Preliminary Findings Using Dynamic Light Scattering to Study Vitreous Effects of Pharmacologic Vitreolysis

Pharmacologic Vitreolysis is a new therapy intended to enzymatically liquefy vitreous and separate the posterior vitreous cortex from the retina. There are presently no non-invasive methods with which to quantify vitreous liquefaction. This study evaluated non-invasive Dynamic Light Scattering (DLS) to assess vitreous liquefaction in model vitreous solutions. Vitreous of 5 bovine eyes was measured by DLS. Methodology involved the addition 50 IU/ml of hyaluronidase and 5 mg/mI of collagenase to solutions of 0.1mg/mi ofhyaluronan and collagen with polystyrene beads (3Onm diameter), respectively. Solutions were incubated at 37°C for 24 hours and DLS measurements were made at various time intervals. Results showed that the diffusion coefficients and particle size distributions determined from DLS measurements in the 5 bovine vitreous specimens were consistent and reproducible. Adding enzyme to the model vitreous solutions increased diffusion coefficients in the collagen as well as the HA solutions. These results suggest that DLS is a useful non-invasive method to measure diffusion coefficients in both model solutions and bovine vitreous. This approach may provide a quantitative means to assess different pharmacologic vitreolysis agents in vitro, and may also serve as a clinical tool for monitoring the effects ofpharmacologic vitreolysis in vivo