Vitreous Degeneration and Detachment Associated Opacities (“Floaters”)
Synchysis and syneresis result in loss of the highly organized vitreous anatomy. The collagen fibers that make up the vitreous can coalesce, or tangle, producing small areas that are no longer transparent and can cast shadows. These shadows are perceived by patients as floaters, and patients may find them bothersome. In some cases, for example as in cases of myopic vitreopathy, a large, dense central opacity can form, obstructing vision.
Following vitreous detachment, the coalescence and tangling of vitreous collagen fibers can worsen. In addition, areas where the vitreous was attached more firmly, such as at the optic nerve, are less transparent. When these areas move away from the retinal surface, they too can cast shadows and may be perceived as floaters. Varying amounts of bleeding can occur at the time of vitreous detachment, producing vitreous opacities.
Over time, as the vitreous continues to liquefy, the vitreous opacities may sink toward the bottom and become less noticeable. Also, the brain has the capacity to learn to selectively ignore the floaters, an adaptation not unlike how people who live next to a train track eventually do not hear trains passing unless they are specifically paying attention. As a result, most patients become asymptomatic or minimally symptomatic and do not require any intervention.
Figure 17-11 Familial exudative vitreoretinopathy (FEVR) with the LRP5 mutation. A–B, The temporal retina shows a zone of nonperfusion that is horizontally V-shaped, causing a tractional macular fold. C–D, Fluorescein angiography images of the same patient demonstrate dragging of the vasculature. There is evidence of leakage and avascularity. E, Color fundus image montage from a patient with FEVR shows folding of the retina with massive exudation.
(Courtesy of Audina M. Berrocal, MD.)
Table 17-2 Genes That Cause Familial Exudative Vitreoretinopathy
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.