The vitreous humor is a gel-like substance which fills the space in the eye between the lens and the retina. It is primarily composed of water with the remainder being hyaluronic acid and collagen fibers. It is transparent which enables light to pass through while the gel form provides support to the retina and helps the eye hold its shape, essentially acting as a shock absorber. As the eye ages, the vitreous humor gel begins to lose its form and liquefy – a process referred to as synchysis. As synchysis progresses, the vitreous may separate from the retina – a condition referred to as posterior vitreous detachment (PVD). Without the stable gel form, the collagen fibers can collapse upon themselves, bind together, and become mobile. These fibers cast shadows on the retina and appear as spots and strings in the visual field referred to as floaters.
References:
Scott, J.E., “Secondary and Tertiary Structures of Hyaluronan in Aqueous Solution. Some Biological Consequences.” Glycoforum, Mar. 15, 1998.
Bishop, P. N., Takanosu, M., le Goff, M., and Mayne, R., “The Role of the Posterior Ciliary Body in the Biosynthesis of Vitreous Humor”, Eye (2002) 16, 454-460.
Matteucci, A., Formisano, G., Paradisi, G., Carnovale-Scalzo, G., Scorcia, G., Caiazza, H., Hoerauf, H., Malchiodi-Albedi F., “Biocompatibility Assessment of Liquid Artificial Vitreous Replacements: Relevance of In Vitro Studies”, Surv Ophthalmol 52:289-299, 2007.
Suri, S. and Banerjee R., “Biophysical Evaluation of Vitreous Humor, Its Constituents and Substitutes”, Trends Biomater. Artif. Organs, (2006) 20(1), 72-77.
Soman, N., and Banerjee R., “Artificial Vitreous Replacements”, Bio-Medical Materials and Engineering, 13 (2003) 59-74.
Hoerauf, Hans; "Vitrectromy Against Floaters." In Essentials in Ophthamology: Vitreo-Retinal Surgery ; Kirchof, B., Wong, D. Eds.; Springer Berlin Heidelberg 2007; pp. 115-124.
