densitometry in Fuchs endothelial dystrophy before and after DMEK]

In Germany, each surgical corneal center defines individual criteria for the indications for Descemet membrane endothelial keratoplasty (DMEK). Clinical experience shows a clear discrepancy between best corrected visual activity (BCVA) and subjective complaints, such as increased sensitivity to glare. Increasing symptoms with apparently stable visual acuity suggest that BCVA alone is not sufficient to adequately capture the overall visual impairment. The aim of this study is therefore to make subjective complaints, in particular the perceived scattered light, measurable by means of quantitative parameters and to analyze their progression preoperatively and postoperatively in the context of DMEK longitudinally and to evaluate the extent to which ocular forward scattered light can determine the optimal time for surgical intervention.

This retrospective study included 149 patients with Fuchs endothelial corneal dystrophy (FECD) who underwent DMEK or triple DMEK surgery at the Saarland University Hospital Medical Center between 2018 and 2020. The prerequisite for participation was the availability of complete preoperative and postoperative measurement data after 6 weeks and 6 months. All patients underwent BCVA, central corneal thickness (CCT), corneal densitometry (backward scattered light) using Pentacam and ocular forward scattered light using C‑Quant.

The ocular forward scattered light showed a significant improvement comparing the preoperative and 6‑month values; however, ocular forward scattered light did not correlate with BCVA or CCT at time. The CCT and backward scattered light decreased significantly after 6 weeks and remained stable in the further course. The BCVA significantly improved after 6 weeks postoperatively. There was a significant correlation between ocular forward scattered light and backward scattered light at all measurement times. Additionally, there were significant positive correlations between preoperative backward scattered light and both CCT and BCVA.

The measurement of ocular forward scattered light via C‑Quant alone has not proven to be a reliable criterion for determining the indications for DMEK or triple DMEK; however, both surgical procedures led to a sustained reduction in CCT and backward scattered light (densitometry) as well as a significant improvement in BCVA.