What is the Vitreous?
The vitreous is a jelly-like material that resides in the large cavity of the eye located behind the lens. It is 98% water and 2% solid, and during the early part of life, it is very uniform and clear. It has a surface which is in direct contact with the retina. This contact is more than just surface to surface, but a molecular bond early in life, which weakens over time, at least in most places. This bonding is relatively tight at the optic nerve, at the macula and at the anterior border of the retina several millimeters just behind the junction where the white part of the eye meets the colored part. Other areas where the vitreous is more tightly adherent to the retinal is at blood vessel crossings and where there is scarring or thinning of the retina due to some pathology. The vitreous is important only in the very early stages of the formation and development of the eye. Its presence later in life is only to occupy space thus helping to maintain the shape of the eye.
What Are Floaters In The Eye?
As a person ages, so does the vitreous. Some of the vitreous condenses and some of it liquefies. Condensed vitreous will cast shadows on the retina which are perceived as a “floaters.” Floaters, in turn are described as dots, spots, lines, hair, cobweb, etc. There is one floater that can be particularly annoying, in that it is rather large. It is called a Weiss ring and it is a ring of connective tissue which attaches the vitreous to the retina around the optic nerve. If it comes off intact, it is often described as a “smoke ring” and if it is incomplete it is described as “C-shaped.” Liquid vitreous results in a collapse of the vitreous surface away from the retina. As this occurs the vitreous will pull on the retina before it pulls completely free. This pulling mechanically stimulates the retina which is perceived as a light flash, occurring in the far periphery of the visual field. This aging of the vitreous, if it only involves floaters and light flashes is benign and requires no intervention.
What Happens to Floaters and Light Flashes?
Over time, one either gets used to the floaters, or more commonly, as the vitreous continues to degenerate the floaters will appear to disappear. In reality, they are still present. The condensed particles that caused the floaters have actually fallen below the line of sight and more anteriorly within the eye.
Light flashes, which are only seen in subdued lighting or in the dark, eventually stop, but this may take several weeks to months. Fortunately, their frequency decreases rather rapidly.
Are Floaters and Light Flashes Ever an Indication of a Problem?
The onset of floaters and light flashes should always require an examination to rule out a retinal tear and/or an early retinal detachment. This is particular true if the floaters are reddish and numerous (100’s to 1000’s) or described as large vertical blobs or strands. In this case, it is usually blood and there is often a decrease in vision. Additionally, if one perceives a “curtain” over their field of vision, this and a decrease in vision would be ominous signs of a retinal detachment and require an urgent eye examination.