Quantification of Corneal Hydration by Means of Dynamic Light Scattering

Abstract

Abstract: : Purpose: To determine in vitro the feasibility of quantification of corneal hydration non invasively by means of dynamic light scattering(DLS). Method: The corneae of thirty freshly enucleated porcine eyes were brought into defined hydration with dextran solution. Intraocular pressure was brought from 10 to 60 mmHg in 5 mmHg steps and measured by applanation tonometry (perkins). Corneal hydration was measured by quantification of corneal thickness determined by ultrasound pachymetry (DGH-technology). After 5 minutes measurements by means of DLS (Haag-Streit AG) were performed in the anterior, middle and posterior stroma. Each measurement was repeated 3 times. Results: With increasing IOP there was a linear increase of corneal thickness as well as an increase in the static and dynamic component of the backscattered light recorded by DLS. There was a shift in the autocorrelation towards fast component of the average diffusion coefficient of the cornea. There was no statistically significant difference between the different parts of the corneal stroma. Conclusion: DLS seems to be suitable determine changes in corneal hydration non-invasively. However, due to the in vitro character of this study it is not clear if this correlation can be detected in vivo when the corneal endothelium is not affected by postmortal changes. An in vivo study to measure corneal hydration with DLS in patients undergoing IOP changes during LASIK is set.

Keywords: 370 cornea: basic science • 444 intraocular pressure • 548 refractive surgery: LASIK