Am I Imagining Worms Floating in my Vision? All You Need About Eye Floaters

Most individuals over the age of 50 to 60 years would have noticed strange shapes floating in their vision from time to time. These may take on a bewildering array of shapes, sizes and forms, and appear as tiny spots, dust, flies or mosquitoes, tangle of threads, filaments, a blob of an amoeba, worms, strands of hair, cobwebs, or even a ring!

This is in fact perfectly normal, and a natural part of getting a bit older. So you are definitely not imagining things, and these images are caused by actual changes called eye floaters which are truly there, constantly drifting about inside your eyes.

Individuals who are quite short-sighted are at higher risk for early development of vitreous degeneration and thus can experience an earlier onset of floaters, e.g. in their 30s or 40s.

A layer of light-sensitive cells lining the back of the wall of the eye is called the retina. Think of this as the film in a camera. When the nerve cells that form the retina become excited by light, they transmit signals to the brain to tell you what you’re seeing. Between the lens and the retina is the vitreous gel, which is a gel-like substance that fills this space and is also firmly stuck to the retina.

Floaters occur when the collagen in the vitreous gel starts to break down as we get older, usually starting around the ages of 50 to 60 years. Medically, we call this “vitreous degeneration”. When you are born, the vitreous gel is very firm, but as you get older, the jelly softens and parts of the jelly become softer or more liquid. Think of it as agar-agar becoming Jell-o. The collagen in the vitreous begins to change, becoming thicker and forming clumps, like debris suspended in fluid.

When you move your eye about, these clumps move around and catch the light, much like how snowflakes in an ornamental snow globe behave when the globe is shaken hard. The movement of these clumps casts little shadows on the retina, giving rise to what we perceive as “floaters”.

Whilst vitreous degeneration is the most common cause, there are sometimes less common but still important causes. These include:

• A vitreous hemorrhage, which is bleeding into the vitreous cavity. Here, blood cells, instead of collagen debris, are dispersed in the vitreous cavity. This is most commonly caused by advanced diabetic eye disease, but can be caused by any diseases affecting the blood vessels in the retina.
• Uveitis, which is essentially inflammatory eye disease. Inflammatory cells which float around in the vitreous gel account for the visual sensation of floaters. There are many subtypes of uveitis, and further assessment and examination by your ophthalmologist is important to ensure that you receive appropriate advice, monitoring, and treatment.

• Floaters come in various forms, shapes and sizes
  As mentioned, they might appear as little black dots moving across your vision, wafting in and out of view. Or they may appear as hair-like forms, worms, strings or ropes, or even small fly-like insects. In fact, different individuals experience floaters differently.
• Floaters may appear in and disappear out of your vision
  They are sometimes not immediately apparent, appearing when your eye moves, but then appearing to slow down as your eyeball stops moving. However, when you shift your glance, they may then reappear again. So the symptoms are usually transient.

• Floaters are also usually more noticeable when viewed against a light or uniform background, for example computer screens or a clear sky, or when you gaze out to sea. So people in certain jobs, for instance, those who do a lot of computer work, may notice them more than usual. In Singapore, where there is a lot of daylight, floaters are quite commonly perceived.
  

A retinal tear caused by a posterior vitreous detachment can be treated with laser in a fairly straightforward clinic procedure. However, if a retinal tear in this situation is left untreated, for even more than a few hours, it can quickly progress to a retinal detachment, for which retinal reattachment surgery is then required.

Now, having a posterior vitreous detachment does not always mean that a retinal tear is present, as the gel may peel away from the retina without causing a tear, but an eye examination is still absolutely essential to make sure that this is the case!

Floaters are usually visible only for a short period of time before the brain filters out the floater images. That is not to say that the floaters have physically disappeared – they are still there – but after a while, the brain trains itself to understand that the floaters are insignificant, and the floaters will begin to fade, except in certain situations, e.g. bright lighting conditions, or against a light uniform-shade background, when they become visible again.

Thus, over time, most individuals actually get less annoyance with the floaters.

A second reason why we perceive floaters less over time is specific to the case of posterior vitreous detachments. When the vitreous separation is complete, the gel moves further away from the retina. Thus the light-scattering effect, and the shadows cast onto the retina, becomes less!

There are also individuals in whom the floaters may be significantly more troublesome, because the debris are located nearer the retina and cast more defined shadows onto it.

There is certainly a degree of psychological stress that floaters can cause, especially in individuals with vision-demanding tasks in their occupations. These may include anyone from office workers who constantly need to use the computer, to drivers, to musicians, or individuals in potentially high-risk occupations, e.g. site engineers.

• Vitrectomy Surgery
  The surgical treatment of floaters is known as vitrectomy (sometimes nicknamed “floaterectomy”). Vitrectomy is a commonly-performed surgical procedure, but usually for other reasons, i.e. to reattach a detached retina, or remove membranes on the retina, rather than to remove floaters per se. It is essentially a micro-incision surgical procedure performed under local anesthesia. It is an outpatient procedure that usually takes less than 1 hour. The retinal surgeon will remove the vitreous gel completely, and along with it all the floater debris. The efficacy of this procedure to remove floaters is undoubted, and patients will have complete eradication of floaters after the procedure.

  The main consideration in deciding whether a patient should undergo this procedure, is that there lies a 3-5%, i.e., small but not negligible risk of causing visual complications, which cannot be eventually corrected with glasses. Most important amongst these complications are retinal detachments arising from retinal tears caused by the vitrectomy procedure. Retinal detachments are sight-threatening and will require surgery to reattach the retina.

  In patients who have not yet had cataract surgery, a vitrectomy will also accelerate cataract development, and so patients would need to accept that cataract surgery might be needed at some point in the near future.