Imaging vitreous.

Purpose Imaging vitreous is a quest to view what is, by design, invisible. This treatise will review significant historical aspects, past and present imaging methodologies, and imaging techniques that are currently in development for future research and clinical applications. Methods Classic and modern histologic techniques, dark-field slit microscopy, clinical slit lamp biomicroscopy, standard and scanning laser ophthalmoscopy, ultrasonography, optical coherence tomography, magnetic resonance and raman spectroscopy, and dynamic light scattering methodologies are presented. Results The best available histologic techniques for imaging vitreous are those that avoid rapid dehydration of vitreous specimens. Dark-field slit microscopy enables in vitro imaging without dehydration or tissue fixatives. Optical coherence tomography enables better in vivo visualization of the vitreo-retinal interface than scanning laser ophthalmoscopy and ultrasonography but does not image the vitreous body. Dynamic light scattering can determine the average sizes of vitreous macromolecules within the vitreous body as well as possibly image the posterior vitreous cortex once detached, while Raman spectroscopy can detect altered vitreous molecules, such as glycated collagen and other proteins in diabetic vitreopathy. Conclusions The inability to adequately image vitreous hinders a more complete understanding of its normal structure and how this changes in aging and disease. The combined use of more than one technique could provide better imaging of vitreous for future investigational and clinical purposes.