This common complaint of patients has the highly technical name of floaters. Floaters are not on the front of your eye and you cannot wash them out. They become more common with age. One cause of floaters ia a blood vessel that connects the back of the eye to the developing clear structures at the front of the eye before birth. Since this vessel passes through the center of the eye, you would not be able to see through it, so your body shuts it off before birth and tries to remove the left over tissue, however there are usually a few left over bits and pieces. As we age, the gel inside the eye becomes more liquid and those left over pieces start to “slosh” around when you move your eye casting a shadow that moves over the retina.
This gel, called the vitreous, is attached inside your eye as though it were sewn in place. The “stitches” are made of collagen fibers. As the gel becomes more liquid some of these stitches may “pull out” leaving a small hole in the retina in a manner very similar to pulling a stitch out of fabric. These bits of collagen also move about with eye movements and are another source of floaters. The small hole left behind increases the chance of developing a retina detachment in the weeks after the stitch pulls out. This type of floater is a symptom of a vitreous detachment and is pretty common for patients in their fifties.
My personal favorite floater is caused by red blood cells moving through the fine blood vessels on the surface of the retina. These vessels are just big enough to allow one red blood cell to pass through at a time. Because the vessel walls are almost clear, each red blood cell casts its shadow on the rods and cones of the retina looking like a tiny ring. The appearance is due to the fact that the center of a red blood cell is thinner than the perimeter, similar to a lifesaver candy. These are best seen when looking against a bright blue sky or a white ceiling. If you hold still, you will see these tiny rings following each other along a very defined path through the circulation of the retina. Ancient anatomists called these Muscae Volitantes, latin for flitting flies.
The take home message about floaters is that if you see a sudden increase in the number of floaters, or you notice a flickering light in your vision, you should seek attention as soon as possible as this may be a sign of a retina detachment. The prognosis for repairing a retina detachment is much better with early detection
