Vitreous floaters

Published on June 30, 2016   22 min
I'm Jerry Sebag, professor of clinical optomology at the Doheny Eye Institute and founding director of the VMR Institute for Vitreous Macula Retina in Southern California. We'll now consider the visual impact of a posterior vitreous detachment that is not anomalous in part 2.
The last topic that I'm going to be discussing is a consequence of posterior vitreous detachment that has previously been considered an innocuous event but is currently being reconsidered in terms of a disease. Recall that posterior vitreous detachment requires liquefaction of the gel, vitreous, as well as dehiscence at the vitreo-retinal interface in order for the poster vitreous detachment to be innocuous. And by innocuous, what we're referring to is that there are none of the anomalous changes that we've just considered that result in retinal tears and detachments, vitreo-macular traction syndrome, macular holes, and macular pucker. In the absence of all of those manifestations of anomalous PVD, it has previously been considered that a PVD is innocuous. However many patients experience floaters. And in some of those individuals, the floaters are serious.
The origin of the floaters is light scattering by the dense collagen matrix of the posterior vitreous cortex. Recall that I mentioned earlier, the reason we can visualize the peripheral vitreous by dark field slit microscopy is because there's a very dense aggregation or a high density of collagen fibrils in the peripheral vitreous. And that's shown here on scanning electron microscopy. It is a bit exaggerated by the dehydration that the specimens have to undergo in order for the preparation for scanning EM, but I think it's very useful for demonstrative purposes, to appreciate what that looks like. And here you can see the appearance of the posterior vitreous cortex in preset lens biomicroscopy in an eye. This is the optic disk here. The retinal vessels are branching from the optic disk, and this is the location and the typical appearance of posterior vitreous detachment.