Light Scattering by Vitreous of Humans With Vision Degrading Myodesopsia From Floaters.

Purpose: Vision-degrading myodesopsia (VDM) from vitreous floaters significantly degrades vision and impacts visual quality of life (VQOL), but the relationship to light scattering is poorly understood. This study compared in vitro measures of light scatter and transmission in surgically excised human vitreous to preoperative indexes of vitreous structure, visual function, and VQOL. Methods: Pure vitreous collected during vitrectomy from 8 patients with VDM had wide-angle straylight measurements and dark-field imaging, performed within 36 hours of vitrectomy. Preoperative VQOL assessment with VFQ-25, contrast sensitivity (CS) measurements with Freiburg acuity contrast testing, and quantitative ultrasonography were compared to light scattering and transmission in vitro. Results: All indices of vitreous echodensity in vivo correlated positively with straylight at 0.5° (R = 0.708 to 0.775, P = 0.049 and 0.024, respectively). Straylight mean scatter index correlated with echodensity (R = 0.71, P = 0.04) and VQOL (R = -0.82, P = 0.0075). Dark-field measures in vitro correlated with degraded CS in vivo (R = -0.69, P = 0.04). VQOL correlated with straylight mean scatter index (R = -0.823, P = 0.012). Conclusions: Increased vitreous echodensity in vivo is associated with more straylight scattering in vitro, validating ultrasonography as a clinical surrogate for light scattering. Contrast sensitivity in vivo is more degraded in the presence of dark-field scattering in vitro and VQOL is decreased in patients whose vitreous has increased light scattering. These findings could form the basis for the development of optical corrections for VDM or support new laser treatments, as well as novel pharmacotherapy.